Taxonomic review of Australian Mecyclothorax Sharp ( Coleoptera , Carabidae , Moriomorphini ) with special emphasis on the M . lophoides ( Chaudoir ) species complex

The Australian fauna of Mecyclothorax Sharp (Coleoptera: Carabidae: Moriomorphini) is reviewed, with special focus on species assigned to the monophyletic subgenus Eucyclothorax Liebherr: M. isolatus, sp. n. from Western Australia, M. moorei Baehr, M. punctatus (Sloane), M. curtus (Sloane), M. blackburni (Sloane); M. eyrensis (Blackburn); M. peryphoides (Blackburn); M. darlingtoni, sp. n. from Queensland; M. jameswalkeri, sp. n. from Western Australia; M. lophoides (Chaudoir); and M. cordicollis (Sloane). The last six species listed above–the M. lophoides species complex–have been the source of long-term confusion for taxonomists, with male genitalic characters providing trouble-free species circumscription. One new subspecies, M. lewisensis estriatus, subsp. n. from Queensland is added to the seven previously described taxa of the monophyletic subgenus Qecyclothorax Liebherr. The balance of the fauna consists of four species in the subgenus Mecyclothorax: 1 and 2, the sister-species pair M. lateralis (Castelnau) and M. minutus (Castelnau); 3, M. ambiguus (Erichson); and 4, M. punctipennis (MacLeay). Mecyclothorax fortis (Blackburn), syn. n., is newly synonymized with M. minutus. Mecyclothorax ovalis Sloane is recombined as Neonomius ovalis (Sloane), comb. n., and a neotype is designated to replace the destroyed holotype. Phylogenetic relationships for the Australian Mecyclothorax are proposed based on information from 68 terminal taxa and 139 morphological characters. The biogeographic history of Australian Mecyclothorax is deduced based the sister-group relationship between Mecyclothorax and the Amblytelus-related genera, with both groups hypothesized to have originated during the late Eocene. Diversification within Mecyclothorax has occurred since then in montane rainforests of tropical Queensland, temperate forest biomes of the southwest and southeast, and in grasslands and riparian habitats adjacent and inland from those forests. Several species presently occupy interior desert regions, though no sister species mutually occupy such climatically harsh habitats. The M. lophoides species complex exhibits profound male genitalic diversification within the context of conserved external anatomy. This disparity is investigated with regard to the functional interaction of the male internal sac flagellum and female spermathecal duct. Though limited association of flagellar and spermathecal duct configurations can be documented, several factors complicate proposing a general evolutionary mechanism for the observed data. These include: 1, the occurrence of derived, elongate spermathecal ducts in three species, two of which exhibit very long male flagella, whereas males of the third exhibit a very short flagellum; and 2, a highly derived and exaggerated male flagellar configuration shared across a sister-species pair even though the two species can be robustly diagnosed using external anatomical characters, other significant genitalic differences involving male parameral setation, and biogeographic allopatry associated with differential occupation of desert versus forest biomes.


Introduction
Although relatively few in number of species, the Australian Mecyclothorax have proved confusing throughout much of their taxonomic history.This is partly due to the description of species and associated deposition of type specimens by taxonomists working half a world away from Australia.Yet, the confusion has been also caused in part by the broad geographic distribution of the taxon across Australasia, Java, Borneo and Polynesia, with constituent radiations in islands and island continents distantly separated from each other.Mecyclothorax taxonomy started in mid-19th century Berlin with Erichsonʼs (1842) study of the insect fauna of Vandiemensland, a treatise predominantly focusing on Coleoptera, but also treating some Orthoptera s.l., Hymenoptera, Diptera, and Hemiptera.Among Carabidae, Erichson perceived and described as new the distinctive genera Lestignathus, Amblytelus and Scopodes, but he consigned one apparently unremarkable new species from Melbourne-Anchomenus ambiguus Erichson-to a Bonelli (1810) genus now recognized as a monophyletic, holarctically restricted taxon of tribe Platynini (Liebherr 1991, 1994a, Schmidt 2014).Throughout much of the mid-19th century, species were described in Bonelliʼs Anchomenus that are now known to be members of a broad array of phylogenetically distant, morphologically disparate, and geographically disjunct platynine taxa including, non-exhaustively: 1, Neotropical Glyptolenus Bates (e.g.Anchomenus chalybaeus Dejean, 1831;Whitehead 1974); 2, Hawaiian Blackburnia Sharp (e.g.Anchomenus corruscus Erichson, 1834;Liebherr and Zimmerman 2000); 3, Asia-Pacific Metacolpodes Jeannel (e.g.Anchomenus laetus Erichson, 1834;Liebherr 2005); 4, South American Incagonum Liebherr (e.g.Anchomenus aeneum Reiche, 1843;Liebherr 1994b, Moret 2005); 5 New Zealand Ctenognathus Fairmaire (e.g.Anchomenus colensonis White, 1846;Larochelle and Larivière 2007); 6, Australasian Notagonum Darlington (e.g.Anchomenus lafertei Montrouzier, 1860;Darlington 1952); 7, Mediterranean and Macaronesian Paranchus Lindroth (e.g.Anchomenus nicholsii Wollaston, 1864;Machado 1992); 8, Mexican Elliptoleus Bates (e.g.Anchomenus vixstriatus Bates, 1878; Bates 1882); and 9, Holarctic Agonum Bonelli (e.g.Anchomenus (Agonum) charillus Bates, 1883;Habu 1978).Consistent with the use of Anchomenus as a catch-all genus, Chaudoir (1854) described the second Mecyclothorax from Australia as Anchomenus lophoides.As with Erichson, this description was done remotely, in the Ukraine (Ball and Erwin 1983), based on specimens from Melbourne sent to Chaudoir by the English entomologist André Melly.Then in 1867 Australia received its first home-grown descriptions for species of Mecyclothorax: Phorticosomus lateralis Castelnau and P. minutus Castelnau.Castelnauʼs confusion concerning placement of these species was evident in that he described the two species destined for future membership in Mecyclothorax within an assemblage of five new species he assigned to Schaumʼs (1863) genus Phorticosomus; these also including one future Simodontus, as well as two currently recognized Phorticosomus.Castelnauʼs specimens of the two future Mecyclothorax species were deposited in the Museo Civico in Genoa after his death in 1880, not with the balance of his Australian collections deposited in Museums Victoria, Melbourne (Evenhuis 2012).It was not until Barry Moore visited Genoa in 1968 that these specimens were compared to those of other Australian taxa.
When William MacLeay (1871) described Cyclothorax punctipennis from Gayndah, N.S.W., Australia witnessed the beginning of a local network of taxonomists that would describe the bulk of Australian Mecyclothorax.However, at that early date MacLeay admitted his confusion regarding placement of his species, writing: "I am not at all sure of the position of this genus, the dilitation of the tibiae in the male is so slight as to be in most instances unnoticeable (MacLeay 1871: 105)."His placing the species after Acupalpus and before Abacetus suggests an ambiguous placement within generalized Harpalinae.The Cyclothorax name then traveled to the middle of the Pacific, at the eastern end of the generic distributional range, where Thomas Blackburn recognized the similarity between Hawaiian species he was collecting and MacLeayʼs species.Blackburn (1878aBlackburn ( , 1878bBlackburn ( , 1879Blackburn ( , 1881Blackburn ( , 1882) ) described 21 species that he placed in Cyclothorax, forever moving the center of diversity of the genus to Hawaii.Blackburn was able to continue his study of the genus when he was assigned in 1882 as rector to a church in Port Lincoln, South Australia (Lea 1912).During the remainder of his life he described several thousands of Australian beetle species, including four future Mecyclothorax: understandably including two junior synonyms of Castelnau names, the types for those specimens unavailable to him as they had sailed for Europe.
The closing of the 19th century saw Thomas G. Sloane take up description of Mecyclothorax from specimens he collected or received from colleagues (Sloane 1895(Sloane , 1898(Sloane , 1900)).With Sloane the confusion concerning Cyclothorax began to dissipate: "I believe Dr. Sharp has placed Cyclothorax in the tribe Feronini, but it is evident this is not its true position, which cannot be far from Amblytelus ... (Sloane 1895: 447)."Nonetheless on that same page he also wrote: "A species of Cyclothorax is found everywhere in south-eastern Australia ... I believe it to be identical with C. ambiguus, Erichs., and that C. lophoides, Chaud., is also founded on it.I do not feel that C. punctipennis, Macl., is a distinct species from C. ambiguus, though it is quite likely that it is (Sloane 1895: 447)."Sloane was also the first taxonomist to look carefully at more than the dorsal surface of card-mounted specimens.Of M. (Eucyclothorax) punctatus, treated below, he wrote: "The episterna of the metasternum are punctate, and probably more of the undersurface as well, but not having detached the specimen before me from the card to which it is gummed, the episterna only have been seen (Sloane 1898: 473)."Of the last Mecyclothorax he described-M.cordicollis (Sloane) (Sloane 1900)-he wrote of his confusion, but in fact he had deduced the specific differences between M. cordicollis and M. peryphoides, confirmed by results of this study completed 118 years later: "This is the species I formerly regarded as C. peryphoides, Blkb.* but Mr. Blackburn has informed me that it differs from that species.The only difference the description of C. peryphoides suggests to me is the darker colour of the legs in that species, a character that seems of little value, but probably C. peryphoides has the prothorax more strongly sinuate near the base, the basal angles more marked, and perhaps a coarser puncturation on the basal area" (Fig. 2H versus 2I).Sloane (1903) was also the first to point out homonymy of Cyclothorax MacLeay, 1871 with Cyclothorax Frauenfeld, 1868, solving that issue by nomenclaturally uniting Cyclothorax MacLeay with Mecyclothorax Sharp, 1903.
The beginning of the modern era of Australian Mecyclothorax taxonomic research is synonymous with Mooreʼs (1984) type examinations and associated male dissections, which clearly defined the species boundaries between the two most commonly encountered Australian species, M. ambiguus and M. punctipennis.Moore was able to examine the types of the long-mysterious Anchomenus lophoides, available at the Paris Museum after more than a century of seclusion in the Chaudoir and Oberthür private collections, and he established its independence from M. ambiguus while proposing its close relationships to M. cordicollis, M. peryphoides, and M. eyrensis.Moore also described the first two Queensland species of subgenus Qecyclothorax Liebherr, which laid the foundation for Baehrʼs (2003) comprehensive revision.

Material and methods
This taxonomic review is based on 3273 specimens of Australian Mecyclothorax held in 21 institutional or personal collections (codens used in species treatments): American Museum of Natural History, New York (AMNH); Australian Museum, Sydney (AMS); Australian National Insect Collection, Canberra (ANIC); The Natural History Museum, London (BMNH); Bernice P. Bishop Museum, Honolulu (BPBM); California Academy of Sciences, San Laboratory methods follow Liebherr (2015Liebherr ( , 2018)).The qualitative configuration of various features of the beetles was quantified using a variety of ratios.Three ratios were used to assist in description of the eyes: 1, the ocular ratio, or the maximum head width across the eyes divided by the minimum breadth of the frons between the eyes (MHW/mFW); 2, ocular lobe ratio, or the length of the compound eye measured from above divided by length of the protruded ocular lobe measured from the anterior margin of the eye to the groove at the ocular lobegenal juncture (EyL/OLL); and 3, eye convexity, or eye length divided by the maximal depth of the eye measured with the internal margin vertical in the field of view (EyL/ EyD).Pronotal configuration was assessed using three ratios: 1, maximal pronotal width divided by median pronotal length (MPW/PL); 2, relative basal constriction of the pronotum, or the maximal pronotal width divided by pronotal breadth across the hind angles (MPW/BPW); and 3, relative apical and basal pronotal widths (APW/ BPW).The elytral configuration was described using the ratio MEW/EL, or maximum elytral width (usually situated near midlength) divided by elytral length, measured from the basal margin of the flattened posterior surface of the scutellum to the apex of the longer elytron (if elytral lengths differ slightly side to side).Presence or absence of macrosetae at specific positions on the bodies of Mecyclothorax beetles prove diagnostic for several taxa within the Australian fauna.Information regarding setal configuration is summarized using a setal formula comprising presence (+) or absence (-) of: 1, the anterior and posterior supraorbital setae; 2, the lateral and basal pronotal setae; 3, the parascutellar seta; 4, the dorsal elytral setal number (in these taxa 1-2); 5, the subapical and apical elytral setae, the former situated in stria 7 apicad the lateral elytral setae of interval 8, the latter between the apex of stria 2 and the elytral apex.For ease of visualization, the various somites or structures-head, pronotum, elytra-are demarked by a slash: "/."Thus, ++/++/+2++ is the setal formula for presence of both supraorbital setae, both pronotal setae, the parascutellar seta, two dorsal elytral setae, and both the subapical and apical elytral setae.Standardized body length is used to assess body size, and consists of the sum of three measurements: 1, head length measured as the distance from the middle of the labrum to the cervical carina at the posterior margin of the vertex; 2, median pronotal length; and 3, elytral length measured from the basal margin of the flattened posterior surface of the scutellum to the apex of the longer elytron (if elytral lengths differ slightly side to side).
Sclerites associated with the male aedeagal sac flagellum proved essential for species diagnosis and circumscription within the M. lophoides assemblage of cryptic species.Dissected aedeagi were temporarily slide-mounted in glycerin, and viewed under phase contrast microscopy using an Olympus BH2 scope.At least one male specimen from each collecting series was dissected, with the cleared aedeagal median lobe assessed for the configuration of the flagellum and the flagellar sheath.These two structures occur at the apex of the internal sac, with the flagellum near the gonopore, and the flagellar sheath situated to the right of the gonopore (Figs 7H,14B,14F,14H).A broad sclerotized plate is situated to the left of the gonopore and flagellum; herein called the dorsal plate.The parameral configuration varies among the species treated, both in shape and setation (Figs 8,13,16).For diagnosis of the adelphotaxa M. eyrensis and M. peryphoides, the numbers of setae along the ventral margin of the right, or ventral paramere were assessed in 10 individuals of the former and 15 of the latter.The distributions of setal numbers were compared using the Wilcoxon ranksum test for individual samples with unequal sample sizes (Snedecor and Cochran 1980).
Other structures of the male genitalia and female reproductive tract and gonocoxae are presented as in Liebherr (2018), with figured abbreviations presented in Table 1.Terminology of the female characters follows Liebherr and Will (1998).For presentation of male genitalic characters, and female reproductive tract characters, the numbers of individuals dissected, examined, and photographed are provided parenthetically (n = X) at the start of those sections.The numbers of individuals measured to calculate ratios of various external structures are presented at the beginning of each diagnosis.Specimens that were chosen for measurement included both the largest and smallest individuals, males and females, and representatives from multiple localities.Type label data are presented verbatim, including typeface.
Nomenclatural actions conform to The Code (I.C.Z.N. 1999).In order to clarify the ambiguous status of allotypes under the current version 4 of The Code (Santiago-Blay et al. 2008), the allotype for M. darlingtoni, sp.n. is designated as an allotypic paratype.
Cladistic methods are identical to those utilized in the earlier associated analysis of New Caledonian Mecyclothorax (Liebherr 2018), augmented with the following additional data.Two additional characters are reported, with these characters added to the end of the prior character matrix so as not to disturb the character numbering scheme presented in Liebherr (2018, pp. 6-11, Supplementary Material 1).These characters include: 137.Clypeus with: two setae, one each side (0); with four setae, two each side, the medial pair smaller (1).
Additional taxon-related information is also presented below, including the addition of the newly described species M. isolatus and M. jameswalkeri, the addition of male genitalic characters for M. curtus (characters 92-113) and both male genitalic and female reproductive tract characters for M. punctatus (characters 92-136).The previously mentioned M. sp.n.D (Liebherr 2018) is newly described as M. darlingtoni.Thus the present taxon-character matrix includes 68 terminals representing 67 species and 139 characters.The analysis is rooted at Neonomius laevicollis Sloane, a member of the subtribe Moriomorphina, and thus outside the ingroup representatives of this analysis which are all members of the subtribe Amblytelina (Liebherr 2018).Within Amblytelina, the genera related to Amblytelus Erichson comprise the primary outgroup to the various representatives of Mecyclothorax (Liebherr 2018, table 1).
Cladistic data were compiled using WinClada (Nixon 2002) with the search for most-parsimonious cladograms using the parsimony ratchet (Nixon 1999) with tree searches run using NONA (Goloboff 1999).Tree searches were conducted using standard WinClada defaults for 1000 iterations of the ratchet.Once the shortest trees were found using NONA and the ratchet, the results were checked using TNT (Goloboff and Catalano 2016).The TNT analysis used sectorial search, the ratchet, tree fusing, with the minimum tree cache set at 50 trees.

Cladistic analysis
The NONA/WinClada analysis found 2 shortest trees of 1232 steps in 1000 iterations of the ratchet (C.I. = 0.21, R.I. = 0.67), with the strict consensus collapsing 1 node and resulting in a consensus tree length of 1235 steps (Fig. 1A).The TNT search for 1000 minimum-length trees, using sectorial search and the ratchet, also resulted in 2 trees of 1232-step length (3,572,933,738    ments tried).The consensus cladogram maintains monophyly of the five previously recognized Mecyclothorax subgenera (Liebherr 2018), although the subgenus Qecyclothorax is hypothesized to be the adelphotaxon of the other four subgenera.The four subgenera Eucyclothorax, Meonochilus, Phacothorax, and Mecyclothorax s. s. are hypothesized as successive sister groups (Fig. 1A).In all trees, relationships proposed for the Australian Mecyclothorax species are identical; e.g.Fig. 1B for the species of subgenus Eucyclothorax.Cladistic analysis demonstrates the Australian Mecyclothorax fauna to be composed of several species or species assemblages interpolated among non-Australian taxa.The Queensland Qecyclothorax represent a the earliest divergent clade in Australia (Fig. 1A).Subgenus Eucyclothorax, a principal focus of this study, comprises the next divergent lineage (Fig. 1A-B).Subgenus Mecyclothorax, by far the most diverse component of the genus with over 350 species included (Liebherr 2013(Liebherr , 2015(Liebherr , 2017(Liebherr , 2018)), is represented in mainland Australia by only four species; the adelphotaxa M. lateralis and M. minutus, and the more widespread species M. ambiguus and M. punctipennis.This subgenus diversified first in New Guinea, with species from Lord Howe and Norfolk Islands, and Borneo cladistically derived from that grade (Fig. 1A, Liebherr 2018).The Australian species pair M. lateralis plus M. minutus (Fig. 1A) are related to New Guinean taxa, whereas a third Australian species-M.ambiguus-is the adelphotaxon to M. rotundicollis of New Zealand.Most spectacularly, M. punctipennis is the most closely related species to not only M. sculptopunctatus of the St. Paul and Amsterdam Islands, but also to M. montivagus, the most generalized Hawaiian species that serves in this analysis as the surrogate representative for the 239 Mecyclothorax species that have radiated from a single ancestor in the Hawaiian Islands (Liebherr 2015).

Taxonomic treatment
At present, the best means to determine Australian Mecyclothorax beetles to genus is the key of Moore (1963), though the phylogenetic relationships of the Mooreʼs recognized generic-level taxa are better represented in the analysis of Liebherr (2011a).It should be noted, however, that the relationships of the Amblytelus-related genera and Mecyclothorax should be assessed using the present analysis (Fig. 1A) as the enhanced taxonomic representation of Liebherr (2018) and this paper allow a more robust delineation of Mecyclothorax monophyly and its constituent subgenera.
Species treatments below follow one of three formats: 1, a diagnosis and full description of external characters for all newly described taxa; 2, an extended diagnosis presenting all salient external characters for previously described species of the M. lophoides species complex (see key below); and 3, brief diagnostic combinations sufficient to allow determination of the balance of species in the subgenera Eucyclothorax and Mecyclothorax.

Genus Mecyclothorax Sharp
Mecyclothorax Sharp, 1903: 243 ( Diagnosis.Moore (1963) diagnosed Mecyclothorax based on: 1, apical palpomeres glabrous; 2, pronotum cordate; 3, male parameres narrowed apically.These characters were chosen to differentiate Mecyclothorax from Neonomius Moore, a genus now placed far from Mecyclothorax in the subtribe Moriomorphina.The first character works well for Mecyclothorax, with the rare occurrence of very short setae on the apical palpomeres, those setae about 0.10× the palpʼs maximal diameter.Since Mooreʼs pioneering exposition, pronotal shape has been shown worthless for diagnosing Mecyclothorax given the great diversity in shape among the Tahitian (Perrault 1984, Liebherr 2013), Hawaiian (Liebherr 2015), and New Caledonian species (Liebherr 2018).The male parameres differ in configuration among the various subgenera of Mecyclothorax, but as Moore proposed, both right and left parameres are elongate and setose apically (Liebherr 2018, fig. 5)  Nomenclatural note.Sloane (1915) described Mecyclothorax ovalis from Manjimup, WA, with label data (ANIC): Manjimup, W.A. / 31.12.13 T. G. S. // Mecyclothorax / ovalis Sl.Type // Holotype [pink label].The pink holotype label is consistent with those used by P. J. Darlington, Jr. during his curation of the Sloane collection in 1957 (Darlington 1962: 328).The specimen is mostly destroyed, with only partial remnants of the legs remaining glued to the card.As such, because the holotype specimen can no longer be used to diagnose the species nor the species' generic placement, a neotype is designated.As this neotype designation is required to stabilize both the concept of this species and the species' new generic combination, such an action is valid under Article 75 of The Code (I.C.Z.N. 1999).Therefore a Neotype male (MCZ specimen deposited in ANIC) is hereby designated: Mullewa, W.A. / Sept. 19 1931 // Australia / Harvard Exp., / Darlington // MCZ // Neotype / Mecyclothorax / ovalis Sloane / det.J.K. Liebherr 2004 [black-margined red label].These specimens, both neotype and others in the series (MCZ) exhibit densely setose apical palpomeres as well as the small ovoid body diagnostic for Neonomius Moore (1963).The male genitalia conform to the configuration observed in the subtribe Moriomorphina (Liebherr 2011a), with both parameres broad, parallel-sided with rounded apices, and the right paramere ventrally setose, as observed in the generic type species N. laevicollis (Sloane) (Moore 1963, fig. 7).Based on these characters, Sloaneʼs species is newly combined as Neonomius ovalis (Sloane), comb.n.Among species of Neonomius, N. ovalis is diagnosable from the sympatric N. australis (Sloane) by: 1, the smaller body size, standardized body length 3.2-3.6mm for the N. ovalis neotype seriesagreeing with Sloane (1915;451) -versus 5.0 mm for N. australis (Sloane 1915: 450); and 2, the reddish-brown body color versus "black, nitid; legs piceous-red; antennae reddish (Sloane 1915, 450)" for N. australis.Neonomius ovalis can be diagnosed from the other two southeastern Australian species placed in the genus -N.laevicollis (Sloane) and N. laticollis (Sloane) -by the apically less convex elytral interval 8, versus the laterally compressed, subcarinate interval 8 characterizing those two species.The type locality for M. ovalis (Sloane) becomes Mullewa.That Moore et al. (1987) did not recognize Sloane's Mecyclothorax ovalis as a member taxon of Neonomius Moore is based on the lack of any other specimens in the ANIC beyond the destroyed holotype of M. ovalis Sloane, whereas Darlington made this nomenclatural connection, but only for specimens he deposited in the MCZ.
All other names placed under Mecyclothorax Sharp in Moore et al. (1987: 147-149) are treated below.

Key to the adults of the species of Mecyclothorax Sharp from mainland Australia
This key can be used to identify all mainland Australian species of Mecyclothorax.All previously recognized species of subgenus Qecyclothorax revised by Baehr (2003) are included, with his key couplets complemented by the addition of M. lewisensis estriatus subsp.n.  2D-F).The pronotum may be distinctly punctate (Fig. 2A-B) or not (Fig. 2C-I), but in all species the median pronotal base is coplanar to only slightly depressed relative to the pronotal disc, not greatly depressed as in Australian species of subgenus Mecyclothorax (Fig. 2J-M).The vertex is transversely flat to convex, without a transverse dorsal impression, or neck.Generally the species conform to the full complement of standard setae; formula ++/++/+2++.However the basal pronotal seta is absent in M. darlingtoni and M. jameswalkeri, the parascutellar seta is polymorphically present or absent within M. punctatus, and M. isolatus exhibits only a single dorsal elytral seta.Body size ranges from small to moderately large, with standardized body length 2.7-6.0 mm.All Eucyclothorax spp.are characterized by male genitalia that possess a flagellum, flagellar sheath, and dorsal plate at the apex of the internal sac, as well as robust aedeagal median lobes, i.e. dorsoventrally broad (Figs 7,14).The female reproductive tract is configured with the spermathecal duct joined ventrally to the juncture of the common oviduct and the bursa copulatrix (Fig. 9).A helminthoid sclerite is present on the bursal wall ventrad the juncture of the spermathecal duct and common oviduct.Like all other Mecyclothorax, the gonocoxae have setae along the apicolateral margin of the basal gonocoxite (Fig. 10), and the apical gonocoxite has 1-3 (usually 2) lateral ensiform setae.Mecyclothorax moorei Baehr, 2009: 90.Diagnosis (n = 2).This species is diagnosed by the broadly punctate pronotal disc (Fig. 2A), punctate head with a transverse line of about 5 large punctures between the posterior supraorbital setae, and convex, smooth elytra with only striae 1-4 in evidence, striae 2-4 only a series of small isolated punctures.The prosternum and proepisternum are also broadly punctate, the punctures large and separated from each other by a distances equal to the punctural diameters (Liebherr 2018, fig. 2F).The punctate pronotal disc, head, and prosternum + proepisternum are shared with M. punctatus, but the pronotal punctures are more numerous and less separated in M. punctatus (Fig. 2A-B), with about 30 punctures each side in M. moorei, and about 60 each side in M. punctatus.In addition, the elytral striae are more distinct in M. punctatus, with striae 1-5 present in the basal half of the elytra, though the punctures of stria 5 are smaller and shallower.The elytra of M. moorei are more ovoid, with the lateral margins more narrowly rounded behind the subangulate humeri (Fig. 3A-B).Whereas the parascutellar seta is present or absent in M. punctatus, and if present appearing short and narrow, this seta is well developed in M. moorei, with the setal articulatory socket set within a depression coincident with the base of the parascutellar striole, the seta as long as the breadth of 2-3 elytral intervals.The eyes of M. moorei are convex but they cover only the anterior 4/5   Male genitalia (n = 2).Aedeagal median lobe apex narrowly rounded and only slightly projected beyond apical ostial margin (Fig. 7A); aedeagal internal sac elongate, membranous, with apical dorsal plate, flagellum, and flagellar sheath (Fig. 7B); right paramere narrow, elongate, with 6 setae along the ventral margin, 1-2 apical setae, and the dorsal margin glabrous except for a small apical seta (Fig. 8A); left paramere broadly quadrate basally, the apical 1/3 of length very narrow in contrast to broad base.
Distribution and habitat.M. moorei is restricted to northeastern New South Wales (Fig. 11A), with populations allopatrically distributed relative to eastern populations of the more southerly distributed M. punctatus.Recorded elevations of collecting localities range from 110 m near Ramornie and 1100 m in Mt.Boss State Forest (Baehr 2009).Philip Darlington collected this species in Bellangry Forest NW of Wauchope (MCZ).All specimens are vestigially winged.

Diagnosis (n = 5
).This species is most similar to M. moorei, with several diagnostic characters differentiating the two listed there.The eyes are large and convex, largely covering the ocular lobes; EyL/OLL = 0.92-0.96.The elytra are broad, with broadly rounded humeri (Fig. 3B).The single available female specimen assignable to M. p. peckorum has the elytral base broad, slightly different from the nominate form.However the pronotal and elytral strial punctures are deeper and less dense in M. p. peckorum-as reported in Baehr (2016a)-resulting in recognition of the two forms here.In addition, the parascutellar seta is much less in evidence among individuals of this species.When present it is short and fine, and it is certainly absent from the majority of examined spec-imens.Standardized body length 2.7-3.2mm.Setal formula ++/++/±2++.
Distribution and habitat.Following Baehrʼs (2016a) circumscription of this species, it is distributed across an easterly set of populations in southern New South Wales and northern Victoria (Fig. 11A), plus a disjunct set of western localities in the southwest region of Western Australia.Sloane wrote of the type series, "I have found it in considerable numbers under logs and the leaves of saplings at a place about twenty-five miles north-west from the town of Urana.It is sluggish in its movements (Sloane, 1895: 449-450)."Thus the type locality is very close to one of the localities where he collected types of M. cordicollis (Sloane 1900).More recently, specimens from the western localities have been collected via litter sifting of jarrah forest litter (Eucalyptus marginata Donn ex Sm.).All specimens are vestigially winged.

Mecyclothorax curtus (Sloane)
Cyclothorax curtus Sloane, 1895: 448.Mecyclothorax curtus Sloane, 1903: 585.Diagnosis (n = 4).The transverse pronotum-MPW/PL = 1.39-1.47with nearly impunctate median base and broadly convex margins (Fig. 2C), and broad, subpar- allel elytra (Fig. 3C), are unique within Mecyclothorax, unmistakably diagnosing this very rarely collected species.The pronotal hind angles are defined by denticles on a more broadly convex margin, the basal pronotal setae associated with a broadened marginal bead at their point of insertion.There are 5-6 minute punctures each side on the median base inside the laterobasal depressions, which are marked by 2-3 oblique lines of larger punctures associated with the depression (Fig. 2C, left side).Ventral prothoracic punctation is restricted to the lateral reaches of the prosternum (Liebherr 2018, fig. 2D).The lateral margins of the abdominal ventrites are also distinctly punctate, the punctures distributed densely and irregularly enough to give the surface a dented look.As in the above two species, both males and females have 4 setae along the apical margin of the apical abdominal ventrite.As in M. punctatus, the eyes are large and convex, EyL/OLL = 0.87-0.91.However unlike M. punctatus and M. moorei, the elytral striae are fully developed, with all striae evident nearly to the elytral apex.There is a well-developed carina immediately laterad stria 7 that extends from the position of the posterior series of lateral elytral setae to the elytral margin distad the well-developed elytral plica, parsimoniously interpreted as a parallelism also observed in M. blackburni (Fig. 1B, Liebherr 2018, fig.2L).The apical palpomeres bear a sparse pelage of very short setae, a character otherwise only observed within the genus in Norfolk Islandʼs M. monteithi.Standardized body length 3.8-4.1 mm.Setal formula ++/++/+2++.
Male genitalia (n = 1).Aedeagal median lobe apex narrowly rounded with broad dorsal expansion, the apical face of the lobe concave (Fig. 7D); flagellum short, associated with very elongate sclerotized saccal surface herein interpreted as flagellar sheath (single available male with sac uneverted); right paramere elongate but broad apically (Fig. 8C), the paramere more robust than in other Eucyclothorax (Figs 8,13), and with ventral surface bearing only a single short seta complementing the 2 long apical setae, and the dorsal surface glabrous; left paramere broad basally (as in males of M. moorei and M. punctatus), but also broad apically, the apex more than half the breadth of base, a single longer seta present at apex.
Distribution and habitat.The lone holotype was collected by W.W. Froggatt at Bendigo, Victoria.Besides the holotype, I have had the opportunity to examine only a second specimen from Bendigo (MVM), two specimens from Sea Lake, Victoria (Fig. 11B; ANIC, MVM) and a single female from 27 km W Manangatan (ANIC).This last specimen is labeled "South Australia", but based on the locality data it must be from Victoria.Nothing is recorded concerning this speciesʼ habits, though occupation of a terrestrial microhabitat associated with forest vegetation near water would be consistent with the habits of its adelphotaxon, the sister-species pair M. moorei and M. punctatus (Fig. 1B).All specimens are vestigially winged.
Diagnosis (n = 5).Beetles of this species are very narrow-bodied, with a narrow, cordate pronotum (Fig, 2D), and narrow, subparallel elytra and an elongate head (Fig. 3D).The pronotal median base is coplanar with the disc, but distinguished by the presence of about 14 large deep punctures each side.The right pronotal hind angles protrude both laterally and posteriorly in association with a broadened marginal bead at the articulatory socket of the basal pronotal seta.Otherwise the pronotal lateral margin is extremely narrow, defined only by a marginal bead.Basally the elytral striae consist of series of closely spaced punctures, their separations equal to their diameters.Puncture size decreases, and puncture distances increase laterally and apically on the elytra, with stria 7 represented by only a few small punctures at mid-length.Interval 8 is broadly convex apically, and the elytral plica is well developed and evident in dorsal view.Ventrally, the body punctation includes a punctate median depression anterad the prosternal process, punctures along the lateral reaches of the prosternum, and a punctate anteapical groove (Liebherr 2018, fig.2E).The lateral reaches of the mesosternum, metasternum, and all of the metepisternum are also intensely punctate.The basal 3 abdominal ventrites are covered with numerous small punctures laterally, and the suture between visible ventrites 2 and 3 is traceable only as a shallow groove.The apical margin of the male apical abdominal ventrite bears the usual 2 setae, 1 each side, but also 4 small medial setae in the position observed in Mecyclothorax females.Standardized body length 4.2-4.9mm.Setal formula ++/++/+2++.Male genitalia (n = 2).Aedeagal median lobe very broad and only slightly curved, the apex with subacuminate ventroapical projection and a broadly convex dor-soapical expansion resulting in a broadly concave apical face (Fig. 7E); flagellum short, flagellar sheath robust, and dorsal plate lightly sclerotized, difficult to discern in single available uneverted male; right paramere narrow, with 4 small setae ventrally and dorsal surface glabrous (Fig. 8D); left paramere broad basally, narrowly attenuate apically.
Distribution and habitat.M. blackburni is known only from coastal Western Australia (Fig. 11B) from Perth south to Harvey (ANIC, 2 specimens).The Perth locality is denoted as "Bridgelʼaʼ (MVM, 1 specimen), which is here interpreted to be an abbreviation of Bridgeleigh, a remnant area of bush vegetation in Swan Valley, Wanneroo.Commander J.J. Walker, Royal Navy, collected a specimen at Fremantle in 1914 (BMNH).When Sloane (1898) described the species based on one specimen received from Arthur Lea he listed no biological information, and none accompanies the other four available specimens.Those four specimens are all macropterous.
Diagnosis (n = 1).The larger body size, standardized body length 6.0 mm, ferruginous body color, and broadly transverse, ovoid pronotum (Fig. 3E) serve to diagnose this species from others of subgenus Eucyclothorax, except perhaps the smaller-bodied M. curtus (Fig. 3C).However the lateral margin of the pronotum is broadly rounded behind in this species, with the margin explanate in the region of the basal pronotal seta.The metathorax is remarkably abbreviated, more so than in any other Australian species of Mecyclothorax, with the metepis-ternum transversely broader than its lateral length.The elytra exhibit a subcarinate ridge along the eighth interval dorsad the subapical sinuation, reminiscent of such a carinate ridge observed in M. blackburni.The carinate ridge lies dorsad a well-developed internal elytral plica, with the plica and elytral margin fitting into a corresponding invagination along the margin of the apical abdominal ventrite, thereby forming, in concert with the conjoining of the elytra at the suture, a very robust, shell-like hindbody.Finally, there is a single dorsal elytral seta on each elytron (Fig. 3E), situated near midlength as observed in species of subgenus Qecyclothorax (Fig. 5D).Setal formula +/+/+/+/+/1/+/+.
Female reproductive tract (n = 1).The unique female holotype was not dissected, however the gonocoxae are exerted from the specimen allowing the following characters to be assessed: basal gonocoxite with 2 stout apicolateral setae, medioapical surface glabrous (as in Fig. 10A); apical gonocoxite extended laterally at base, basal width about 0.7× length, 2 stout lateral ensiform setae along lateral margin of coxite and an elongate dorsal ensiform seta present; apical nematiform setae within fossa at about 0.8× gonocoxite length.Thus the gonocoxal configuration is most like that of M. moorei (Fig. 10A), another early divergent species within subgenus Eucyclothorax (Fig. 1).a series of deep, interrupted punctures at midlength, deep and continuous mesad the posterior series of lateral elytral setae; lateral elytral setae arrayed in 7 + 6 (anterior series setae and posterior series setae), with the posterior seta of the anterior series slightly separated from the rest; subapical sinuation angulate, abruptly curved anteriorly, with well-developed internal elytral plica visible in quarter view, though obscured by the elytral margin in dorsal view.Metepisternum short, trapezoidal, maximum breadth 1.1× lateral length, metepimeron broadly convex posteriorly; metasternal process with sides acute, apex narrow, triangular with margin very broad medially in apex of process.Abdomen with broad linear depressions on lateral reaches of visible ventrites 3-6; suture between ventrites 1 and 2 deeply sinuous laterally, ventrite 2 depressed within sinuosity; female with 2 setae each side and a median patch of 4-5 smaller setae; apical margin of the female apical ventrite with deep emargination each side bordered laterally by a vertical, sclerotized border, these emarginations and lateral wall fitting into the elytral plica above.Microsculpture absent from frons, the surface glossy, micropunctures visible across the surface; pronotal disc and base with indistinct transverse microsculpture consisting of transverse lines and elongate meshes, these visible in surface irregularities such as wrinkles and depressions; elytral disc glossy with fine transverse lines faintly visible outside areas of reflection, elytral apex with Etymology.The adjectival species epithet isolatus signifies both the geographic isolation of this species that is distributed in the south coast region of Western Australia (Fig. 11B), as well as the phylogenetic isolation of this   species, as it comprises the adelphotaxon to all other species of subgenus Eucyclothorax (Fig. 1) Distribution and habitat.This species is known only from the tingle tree (Eucalyptus jacksoni Maiden) forest in the south coast region of Western Australia (Fig. 11B).The single individual was collected in berlesate moist enough to support growth of fungal hyphae (S.B. Peck, pers.comm.).The vestigialized flight wings occur in concert with an extremely abbreviated metathorax and a well-developed plical lock between the elytra and apical abdominal ventrite.This species' adelphotaxic relationship to the remainder of subgenus Eucyclothorax (Fig. 1) supports its long-term term persistence in this region since the early diversification of all Mecyclothorax.
Etymology.The species commemorates Prof. Philip J. Darlington, who collected extensively across Australia during various expeditions undertaken throughout his career.He personally developed the most extensive collection of Australian Carabidae housed in North America, allowing American scientists the ability to work with the fauna.He also curated the Thomas G. Sloane collection after its receipt by C.S.I.R.O., stabilizing the specimens and thereby preserving their information for future researchers.Although he focused on the New Guinea carabid fauna (summarized in Darlington 1971), he rightfully viewed the New Guinean fauna as an extension of the Australian, making biogeographic connections underpinned by taxonomic relationships for much of the Australian Region (Wallace 1876).
Distribution and habitat.M. darlingtoni is broadly distributed along the Queensland coast, with recorded localities spanning the vicinity of Brisbane to Mt. Webb in northern Queensland (Fig. 11C).The extensive numbers of specimens collected in Woondom Forest Reserve (FMNH) were extracted from Berlese samples from mesic litter under palms, or from wet litter along a stream.The single specimen from the northerly and, based on present specimens, disjunct Mt.Webb locality is macropterous, as is one of the two specimens from Dalby, whereas all other specimens from southern Queensland are vestigially winged.Diagnosis (n = 1).This, the second of two Australian species of subgenus Eucyclothorax-with M. darlingtonicharacterized by the absence of basal pronotal setae, can be diagnosed by aspects of the narrow body, including: 1, a narrow, basally constricted pronotum, MPW/PL = 1.28,MPW/BPW = 1.88; and 2, narrow, subparallel elytra, MEW/EL = 0.64.Like M. darlingtoni, the prosternum of this species has a punctate medial depression anterad the prosternal process, in this instance lined with 7 punctures.The prosternal anteapical groove is continuous and distinctly punctate laterally, more irregular and smoother ventrally.The eyes are large and moderately convex, and they cover much of the ocular lobe; EyL/OLL = 0.95.The parascutellar striole is composed of 7-8 deep, isolated pits.Standardized body length 4.9 mm.Setal formula ++/+-/+2++.
Female reproductive tract (n = 1).The single teneral female specimen of this species was not dissected.
Etymology.This species commemorates James John Walker, Commander and Fleet Engineer, Royal Navy, active member and officer in many scientific societiesincluding President of the Linnean Society of New South Wales (Walker 1921)-and in retirement, an editor of the Entomologistʼs Monthly Magazine (Poulton 1939).Walkerʼs collections from Australia and New Zealand were passed to George C. Champion, his brother-in-law, and then bequeathed by Champion to The Natural History Museum, London.Walkerʼs collections were as far flung as the British Empire, with his naval duties taking him to places where he could collect.Among many other species, carabid beetles named after him include: Protopaussus walkeri Waterhouse (1897) from China; Calosoma walkeri Waterhouse (1898), junior synonym of C. oceanicum Perroud, from Australia; Rhaebolestes walkeri Sloane (1903) from New South Wales; Duvaliomimus walkeri (Broun 1903), Megadromus walkeri (Broun, 1903), and Mecodema walkeri Broun (1903), the last a junior synonym of Mecodema howitti (Castelnau 1867), all from South Island, New Zealand; and Trirammatus walkeri (Andrewes 1931) from Juan Fernandez Island.Walkerʼs collecting acumen can be attested to by his discovery of this broad assortment of carabid diversity.
Distribution and habitat.The lone specimen of this species is from Albany, W.A. (Fig. 11C).We know nothing specific about the habitat in which this beetle was discovered.The specimen is macropterous with the wings bearing well-developed venation and a reflexed apex, the wing structures being visible through the very translucent elytra of the teneral specimen.Thus occupation of a riparian habitat requiring recolonization of habitat patches may be predicted (Darlington 1936(Darlington , 1943)).

Mecyclothorax lophoides (Chaudoir)
Figures 2F, 4C-D Diagnosis (n = 5).This species is characterized by a narrow, moderately cordate pronotum, the lateral margins slightly sinuate anterad obtuse, moderately projected hind angles (Fig. 2F); MEW/BPW = 1.57-1.68,MPW/ PL = 1.18-1.22.The pronotal lateral marginal depression is very narrow, with only the narrowest indication of microsculpture between the convex disc and the marginal bead.The hind angle is obtuse, rounded at its apex, with the basal pronotal seta set slightly anterad the angle.The marginal depression continues for only a short distance mesad the hind angle.The median base is covered with ~10 erratically distributed small punctures each side of midline.The laterobasal depression is a longitudinal depression lined with 4-5 larger punctures, with the flat area between depression and the marginal bead also bearing several larger punctures.The prosternum is medially depressed from the prosternal process between the procoxae 1/2 the distance toward the anterior margin, the depression lined with 6-7 pits.The anteapical groove is shallowly punctate laterally, continuous and irregularly indented medially, and the marginal bead of the procoxal cavity is bordered anteriorly by about 3 very shallow punctures.The mesepisternum is punctate at its deepest portion, about 9 deep punctures in 2-3 dorsoventral rows.
Specimens of this species collected by John Nunn on King Island (Moore 1984: 164) were preceded temporally by beetles laid down from 143,000-75,000 years ago in subfossiliferous deposits at Yarra Creek, King Island, during the Pleistocene last interglacial (Porch et al. 2009).Long-term residence on King Island suggests the species can persist in communities ranging from the present more mesic, more seasonal forest types to the wetter, more aseasonal forests present on King Island during the Pleistocene.All specimens are vestigially winged.

Mecyclothorax eyrensis (Blackburn)
Figures 2G, 5A, 9G, 10G, 11D, 12C, 13C, 14D Cyclothorax eyrensis Blackburn 1892: 480.Mecyclothorax eyrensis Csiki, 1929: 488.Diagnosis (n = 5).Among species of the M. lophoides complex this species stands out based on its rufous coloration (Fig. 5A), and distinctly cordate pronotum with projected, nearly right hind angles (Fig. 2G).In the most melanized specimens, the forebody-head and pronotummay be rufopiceous, but the elytra retain rufous coloration, and the legs are pale, flavous, with a slightly smoky piceous cast.The eyes are moderately convex, MHW/ mFW = 1.51-1.57,less convex than those of the other M. lophoides complex species (Figs 4, 5B-C).The pronotum is quite constricted basally, MEW/BPW = 1.76-1.82,and moderately transverse, MEW/PL = 1.22-1.28.The pronotal lateral marginal depression is moderately broad, with the marginal bead only slightly upraised.The me-dian base is minutely punctate, with 5-8 isolated punctures each side from midline to the ill-defined laterobasal depressions, those defined mostly by a longitudinal line of larger punctures, with several larger punctures also present between that line and the marginal bead.The hind angle is right to slightly obtuse, with the posterior margin transverse and anterad the convex median basal margin, which is smooth not beaded.The prosternum is flat to depressed medially, the medial area bearing a longitudinal series of 7 distinct punctures.The anteapical groove is deep and distinctly punctate laterally, continuous and more shallowly punctate medially, and the marginal bead of the procoxal cavity is bordered anteriorly by 5-6 strigose punctulae.The mesepisternum is covered with punctures, about 13 deep punctures arrayed in 3-4 irregular rows.The elytra are relatively broad, MEW/ EL = 0.67-0.73,and flat medially on disc.Elytral striae 1-4 bear large punctures, those serial punctures close set enough on the disc to depress the intervening cuticle.Strial punctation is more strongly developed in this species than in other species of the M. lophoides complex (Fig. 12), with the sutural stria distinctly punctate mesad the posterior dorsal elytral seta.In this species cuticular microsculpture is less well developed than in the other M. lophoides complex species, with: 1, frons smooth, glossy, with micropunctures sporadically visible across surface; 2, pronotal disc glossy with sporadic micropunctures visible, very transverse lines sporadically visible laterally and near concavities of median longitudinal impression and laterobasal depression; 3, elytral discal intervals largely glossy, with shallow transverse lines sporadically visible over surface (Fig. 12C), transverse microsculpture more developed on elytral apex where it forms an elongate transverse mesh, sculpticells 3-4× broad as long.Body coloration varies from a bright rufous, mostly in desert inhabiting beetles from the northern part of the range including the type locality of Leighʼs Creek (Fig. 11D), to darker with rufopiceous head and pronotum and rufous elytra at localities on the southern edge of the range; Mt.Remarkable and Telowie Gorge.Even in the darker specimens, the base of the pronotum is an amber rufous, the cuticle appearing translucent.Standardized body length 4.2-5.5 mm.Setal formula ++/++/+2++.
Male genitalia (n = 10).Aedeagal median lobe broadest near basal 1/3 of length, ventral margin distinctly and evenly curved (Fig. 14D); internal sac bearing a long sinuous flagellum, a large bean-shaped dorsal plate, and a well-sclerotized, smooth flagellar sheath, the sheath length less than 1/4 flagellar length (Fig. 14D, as in Fig. 14F); right paramere expanded dorsally in basal half, the dorsal margin convex, 7-11 setae along ventral margin and ~1 on dorsal margin (Fig. 13C); left paramere broadly quadrate basally, extended as a narrowly attenuated whip to apex.Comparing the dissected aedeagi of 10 M. eyrensis males (e.g.Fig. 14D) and 16 M. peryphoides males (e.g.Fig. 14E) resulted in no discernible differences in overall shape of the median lobe, in curvature or expanse of the apex, in the basal bulb or development of the sag-ittal crest, nor in structures of the internal sac such as the flagellum, flagellar sheath, or dorsal plate (Fig. 14D-E).The only male genitalic differences noted between males of these two species involved the presence of fewer setae along the ventral margin of the right parameres of M. eyrensis versus M. peryphoides (e.g.Fig. 13C-D).To determine whether these differences could diagnose the species, the numbers of setae along the ventral margin of the right paramere in 10 individuals of M. eyrensis (setal numbers: 7, 7, 8, 8, 8, 8, 9, 11, 11, 11) were compared to those in 15 individuals of M. peryphoides (setal numbers: 9, 10,10,11,11,11,12,12,13,13,13,14,15,15,17) using the Wilcoxon rank-sum test (Snedecor and Cochran 1980).The distribution of values resulted in a minimal T 1 = 69, below the threshold value of 84 for a p = 0.01 level of significance for difference between the two distributions (Supplementary material 2).Even though the values among individuals overlap slightly in the 9-11 setal counts, there is a statistically significant difference between the setal configurations of the two species.This significant difference augments the diagnostic differences found in the external characters.
Diagnosis (n = 5).Among the species of the M. lophoides complex characterized by darker bodies and contrastingly pale legs (Figs 4B, 5B-C), this species has an ellipsoid elytra with large strial punctures, a pronotum with distinct obtuse hind angles, and concolorous elytral disc and apex, i.e. without an apical flavous marginal band (Fig. 5B).The eyes are broadly convex, MHW/mFW = 1.60-166.The pronotal margins are sinuate anterad the well-defined hind angles, but the posterior margin behind the angle is at most slightly sinuate, and usually convex, smoothly meeting the curved median basal margin (Fig. 2H).Body coloration is dark, with the head, pronotum and elytra piceous.The pronotum is transverse and constricted basally-MEW/EL = 1.20-1.28,MPW/BPW = 1.63-1.71-thoughthe basal constriction less than that observed in beetles of M. eyrensis; MEW/BPW = 1.76-1.82.The pronotal median base is covered with distinct punctures, about 20 punctulae each side from midline to the very shallow, poorly defined laterobasal depression (Fig. 2H).The pronotal lateral marginal depression is narrow, but broad enough for sculpticells to line the deepest part, and the margin is beaded.Like M. eyrensis: 1, the prosternum is flat to depressed medially, the medial area bearing a longitudinal series of 4-7 distinct punctures; 2, the anteapical groove is deep and distinctly punctate laterally, continuous and more shallowly punctate medially; 3, the marginal bead of the procoxal cavity is bordered anteriorly by 5-6 strigose punctulae; and 4, the concave mesepisternal surface is lined with 13 deep punctures arrayed in 3-4 irregular rows.The elytral striae are punctate on the disc, though the punctures are far enough apart that the cuticle is coplanar with the intervals between the punctures.Like M. eyrensis, the punctures of striae 1-6 are progressively more isolated laterally on the elytra, but the sutural stria is more shallowly and irreg-ularly punctured mesad the posterior dorsal elytral seta in this species (Fig. 12C-D).Cuticular microsculpture is well developed in this species, with: 1, frons covered with indistinct transverse lines, vertex with more well-developed sculpticells, transforming from transverse just behind posterior supraorbital setae to nearly isodiametric near pronotum; 2, pronotal disc with indistinct transverse lines visible outside areas of direct reflection, irregular surface of pronotal base covered with irregular transverse mesh; 3, elytral disc with transverse lines visible outside areas of direct reflection, apex covered with well-developed elongate transverse mesh.Standardized body length 4.3-5.0mm.Setal formula ++/++/+2++.Male genitalia (n = 16).As stated under M. eyrensis, the aedeagal median lobe and flagellar complex of that species and M. peryphoides show no differences (Fig. 14D-E).However the right paramere of this species bears significantly more setae (9-17) along its ventral margin.

Mecyclothorax cordicollis (Sloane)
Figures 2I, 5C, 9I, 10I, 11E, 12E, 13E, 14G-H Cyclothorax cordicollis Sloane 1900: 563.Mecyclothorax cordicollis Csiki, 1929: 488. Diagnosis (n = 5).This species (Fig. 5C) and M. lophoides (Fig. 4C-D) include the smallest-bodied, most gracile beetles in the M. lophoides species complex, with standardized body length for this species = 4.0-4.7 mm.Individuals exhibit a flavous marginal band on the elytra, brunneous to rufobrunneous body, and pale, flavous legs.The pronotum is very similar to that of M. lophoides (Fig. 2F, I); moderately transverse, MPW/PL = 1.17-1.24,and basally constricted, MPW/BPW = 1.62-1.68,these values broadly overlapping those calculated from specimens of M. lophoides.The eyes are also similar in configuration in the two species: here MHW/mFW = 1.63-1.71,with the eyes covering most of the ocular lobe, EyL/OLL = 0.86-0.91.The pronotal lateral marginal depression is slightly broader in this species than in M. lophoides, with microsculpture evident in its deepest part.The pronotal hind angles are obtusely rounded, with the margin behind the angle smoothly curved onto median base.The marginal bead terminates at the laterobasal depression just mesad the hind angle, and the bead is only slightly broader at the setal insertion.The pronotal median base is covered with 10-13 large isolated punctures present each side of midline.The laterobasal depression is defined by a medially arcuate line of punctures commencing at the termination of the marginal bead mesad the basal seta.The prosternum is medially depressed from the prosternal process anterad slightly less than 1/2 the distance to the anterior margin, the depression broader anteriorly, and lined with ~8 pits.The anteapical groove is punctate laterally, continuous and indistinctly punctate medially, and the procoxal cavity marginal bead is bordered by 4-5 small punctures along its anterior margin.The mesepisternum is variously punctate, the deepest portion covered with about 9 shallow to deep punctures arranged in 2-3 dorsoventral rows.The elytra are broad basally, subparallel, and broad relative to their length (Fig. 5C), MEW/EL = 0.69-0.71,versus values of 0.64-0.69for individuals of M. lophoides (Fig. 4C-D).The elytral disc is flat, with the sutural intervals apically raised into a callus.Elytral striae 1-6 are distinctly punctate on the disc, with the punctures nearly contiguous on the inner striae, however the intervening intervals are nearly flat.As in the other M. lophoides complex species, strial punctures are smaller and therefore further apart along the lateral striae, though in this species stria 6 is indicated until posterad midlength.As in M. peryphoides, the sutural stria is indistinctly punctate mesad the posterior dorsal elytral seta (Fig. 12D-E), but the punctures in striae 2-4 are more well developed, agreeing with M. eyrensis, but not M. lophoides (Fig. 12 B-C).Coincident with the presence of a flavous marginal band on the darker elytra, other body coloration tends toward the polychromat-ic: 1, elytral epipleura dorsally flavous versus ventrally rufobrunneous adjacent to the metepisternum; 2, coxae dark brunneous, trochanters rufous, femora flavous, and tibiae and tarsomeres brunneous with smoky cast.Cuticular microsculpture includes: 1, vertex glossy with an indistinct transverse mesh in parts; 2, pronotal disc glossy with an elongate transverse mesh restricted to transverse wrinkles, and a shallow elongate transverse mesh on the median base, sculpticells more irregular in the laterobasal depression; 3, elytral disc with a shallow, elongate transverse mesh, sculpticell breadth 3-4× length, the convex apex covered with traceable transverse lines, the entire elytral surface subiridescent.Setal formula ++/++/+2++.
Sloaneʼs perspicacity with regard to species boundaries is very evident in his sorting out this taxon from the very similar appearing beetles of M. lophoides and M. peryphoides.What we know about the habits of this species can be taken from Sloaneʼs description, quoted above.The species is uniformly represented by vestigially winged individuals with the exceptions of macropterous beetles from two Queensland localities: 1, one of two beetles from Ravenshoe; and 2, two of two specimens from Dalby.

Subgenus Qecyclothorax Liebherr
Diagnosis.These robust-bodied species (e.g.Fig. 5D) are geographically restricted to Queensland, Australia, and have been recently revised by Baehr (2003).The pronotum of species in this subgenus is broad, with obtuse or obtusely rounded hind angles.Each elytron bears a single dorsal elytral seta just before midlength (Fig. 5D).The prosternum is medially depressed both between and anterad the procoxal cavities, a condition shared with most member species of Eucyclothorax, although punctures are not present in the depression.The elytral striae are reduced; striae 1-3 to 1-4 shallow to evanescent, striae 4-or 5-7 obsolete.Striae 1, 7, or both may be present apically on the elytra, but striae 4-6 are consistently absent there.The elytra are broadly convex, with interval 8 not, or only slightly upraised (M.lewisensis) relative to the general curvature of the elytral surface.The suture between abdominal ventrites 1 and 2 is nearly straight, with the second ventrite hardly depressed relative to the first.Body size is small for the genus; standardized body length 2.6-3.7 mm.
Member species.Baehr (2003) recognized four species, three of them represented by two subspecies each, for a total of seven specific and subspecific forms.The subspecies described below is added to the inventory of M. lewisensis, resulting in three subspecies; M. lewisensis, M. lewisensis uncinatus, plus the newly described subspecies.
Mecyclothorax lewisensis Moore, 1984: 165.Mecyclothorax lewisensis uncinatus Baehr, 2003: 74.Diagnosis (n = 1).This taxon is distinguished from all others of subgenus Qecyclothorax by the reduced elytral striation, with only the sutural stria evident, and the positions of all outer striae only traceable by the longitudinal tracks of trachea (Shelford 1915).As for all Qecyclothorax, the elytra exhibit only a single dorsal elytral seta positioned near midlength (Fig. 5D).Consistent with membership in M. lewisensis, this beetle exhibits a quadrisetose clypeus and a pronotum with explanate lateral margins that are indistinctly sinuate basally.The parascutellar seta are very short and fine, and they are set in shallow depressions, however careful examination allows their discernment along with the fine articulatory sockets from which they extend.Baehr used the comparative breadth of the pronotal base relative to its apex as one criterion to differentiate the two subspecies M. lewisensis and M. l. uncinatus: the former with a ratio APW/BPW < 0.83 (note inverted ratio herein versus Baehr 2003), the latter with APW/BPW > 0.85.In the single specimen of M. l. estriatus, APW/BPW = 0.85.Standardized body length for the type specimen below, 3.3 mm.Setal formula ++/++/+1++.
Female reproductive tract (n = 1).The unique female holotype was not dissected.Nonetheless, the gonocoxae extend from the abdominal apex, allowing the following characters to be assessed: basal gonocoxite with medioapical margin glabrous; apical gonocoxite broad basally with 2 lateral ensiform setae; apical nematiform setae in subbasal sensory furrow.These characters conform to states previously scored for M. lewisensis (Liebherr 2018) though they are not definitive.
Distribution and habitat.The lone specimen of this subspecific taxon is from near the Queensland coast south of Cannonvale (Fig. 11E), approximately 600 km south of the localities near Mossman from where the other subspecies of M. lewisensis have been described (Baehr 2003, fig. 6).

Subgenus Mecyclothorax Sharp
Diagnosis.This subgenus comprises over 350 species (Liebherr 2018), and so morphological variation among the species is the most extreme observed among the various Mecyclothorax subgenera.However, throughout taxa of this subgenus, the labrum is emarginate apically, either distinctly and angularly as in M. goweri Moore of Lord Howe Island (Liebherr 2018, fig.1A), or less so as in M. aeneipennis Liebherr of Haleakalā, Maui, Hawaiʻi (Liebherr 2015, fig. 7).The ligular margin is generally truncate with the ligular setae well separated (Liebherr 2018, fig.1G), though as exceptions, the ligula is apically rounded in the Papuan taxa M. brispex and M. andersoni (Liebherr 2017(Liebherr , 2018, fig. 7, fig. 7).The prosternum exhibits a smooth to distinctly punctate anteapical groove, though never any other punctures, such as in the median depression observed among species of subgenus Eucyclothorax.The parascutellar striole is present, and may be smooth or punctate, with up to 8 punctures along its length (Fig. 6).Among the mainland Australian species, the pronotal median base is depressed relative to the disc, and punctate; a distinction noted by Blackburn (1889).
The male aedeagus has an internal sac with an apical flagellar plate surrounding the gonopore (Fig. 15E).The female reproductive tract most often has the spermathecal duct entering the bursa copulatrix mediodorsally (Fig. 17C-D), however the sister-species pair M. lateralis + M. minutus (Fig. 1A) revert to the plesiomorphic configuration wherein the spermathecal duct basally joins the juncture of the common oviduct and the bursa copulatrix (Fig. 17A-B).
Member species.This subgenus is represented by four species in mainland Australia.Numbers of taxa in the substantial radiations from Hawaii, the Society Islands, New Guinea, New Zealand, the Sundas, and Lord Howe, Norfolk, and St. Paul and Amsterdam Islands are summarized in Liebherr (2018: 15).Diagnosis (n = 5).This large-bodied species-standardized body length 5.2-6.4mm-is further distinguished by the rufous to brunneous body with contrasting, flavous elytral margins (Fig. 6A).The labrum is broadly and distinctly emarginate apically.The ligula is truncate apically, with the 2 apical setae separated by 4 setal diameters, the ligular surface longitudinally depressed between the setal articulations.The paraglossae are elongate, apically extended beyond the ligular apical margin twice the distance from ligular margin to their base.The pronotum is robust, transverse, with a convex disc, and depressed and circularly punctate median base (Fig. 2J); MPW/BPW = 1.45-1.56,MPW/PL = 1.35-1.40.The prosternal process is broad, only slightly depressed between the coxae, and convex anterad the coxae.The prosternal anteapical groove is deep and narrow, with only slight irregularities along its length at its deepest part.As in its sister species M. minutus, the parascutellar seta is absent.The metepisternum is abbreviated, with lateral length about 2× maximum width, and the metathoracic wings are vestigial in examined material.The suture between visible ventrites 1 and 2 is sinuous, with the area behind markedly depressed.Microsculpture of the head is reduced, with frons glossy, vertex with indistinct transverse sculpticells; pronotal disc and median base glossy, indistinct transverse lines visible in places; elytral surface glossy with well-defined isodiametric sculpticells visible over entire surface, the apex with sculpticells more upraised; thoracic ventrites glossy, abdominal ventrites glossy medially but with isodiametric sculpticells visible in lateral depressions.Setal formula ++/++/-2++.
Nomenclatural note.In the paragraph within which Chaudoir (1873) combined Phorticosomus minutus Castelnau with Simodontus , Chaudoir writes "Je crois que son Ph. lateralis est encore une espèce de Simodontus, qui mʼa semblé différente du curtulus (p.114)."Such a statement falls short of a nomenclatural act proposing a valid new combination.Csiki (1929) interpreted Chaudoir (1873) to have officially combined Ph. lateralis with Simodontus, however his listing the page of that action as Chaudoir (1873: 113) suggests that he did not see the work personally, thus leading him to give Chaudoir credit for a nomenclatural act that Chaudoir did not commit.Sloane agreed that Chaudoir did not combine Ph. lateralis with Simodontus, writing: "Ph.lateralis is a species of Mecyclothorax.Ph. minutus, from the Paroo River, has been examined by Chaudoir, who referred it to Simodontus ... (Sloane, 1915, 462)."Mooreʼs labelling of the lectotype as holotype was corrected in Moore et al. (1987), where the presence of a paralectotype was also noted.
Distribution and habitat.This species is distributed in interior Victoria, western New South Wales and southeastern South Australia (Fig. 19A).Localities and repositories for non-type specimens I have examined include: SA: Lucindale (MCZ, 1); Pt.Lincoln (MVM, 1); VIC: Bendigo (MVM, 1); Birchip (MVM, 1); Evansford (BMNH, 15); Lake Hattah (MVM, 1); Maldon (MVM, 1); Wedderburn (MVM, 1).These records represent beetles collected between 1911 and 1950, none with any ecological data, and so nothing can be reported with confidence concerning the ecological preference of this species: but see M. minutus below.This species is polymorphic for flight-wing configuration, with 3 brachypterous individuals observed among the 27 beetles examined; 2 of the individuals from Evansford exhibit wings that are broad, slightly more than half as long as the elytra, and without a reflexed apex.Other examined individuals have vestigialized wings, with the wing stubs shorter than the metanotum.Diagnosis (n = 5).This species shares the rufous to brunneous body color (Fig. 6A-B) and lack of the parascutellar seta with M. lateralis, however the beetles are smaller-standardized body length 4.9-5.7 mm-and the elytral lateral and apical margins do not markedly contrast with the elytral disc.In teneral individuals the margins may appear somewhat paler, partly due to reflection of the underlying abdominal tergites through the cuticle, and partly due to a smoky infuscation of the median elytral disc.However, the difference in coloration from disc to margin is gradual, never marked.Males exhibit 2 setae each side of the apical ventrite margin, for a total of 4 apical setae, differing from M. lateralis which retains the plesiomorphic single seta per side: i.e. a total of 2 apical abdominal setae.The labrum is distinctly emarginate apically, the 2 sides subangulate medially.The ligula is truncate apically, with the 2 apical setae separated by 4 setal diameters, the ligular surface longitudinally depressed between the setal articulations.The paraglossae elongate, extending twice as far beyond the ligular apical margin as the distance from paraglossal base to ligular margin.The pronotum is transverse, with the depressed median base margined at the disc with strigose punctures (Fig. 2K); MPW/BPW = 1.47-1.56,MPW/PL = 1.42-1.51.The prosternal process is broad and only slightly depressed between the coxae, convex anterad the coxae.The prosternal anteapical groove is deep and narrow, smooth at depth.As in M. lateralis, the metepisternum is abbreviated, with lateral length about 2× maximum width, and the metathoracic wings are vestigial in examined material.The suture between visible ventrites 1 and 2 is sinuous, with a broad circular depressed area posterad the sinuosity.Microsculpture of the head is reduced, with frons and vertex glossy, the surface interrupted only by scattered micropunctures.Similarly the pronotal disc and median base are glossy, with indistinct transverse lines visible in places.The elytral surface is glossy with micropunctures covering the surface of the disc, the apex with margins of transverse sculpticells upraised.Ventrally, the thoracic ventrites are glossy; abdominal ventrites glossy medially but with swirling transverse sculpticells visible in lateral depressions.Setal formula ++/++/-2++.
Diagnosis (n = 5).Moore (1984) deferred reliable diagnosis of this species from M. punctipennis based on the configuration of the male aedeagus (e.g.Fig. 15C-D), however the pronotal lateral margins are reliably narrower in individuals of this species (Fig. 2L).Although variable melanization of the pronotal disc and marginal depressions may confuse the appearance of the width of the lateral depressions, other aspects of the pronotum may be used, including: 1, punctation of the median base, with about 20-22 punctures each side in this species versus nearly 30 deeper punctures each side in M. punctipennis (Fig. 2L-M); 2, median base juncture with pronotal disc lined with deep, nearly round to moderately elongate punctures in this species, versus distinctly strigose depressions with 1-2 punctures in each depression for M. punctipennis.Microsculpture also varies unambiguously between the two species: 1, in M. ambiguus a transverse mesh visible over portions of the pronotal disc and median base, best viewed adjacent to areas of reflected microscope light, versus glossy pronotal disc and median base, with only indistinct transverse lines within irregularities of the cuticular surface in M. punctipennis; and 2, discal elytral intervals with well-developed transverse mesh, sculpticell breadth 2-3× length, and surface subiridescent in M. ambiguus, versus discal elytral intervals glossy, with at most indistinct transverse sculpticells visible at margins of fields of reflected light, the surface without any iridescence in M. punctipennis.The depth of elytral striae varies on the elytral apex, however in M. ambiguus, interval 8 is broadly convex adjacent to the well-developed stria 7 between the subapical and apical elytral setae, whereas in M. punctipennis, interval 8 is internally subcarinate and angularly depressed laterally (Liebherr  2012a, fig.7).For M. ambiguus, the mentum tooth has sides obtuse, the apex broadly rounded, whereas M. punctipennis is characterized by an acute mentum tooth with apex tightly rounded.The prosternal anteapical groove is deep and smooth here, but broader and distinctly punctate laterally, though smoother and slightly irregular medially, in M. punctipennis.In addition, the depressions surrounding the dorsal elytral setae span 1/4-1/2 of elytral interval 3 in this species, but up to 1/2-3/4 of the interval width in M. punctipennis.Standardized body length 5.0-5.7 mm.Setal formula ++/++/+2++.
Male genitalia (n = 3).Aedeagal median lobe gracile, narrow dorsoventrally relative to length, apex broad, expanded both ventrally and dorsally resulting in a nearly straight apical face (Fig. 15C); ostial ventroapical operculum well developed as a broadly triangular sclerite; flagellar plate very large, well-sclerotized with longitudinal ridges; aedeagal internal sac bearing a ventral spicular sclerite; right paramere slightly broadened basally, even-ly narrowed to apex, ventral surface with ~20 setae along margin, additional very small setae may be present near apex (Fig. 16C); left paramere slightly expanded in basal half, apically narrowed to whip-like apex.
Distribution and habitat.This species is broadly distributed in numerous habitats across Australia (Fig. 19D).Recorded collection localities range in elevation from sea level to over 2000 m near the summit of Mt.Kosciuszko.These beetles are at home in leaf litter on the floor of Eucalyptus forests, under dense mats of dead leaves surrounding the bases of Xantharrhoea (Asphodelaceae) grass trees, in tussock grass clumps of high-elevation grasslands, under wrack on sea beaches, and in home gardens in urban settings.The species is monomorphically macropterous, with adults often collected at lights in great profusion.
Even given this speciesʼ catholic ecological preferences and propensity for winged flight, its geographic distribution is discontinuous across Australia (Fig. 19D).Moreover, the Western Australian populations of this bicentric species distribution interact little if at all with coastal populations east of the Great Australian Bight, based on geographic restriction of polymorphic male genitalic chiral antisymmetry to the populations inhabiting Western Australia (Liebherr and Will 2015).In contrast, all eastern populations monomorphically comprise males with plesiomorphic genitalic torsion, whereby the right side of the aedeagus is held ventrally when in repose.The Western Australian populations vary greatly in the proportions of left-and right-torsioned males, demonstrating that their mutual geographic isolation is great enough to preclude extensive homogenizing dispersal among populations.Baehr (2000) reported a 1998 record for M. punctipennis from Rocky Cape N. P. as the first Tasmania record.However, Darlington material (MCZ) indicates M. punctipennis was present at Hobart in 1956-1957(Liebherr and Will 2015).Tasmanian localities and repositories represented in material examined for this review (Fig. 19D) include: Corinna, West Tasmania (MCZ, 4); Hobart (MCZ, 8); Great Lake, north end (MCZ, 5); Waldheim nr.Cradle Mtn.(MCZ, 1); Zeehan,north (MCZ,3).

Discussion
Biogeographic History.The adelphotaxon relationship (Liebherr 2011a) between Mecyclothorax and genera allied with and including Amblytelus Erichson -i.e.Epelyx Blackburn, Dystrichothorax Baehr, Paratrichothorax Baehr, and Trichoamblytelus Baehr -requires both clades to be of equal age of origin.Baehr (2004) proposed an Eocene age of origin for the Amblytelus lineage, based on the restriction of Paratrichothorax and Trichamblytelus to coastal forests of southwest Australia.The late Eocene marine transgression would have isolated the ancestors of extant species in these genera from other lineages diversifying in eastern Australia, with subsequent aridification and periodic marine transgressions maintaining that isolation (Mast and Givnish 2002).Oligocene cooling allowed the evolution of rain forest communities, whereas Miocene drying (associated with the rise of Myrtaceae) resulted in the assembly of communities dominated by Eucalyptus (Crisp et al. 1999).The intense association of the tree-dwelling Amblytelus lineages with Eucalyptus forests allowed those taxa the opportunity to diversify over the past 20 Myr, with many of the more than 100 species evolving arboreal life styles (Baehr 2004(Baehr , 2016b)).Mecyclothorax spp., on the other hand, have been principally restricted to terrestrial microhabitats in southwest or southeast Australia, Queensland, New Caledonia, and especially New Guinea during the Miocene orogeny (Liebherr 2018).Species of the montane rainforest, Queensland Qecyclothorax have been principally collected in sieved litter from terrestrial situations, though some specimens have been collected via pyrethrin spray of mossy logs and trunk bases.The early divergence of Qecyclothorax in these rainforests is hypothesized to have occurred commencing in Oligocene when these communities were being assembled.Conversely, based on collecting records for Australian Mecyclothorax of the subgenus Eucyclothorax, we know that these species are distributed along waterways and in wetlands, often in association with open forest vegetation, fallen wood, and massed vegetation such as flood debris.Thus, like Amblytelus, this line could have diversified in the myrtaceous communities of southern Australia.
Though most of the diversification occurred in southeastern Australia, multiple east-west vicariance events of different ages are mandated by the cladistic taxon-area relationships of the taxa (Rix et al. 2015).The earliest east-west vicariance event would have isolated M. isolatus in the forests of the south west coastal region.That M. isolatus has a remarkably reduced metathorax and well-developed plical lock between the abdominal ventrites and elytra points to prolonged occupation of stable, persistent forest habitats (Southwood 1977) now conserved within Walpole-Nornalup National Park.Subsequently M. blackburni was isolated in Western Australia (Figs 1B, 11B) prior to diversification of the six species in the M. lophoides complex (Fig. 1B).Later in the history of that same clade, M. jameswalkeri was derived as a Western Australian isolate related to M. dar-lingtoni from Queensland and M. lophoides from southeast Australia (Figs 1B,11C).The most recent east-west pattern involves widespread species with populations in both eastern and western Australia: 1, M. punctatus, with the subspecific form M. p. peckorum described from the southwest Cape region; 2, M. minutus (Fig. 19B); and 3, M. punctipennis (Fig. 19D).
Within the subgenus Mecyclothorax, the vast majority of Australian Plate species evolved first in association with rainforest habitats in New Guinea (Fig. 1A; Baehr 2014, Liebherr 2017), and subsequently following overwater dispersal to locales such as Lord Howe and Norfolk Islands (Moore 1985(Moore , 1992)), Borneo (Baehr and Lorenz 1999), Java (Andrewes 1933, Louwerens 1949, 1953), Timor Leste (Baehr and Reid 2017), New Zealand (Liebherr and Marris 2009), and most recently the Hawaiian and Society Islands.The colonizing taxon founding the very diverse Hawaiian radiation occupied terrestrial grassland, based on sharing of this habitat preference by the very close relatives M. punctipennis and M. montivagus (Fig. 1A, Liebherr 2015).The third species completing this triplet, M. sculptopunctatus of St. Paul and Amsterdam Islands, also occupies such an open habitat on these very small, windswept Indian Ocean islands (Jeannel 1940, plate IV, fig.1), corroborating an open grassland habitat as the initial landing area for these island species.It is within the many Hawaiian species that have radiated from the common ancestor with M. montivagus that ecological diversification has reached its maximal range among known Mecyclothorax, with the evolution of alpine, riparian, and arboreal epiphyte-loving species (Liebherr 2015), as well as a cave-adapted troglophilic species (Liebherr 2008a).Even within the estimated 10% of Mecyclothorax species predicted to be discovered in New Guinea (Liebherr 2017), species have evolved to occupy alpine habitats-M.sedlaceki Darlington, M. toxopei Darlington, and M. kavanaughi Liebherr (Liebherr 2008b)-as well as dense lowland rainforest; M. amingwiwae Liebherr, M. andersoni Liebherr, and M. gressitti Liebherr (2017).Being highly complex geologically and largely unexplored, the New Guinea highlands on the active tectonic margin of the Australian plate are likely to provide further examples of ecological diversification within the genus.
Paleoecological research has resulted in the discovery of Australian subfossils assignable to Mecyclothorax (Sniderman et al. 2009).In deposits laid down ~1.84-1.56Ma in the Stony Creek Basin, Victoria, subfossils determined as "Mecyclothorax 'punctatus' grp n. sp." and "Mecyclothorax sp. 3 (cordicollis grp.)" were recovered.The site is within the present-day distributional range of M. punctatus (Fig. 11A), and so these subfossils presumably represent extant species or representatives of an ancestral population that evolved to become the extant species.Most parsimoniously then, the common ancestor of M. punctatus and its sister species M. moorei can be dated to the Pleistocene age of this assemblage (Fig. 1B).For the "cordicollis grp." taxon, the site lies within the distributional ranges of M. lophoides, M. peryphoides, and M. cordicollis (Fig. 11C-E).Given this contribu-tionʼs sorting out of species in the M. lophoides species complex based on comprehensive use of external and male genitalic characters, more concise determination of these subfossils may allow more precise dating of cladogram nodes connecting these species (Fig. 1B).Regardless of the outcome of such a determination, the rate of speciation for these Eucyclothorax species is an order of magnitude lower than that observed in the Pacific Island radiations, where time between speciation is estimated to be 220,000 years for Hawaii (Liebherr 2015) and 300,000 years for the Society Islands (Liebherr 2013).
Genitalic Evolution.Confirmation of species assignment for specimens in the M. lophoides species complex is greatly assisted by examination of the male aedeagus, a finding in keeping with the utility of male genitalia for diagnosis of cryptic species in the Hawaiian Mecyclothorax fauna (Liebherr 2007(Liebherr , 2008a(Liebherr , 2011b(Liebherr , 2015)), where numerous species may be sympatric across a limited portion of an island.In contrast, male genitialia vary infraspecifically within species of the New Caledonian Mecyclothorax subgenus Phacothorax on an island where often only two species occur sympatrically (Liebherr 2018).Even though the overall diversity of Australian Mecyclothorax is modest, the aggregate distributional patterns are more like those observed in Hawaii, as nine species are broadly sympatric across portions of New South Wales and Victoria (Figs 11,19).Given the long duration of Mecyclothorax species in Australia (Sniderman et al. 2009), there has been abundant time for the evolution of discrete male genitalia, thereby assisting species recognition during the encounters of male and female beetles (Nagata et al. 2009, Okuzaki andSota 2014).The only region of Australia where this pattern breaks down is Western Australia, where chiral antisymmetry occurs within populations of Mecyclothorax punctipennis.Here only that species and M. minutus share much of the region (Fig. 19), as the four Eucyclothorax species are allopatrically distributed within limited areas along the coast (Fig. 11A-C).
Species diagnosis within the M. lophoides complex (Fig. 1B) lies most specifically in differential characters of the internal sac flagellar complex 14).This is especially so for the sympatric species M. lophoides, M. cordicollis, and M. peryphoides (Figs 14B, F,  H).A succession of taxonomists have routinely confused these closely related species (Fig. 1) because the external anatomical characters vary little among the species, and infraspecific variation blurs the subtle patterns of external character evolution.Yet the beetlesʼ flagellar complexes differ very dramatically, with no possibility of misidentification given access to a male specimen.This disparity points to relative stasis in external anatomy during accelerated evolution of male genitalic characters.Two questions may be asked about this evolutionary disparity.
Firstly, what are the functional ramifications for mating given the dramatic differences among species?Secondly, what are the evolutionary selection pressures that have resulted in accelerated genitalic evolution?
The internal sac flagellum of male tiger beetles functions during copulation as a semi-rigid structure that enters the female spermathecal duct (Schincariol and Freitag 1986).The Cicindela L. flagellum is elongate, sclerotized, and in cross-section U-shaped, with either the internal surface of the groove, or the convex outer surface of the flagellum bearing basally directed, microserrate teeth (tempers).These act to hold the flagellum in the duct when required, but can be detached from the ductʼs surface through flagellar flexion when removal of the flagellum is required (Freitag et al. 2001).The flagellum ranges from about half the length of the spermathecal duct to slightly longer than the duct in four species of Cicindela and Pseudoxychila tarsalis Bates (Freitag 1966, Freitag et al. 1980, Rodríguez 1999).In all instances, the flagellar diameter is similar to the diameter of the spermathecal duct, though the flagellar base is larger than the duct and presumably does not enter it.The flagellum cannot transfer sperm, as its base is closed, and it does not connect directly to the male gonopore.Its function includes opening of the spermathecal duct during the complicated multi-phase mating behavior of cicindelines (Schincariol and Freitag 1986), and possibly facilitating insertion of the spermatophore neck into the spermathecal duct (Rodríguez 1999), allowing sperm passage into the duct and to the spermatheca.
Aedeagal internal sac flagella occur throughout the Carabidae (Jeannel 1955, Maddison et al. 2013).In Hawaiian Bembidion Latreille beetles of the subgenus Nesocidium Sharp, the male flagellum length is subequal to the female spermathecal duct length, to 60-75% longer than the duct (Liebherr 2008c).Correspondence in length between male flagellum and female spermathecal duct was maximal in Nesocidium spp. with spermathecal ducts of uniformly narrow diameter, whereas species in which the male flagellum was longer than the duct included females with a basally broad duct, suggesting that the flagellum touches the walls of the duct, undergoing circular torsion and thus expanding the duct to its maximal diameter as it is pushed into the duct by the male.The presence of a short male flagellum is a groundplan character for the tribe Moriomorphini (Liebherr 2011a).Among species of Mecyclothorax subgenus Eucyclothorax, the flagellum ranges from a plesiomorphic shortened condition, as in M. moorei, M. punctatus, M. curtus, and M. blackburni (Fig. 7A-E), to the highly derived, elongate, and rigidly sinuous structure of M. eyrensis and M. peryphoides (Fig. 14D-F).The other species of the M. lophoides complex exhibit a flagellum of intermediate length; 1, slightly longer than the associated flagellar sheath in M. darlingtoni (Fig. 7G-H): 2, equal in length to the flagellar sheath in M. lophoides (Fig. 14B); and 3, slightly shorter than the flagellar sheath in M. cordicollis (Fig. 14H).Among the females, most species have spermathecal ducts equal in length to the apical spermathecal reservoir, i.e. of moderate length (Fig. E-F, I).However, in females of M. curtus, M. eyrensis, and M. peryphoides the spermathecal duct is elongate, i.e. more than twice the length of the fusiform apical reservoir (Fig. 9C, G-H).In the species pair M. eyrensis + M. peryphoides, insertion of the long, semi-rigid and sinuous flagellum would make the spermathecal duct conform to the flagellar configuration.
The species pair M. eyrensis and M. peryphoides are also unique within subgenus Eucyclothorax in that the highly derived structures of the male aedeagal median lobe and internal sac are identical among males of both species, apparently violating one of the precepts of modern taxonomy that associate species diagnosis with male genitalic differences (Huber 2003).However parameral setation varies significantly among males of these species.This finding begs the question of how the male parameres interact with the external surface of the female abdomen during intromission, at the same time providing a genitalic difference between the species to accompany diagnostic external characters that include differences in: 1, pronotal shape, especially at the pronotal hind angles; 2, cuticular microsculpture; and 3, coloration.The two species also occupy very different ecological zones in Australia; with M. eyrensis residing in the arid interior of South Australia, Northern Territory and New South Wales, whereas M. peryphoides occupies the more temperate grass-and woodland habitats to the south and east (Fig. 11D).Both species occupy riparian habitats within their respective distributions, perhaps the reason that M. eyrensis can persist in the dry interior, as the larvae would be seriously impacted were the occupied habitat too xeric during the period of larval development.Though only a single datum, the genitalic situation in M. eyrensis and M. peryphoides parallels that reported by Huber and Dimitrov (2014) for a sister-species pair of Taiwanese pholcid spiders: two species sharing highly distinctive yet identical male genitalia (i.e.chelicerae), while differing in body coloration and proportions, and occupying discrete ecological situations across allopatric distributions.Molecular divergence is minimal between the two pholcid species, supporting very recent speciation between them.
The second question posited above concerning the evolutionary basis for male and female genitalic correlations can be addressed preliminarily by the distribution of differences among the species in subgenus Eucyclothorax.It seems likely that genitalic characters provide specific cues for mate recognition (e.g.Nagata et al. 2009).Can such differences be interpreted as the results of sexual selection (Eberhard 1985(Eberhard , 2004))?Males of M. moorei, M. punctatus, and M. curtus exhibit short flagella (Fig. 7A-D), whereas the females exhibit several derived characters of the reproductive tract.Females of the sister species M. moorei and M. punctatus exhibit a basally sclerotized and bulbously expanded spermathecal duct (Fig. 9A-B).Females of M. curtus deviate from that by having a spermathecal duct that is elongate and moderately sclerotized (and therefore coiled when at rest), as observed in females of M. eyrensis and M. peryphoides.If we invoke runaway sexual selection to explain the association of elongate male flagella and spermathecal ducts of M. eyrensis and M. peryphoides, then how do we explain the similarly elongate duct in M. curtus, here in association with a short male flagellum?Moreover, given that we do not understand the function of the basally expanded and sclerotized spermathecal ducts in M. moorei and M. punctatus females, nor how the duct might interact with the male flagellum, currently we are best left to report the findings and introduce their use in phylogenetic inference.Finally, if we were to implicate the difference in parameral setation between M. eyrensis and M. peryphoides as the result of sexual selection, then we must posit the introduction of a novel focus of selection in the mating system at this point; a decidedly unparsimonious rescue attempt for a hypothesis compromised by the phylogenetic distribution of female spermathecal duct configurations.
Based on revisionary taxonomy for the Mecyclothorax faunas of the Hawaiian Islands (Liebherr 2006(Liebherr , 2007(Liebherr , 2008a(Liebherr , 2009a(Liebherr , 2009b(Liebherr , 2011b(Liebherr , 2015)), the Society Islands (Liebherr 2012a(Liebherr , 2012b(Liebherr , 2013)), New Zealand (Liebherr and Marris 2009), Papua New Guinea (Liebherr 2017), New Caledonia (Liebherr 2018) and now Australia, we have accrued information on genitalic correlates between the sexes for more than 350 species.Plucking from this cornucopia of genitalic riches, all manner of genitalic correlates among closely related species can be observed.The parapatric Molokaʻi sister species M. lissopterus Liebherr and M. arcuatus Liebherr of the M. ovipennis species group are not distinguishable based on external anatomy.However, genitalia of both sexes are both diagnostic and concordant with regard to size: 1, the male aedeagal median lobe of M. arcuatus has a much longer and broader apex (Liebherr 2007, figs 75-78); and 2, the female bursa copulatrix of M. arcuatus is much broader and more elongate (Liebherr 2007, figs 157, 159).In this instance, an elongate male median lobe is associated with an elongate female bursa, with the structures functionally related because the former enters the latter during intromission, followed by eversion of the male internal sac and transfer of the spermatophore.A second pair of allopatric M. ovipennis group sister species from Molokaʻi -M.joni Liebherr and M. lisae Liebherr -exhibit males with significantly different aedeagal median lobe lengths across species, but females with bursae of very similar lengths (Liebherr 2007 figs 71-74, 150, 152).A similar non-correlated pattern is observed among five sympatric species of Oahuʼs monophyletic M. brevis species complex, with the male aedeagal median lobes and internal sacs varying dramatically among the species, but the known female bursae differing little (Liebherr 2009a, figs 6A-K, 9A, C).If we wish to implicate sexual selection across just these three examples, each involving most-closely related species, the first example of concordant transgender-based association of dramatically larger male and female genitalia in M. arcuatus would better fit the model of antagonistic sexual selection, whereas the latter two examples involving dramatic changes in male genitalia along with female genitalic stasis would fit conditions of Eberhard's (2004) female choice model.Yet, the latter two examples consistent with observations of female choice also differ in that the former involves allo-patric sister species, and the latter involves five sympatric species.Females could choose among sympatric males, but not among allopatric males.Alternatively species-specific male genitalia could have evolved during allopatric speciation, with secondary sympatry enhancing either or both pre-mating sexual discrimination and post-mating reproductive isolation (Malone et al. 2015).Character displacement operating on characters of either system could reinforce divergence among secondarily sympatric species or populations (Brown and Wilson 1956).These myriad options point to the requirement for hypothesis testing specific to singular or closely associated evolutionary events when studying sexual selection (Simmons 2014).They also suggest that it is inappropriate to consider sexual selection as a singular factor responsible for the accelerated speciation of Polynesian Mecyclothorax beetles.

Figure 1 .
Figure 1.Cladograms resulting from cladistic analysis.Species terminals are labeled with species epithet and three-letter abbreviation of relevant generic or subgeneric name: Neo, Neonomius Moore; Par, Paratrichothorax Baehr; Epe, Epelyx Blackburn; Amb, Amblytelus Blackburn; Dys, Dystrichothorax Baehr; Euc, Eucyclothorax Liebherr; Qec, Qecyclothorax Liebherr; Meo, Meonochilus Liebherr and Marris; Pha, Phacothorax Jeannel; Mec, Mecyclothorax Sharp.Areas occupied by the included taxa are indicated by abbreviations following species epithets: Bo, Borneo; EOZ, eastern Australia, i.e. restricted to east of the Nullarbor Plain; FP, French Polynesia, Tahiti; HI, Hawaiian Islands, Maui; Jv, Java; LH, Lord Howe Island; NC, New Caledonia; Nf, Norfolk Island; NNZ, North Island of New Zealand; NZ, generally distributed across New Zealand; OZ, generally distributed across Australia; PNG, Papua New Guinea; QOZ, restricted to Queensland, Australia; SNZ, South Island of New Zealand plus Chatham Islands; SP&A, St. Paul and Amsterdam Islands; WOZ, western Australia, i.e. restricted to west of the Nullarbor Plain. A. Strict consensus cladogram of 2 equally most-parsimonious trees.Green-colored terminals represent mainland Australian taxa.B. Resolved cladistic relationships of 11 Mecyclothorax (Eucyclothorax) spp.represented in all cladograms.Character numbers are shown to left of cladogram edges, character states to right.Filled boxes represent characters that change to the indicated state only once on cladogram.

Table 1 .
Key to abbreviations for morphological structures labelled in illustrations of male genitalia, female reproductive tracts, and female gonocoxae.