Research Article |
Corresponding author: Kipling Will ( kipwill@berkeley.edu ) Academic editor: James Liebherr
© 2020 Kipling Will.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Will K (2020) Phylogeny and classification of the genus-group taxa of Loxandrina (Coleoptera, Carabidae, Abacetini). Deutsche Entomologische Zeitschrift 67(2): 151-182. https://doi.org/10.3897/dez.67.55985
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Bayesian and parsimony phylogenetic analyses of combined and partitioned datasets of molecular (partial sequences of 28S, wg, COI, and CAD) and morphological (51 characters of adults) data for exemplar taxa of five outgroup and 76 ingroup abacetine carabids resulted in a monophyletic Loxandrina Erwin & Sims, 1984 that is split into Australian and American clades. The genus Loxandrus LeConte, 1853 as previously delimited is not monophyletic relative to numerous genus-level taxa in Abacetini Chaudoir, 1873 and is restricted to a subgenus of North American species. A reclassification and nomenclatural changes for the subtribe that are consistent with the phylogeny are provided. Three genera are removed from Loxandrina: Aulacopodus Britton, 1940 moved to Pterostichini Bonelli, 1810; Cosmodiscus Sloane, 1907 and Tiferonia Darlington, 1962 moved to Abacetina. Based on the phylogenetic relationships and nomenclatural priority only four genera are recognized in Loxandrina: Cerabilia Laporte, 1867, Zeodera Laporte, 1867, Pediomorphus Chaudoir, 1878, and Oxycrepis Reiche, 1843. All other previously recognized genera are treated as subgenera. The classification change created eight secondary homonyms that are resolved by the proposal of the following: Oxycrepis gebi, replacement name for O. balli (Straneo, 1993); O. amatona, replacement name for O. matoana (Straneo, 1993); O. xiproma, replacement name for O. proxima (Straneo, 1993); O. rasutulis, replacement name for O. suturalis (Straneo, 1993); O. laevinota, replacement name for O. laevicollis (Bates, 1871); O. arvulap, replacement name for O. parvula (Straneo, 1951); O. noaffine, replacement name for O. affinis (Straneo, 1991); O. alutona, replacement name for O. notula (Tschitschérine, 1901). An overview of the morphological characteristics and diagnostic features of Loxandrina taxa is provided. A key and habitus images are provided for identification of genera and subgenera. The possible historical biogeography of the group is discussed in light of their phylogenetic relationships and past geological events.
Australia, elytral striae homology, Gondwanan distribution, Ground beetles, South America
For more than 100 years, coleopterists such as
The possible association of loxandrines with abacetines (e.g., Loxandrus series of
A rigorous analysis testing the monophyly and relationships at various levels for the abacetine-loxandrine complex has not been previously undertaken. In all preceding studies Loxandrina or Abacetini were only represented incidentally by a small sample of exemplars. Earlier works were necessarily restricted to a select fauna or loxandrines were not the central focus in those studies.
Abacetini sensu Bousquet has over 800 described species (
This contribution focuses on Loxandrina, which is found in the Australian region (Australia, New Caledonia, New Guinea, New Zealand, and Sulawesi) and in the New World (Argentina to southern Canada) using exemplar Abacetina taxa to test the monophyly of the subtribe Loxandrina. The purpose of this study was to determine what genera should be included in the subtribe, to test their monophyly in a phylogenetic framework using a combined, multi-locus DNA and morphology dataset and to devise a new, evidence-based classification that is compatible with well-supported phylogenetic relationships.
As a starting point, it is necessary to establish a reasonable working hypothesis of Abacetini monophyly exclusive of other Harpalinae tribes. To do this, a parsimony analysis was done using an unpublished dataset with over 500 taxa from across Carabidae, the vast majority being in Harpalinae, Pterostichini, and Abacetini. This large preliminary screening used an exemplar dataset including partial sequence data for three loci: 28S, wg and CAD, and a partially coded matrix of about 100 morphological characters (Will unpubl. Data). Exemplars of all the major abacetine genera that were included in this analysis form a clade separate from Pterostichini (including Aulacopodus Britton, 1940 discussed below) and other Harpalinae tribes. The clade is always rooted between Abacetus and the other abacetine taxa. Study of the morphology of dried specimens and descriptions from the literature indicate that the remaining Abacetina (non-Loxandrina taxa as listed by
The two included species of Abacetus represent crown-group Abacetina, i.e., species with the following combination of features: antennomere 2 inserted eccentrically to antennomere 1, very short, transverse mentum, stridulatory structures on the proepisternum, and deeply impressed clypeo-ocular sulci. Each of the other Abacetina taxa, Inkosa, Cyrtomocelis and Metabacetus, lacks one or more of those features and are placed in the broader concept of Abacetini as incertae sedis, but are, for convenience and as a working hypothesis referred to as being in Abacetina. Currently there is no evidence that Abacetina taxa form a clade beyond Abacetus and its close relatives. All of the morphological features listed above for these Abacetina genera, except for a somewhat transverse mentum, are absent from all Loxandrina taxa.
The putative in-group terminals included in the analysis are exemplars from all recognized loxandrine genera from the New World and Australian region. Many genera are monotypic or have very few species, but Loxandrus auct. has more than 200 species and Cerabilia, more than 50. From these larger genera the exemplars included cover the apparent morphological diversity, most of the informal groups previously recognized (
Both DNA (minimum of two loci of the four sought) and morphological data are included for all taxa with the only exception being Zeodera (Haploferonia) simplex (Darlington, 1962), which is only known from the holotype specimen. For that species only morphological data is available. The full matrix includes 81 OTUs (operation taxonomic units (
The basis of this study has been built over the last more than 20 years by studying and taking numerous specimens of Abacetini on loan for examination, including types, from the holdings of the following collections:
QDAF Queensland Department of Agriculture and Fisheries, Brisbane;
Many of the specimens examined are enumerated in various publications on Abacetini (e.g.,
Based on these museum specimens, of the 343 currently named species-level taxa in Loxandrina I have studied in detail or at least made a cursory examination of identified exemplars of 247. Described species represented in material I have examined are indicated in the supplementary file (Suppl. material
Of the remaining species that I know only from descriptions, nearly all are adequately described such that there is no doubt of their inclusion in Loxandrina and it seems extremely unlikely that any of those represent a lineage worthy of genus-level recognition. Based on museum material I have studied there are many undescribed species in the subtribe. Oxycrepis alone appears to have many dozens of undescribed species from the New World.
Observations of anatomical features were made using a Leica MZ12s stereomicroscope or similar. Measurements were made using an ocular reticle. Habitus photos of beetles were taken as image stacks using a modified Microptics XLT digital imaging system that were then aligned and assembled with Helicon Focus version 5.3 and those image files were edited to enhance clarity using standard image editing software.
A total of 51 morphological character are used in the phylogenetic analysis. The characters and character states are discussed and detailed in the morphology section below, divided by body tagma, and with continuous numbers as they appear in the matrix. Most characters (32) are binary. Multistate characters were treated as unordered in the parsimony analysis. The morphology matrix is largely complete, with only three characters of the female tract not scored for 19 OTUs in which the female is unknown or has not been studied and similarly, four OTUs are not scored for male leg and aedeagus characters. The full matrix is included as a Mesquite file on Data Dryad (https://doi.org/10.6078/D10411).
Male genitalia and female tract preparations. Specimens were relaxed either by placing them in near-boiling distilled water with a drop of dishwashing detergent for about 30 min or by placing them in a relaxing chamber with water and chlorocresol for one to three days. For the female reproductive tract the entire abdomen was removed and invaginated tergites and sternites connected to the female reproductive tract removed. Male genitalia, typically including the ring sclerite, was extracted from abdomen. For both males and females soft tissues digested by placing the sample into room temperature, 10% KOH or by placing the sample in a pancreatin solution (
Abbreviations used for loci and their aligned length in the matrices are as follows: 28S: 28S ribosomal DNA (1297bp); COI: cytochrome oxidase I, (851bp, JER-PAT primer region (COIjp), 707bp, HCO-LCO region (COIf)); wg: wingless (529bp); CAD2: carbamoyl phosphate synthetase domain of the rudimentary gene (931bp). Fragments for these genes were amplified using polymerase chain reaction, exo-sap cleaned and sequenced following the same procedures and primers given by
The matrix is complete for all loci for 72 of the 80 terminals where material was available for DNA extraction. At least two loci were required for inclusion in the dataset. The few lacking loci are: wg- Cerabilia edentata Will, 2020, C. montivaga Will, 2020, and Zeodera lata (Darlington, 1962); 28S- C. iridescens Will, 2020 C. spinifer Will, 2020 and Z. subiridescens (Macleay, 1871); COI- C. orbiculata Will, 2020 and Oxycrepis epiphyta (Will, 2004); CAD2- C. spinifer and O. epiphyta. All sequences are of approximately the lengths given above with a few exceptions. The 28S sequence for Pediomorphus obtusus Will, 2019 failed to sequence clearly for the d3i primer and the included sequence ends at aligned position 804 and is derived from the d1 primer. Similarly, C. klingonorum Will, 2020 failed to sequence for CAD2 for the CD668R primer and the 462bp included are derived from the CD439F primer only.
Alignment of the protein-coding sequences was straightforward with the only insertions or deletions in wg in the region of the aligned position 170–193 representing two to four amino acids. Multiple sequence alignment of 28S was performed by MAFFT (
All matrices, input files, script files, and output files for all analyses are included on Data Dryad (https://doi.org/10.6078/D10411).
Three Bayesian analyses were done; 1. the 80 OTU matrix with sequence data and morphological data, 2. the 80 OTU matrix with sequence data alone, and 3. the 81 OTU matrix that also includes Z. simplex, represented in the matrix only by the morphology of the holotype. Models of nucleotide evolution where chosen with the aid of mrModelTest (
A parsimony analysis of the morphology partition for all 81 OTUs was done. The matrix was submitted to TNT parallel version (
The resulting trees from the Bayesian analysis of the combined data (analyses 1 & 3, (Suppl. material
Phylogeny of Loxandrina inferred from a Bayesian analysis of the combined dataset (analysis 3). Numbers at nodes are posterior probability values (PP). Stars at nodes mark clades found in a parsimony optimality analysis using the morphology partition. Diamonds at nodes mark recognized genera and subgenera inferred from a Bayesian analysis of the sequence data partition (analysis 2).
The parsimony analysis of the morphological matrix for all OTUs resulted in shortest trees of 227 steps and a strict consensus tree that was largely unresolved (Suppl. material
Given that the analyses are generally compatible, the resulting tree from the combined matrix including all OTUs (Fig.
The clade of taxa from the Australian region includes Cerabilia as sister to Zeodera + Pediomorphus, which are each reciprocally monophyletic. Zeodera includes all taxa formerly included in Loxandrus from the region and all the Zeodera-like New Guinea genera, Nebrioferonia Straneo, 1939, Haploferonia Darlington, 1962, and Homalonesiota Maindron, 1908. Cerabilia includes an exclusively New Caledonian clade, subgenus Biliacera Will, 2020, which contains a derived clade of Cerabilia (Biliacera) inversa Will, 2020, C. (B.) klingonorum, C. (B.) letalis Will, 2020, C. (B.) sternovillosa Will, 2020, C. (B.) vitalis Will, 2020, and C. (B.) wisei Will, 2020, which all share an inverted – right side up – position of the aedeagus when in repose. All Australian Cerabilia are in the subgenus Feronista Moore, 1965 and are placed in a single clade, though with rather modest support (PP 0.63).
Many species of the tribe have a generalized form that is similar to species of Platynini or Harpalini. They are generally, but not universally, separable from these taxa by lack of the angular base of stria 1 (Fig.
Basal portion of the left elytron paired with a labeled, schematic representation of configurations of striae and basal setae. Schema after
Most tribal-level keys will trace loxandrines to Pterostichini (e.g.,
Characters discussed below have been used by at least some previous authors and most were presented by
General habitus: Figures
The majority of species, primarily members of Oxycrepis and Zeodera, have the microsculpture of the dorsum, on one or more body region, with microlines that cause an iridescent reflection, i.e. diffraction gratings (
Head: The structure and form of the head varies little across all loxandrine taxa. The head is moderately elongate, mandibles moderately prominent and slightly curved. Palpi are fusiform and have very few setae, except in Pediomorphus, where the apical labial palpomeres are enlarged, setose and bear a ventral sensorium (
In Abacetina a very short, transverse mentum is common. Some Loxandrina approach this condition but are never as short as in many Abacetus species where the epilobes are less prominent than the medial tooth (
Thorax and legs: The form of prothorax is quite variable, but is typically slightly transverse or quadrate with the margins arcuate for their most of their length and somewhat sinuate in the basal half. Rarely the base of the pronotum is greatly constricted and the sides prominently rounded as in the subgenera Oxycrepis s. str. and Stolonis. Elytra are normally not fused and the flight wings are typically fully developed, i.e. large enough to have an apically folded region. However, flight wing reduction has occurred in many taxa e.g., all Cerabilia, some Zeodera (e.g., Z. atra, Z. simplex) and some North American Oxycrepis (
Protarsomeres and metepimera. Male left tibia and protarsomeres: A. Oxycrepis (Loxandrus) recta (Say). Asymmetrically expanded, as in typical many Loxandrina species; B. Oxycrepis (Adrimus) gebi Will narrow, symmetrically, slightly expanded. Metepimera, left side: C. Oxycrepis (Loxandrus) recta. Large, elongate, apically rounded form, as in typical Loxandrina species. Black outline added to emphasize shape; D. Oxycrepis (Adrimus) rasutulis Will. Rectangular, narrow, truncate form, black outline added to emphasize shape. Drawings of alternative metepimera shapes: E. short, apically rounded form; F. narrowly triangular, truncate form.
The terms “scutellar striole,” “abbreviated stria,” “parascutellar striole,” and their variants in non-English languages, have been used to refer short striae near the scutellum or in the region of stria 1 or 2. However, these terms do not necessarily refer to homologous structures across all groups and are not consistently used by various authors. Given that both the base of stria 1, whether connected to the rest of stria 1 (Fig.
In beetle elytra the path of the tracheal trunks, main nerves, and flow of hemolymph is through wing veins. These veins are homologous across pterygotes and arranged, from the suture to the lateral margin: 2nd anal, 1st anal, cubitus, media, radius, subcosta+costa (
The 2nd anal vein (interval 1) is branched basally, forming the parascutellar striole between its two branches. The parascutellar striole originates at the elytral base near the scutellum. In most carabids the parascutellar striole is relatively short. However, in some, such as most Migadopini, the parascutellar stria is nearly the length of the elytra, joining stria 1 in the apical third. In such cases the first two apparent elytral intervals actually correspond to the branches of the 2 anal vein.
The stria that forms the boundary between interval 1 and interval 2 is referred to as stria 1. At the point that interval 1 (2nd anal) branches, stria 1 angles away from its path that is otherwise parallel to the suture as its origin is near the basal setigerous puncture, usually close to or joining stria 2. When this basal section of stria 1 is interrupted (Fig.
The parascutellar striole is directly adjacent to the scutellum on the elytra and continuous with the basal marginal border of the elytra when the border is evident (Fig.
In all abacetine taxa, elytral stria 1 is joined with the parascutellar striole and the angular base of stria 1 is absent (Figs
A single setigerous puncture on interval 3, often touching stria 2, is found in nearly all loxandrine taxa. An impunctate elytron is only seen in Australian Pediomorphus and the subgenus Feronista. Multiple setae on interval three and other intervals as well, has arisen multiple times in the South American taxa, e.g., Oxycrepis s. str., Metoncidus, Stolonis, group-17 species of
A single, linear basal impressions of the pronotum on each side is the typical state for both Abacetina and Loxandrina taxa. However, these impressions may also be punctiform, broad and shallow, or even absent or nearly so (e.g., many Cerabilia species). No loxandrine taxa have both a medial and lateral impression on each side such as is found in various pterostichine taxa such as, Pterostichus and Prosopogmus Chaudoir, 1865.
Obliquely dilated protarsomeres in males is a feature that is found in many loxandrine taxa with notable exceptions in species from several genera and subgenera including Adrimus, Metoncidus, Cerabilia and some Oxycrepis. The usual tarsomere form is asymmetrically expanded and somewhat cordate (Fig.
Ventrites are glabrous or rarely finely and sparsely pubescent and the sculpturing is smooth or slightly rugulose. Ventrites do not have deep foveate punctures nor transverse sulci. Ventrite 6 of males has two paramedial setae except in Metoncidus, which has four, and females have four setae except in a few Oxycrepis species with only two, e.g., O. strigomeroides.
One of the most striking features of species of Loxandrina is the variation in the female reproductive tract. Species may have the typical, elongate spermatheca, such as is found in nearly all Pterostichini (e.g.,
The ostium of the median lobe is almost universally positioned dorsally and only rarely, and slightly, rotated laterally. The dorsal position of ostium of median lobe of the aedeagus is most likely plesiomorphic as it is the state of nearly all loxandrines. In those few taxa with a somewhat deflected ostium, the deviation is slight and not comparable to strongly contorted structures that are distinctly oriented to the left, as in many Northern Hemisphere Pterostichini, or to the right, as in various Australian Pterostichini (
Salicylaldehyde was found to be the primary pygidial gland chemical in two Australia species of Loxandrus (
Larval characters have not been studied for many loxandrines or related taxa. Only Oxycrepis velocipes (Casey, 1918), O. semperfidelis (Will, 2008), and O. oophaga have described larvae (
Genus-group names are defined here to represent monophyletic groups as far as the available evidence allows and then nomenclatural precedence is followed for generic and subgeneric names used. Shifting to an evidence-based classification consistent with the phylogeny requires recombining a large number of species previously included in Loxandrus in either Zeodera Laporte, 1867 or Oxycrepis Reiche, 1843. These two genera in their traditional, strict sense were monotypyc (Zeodera) or included only four species (Oxycrepis), but given the new concept of the genera presented here, now include many dozens of species each (Fig.
Classifications are most effective and have their greatest information content when they are consistent with the process that produced the pattern of relationships and diversity of the currently recognized biologically significant entities, i.e., monophyletic genera and species. The division of Loxandrus auctorum into two great clades that don’t share a most recent common ancestor exclusive of Pediomorphus Chaudoir, 1878 and Cerabilia Laporte, 1867 is reflected in the nomenclatural changes as demanded by the Linnaean system now implemented by The Code (
Subgenera are retained and restricted to include only those species in this analysis or those that have been studied sufficiently and have explicit, published character evidence that can be used as a basis for inclusion. Many species that have not been adequately studied or documented are included as incertae sedis at the level for which evidence exists. For example, most species of Central and South American Oxycrepis have only brief descriptions and I have only made a cursory study of them. These are all placed as Oxycrepis incertae sedis given that they can only be placed in the large, New World clade and cannot be confidently assigned to the subgenus Loxandrus clade or the clade containing Oxycrepis s. str. A more complete analysis including all or many more of the New World species may be able to place all taxa. At that point the generic concepts may need further adjustment.
Tribe Pterostichini Bonelli, 1810
Pterostichus sharpianus Broun, 1893: 163, by original designation.
Keys and descriptions in papers by
Four species restricted to New Zealand.
Species are very typical looking pterostichines, similar to a medium sized unadorned species of Notonomus or Pseudoceneus Tschitschérine, 1901. All are reddish-brown to black, 8–12 mm in length, and brachypterous.
In general, Aulacopodus species are not particularly loxandrine-like. Specifically the truncate metacoxal sulcus and the abs1 are not known from any loxandrine species. All the other characters noted above are found in some loxandrine species but never in combination as in Aulacopodus. The combination of two or three setiferous punctures on elytral interval 3 and the short metacoxal sulcus is typical for Setalis series species (sensu
Tribe Abacetini Chaudoir, 1873
Abacetina
Cosmodiscus rubripictus Sloane, 1907: 372, by monotypy.
Key to New Guinea species (
Eight species that cover a range from India, to Japan, New Guinea, and Australia.
Species are medium to small sized, 5–9 mm, rather broad bodied beetles with very prominent eyes and sharply curved mandibles. In general they are reminiscent of some Drimostomatini taxa but do not share the characteristic rotated, right side up aedeagus found in that tribe (
In leaf-litter on the ground in New Guinea rainforests (
While Cosmodiscus is clearly within Abacetini there is no evidence that it is a member of Loxandrina.
Tiferonia parva Darlington, 1962: 562, by original designation.
Review of genus and key to species (
Four species from New Guinea, the Philippines, Cambodia (B. Gueorguiev in litt.), and central Africa.
Small sized beetles (3.5–5.0 mm). These beetles are moderately convex, shiny, brown and the elytra somewhat or significantly iridescent. In general form they are similar to some small species of Lecanomerus Chaudoir, 1850 or larger Tachys Dejean, 1821. Recognizable from other, similar looking abacetine genera by the combination of deep post-ocular sulcus, smooth elytral margins; and lack of elytral discal setae.
Wet, shady areas near water (
Darlington described Tiferonia as being “a minute Loxandrus” with a few significant differences, he also discusses the possibility that they are related to Melanchrous Andrewes or Holconotus Schmidt-Goebel, 1846 (= Fouquetius Maindron, 1906), with the latter relationship having more character support. Tiferonia has sinuate metacoxal sulci that end in the middle of the coxa, sharply impressed and divergent frontal impressions, symmetrically expanded male protarsi, a moderately transverse mentum, and lacks the puncture on interval 3 of the elytral disc. All of these characteristic are also found in Holconotus, but also in many other Abacetina taxa. Tiferonia and Holconotus species share the presence of a sharply impressed sulcus on the non-ommatidia portion of the ocular orbit just behind the eye, a character not found in any other Abacetini species and likely a synapomorphy for these two genera. Tiferonia lacks the serrulations near the humeri on the elytral marginal bead that are found in Holconotus species (
All presently described species of Loxandrina are placed in recognized genera, subgenera, or as incertae sedis (Suppl. material
Loxandrus LeConte, 1853: 250. Type species Feronia recta
Oxycrepis leucocera Reiche, 1843: 78, by monotypy.
subgenus Loxandrus LeConte, 1853; type species Feronia recta Say, 1823: 58, designated by
=Megalostylus Chaudoir, 1842 nec Schoenherr, 1840; type species Feronia recta Say, 1823 designated by
subgenus Adrimus Bates, 1872; type species Loxandrus viridescens Bates, 1871: 132, designated by
subgenus Metoncidus Bates, 1871; type species Metoncidus tenebrioides Bates, 1871: 134, by monotypy.
subgenus Stolonis Motschulsky, 1866; type species Stolonis notula Motschulsky, 1866: 231, by monotypy.
= Prostolonis Mateu, 1976; type species Prostolonis martinezi Mateu, 1976, by original designation. Synonymy by
Review of some South American species (
Currently 244 species are described. The vast majority of species are found in tropical South America. The group extends south to at least southern Buenos Aires Province, Argentina, north through tropical South America, Central America, the Caribbean and eastern North America as far north as Ontario, Canada, in the southwest west to Arizona, USA and east to the Atlantic coast.
The most diverse genus in Loxandrina. Though most Oxycrepis species are very similar looking, with a body form generally similar to an average platynine or small pterostichine, the genus includes several highly divergent forms that have been described and recognized as genera. The most common form is well represented by, O. recta the type species of the subgenus Loxandrus (Fig.
These beetles are terrestrial, epigeal, usually found in moist to very wet habitats. They may be associated with standing or running water, though species in Central and South American rainforests can frequently be found far from water in very wet, closed canopy forests. They are nocturnally active, generalist predators that are frequently found in mixed species aggregations. I have collected as many as six species together under a single rock in localities in southeastern USA. Tropical species are frequently found at high density in areas with fallen flower-petals and/or fruits (
Nominally seven genus-level taxa are subsumed in this clade. Of those, Megalostylus is a junior homonym of Megalostylus Schoenherr, 1840 (Curculionidae) and Prostolonis is currently considered a junior synonym of Stolonis. The other five have been considered generically distinct, but Oxycrepis s. str., Adrimus, Stolonis and Metoncidus are all derived from within a clade of New World species that were classified as Loxandrus by previous authors. This renders a concept of Loxandrus that includes all the New World species paraphyletic (Fig.
The species of these five groups are all included in the subgenus Loxandrus. They are all similar in general form and share a combination of character states. They are typically medium sized (5–13 mm), black or piceous, with legs, antennae, and mouthparts often paler, flavous or orangish brown. Elytra are uniformly dark or rarely have an orange spot near the apex. Many are somewhat or very glossy and have an obvious spectral iridescence, especially ventrally. The majority of species appear to have large and functional flight wings, but rarely the flight wings are reduced. Elytral interval 3 has a single puncture and the elytral plica is well-developed. Males have distinctly asymmetrically expanded protarsomeres. The metepisternum is long and apically rounded. The apex of the prosternal process does not have a raised margin. The mentum tooth does not reach the level of apices of lateral lobes and the paramedial pits are indistinct.
The subgenus Adrimus was initially established as a genus by
Five Adrimus species are known only from the female holotype and for five others I have not examined males. Among the species I have examined male protarsomeres have three forms (Fig.
There is no clear correlation of the states for the characters of the male protarsi and metepimeron. Oxycrepis (A.) viridescens was selected by
Unfortunately specimens of Adrimus-like species are rarely collected. I included only two species in my analysis from which I could extract DNA, one from Brazil and one from Colombia. Both are typical Adrimus in that they have a very short, truncate metepimeron. As these two are found to be most closely related to each other with very high support (PP 1.0, Fig.
Stolonis species are typically recognized by their narrowly constricted pronotal base and serrulate protibial spurs. This subgenus appears to be monophyletic but there is a great deal of variation and overlap in some characters with other Oxycrepis. Stolonis includes some species with bi-colored antennae and legs, states also found in Oxycrepis s. str. and Straneo’s group-17 species. A few Stolonis species have additional setae on elytral intervals 3, 5, and 7, such as is found in species of Metoncidus. Some species have the dorsal surface of the median lobe with a region of thin, translucent and almost membranous cuticle similar to what is found in some species of Adrimus. There is variation in pronotal shape, but all are notably basally narrowed, most are more or less prolonged beyond the level of the hind setae (
Metoncidus is a small, exclusively South American subgenus that includes three species with a distinctive combination of character states including an elongate, parallel-sided form, relatively short antennae, male ventrite VI with four setae, and many setae on elytral intervals 3, 5, and 7. The species were recently treated (
More than 150 species are placed in Oxycrepis incertae sedis. Informal groups of species that have been created in previous works are used to help organize these taxa by some notion of similarity (Suppl. material
Pediomorphus planiusculus Chaudoir, 1878: 29, by monotypy.
Review of genus, key to species and synonymies (
Thirteen species all restricted to Australia.
Species of Pediomorphus are small, 3.5–8.2 mm (most around 4.5 mm), dorsoventrally depressed, usually pale, flavous or castaneous, usually with crenulate elytral stria. All species have enlarged labial palpomeres with a setose, ventral sensorium, subocular carina, evident elytral plica, and lack elytral discal setae.
Pediomorphus are commonly taken at lights at night and are known from open habitats (
The species included form a well-supported clade sister to Zeodera. In addition to DNA sequence data for the exemplars, the modified palps and derived lack of dorsal puncture on the elytra found in all species are synapomorphies.
= Poeciloidia Tschitschérine, 1891. Type species Feronia iridescens Laporte, 1867: 132 (sensu Tschitschérine, see
Zeodera atra Laporte, 1867: 114, by monotypy.
subgenus Haploferonia Darlington, 1962
Type species. Haploferonia simplex Darlington, 1962: 548, by monotypy.
subgenus Homalonesiota Maindron, 1908
Type species. Homalonesiota karawarii Maindron, 1908: 295, by monotypy.
subgenus Nebrioferonia Straneo, 1939
Type species. Nebrioferonia strigitarsis Straneo, 1939: 119, by monotypy.
Keys to genus-level taxa (
Twenty five species are presently described from Australia, New Guinea and Sulawesi.
Medium to moderately large sized beetles (6.0–22.0 mm). Most are black or piceous and some are castaneous or brown. Legs, mouthparts and the ventral surface of the body may be paler than the dorsal surface, but not more than moderately contrasting. The elytra are concolorous and never have distinct pale spots or vittae; at most the elytron may be slightly paler on the first interval and vaguely paler near the apices of the elytra. Many are very glossy and often with a more or less prominent spectral iridescence. Species from the drier interior of Australia are frequently a dull matt from the prominent mesh microsculpture. The apex of the prosternal process has a raised margin in the majority of species. The elytral plica varies from large and well-developed to completely absent. Elytral interval 3 consistently has a single discal puncture. Though most species are very typical looking Loxandrina and so reminiscent of platynines in general body form, the genus also includes forms from very broad, Abax-form as in Z. atra, (Fig.
No larval descriptions have been published for any Zeodera species. I have examined a larva of Z. longiformis (reared by B.P. Moore). It is a typical looking loxandrine larva, similar to the described larvae of O. velocipes.
Species of Zeodera are found across habitats from rainforest (uncommonly), closed forests (
There are five genus-level taxa that were recognized by previous authors that are included in the Zeodera clade: Loxandrus, which is herein restricted to New World taxa, Zeodera, Homalonesiota, Nebrioferonia, and Haploferonia. Zeodera has priority as the earliest established genus-level taxon among the four names for taxa in the clade.
The four subgenera were all originally established as genera based on overall body shape and a small number of morphological features that in combination distinguish them (see the key). The nominate subgenus of Zeodera only includes Z. atra, which has a distinctive broad body form, short metepisternum and evident elytral interval 10. Zeodera (Haploferonia) simplex (Fig.
While Z. simplex is placed within the Zeodera clade its relationship to other species remains uncertain. It is only known from the single female holotype and the character data available for analysis is very limited.
Homalonesiota (Fig.
Aside from the trisetose mesocoxae in Nebrioferonia and the notably elongate antennomere 1 in Homalonesiota, there is no significant difference between these species and other Zeodera species. There is also no clear evidence that these taxa form a clade within Zeodera. The New Guinea Zeodera species are scattered across the clade suggesting that there are multiple connections, possibly dispersal events, between Australia and New Guinea.
= Nelidus Chaudoir, 1878; type speciesNelidus australis Chaudoir, 1878: 50, by monotypy. Synonymy by
= Zabronothus Broun, 1893; type speciesZabronothus striatulus Broun, 1893: 1327, designation by
= Australomasoreus Baehr, 2007; type species Australomasoreus monteithi Baehr, 2007: 6, by original designation. Synonymy by
Cerabilia maori Laporte, 1867: 116, by monotypy. Republished description Laporte, 1868: 202. subgenus Feronista Moore, 1965; type species Feronista amaroides Moore, 1965: 26, by original designation. subgenus Biliacera Will, 2020; type species Cerabilia vitalis Will, 2020:79, by original designation.
Revision, keys to species, generic descriptions, and synonymies for Australian and New Caledonian taxa (
Sixty-one species described from northeastern Australia (30 spp.), New Zealand (7 spp.), and New Caledonia (24 spp.).
Very small to medium sized beetles (3.4–11 mm), slightly to significantly broader and more convex than typical for taxa in the subtribe. At one extreme of the body forms Cerabilia species are nearly as oval and convex as a typical Cosmodiscus and on the other extreme, they are elongate ovoid, approaching the typical Zeodera body form. Easily recognizable among loxandrines by combination of the very short metepisternum, completely reduced flight wing, heavily built legs with robust spines, and absence of the elytral plica. Among Zeodera, only Z. lata (Darlington) (Fig.
All species are found in rich leaf litter of wet forests and rainforests. They are difficult to find during the day, but are readily collected at night in forest leaf litter. It appears that they are in the upper soil layer during the day and emerge during the night. They are uncommonly found under rocks or woody debris in the forest.
The phylogeny presented here includes less than half of the described species of Cerabilia but it shows strong support for the monophyly of the genus in the combined analysis (PP 0.99), however, analyses of sequence data alone does not include a Cerabilia clade. The monophyly of the New Caledonian subgenus Biliacera is well supported in all analyses and very strongly (PP 1.0) in the combined data analysis. The exclusively Australian subgenus Feronista is supported as a clade in combined analysis, but with modest support (PP 0.63). In both combined and sequence data only analyses all species of Feronista are found to comprise a clade except for Cerabilia (F.) oodiformis, which is sister to the Biliacera clade but with modest support (PP 0.70). Cerabilia s. str. is only represented in the analyses by two species and while the pair always emerges as sister species, their position as sister to Feronista only has modest support (PP 0.64) in the combined analysis and in the sequence data only analysis they are sister to the Cerabilia (F.) oodiformis + Biliacera clade.
A variety of Harpalinae taxa are superficially similar to members of Abacetini. Typically abacetines will run to Pterostichini, or the equivalent supertribal or subfamilial taxon in regional keys. A combination of character states, most of which are the absence of identifying features of other tribes, can be used to identify a specimen as a member of Abacetini.
Readily observable anatomical features typically used for identification are variable in Loxandrina, this requires running some of the taxa out at multiple points in the key. In addition to character states, distributional information is a very useful guide to a correct identification.
1 |
Harpalinae with the presence of any one or more of the following character states: angular base of stria 1 present (Fig. |
other pterostichine grade or Pterostichini-like Harpalinae taxa, consult regional keys if available. |
– | Without any of the characteristics above. Abacetini | 2 |
2 | Presence of any one or more of the following character states: Antennomere 2 prominently asymmetrically inserted onto 1; metacoxal sulcus arcuate, sinuate and/or ending well before lateral apex; mentum extremely short and transverse or proepisternum with stridulatory file or pegs. In addition the elytral plica is usually present and male protarsomeres symmetrically expanded. Distributed throughout Africa to southern Europe, tropical and subtropical Asia south to Australia (Fig. |
Abacetina |
– |
Without any of the characteristics above, except for the elytral plica, which may be present or absent and male protarsomeres, which may be broadly, asymmetrically expanded, symmetrically expanded or narrow (Fig. |
Loxandrina |
1 | Dorsal surface of pronotum and elytra entirely hirsute |
Oxycrepis (s. str.) (Fig. |
– | Dorsal surface of pronotum glabrous and elytra glabrous, usually with a single setigerous puncture in interval 3. Rarely without the setigerous puncture or with a few fixed elongate setae in interval 3 or in all odd numbered elytral intervals | 2 |
2(1) | Elytral interval 3 without setigerous punctures | 3 |
– | Elytral interval 3 with one or more setigerous puncture | 6 |
3(2) | Labial apical palpomere fusiform or acuminate, lacking a ventral sensorium. Body somewhat or very convex | 4 |
– | Labial apical palpomere subglobose with a ventral sensorium. Body somewhat or distinctly flat |
Pediomorphus (Fig. |
4(3) | Elytral humeral angle with prominent, sharp denticle | 5 |
– | Elytral humeral angle rounded, without denticle |
Cerabilia (Feronista) (Fig. |
5(4) | Distinctly oodine-like body form. Parascutellar puncture present. Elytral striae shallowly impressed apically and not impressed in basal 5th | Cerabilia (Feronista) oodiformis [Australia] |
– | Elongate ovoid body form. Parascutellar puncture present or absent. Elytral striae impressed to or nearly to base |
Cerabilia (s. str.) in part (Fig. |
6(2) | Pronotum with lateral margins straight, sinuate or rounded to the base, but width never very narrowly constricted to the base. Level of the pronotal basal margin at or very nearly at the same level as the baso-lateral setae | 7 |
– | Pronotum cordiform, very distinctly narrowed basally. Basal margin at a level produced well beyond the level of the baso-lateral setae in most species |
Oxycrepis (Stolonis) (Fig. |
7(6). | Metepimeron elongate or somewhat short but rounded apically (Fig. |
8 |
– | Metepimeron very short, rectangular or narrowly triangular and truncate apically (Fig. |
Oxycrepis (Adrimus) (Fig. |
8(7) | Elytral interval 3 with two, one, or no setigerous punctures in apical half or third | 9 |
– | Elytral interval 3 with five to ten setigerous punctures in apical half or third |
Oxycrepis (Metoncidus) (Fig. |
9(8). | Pronotum without posteriolateral seta. Elytral interval 3 with one to five setigerous punctures. | 10 |
– | Pronotum with posteriolateral seta. Elytral interval 3 with only one setigerous puncture. | 11 |
10(9) | Elytra with evident plica. Elytral interval 3 with one setigerous puncture. |
Zeodera lata (Fig. |
– | Elytra without evident plica. Elytral interval 3 with one to five setigerous punctures |
Cerabilia (Biliacera) (Fig. |
11(9:) | Antennomere 1 equal or shorter than 2 and 3 combined. | 12 |
– | Antennomere 1 longer than 2 and 3 combined. |
Zeodera (Homalonesiota) (Fig. |
12(11) | Mesocoxae with two setae, one lateral and one posteriomedial. | 13 |
– | Meoscoxae with three setae, two lateral and one posteriomedial. |
Zeodera (Nebrioferonia) (Fig. |
13(12) | Prosternal process without raised marginal border at apex. | 14 |
– | Prosternal process with raised marginal border at apex. | Zeodera, in part [Australia, New Guinea and Sulawesi]. |
14(13) | Elongate, parallel-sided or ovoid body form. Flight wing and pronotal form variable. Medium to small size, rarely over 12 mm. | 15 |
– | Broad, Abax-like body form. Flight wing reduced. Pronotum trapezoidal. Large size, 16–22 mm |
Zeodera (s. str.) atra (Fig. |
15(14) | Lacking one or more of the features below. Typically black iridescent (maculate elytra in many New World species), moderately depressed body form, elytra usually with plica and normally full flight wing. | 16 |
– | With the following combinations of features: convex body form, concolorous brown, flight wing reduced, elytra without plica, elytral humeral angle with prominent, sharp denticle |
Cerabilia (s. str.) in part (Fig. |
16(15) | Distributed in Australia, New Guinea and Sulawesi. Raised marginal bead of the prosternal process usually present. | 17 |
– | Distributed in North, Central and South America. Raised marginal bead of the prosternal process usually absent | Oxycrepis (Loxandrus) or Oxycrepis incertae sedis, in part |
17(16) | With the following combinations of features: metasternum medial sulcus not apparent. Elytra without plica, flight wing reduced, body form elongate, and pronotum elongate rectangular |
Zeodera (Haploferonia) simplex (Fig. |
– | Lacking one or more of the features above. Metasternum medial sulcus apparent, often deeply impressed; elytra with evident plica, and full flight wing. Body form various |
Zeodera, in part (Fig. |
There is no fossil record for Abacetini. Without the means to confidently, temporally calibrate the phylogeny, testing historical biogeographic scenarios for the group is severely limited (
Past historical biogeographic inferences for abacetines (
Comparative summary of past and present classifications of loxandrine-series taxa.
Taxon | Moore, 1965 | Allen & Ball, 1980 | Allen, 1982 | This study |
---|---|---|---|---|
Aulacopodus | Included | Included | Included | Not included, transferred to Pterostichini |
Cosmodiscus | Included | Included | Removed | Not included, placed in Abacetini incertae sedis |
Tiferonia | Not treated | Included | Included | Not included, placed in Abacetini incertae sedis |
Oxycrepis | Not treated | Included | Included | Included |
Loxandrus | Included | Included | Included | Included, restricted to New World taxa, subgenus of Oxycrepis |
Adrimus | Not treated | Included | Included | Included, subgenus of Oxycrepis |
Stolonis | Not treated | Included (as subgenus of Oxycrepis) | Included (as subgenus of Oxycrepis) | Included, subgenus of Oxycrepis |
Metoncidus | Not treated | Included | Included | Included, subgenus of Oxycrepis |
Pediomorphus | In Abacetus series | Not treated | Not treated | Included |
Zeodera | Included | Included | Included | Included, expanded to include Australian and New Guinea taxa |
Haploferonia | Not treated | Included | Included | Included, subgenus of Zeodera |
Nebrioferonia | Not treated | Included | Included | Included, subgenus of Zeodera |
Homalonesiota | Not treated | Not treated | Included | Included, subgenus of Zeodera |
Cerabilia | Included (Feronista species only) | Included (Feronista species only) | Included (Feronista species only) | Included, three subgenera: Cerabilia s. str., Feronista and Biliacera |
The distribution of the tribe as a whole can be described as Gondwanan and amphi-Atlantic (“transatlantic (south)” and “amphiantarctic” of
There is significant evidence that during the late Jurassic to mid-Cretaceous period an extensive belt of warm, humid climate, at middle to high latitudes, extended over southern South America, southern Africa, India, Australia and Antarctica (
Loxandrina is split into two clades, Oxycrepis species are presently found in the Neotropical and Nearctic regions and the clade of Zeodera, Pediomorphus, and Cerabilia, are now exclusively in the Australian region. Assuming a southern origin, the common ancestor of these clades would have most likely had a trans-Antarctic distribution. The separation of the Australian and American lineages is certain to have been complete by 30 Ma, when the Australian and South American continents are thought to be fully separated from Antarctica. However, it is quite possible that the vicariance was much earlier. Between oldest possible time of the last common ancestor of Loxandrina and its sister group around 165 Ma and the full isolation of Antarctica 30 Ma, ending in the opening of the Tasman Gateway that created the Southern Ocean, several major events occurred. Any one of these events could have precipitated the disjunction. These events include the K-Pg extinction event 66 Ma (
In addition to the source area difference, there is an age difference between the two scenarios corresponding to the likely date of the split of the Abacetini common ancestor across the developing Atlantic. Unlike the southern origin above, under the northern origin scenario Abacetini was in the tropics at around 100 Ma when the equatorial humid zone developed in northern South America and northern Africa and not in the trans-Antarctic region until much later. The northern South America and northern Africa landmasses were still connected or relatively close at the time and one abacetine lineage was in or dispersed to South America and subsequently was separated from the African Abacetina lineages. This scenario was proposed for Galeritini (
Under either the northern or southern scenario, loxandrines from South America were able to enter North America, possibly as early as the mid-Tertiary (
The occurrence of Cerabilia, but not Zeodera or Pediomorphus, in New Caledonia and New Zealand could be due to an old, trans-Antarctic distribution and vicariance (
Some readers will recall when the U.S. National Science Foundation invested in PhD dissertation research by providing students small grants. This is one of many papers (many cited herein) that significantly benefitted from a seed of a little more than $7000 in 1997 (DEB-9700764 to J.K. Liebherr for my dissertation project). Additional financial support was provided by DEB-0444726 for travel to Australia and various museums. I thank both James Liebherr (Cornell University) and David Maddison (Oregon State University) who have provided support, encouragement, and very important critique over the years this project covers and so have contributed in many ways. I thank all the curators and collection managers at the various institutions listed in materials above for being very generous with their time and providing loans and in many cases acting as host for my visits to work in their collections. I am indebted to the reviewers for excellent suggestions that improved the manuscript. Especially helpful were critical suggestions provided by Pierre Moret.
Loxandrina new classification
Data type: species list
Explanation note: Checklist of all species included in Loxandrina.
Table of GenBank numbers
Data type: Genbank Number
Tree figures for MrBayes and TNT analyses
Data type: phylogeny
Explanation note: Tree figures file for Mr Bayes and TNT analyses. Two MrBayes trees for all data 80 OTUs and sequence data only 80 OTUS. Consensus tree from TNT analysis.