Research Article |
Corresponding author: Juuso Paappanen ( japaappanen@gmail.com ) Academic editor: Dominique Zimmermann
© 2024 Juuso Paappanen.
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:
Paappanen J (2024) Lochetica ramii sp. nov. – a new species of Lochetica Kriechbaumer, 1892 (Hymenoptera, Ichneumonidae, Phygadeuontinae) from Finland, with a key to world species. Deutsche Entomologische Zeitschrift 71(1): 193-208. https://doi.org/10.3897/dez.71.121217
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Two tentatively distinct morphological forms belonging to the Darwin wasp genus Lochetica Kriechbaumer, 1892 (Hymenoptera, Ichneumonidae) were found to occur in Finland, although only one species is known in Europe. The identity of the two forms were resolved by examining additional museum material, DNA barcoding and revising the relevant types. Both morphology and molecular results support the recognition of a new species, Lochetica ramii sp. nov., from Finnish specimens – in addition to Lochetica westoni (Bridgman, 1880) already known from Finland. New host associations are given for both species and their ecology is discussed. An identification key is given to the known species of Lochetica of the world to facilitate the recognition of the new species.
Parasitoid wasps, Phygadeuontinae, north Europe, Palearctic, saproxylic, identification, key
The Darwin wasp genus Lochetica Kriechbaumer, 1892 is a species-poor genus within the megadiverse Ichneumonidae, comprising only four species, all occurring in the Holarctic Region (
For the greater part of the 20th century, two species of Lochetica have been known: L. westoni (Bridgman, 1880) and Lochetica pimplaria (Thomson, 1888), until
Two tentatively distinct morphological forms of Lochetica were recognised to occur in Finland. This prompted the present study with the aim to resolve their identities. Subsequently, a new species of Lochetica is here described from Finnish specimens and an identification key for all five known species of Lochetica is provided. New host associations are given and the ecology of the genus is discussed.
The studied material comprises 88 specimens of Lochetica, which are deposited in the following collections (later referred by the given abbreviations):
RJK Secondary collection of Reijo Jussila, Kuhmo, Finland.
All specimens have been given ID labels by the associated museum. This facilitates later revision of the specimens mentioned in this article. In addition, all but three specimens are deposited in public museums.
Morphological terms follow
Tergite Metasomal tergite.
Temple ratio The width of the temples, in dorsal view, measured halfway between the posterior ocelli and the occipital carina, divided by the maximum width of the head (in dorsal view).
Ovi-tib ratio The length of the ovipositor projecting beyond the apex of the metasoma (in Lochetica, equal to the length of the ovipositor sheaths) divided by the length of the hind tibia (measured in outer lateral view).
POL:OOL The distance between the lateral ocelli divided by the distance between a lateral ocellus and the compound eye.
OD:OOL The diameter of the lateral ocellus divided by the distance between the lateral ocellus and the compound eye.
The specimens were examined with a common main objective type Olympus SZX16 stereo-microscope with a plan apochromatic objective, using magnifications 7×–115×. Measurements were done with an ocular micrometer, with one eye closed. The length of the body is usually impossible to measure since the body is rarely straight. The fore-wing length has been widely used as a proxy for body size. Here both measures are reported; however, the body length is not an absolute measurement of the specimen, but partly an evaluation on how long the specimen would be if straightened. This is not the ideal method, but was favoured instead of taking an absolute measurement of the specimen regardless of its posture.
Temple ratio and ovi-tib ratio were statistically compared between the species with the Welch t-test. These analyses, as well as the graphs, were done in R (v. 4.3.2) via the RStudio (v. 12.0-369) software. The package stats (v. 4.3.2) was used to perform the t-tests, the package effsize (0.8.1) was used to calculate the effect sizes and the package beeswarm (0.4.0) was used to produce the graphs.
All morphological examinations, measurements and identifications were done by the author in 2023. Photographs of the types of the Cecidonomus westoni, Phygadeuon pimplarius and L. japonica were examined.
Figs
Ten specimens of Lochetica were sequenced for the cytochrome oxidase subunit I (COI) marker (the standard barcode region sensu
In addition to these ten sequences, all public COI sequences assorted to BINs with at least one specimen identified as Lochetica were downloaded from the BOLD database (downloaded 26 Nov 2023). These included only three sequences, all from Norwegian specimens.
The resulting combined data of thirteen sequences were aligned with the MUSCLE algorithm (
A distance matrix (p-distances) was calculated in R (v. 4.3.2) via the RStudio software (v. 12.0-369), with the package ape (v. 5.7-1). Sites with missing data were deleted in pairwise calculations. The resulting matrix was transferred to Microsoft Excel 2013 (v. 15.0.5153.1000), where the distance measures were obtained. The matrix was also used to create a Neighbour-Joining tree with the same package (ape) in R.
Full data used in this study are available as Suppl. material
Comparing the mean ovi-tib ratio between L. westoni and L. ramii sp. nov. (Fig.
Swarmplots comparing the selected morphological ratios of examined females. A. Comparison of the relative length of the ovipositor. The data on Lochetica japonica Watanabe, 2021 is derived from the original description; B. Comparison of the temple ratio (see the Methods section for definition). Each point represents one specimen, the points are moved horizontally to avoid overlap.
Comparing the mean temple ratio between L. westoni and L. ramii sp. nov. (Fig.
All specimens yielded long sequences, varying in length from 621 bp to 658 bp. The COI sequences of seven specimens of L. ramii sp. nov. and six specimens of L. westoni were compared. No sequences for the other three species of Lochetica are available. The interspecific distances between the two species range from 7.12% to 8.05%, while the intraspecific distances within the specimens of L. ramii sp. nov. and L. westoni are 0.00–0.16% and 0.00–0.61%, respectively. The barcode gap is distinct (Fig.
A simple Neighbour-Joining phylogenetic tree (p-distance) illustrating the barcode gap between the specimens. The scale bar represents 1% divergence. The ID after the species name refers to the sample ID in the BOLD-database (same as the museum (specimen) ID in Finnish material). The specimens marked with an asterisk (*) have not been examined.
Lochetica Kriechbaumer, 1892: 340.
Phygadeuon pimplarius Thomson, 1888. Monotypic.
Dense punctation and hairs across the body surface. The clypeus wide, weakly separated from the face, anterior edge of clypeus and mandibles covered with very dense short hairs. Temples rather wide. Sternaulus long. Propodeum with complete carination and pentagonal area superomedia. Spiracles of first tergite near the middle. The fore wing with a closed areolet, vein 3rs-m is weakly pigmented; vein 2m-cu long, straight, forming acute angle with vein CU, with one short bulla.
Cecidonomus Westoni
Bridgman, 1880: 264. Lectotype designated by
Phygadeuon pimplarius
Thomson, 1884: 941. Lectotype designation of Townes published by
Lectotype of Cecidonomus westoni Bridgman, 1880 (photographs examined) United Kingdom (presumably) • 1 ♀; “from Mr. Weston”; “Westoni”; “lektotypus Cecidonomus westoni ♀ Bridgm. Horstm. det. 1970”; “J. B. Bridgman coll. Norwich Museum 1895.40.1124”.
Lectotype
of Phygadeuon pimplarius Thomson 1884 (photographs examined) Sweden • 1 ♀; “Öke å” [Skåne, Sjöbo, Övedskloster]; [55.684°N, 13.633°E]; “Lectotypus Phygadeuon pimplarius Thm. Tow. 58”;
Finland • 38 ♀♀, 5 ♂♂ [
The female is distinguished by the long epomia (Fig.
Lochetica westoni (Bridgman, 1880), a non-type specimen
A–C. The Lectotype of Cecidonomus westoni Bridgman, 1880. Photo credit: Tony Irwin. A. Labels; B. Head and part of the mesosoma (dorsal view); C. Habitus (lateral view); D–E. Lectotype of Phygadeuon pimplarius Thomson, 1884. Photo credit: Biological Museum, Lund University (
The extent of the red colouration on the metasoma in females varies considerably. In the Finnish specimens, usually only the first tergite is laterally slightly reddish; however, some specimens have extensively red first and second terga. A subspecies Lochetica westoni rufiventris Habermehl, 1919 from Algeria (not examined) has the metasoma completely red.
Most European countries, Turkey, Algeria, Japan (
Both open and forested habitats are used, especially sites with dead wood or other suitable nesting sites for hosts.
The type series has been reared from “galls” (
New rearing records published in this study are the following: a male reared from Passaloecus monilicornis Dahlbom, 1842 (
In conclusion, L. westoni utilises most species of the genus Passaloecus (recorded from P. gracilis, P. monilicornis, P. insignis, P. eremita, P. borealis/turionum and Passaloecus sp.) nesting in (dead) wood (including buildings and other structures), galls and most likely also plant stems.
Lochetica pimplaria f. rufiventris
Habermehl, 1919: 110. Lectotype designated by
This taxon is known from Algeria and, according to
Lochetica japonica Watanabe, 2021: 110, figs 47A–H, fig. 62J, fig 65Q, fig. 66Q.
Holotype
(photographs examined) Japan • 1 ♀; Tochigi Pref., Nasushiobara City, Shiobara, Utou-sawa; 22–28 May 2008; T. Matsumura leg.; Malaise-trap;
The female is distinguished by the long epomia (cf. Fig.
Japan (
Unknown.
Holotype
Finland • 1 ♀ (pinned); Sb [Savonia borealis], Kuopio, Mökinoja; “6966126:3529339” [62.7976°N, 27.575°E]; 18 Jun 2021; Juuso Paappanen leg.; “niitty, hirsirakennuksen seinä” [meadow, on a wall of a log barn]; COI sequence GP.113446;
Paratypes
(37 ♀♀, 1 ♂) Finland • 1 ♀; “Finby” [Särkisalo], [Finnarv, Vedudden]; [60.1143°N, 22.9485°E]; 14 Jul 1950; R. Elfving leg.;
The female differs from L. japonica by the vertex uniformly sloping from the ocelli to the occiput, with shallow, almost granulate sculpture (Fig.
The female differs from L. westoni by the short and weak latero-median carinae of the first tergite, not extending beyond the level of spiracles (Fig.
Both sexes are differentiated from L. agonia by the long epomia ventrad to pronotal sulcus (cf. Fig.
Female is differentiated from L. farta by the area petiolaris of the propodeum having rather weak transverse sculpture concentrated to the sides, usually without sculpture medially (Fig.
Female (holotype and paratypes). Length. Body length 5.6 mm (4.6–6.3 mm (n = 36)) excluding the ovipositor, fore wing length 3.6 mm (3.2–4.3 mm (n = 37)).
Head.
Punctation dense, shallow, individual punctures indistinctly delimited, coalescing, vertex more granulate than punctate (Fig.
Mesosoma.
Mesoscutum and scutellum moderately densely and shallowly punctate, similarly to head. Notauli not crenulate, weakly impressed, but long, extending to middle of mesoscutum. Posterior half of mesoscutum obscured by pin in the holotype. Scuto-scutellar groove smooth, without crenulae. Pronotum with same superficial punctures as rest of body, with stronger rugosity posteriorly and medially with larger shiny interstices between sculpture (about 2× wider than the punctures); pronotal sulcus without transverse crenulae; epomia not particularly strong, long, extending near posterior margin of pronotum ventrad to pronotal sulcus. Mesopleuron covered with denser, stronger, coalescing punctures, especially dorsad to sternaulus coalescing to form rugose areas (Fig.
Legs. Hind femora 3.8× as long as wide. Lengths of tarsal segments in mm from first to fifth: 0.53, 0.27, 0.18, 0.10, 0.02. Claws moderately curved, simple, without teeth, basal lobe or pecten, few longer hairs present at base of claw. Arolium rather small, slightly more than half length of claw. Middle and hind tibiae with two reddish tibial spurs each, subequal in length and very slightly bent at apex. Coxae mainly black, fore and middle coxae with reddish spot on inner side (paratypes: from mostly red with dark patches to black with only small red patches on the inner side of middle coxae). Trochanters black with suffused red colouration, fore trochanters more red than black. Trochantelli, femorae and tibiae red, tibiae with darker outer surface, only weakly in fore leg. Tarsi with mixture of red and dark, with segments darker on outer surface and apically with narrow, indistinct reddish annuli.
Wings. The fore wing vein 3rs-m present, weakly pigmented, areolet symmetrical, pentagonal; vein 2m-cu rather long, straight, with one short bulla, forming acute angle with vein CU; vein RS straight; radius anterior (RA) slightly longer than pterostigma; pterostigma 2.8× as long as wide; vein 1cu-a slightly postfurcal relative to M&RS. Nervellus of hind wing intercepted at lower fifth (paratypes: from one fifth to one fourth below middle). Wing veins, including the pterostigma, uniformly dark brown, excluding narrow zone at the base of the wings with pale yellow veins; humeral plates pale yellow.
Metasoma.
Punctation generally more well defined than on rest of body. First metasomal tergite with strong punctation (shiny interstices smaller than diameter of punctures), posterior part with weakly punctured area, interstices several times diameter of punctures. Dorso-lateral carinae sharp, complete, with spiracle situated just ventrad to carina (Fig.
Ovipositor.
Dorsal valve with weak, but angulate nodus, tip beyond nodus gradually tapering, sharp (Fig.
Male (paratype). Length. Body length 4.9 mm, fore wing length 3.5 mm.
Head.
Mandibles whitish-yellow with black teeth, reddish colouration next to mandibular teeth and mandibular base. Palpi pale reddish-yellow. Malar space 0.8× as long as basal width of mandible. Temple ratio 1.0, POL:OOL 1.3, OD:OOL 0.5. Anterior halves of scapes white, antennae otherwise black, with 21 flagellar segments, conversely to female, apical flagellomeres gradually narrower apically (Fig.
Mesosoma.
Generally rougher surface sculpture than in female: mesopleuron medially strongly rugose; sternaulus with longer, stronger crenulae than in female, longest crenulae as strong as and longer than crenulae on mesopleural furrow (Fig.
Metasoma. Latero-median carinae of first tergite long and rather strong, extending beyond level of spiracles. First tergite 1.5× and second tergite 0.7× as long as wide. Genitalia somewhat obscured. Parameres slightly narrowed apically and slightly downcurved, ventral margin slightly concave in lateral view, small parallel-sided gap between two parameres ventrally. Aedeagus not visible.
L. ramii sp. nov. is my first species description. Thus, I take the opportunity to name the species in the honour of my grandfather Raimo “Rami” Konga (1936–2009) who had a profound impact on the development of my love for nature, which eventually led to the discovery of this species. The specific epithet is to be treated as a noun in the genitive case.
Finland. Mainly in the Palearctic boreal forest biome sensu
The specimens have been collected from both open biotopes (Fig.
Three examined specimens (
There are not enough data to postulate whether a smaller subset of Passaloecus species is utilised as hosts (opposed to L. westoni, which seems to utilise most species) or whether additional genera of cavity-nesting aculeates are used.
Several morphological characters and an ample 7% divergence in COI sequences readily separate the new species from L. westoni. However, no sequences were available for the remaining three species. Colour characters have been partly emphasised to differentiate the new species from the morphologically closest species L. japonica. Colour is known to vary geographically between distant populations on many insects, including the Ichneumonidae. Thereby, it is possible that the differences observed are not diagnostic, which could even imply the synonymy between L. ramii sp. nov. and L. japonica; however, the differences in head structure and surface sculpture of the head and mesosoma, in combination with the differences in colour adequately distinguish the new species from L. japonica. Despite several attempts, accessing the types of L. agonia and L. farta in the collection of the American Entomological Institute failed. The original descriptions are, however, sufficient for the new species to be distinguished from the two by at least two morphological characters. Furthermore, the two species occur in very different regions (western United States and Taiwan) from L. ramii sp. nov. (Finland).
The new species is described from a rather large number of specimens. However, as more specimens from a wider geographical area are revealed, the morphological and molecular gap between L. ramii sp. nov. and other species of the genus will no doubt become smaller. For example, there were no overlapping specimens of L. ramii sp nov. and L. westoni regarding their ovi-tib ratio, but the difference is so small that it is likely that overlapping specimens are likely to surface in the future.
The males of the genus are rarely collected: three of the five species are only known from females and the number of females to males in the studied material is 38 ♀♀:1 ♂ in L. ramii sp. nov. and 40 ♀♀:5 ♂♂ in L. westoni. The sole male of L. ramii sp. nov. and three of the five males of L. westoni were reared. In addition, the reared type series of Cecidonomus westoni consisted of 9 ♀♀ and 15 ♂♂ (
The distribution of L. ramii sp. nov. in Finland is rather widespread, extending from 60° to 64° in latitude. Thus, it is almost certain that L. ramii sp. nov. is also present in the neighbouring countries, but possibly also more widely in Europe and Asia. It is possible it has been previously confused with L. westoni, as it has been in Finland.
There are probably numerous species of Lochetica yet to be described, even in well-studied regions of the world. Future studies should attempt to examine large amounts of museum material from a wide geographic area – something the scope of this study did not allow. There is also an evident scarcity of information regarding most of the described species of Lochetica as well: the hosts and ecology is unknown in three out of five species, the males are unknown in two species and two species are only known from one or two specimens.
The keys include all known species of Lochetica; however, no specimens of L. agonia and L. farta have been examined and their characters are based on
♀♀
1 | The epomia short or absent ventrad to the pronotal sulcus. The ovipositor with a rounded or absent nodus. The legs red and the tegulae yellow | Lochetica agonia Townes, 1983 |
– | The epomia long ventrad to the pronotal sulcus, extending as a weak ruga nearly to the posterior edge of the pronotum (Fig. |
2 |
2 | The area petiolaris of the propodeum very densely transversely sculptured. The latero-median longitudinal carina of the propodeum, separating the area postero-externa from the area petiolaris, is weak. The coxae, trochanters and tegulae dark | Lochetica farta Townes, 1983 |
– | The area petiolaris weakly to moderately transversely sculptured, the sculpture concentrated on the sides (Figs |
3 |
3 | The latero-median carinae of the first tergite strong, extending at least to the level of spiracles (Fig. |
Lochetica westoni (Bridgman, 1880) |
– | The latero-median carinae of the first tergite weak or absent (Fig. |
4 |
4 | The mesosoma with shallower, less defined punctures, especially the area externa of the propodeum with punctures weakly, or not, discernible amongst the weak transversely orientated sculpture (Fig. |
Lochetica ramii sp. nov. |
– | The mesosoma with more clearly defined, deep punctation, especially the area externa of the propodeum with dense, clearly defined punctures (Fig. |
Lochetica japonica Watanabe, 2021 |
♂♂
This key is very tentative. It is based on a very small sample and the males of L. japonica and L. farta are unknown. The characters in parentheses are of uncertain diagnostic value.
1 | The epomia short or absent ventrad to the pronotal sulcus. Tegulae “ivory”. The mandibles mostly red. Nearctic | Lochetica agonia Townes, 1983 |
– | The epomia long ventrad to the pronotal sulcus, extending near the posterior margin of the pronotum, but rather weakly indicated. Tegulae yellow or black. The mandibles mainly white, with blackish or reddish colouration proximally and distally. Palearctic | 2 |
2 | The tegulae yellow, similar in colour to the adjacent humeral plate (Fig. |
Lochetica westoni (Bridgman, 1880) |
3 | The tegulae black, contrasting with the pale yellow humeral plate (Fig. |
Lochetica ramii sp. nov. |
I thank all who gave access to specimens: Juho Paukkunen (Museum of Natural History, Helsinki) loaned the bulk of the material used in this study, Kyohei Watanabe (Kanagawa Prefectural Museum of Natural History) photographed the holotype of Lochetica japonica, David Waterhouse and Dr. Tony Irwin (Norwich Museum) photographed the lectotype of Cecidonomus westoni, Rune Bygebjerg and Christoffer Fägerström (Lund University Biological Museum) photographed the lectotype of Phygadeuon pimplarius, Gergely Várkonyi gave access to the previously barcoded Finnish specimens, including the sole male specimen of L. ramii. Many specimens also originated from recent species inventories conducted as part of the Beetles-LIFE and other projects carried out by Metsähallitus (Sampsa Malmberg, Mervi Laaksonen, Eerikki Rundgren). Marko Mutanen gave much needed comments, corrections and suggestions regarding the DNA barcoding sections of this paper and Ika Österblad sent me a crucial piece of literature.
R script for statistical analyses and graphs
Data type: R
Explanation note: The script file containing all the code to replicate the statistical analyses and recreate the graphs used in the study. The file is a simple text file, which can be opened in R or in any text editor (e.g. notepad).
Aligned sequences
Data type: fas
Explanation note: The aligned COI sequences in .fasta format used in the study.
Specimen and morphological data
Data type: xlsx
Explanation note: A spreadsheet file (MS Excel) containing the data of specimens used in the study. The data includes specimen id, species name, collecting location and date, collector and selected morphological characters.