Research Article |
Corresponding author: Agnieszka Bugaj-Nawrocka ( agnieszka.bugaj-nawrocka@us.edu.pl ) Academic editor: André Nel
© 2024 Jamie Ramirez, Agnieszka Bugaj-Nawrocka, Artur Taszakowski, Christiane Weirauch.
This is an open access article distributed under the terms of the CC0 Public Domain Dedication.
Citation:
Ramirez J, Bugaj-Nawrocka A, Taszakowski A, Weirauch C (2024) New species and reclassification of the fossil assassin bug Koenigsbergia (Hemiptera: Reduviidae: Phimophorinae). Arthropod Systematics & Phylogeny 82: 369-384. https://doi.org/10.3897/asp.82.e114213
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The assassin bug genus Koenigsbergia Popov, 2003 is currently monotypic and represented by a female holotype from Baltic Amber (~33.9–55.8 MYA). The genus was originally described within Phymatinae (Phymatine Complex or phymatine clade). However, our literature review reveals that the amber fossil likely belongs to the subfamily Phimophorinae, which is distantly related to the phymatine clade. The recent acquisition of one male and one nymph of Koenigsbergia provides the opportunity to reevaluate the systematic placement of this genus. We here examine the new fossils, concluding that the adult male represents an undescribed species, and describe it as Koenigsbergia explicativa, new species. Our morphological comparison between Phimophorinae, Phymatinae, and Koenigsbergia (macro imagining, scanning electron microscopy) shows that the fossil genus shares notable similarities with Phimophorus Bergroth, 1886 and Mendanocoris Miller, 1956. We therefore formally transfer the fossil genus to Phimophorinae.
Baltic amber, Eocene, Heteroptera, taxonomy, true bugs
Koenigsbergia Popov, 2003 is a monotypic assassin bug genus described from the female holotype recovered from Baltic Amber (Eocene, ~33.9–55.8 MYA;
However, we noticed that Koenigsbergia in fact shares striking morphological similarities with the assassin bug genera Phimophorus Bergroth, 1886 and Mendanocoris Miller, 1956, which are placed within Phimophorinae Handlirsch, 1897. Among these are two features that were treated by
The discovery of one male and one nymph of Koenigsbergia provides the opportunity to advance our understanding of the systematics of this unusual fossil assassin bug genus. Our aims are threefold: First, evaluate if the newly acquired fossils represent the described species Koenigsbergia herczeki Popov, 2003 or if the adult male should be described as a new species. Second, document the morphology of Themonocoris, Phimophorus and Mendanocoris and compare them with Koenigsbergia. Third, formally transfer Koenigsbergia to Phimophorinae, should our comparison suggest that the fossil genus indeed belongs to Phimophorinae.
The photographs of amber inclusions were taken in the Laboratory of Insect Anatomy and Morphology of the Institute of Biology, Biotechnology and Environmental Protection, the University of Silesia in Katowice (Katowice, Poland) as follows: the focus-stacked color photographs were prepared with a Leica M205C stereo microscope with a high diffuse dome illumination Leica LED5000 HDI, Leica Flexacam C3 digital camera, and LasX ver. 5.1.025593 software (Leica Microsystems, Vienna, Austria). To be photographed, amber pieces were immersed in glycerin to remove most of the optical deformations due to the non-flatness of the surface of the amber. To obtain high-quality figures, fragments of specimens were imaged at high magnifications. Photographs were combined using the Image Composite Editor (panoramic image stitcher). Figures were prepared using Adobe Photoshop CS6 graphic editor. Measurements were made with LasX ver. 5.1.025593 software.
One Mendanocoris milleri specimen was examined: female (private collection of R. Hergovits): Malaysia, Pahang distr., Cameron Highlands, Tanah Rata env. (04°28′25″N 101°22′43″E), 20.3.–7.4.2011, R. Hergovits leg. Color photographs were prepared with a Leica M205C stereo microscope (same settings as for amber inclusion). Scanning electron microscopy (SEM) micrographs were prepared using Phenom XL scanning electron microscope (Phenom-World B.V., Eindhoven, The Netherlands) at 15 kV accelerating voltage with a Back Scatter Detector (BSD). The specimen was cleaned with a micro brush and left uncoated. To obtain high-quality figures, fragments of specimens (for both light microscopy and SEM) were imaged at high magnifications. Photographs were edited and assembled as above. — Three Phimophorus spissicornis specimens were examined: one male (AMNH_ENT 00023173), two females (AMNH_ENT 00023174; AMNH_ENT 00023168) and one nymph (UCR_ENT 00127816). Both Phimophorus male (AMNH_ENT 00023173) and female (AMNH_ENT 00023174) are from the same collection event: Peru: Loreto: Requena Jeraro Herrera 31Aug1987; second female (AMNH_ENT 0002316): Columbia, Antioquia, San Carlos, Vereda Jardín, Finca “El Silencio”, 6-Feb-1990; nymph (UCR_ENT 00127816): French Guiana: 11Jan2015. — Two specimens of Themonocoris endroedyi van Doesburg and Jacobs, 2011: one female (UCR_ENT 00001979) and one nymph (UCR_ENT 0010483) from the same collection event (South Africa: Vryheid Hill Nat. Res. 30Jan-2Feb2007). Phimophorus spissicornis and T. endroedyi specimens were assigned 8-digit UCR_ENT specimen identifier (USI) labels for databasing (Arthropod Easy Capture database) and 4-digit lab-internal tracking RCW code labels. Voucher specimens of extant taxa are deposited in the
Entomology Research Museum at the University of California, Riverside (
Abbreviations used on figures: abd, abdomen; af, antennifer; apl, anterior pronotal lobe; ats, apical tibial setae; bflg, basiflagellomere; bth, bothrium of pedicellar trichobothrium; bucc, buccula; cl, claw; clv, clavus; clvc, claval commissure; cly, clypeus; cor, corium; dflg, distiflagellomere; dlt, dorsal laterotergite; dpsc, dorsal apical processes on scape; fap, femoral apical process; flg, flagellomere; fsp, fossula spongiosa; gcx8, gonocoxa 8; ge, gena; L2–L4, labial segments 2–4; lbr, labrum; mdp, mandibular plate; mesf, mesofemur; mesp, mesopleuron; mest, mesotibia; metp, metapleuron; mett, metatibia; mst, mediosternite; occ, ocellus; par, parempodium; ped, pedicel; pp, pronotal process; ppl, posterior pronotal lobe; prc, pronotal carina; prof, profemur; prop, propleuron; prot, protibia; ptc, protibial comb; prt, proctiger; s1–8, abdominal sternites 1–8; sc, scape; scl, scutellum; sclr, lateral ridge of scutellum; sf, sensory field; smc, submedian carina; spps, subtriangular process of prosternal process; spr, spiracle; tar1, 2, tarsomere 1 and 2; tbs, tuberculate seta; tp, tarsal projection; tpp, pore of tarsal projection; vlt, ventral laterotergite; vpsc, ventral apical processes on scape.
Figures
We here present for the first time SEM micrographs of Themonocoris (Phymatinae), Phimophorus, and Mendanocoris (Phimophorinae). Similarities between the three genera include the two-segmented tarsi (Figs
Dorsal (A, C, E, G) and lateral (B, D, F, H) view of habitus of extant Themonocorini (Phymatinae) (A, B) and Phimophorinae (C–F). A, B female (UCR_ENT 00001979) Themonocoris endroedyi van Doesburg and Jacobs, 2011; C, D male (AMNH_ENT 00023173) Phimophorus spissicornis Bergroth, 1886; E, F nymph (UCR_ENT 00127816) of Phimophorus spissicornis Bergroth, 1886; G, H female Mendanocoris milleri Usinger & Wygodzinsky, 1964. Scale bar: 1 mm.
Dorsal (A, E–H) and left-lateral (B, C, D) view of head and labium of female (UCR_ENT 00001979) Themonocoris endroedyi (A–D) and right antenna of nymph (UCR_ENT 00104834) specimen (E–H). A–D Details of head and labium; E overview of antenna; F basi- and distiflagellomere; G detail of base of distiflagellomere; H apex of distiflagellomere. — Abbreviations: bflg, basiflagellomere; bucc, buccula; cly, clypeus; dflg, distiflagellomere; ge, gena; mdp, mandibular plate; mxp, maxillary plate; L2–L4, labial segments; occ, ocellus; ped, pedicel; sc, scape; tbs, tuberculate seta.
Dorsal (A, B, F) and lateral (C, D, E, G, H) view of the thorax and abdomen of Themonocoris endroedyi (A–G female UCR_ENT 00001979; H nymph UCR_ENT 00104834). A pronotum, scutellum, basal part of hemelytra and base of abdomen covered by wings; B detail of hemelytron showing distal margin of corium, base of membrane, and margin of dorsal laterotergite; C left foreleg; D left side of thorax and anterior part of abdomen; E apex of left tibia, tarsus, and pretarsus; F distal tarsomere with bulbous tarsal projection; G left side of abdomen; H right-lateral apex of abdomen. — Abbreviations: abd, abdomen; ats, apical tibial setae; cl, claw; clv, clavus; clvc, clavus commissure; cor, corium; dlt, dorsal laterotergite; gcx8, gonocoxa and abdominal sternite 8; mesp, mesopleuron; metp, metapleuron; mst, mediosternite; par, parempodium; prc, pronotal carina; prop, propleuron; prt, proctiger; s2–s8, abdominal sternites; spr, spiracles; tar1, 2, tarsomere 1 and 2; tp, bulbous tarsal projection; tpp, tarsal projection pore; vlt, ventral laterotergite.
However, differences between the two phimophorine genera and Themonocoris are striking. The antennifers in Mendanocoris and Phimophorus are stout and shield-like, protecting the antennal insertion (Figs
Dorsal (A, C, G, H) and left-lateral (B, D, E, F) view of female Phimophorus spissicornis (AMNH_ENT 00023174; AMNH_ENT 00023168). A head, thorax, and anterior part of abdomen covered by wings; B head and thorax; C head showing antennifer and antennal scape; D head with buccula and subtriangular prosternal process of prosternum; E apex of labium and subtriangular prosternal process of pronotum; F detail of scape and pedicel; G pedicel showing bothrium of the distalmost trichobothrium; H detail of basi- and distiflagellomere. — Abbreviations: af, antennifer; apl, anterior pronotal lobe; bflg, basiflagellomere; bth, bothrium of pedicellar trichobothrium; bucc, buccula; cly, clypeus; clv, clavus; dflg, distiflagellomere; dpsc, dorsal processes; fap, femoral apical process; L2–L3, labial segments; occ, ocelli; ped, pedicel; ppl, posterior pronotal lobe; sc, scape; sclr, lateral ridge of scutellum; spps, subtriangular prosternal process; vpsc, ventral apical processes.
Dorsal (A, D) and lateral (B, C, E–H) of female Phimophorus spissicornis (AMNH_ENT 00023174; AMNH_ENT 00023168). A pronotum; B left pro-, meso-, and part of metathorax; C left-lateral view of scutellum and base of hemelytron; D articulation between left profemur and protibia, showing femoral apical processes; E two-segmented right protarsus; F tenant hairs potentially representing fossula spongiosa at right tibial apex; G detail of left foreleg fossula spongiosa and position of protibial comb; H detail of protibial comb. — Abbreviations: apl, anterior prontoal lobe; cl, claw; clv, clavus; fap, femoral apical process; fsp, fossula spongiosa; mesp, mesopleurite; metp, metapleurite; par, parempodium; ppl, posterior pronotal lobe; prop, propleurite; ptc, protibial comb; scl, scutellum; smc, submedian carina; tar1, 2, tarsomere 1 and 2.
Dorsal (A, C, E, H) and ventral (B, D, F, G) of female Mendanocoris milleri. A antennae, head, and thorax; B head and prosternite; C details of head; D head with buccula and subtriangular prosternal process of prosternum; E details of scape and pedicel; F details of head and labial segments; G left pedicel showing three bothrium of the distalmost trichobothrium; H detail of right flagellomere. — Abbreviations: af, antennifer; apl, anterior prontoal lobe; flg, flagellomere; bth, bothrium;cly, clypeus; dpsc, dorsal processes; L2–L4, labial segments; lbr, labrium; occ, ocellus; ped, pedicel; ppl, posterior pronotal lobe; sc, scape; sf, sensory field; smc, submedian carina; spps, subtriangular prosternal process; vpsc, ventral apical processes.
Both phimophorine genera also possess distinctive lateral femoral apical processes on all pairs of legs (Figs
Dorsal (A, F), ventral (C, E), and left-lateral (B, D, G) of female Mendanocoris milleri. A thorax, and anterior portion of abdomen; B pro-, meso, and part of metathorax; C ventral view of articulation between left profemur and protibia, showing femoral apical processes; D lateral details of left femoral apical process; E position of fossula spongiosa and left protibial comb; F details of fossula spongiosa and left protibial comb; G abdomen. — Abbreviations: apl, anterior prontoal lobe; cl, claw; clv, clavus; cor, corium; dlt, dorsal laterotergite; fap, femoral apical process; fsp, fossula spongiosa; gcx8, gonocoxa and abdominal sternite 8; mesp, mesopleurite; metp, metapleurite; par, parempodium; ppl, posterior pronotal lobe; prop, propleurite; ptc, protibial comb; s2–s7, abdominal sternites; scl, scutellum; smc, submedian carina; tar1, 2, tarsomere 1 and 2.
Figures
Similarities between Mendanocoris milleri and Phimophorus spissicornis include: a flattened appearance in lateral view (Fig.
There are notable differences between the two genera. Whereas the clypeus in Mendanocoris is elongated and projects between the antennifers (Figs
While Phimophorus only features a single trichobothrium on the pedicel (Fig.
Figures
Compared to the head in Phimophorus (Fig.
Adult of Koenigsbergia explicativa, new species (A–J) and nymph of Koenigsbergia sp. (K, L). A dorsal view; B ventral view; C left-lateral view; D overview of left antenna, ventral view; E head, dorsal view, F head, ventral view; G anterior part of body, ventro-lateral view; H articulation between right profemur and protibia, showing femoral apical processes; I right tibiae apical parts and tarsi of all pairs of legs; J right protarsus; K dorsal view; L ventral view. — Abbreviations: af, antennifer; bflg, basilagellomere; bucc, buccula; cl, claw; cly, clypeus; dflg, distiflagellomere; dpsc, dorsal apical processes on scape; fap, femoral apical process; mesf, mesofemur; mest, mesotibia; mett, metatibia; occ, ocellus; ped, pedicel; pp, pronotal process; prof, profemur; prot, protibia; sc, scape; spps, subtriangular process of prosternal process; tar1, 2, tarsomere 1 and 2; vpsc, ventral apical processes on scape.
In Koenigsbergia, the pedicel is the longest antennal segment (Fig.
Figure
While the holotype of K. herczeki is female, and the newly discovered adult specimen is male, the differences listed in the following are beyond those expected in a sexually dimorphic reduviid species. In the new male specimen, the scape and pedicel are shorter, basiflagellomere and distiflagellomere are longer; the angle between the two shields on the antennifer is much wider, the clypeus is distinctly visible in dorsal view; the head is shorter and wider in dorsal view; and the scutellar spine has a different shape (Fig.
Subfamily Phimophorinae Handlirsch, 1897
Tribe Phimophorini Handlirsch, 1897
Koenigsbergia
Koenigsbergia herczeki Popov, 2003 (Figs
Recognized among Phimophorinae by the body being more than twice as long as wide; head, thorax and scutellum densely covered with granules; head more than 1.5 times longer than wide; anteocular portion slightly longer than postocular; lateral portions of antennifers large; in lateral view, eyes not reaching dorsal margin of head; ocelli present; bucculae very prominent, enclosing base of labium; labium stout, second segment (first visible) longest; antennae thickened, pedicel, basi- and distiflagellomeres shortest, densely covered with short adpressed setae; neck indistinct; prothorax with well-developed stridulatory groove; pronotum with two low longitudinal carinae, anterior angles protruding, scutellum subtriangular with strongly elongate apex, without median carina, carinate at sides; hemelytra hyaline, not distinctly divided into corial and membranous parts, costal margins strongly sclerotized; legs densely covered with rows of very short suberect setae, femora and tibiae almost equal in width; tarsi two-segmented, very short, about one-sixth as long as tibiae; abdomen rather wide, egg-shaped, with broad connexivum.
Distinguished from K. herczeki by the shorter scape and pedicel, longer basiflagellomere and distiflagellomere (Fig.
MALE: Body elongated (Fig.
Measurements of Koenigsbergia explicativa, new species (adult), Koenigsbergia sp. (nymph) and K. herczeki (from the literature). Labial segments I and IV could not be measured.
Koenigsbergia explicativa n. sp. (adult) |
Koenigsbergia sp. (nymph) |
Koenigsbergia herczeki | |
body length: clypeus to apex of membrane | 7.18 | 4.89 | 7.5 |
body maximum width | 3.06 | 1.94 | 3.00 |
head length | 1.32 | 1.07 | 1.70 |
head width including compound eyes | 0.95 | 0.80 | 1.00 |
eye length | 0.23 | — | — |
eye width | 0.14 | — | — |
anteocular portion length | 0.65 | — | — |
postocular portion | 0.43 | — | — |
interocular space | 0.68 | 0.39 | — |
scape length | 0.49 | 0.40 | 0.50 |
pedicel length | 1.46 | 1.06 | 1.50 |
basiflagellum length | 0.31 | 0.31 | 0.30 |
distiflagellum length | 0.29 | 0.31 | 0.25 |
labial segment II | 0.55 | — | — |
labial segment III | 0.28 | — | — |
pronotum medial length | 1.24 | 0.61 | 1.50 |
anterior width of pronotum | 0.98 | --- | --- |
maximal width of pronotum | 1.90 | 1.21 | 1.95 |
scutellum length | 1.18 | — | — |
scutellum width | 0.89 | — | — |
hemelytra length | 4.32 | — | 4.50 |
From Latin explicātīvus and explicō (“to unfold, open out”), in reference to the widened scutellar spine.
Holotype: male in 23 × 14 × 4 mm in a piece of Baltic amber.
Unknown locality on the Baltic Sea Coast: Poland, Kaliningrad Oblast or Lithuania.
Baltic amber, mid-Eocene (ca. 44.1±1.1 Ma old according to
This new species, with a male holotype, is distinct from K. herczeki which was described from a female specimen based on the characters outlined in the diagnosis and illustrated in Figs
NYMPH (probably fourth stage): Body elongated (Fig.
Nymph in 37×20×7 mm in a piece of Baltic amber.
Rovno region, Ukraine.
Baltic amber, mid-Eocene (ca. 44.1±1.1 Ma old according to
Our comparative observations suggest that similarities between Koenigsbergia and Themonocoris are superficial and do not warrant the placement of the fossil taxon within Themonocorini. Some of these similarities are also commonly seen in other subfamilies. Examples include the insertion of the antennae at the apex of the head (also found, e.g., in Salyavatinae and Cetherinae), a flattened appearance in lateral view (also found, e.g., in Phimophorinae), and a highly textured integument (also seen in Phimophorinae and certain Emesinae). However, because of the numerous and striking similarities between Koenigsbergia, Phimophorus and Mendanocoris, we place Koenigsbergia within Phimophorinae. Ongoing work by Masonick and colleagues assembled a morphological and molecular dataset across Reduvioidea that includes Phimophorus spissicornis, but this dataset does not include fossil taxa, including Koenigsbergia or Mendanocoris.
Some of the characters that unite Koenigsbergia, Phimophorus and Mendanocoris are also found in certain other reduviids, but there is phylogenetic evidence in the ongoing work by Masonick and colleagues that they are convergently derived. As an example, bucculae also occur in certain Ectrichodiinae, but that group is placed distantly in phylogenetic hypotheses. Due to the differences we observed between Koenigsbergia, Phimophorus and Mendanocoris outlined above, we recognize the three as separate genera. Interestingly,
The morphological differences between the female holotype of K. herczeki and the newly discovered male appear distinctive, and we are confident that the male represents a distinct species. However, we decided to not determine the new fossil nymph to either K. herczeki or K. explicativa n. sp. because the features we used in the diagnosis may vary between nymphs and adults (e.g., relative length of antennifers).
We would like to thank Jonas Damzen (Vilnus, Lithuania) for providing specimens of Koenigsbergia and Roman Hergovits (Bratislava, Slovakia) for providing the examined specimen of Mendanocoris milleri. We also acknowledge financial support from the University of California, Riverside in the form of a stipend to JR and research funds to CW. This research was also partially funded by NSF DEB 1655769 to CW.