Gerbelius Distant 1903
Creators: name: Castillo, Stephanie
name: Rédei, Dávid
name: Weirauch, Christiane
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hemiptera
Reduviidae
Gerbelius

description: Genus Gerbelius Distant, 1903
Figs 1, 2, 3A, G, 4A, 5, 11, 14, 20
Gerbelius Distant, 1903a: 59.
Type species: Gerbelius typicus Distant, 1903, by original designation.
Revised diagnosis
Distinguished from the other genus in the subfamily, Voconia, by the smooth or corrugated surface of the head and pronotum (Fig. 3G); laterally flattened shape of the maxillary plates (Fig. 3A); long, basally adjacent mandibular plates (Fig. 3A); stout labium densely covered with long macrosetae on the morphologically ventral surface of labial segment I (Fig. 3G); morphologically dorsal surface of labial segment II 0.8–0.9 times length of labial segment I (Fig. 3G); and Cu-An 1 cell slender and tapering apically, similar in size to the M-Cu cell (Fig. 4A).
Redescription
BODY LENGTH. 7.0–8.0 mm.
BODY. Robust; only macropterous morphs known (Fig. 5).
COLORATION. Variable color patterns; scutellum uniform or with contrasting yellow scutellar spine.
INTEGUMENT AND VESTITURE. Head and pronotum: smooth to corrugated with dense pubescence and sparse, long macrosetae; antennifer with macroseta, without lateral protuberance (Fig. 3A); labium with dense, long macrosetae. Thorax: anterolateral angles of pronotal collar with macrosetae. Hemelytron: corium with dense setation. Legs: posterior row of protuberances on mid and hind femora with three large spines on distal half and three or fewer small spines. Abdomen: ventral surface pubescent with long macrosetae.
HEAD (Fig. 3A, G). Elongate, 1.2–1.3 times as long as wide; anteocular region about a third of head length and shorter than postocular region (measured to anterior margin of neck); postocular region in dorsal view globose and longer than eye; pedicel 1.1–1.3 times length of head width; mandibular plates in dorsal view long with basal half adjacent; maxillary plates in dorsal view enlarged laterally forming flattened projections, adjacent to clypeus; clypeus width in dorsal view narrower than maxillary plates; interocular glabrous markings V-shaped, joined medially at interocular sulcus; eye width in dorsal view narrower than synthlipsis, eye not reaching ventral head margin in lateral view; ventrolateral swelling of buccula without lateral protrusion that surpasses buccular margin, flat margin; labium stout; second (first visible) labial segment in lateral view surpassing posteroventral eye margin, gradually widened apically; dorsal surface of third (second visible) labial segment convex, 0.8–0.9 times length of second segment; fourth (third visible) labial segment drawn into bent, slender apex.
THORAX. Pronotal collar narrow medially with anterolateral angles short and flared laterally; anterior pronotal lobe lateral margins rounded; scutellum width 0.8 times length; scutellar spine subhorizontal; anteriad-directed process on prosternum with paramedial lobes; anterior margin of stridulitrum projected into sharp spine; proepimeron with obtuse protuberance on posteroventral margin.
HEMELYTRON (Fig. 4A). Cu-An 1 cell similar in size to M-Cu cell; Cu-An 1 cell slender, tapered apically.
LEGS. Fossula spongiosa present on fore and mid legs in males, present on fore but absent or vestigial on mid legs of females.
ABDOMEN. Anterior margin of terga weakly carinulate; terga II and III with paired, prominent, and longitudinal carinae, almost reaching posterior margin of tergum III.
PYGOPHORE (Fig. 11). Transverse bridge rounded on posterior margin; lateral pygophore margin flat; paramere shape in dorsal view sinusoidal, apex tapered into squarely round tip.
AEDEAGUS (Fig. 15). Endosoma almost entirely covered with spicules; apex of dorsal phallothecal sclerite rounded in dorsal view; basal plate extension 4.4–4.8 times as long as wide.
Distribution
This genus currently comprises two described species from India and Southeast Asia, and we are aware of at least four undescribed species distributed across India, Laos, Thailand, and Vietnam. Gerbelius typicus is the most widespread among them.
Remarks
Photographs of type specimens in their unit trays at the BMNH were used to evaluate species concepts for G. typicus and G. confluens. This genus previously had a third described species that is now transferred to Voconia, V. ornata. Molecular phylogenetics recovered a Gerbelius clade (Gerbelius sp. 3 + [Gerbelius sp. 1 + Gerbelius sp. 4]) sister to Voconia wegneri sp. nov. (Hwang & Weirauch, 2012). We also recovered a well-supported Gerbelius clade sister to Voconia (Figs 1–2). The pygophore of two specimens were dissected for this study (Figs 11, 14); however, the median apical process of G. typicus (AMNH_IZC 00321200) broke off during dissection (Fig. 11). We decided not to describe new species of Gerbelius as part of this study. Since species of Gerbelius somewhat resemble other small-bodied assassin bugs currently classified as Reduviinae, we suspect that our specimen searches in various natural history collections were not comprehensive for this genus. However, this material should be included in a future revision of this genus.
description: Published as part of Castillo, Stephanie, Rédei, Dávid & Weirauch, Christiane, 2022, Pseudocetherinae (Hemiptera: Reduviidae) revisited: phylogeny and taxonomy of the lobe-headed bugs, pp. 1-95 in European Journal of Taxonomy 788 (1) on pages 23-26, DOI: 10.5852/ejt.2022.788.1625, http://zenodo.org/record/5846636