Quedius roma Solodovnikov et Hansen

Solodovnikov, Alexey & Hansen, Aslak Kappel, 2016, Review of subterranean Quedius, with description of the first hypogean species from the Russian Far East (Coleoptera: Staphylinidae: Staphylinini), Zootaxa 4170 (3), pp. 475-490 : 483-487

Quedius roma Solodovnikov et Hansen , sp. n.

Figs 3 and 4

Material examined. Holotype: male, Russia, Khabarovskij Kraj (southern), Sikhote-Alin (Central) range, upper course of river Ko, 47,0716°N, 136,4572°E, 750 m, fir-birch forest, 26.V.2015, talus [rock slides], leg. A. Hansen, M. Justesen & A. Solodovnikov ( ZMUC) ; paratypes: 1 male, 5 females, same data as in holotype (1 male, 2 females at ZMUC, 3 females at ISEA) .

Description. Measurements (7 specimens, min-max, in mm): head length (from base of labrum to nuchal ridge) 1.2–1.4, head width (maximal) 1.3–1.4, pronotum length (along midline) 1.7–1.9, pronotum width (maximal) 1.9–2.0, elytral length (from shoulder to apical margin) 1.6–1.9, elytral width (maximal, when elytra closed along suture) 2–2.2; total body length 9.0– 11.5 mm.

Brown to dark brown, medium large species, distinctly flattened dorso-ventrally, with very small eyes, relatively narrow head, anteriorly strongly narrowed pronotum, shortened elytra and lacking hind wings ( Fig. 3).

Head about as long as wide, without notable temporal angles; surface with distinct fingerprint-like microsculpture and hardly visible micropunctation; eyes small, in dorsal view hardly protruding over contour of head, tempora ca. 2.5 times as long as eyes. ‘Taxonomic’ setae on disk of head capsule represented by pair of anterior and posterior frontal setae, and two pairs of vertical setae (‘f’ and ‘v’ in Fig. 4 A, respectively); posterior frontal setae situated at about same distance from eye margin and nuchal ridge, or closer to the latter. Infraorbital ridges fully developed reaching base of mandibles anteriorly. Antennae moderately long; their second and third antennomeres combined distinctly longer than first; fourth and fifth antennomeres, each, distinctly longer than wide; sixth to tenth antennomeres, each, slightly longer than wide.

Pronotum about as wide as long, widest at about its middle with lateral sides very strongly narrowing anteriad, and weakly-posteriad; latero-anterior areas strongly deflexed downward so pronotal anterior angles not visible in dorsal view; lateral portions in posterior half of pronotal length distinctly explanate, without iridescence; basal margin nearly straight, posterior angles distinct. ‘Taxonomic’ setae on disc of pronotum consisting of two punctures in dorsal row on disk (not counting smaller puncture near anterior margin) (‘d’ in Fig. 4 B), and one-two punctures in sublateral row (of them posterior, when present, situated before or at level of large lateral puncture) (‘s’ in Fig. 4 B). Micropunctation and microsclupture as on head.

Mesoscutellum impunctate, with faint transversal microsculpture.

Legs rather long, posterior distinctly longer than anterior and middle; anterior tarsi enlarged in both sexes; middle and especially posterior femora with dark iridescent inner surface.

Elytra about as long as pronotum, moderately densely punctate, with setiferous punctures sometimes nearly contiguous horizontally but separated by interspaces larger than puncture diameter vertically; interspaces glossy, with very slight microsculpture.

Abdominal tergites sparsely punctate, with distinct irregular microscuplture and slight iridescence; tergite VII without apical seam of palisade fringe. Male: Medial emargination of sternite VIII almost at right angle and not rounded ( Fig. 4 C); sternite IX with asymmetrical, apically pointed glabrous basal portion, and medially sparsely setose symmetrical apical portion with faint apical emargination ( Fig. 4 D); male tergite X apically broadly rounded ( Fig. 4 E). Aedeagus only slightly asymmetrical; median lobe (in parameral and anteparameral view) rather parallel-sided along most of its length, with obtuse apex ( Fig. 4 F), with short blunt apical carina on anteparameral side more basally followed by shallow invagination ( Fig. 4 G); paramere (in parameral view) about as wide as median lobe, apically obtuse, with slight median emargination, with 8–10 sensory peg setae on its underside densely clustered in two lateral groups close to anterior margin, with two pairs of apical and two pairs of apicolateral setae ( Fig. 4 H). Female: tergite X with stronger sclerotized apical lobe and soft, membranous lateral lobes, apically with sparse long setae ( Fig. 4 I).

Sexual dimorphism. Without dissection of genitalia males can be separated from females by medially emarginated sternite VIII (not emarginated, concave in females) only.

Variability. The species slightly varies in size, and distinctly in the body coloration: from darker, nearly blackish to paler, brown specimens. Basal setiferous pores in dorsal and sublateral rows of pronotum may be absent in some specimens, sometimes only in one row.

Systematic position and comparison. Based on two vertical setae in each pair on head, and laterally explanate pronotum, the new species can be safely placed to the subgenus Microsaurus . Within the Russian Far East fauna, Q. roma is the only Microsaurus species with pronounced morphological modifications for hypogean biology and therefore it is very distinct. Based on glabrous, non-punctate scutellum, taxonomic chaetotaxy of head and pronotum, and characteristic structure of the slightly asymmetrical aedeagus (obtuse median lobe having blunt short median carina followed by an invagination; broad, apically only slightly incised paramere with 8–10 sensory peg setae clustered in two groups near its apex), the new species is affiliated with the core of the przewalskii -group (as defined in Smetana 2001). However, relatively more narrow head, more strongly deflexed downwards anterior angles of pronotum, more sparse punctation of abdomen (mostly dense in przewalskii -group) and more elongate subapical segments of antennae easily distinguish Q. roma from any other species of the przewalskii -group even in its broadest sense (as in Smetana 2014, 2015). Although the aedeagus of the new species looks similar to Q. przewalskii and similar species, its paramere is relatively broader and entirely covers the contours of the median lobe in parameral view. Also the new species has lesser number of sensory peg setae that are situated distinctly denser and more apically on the parameral underside. Even though in habitus and chaetotaxy of head and pronotum Q. roma resembles Q. mutilatus and Q. kalabi , it differs from them in glabrous scutellum, relatively more narrow head, and more anterior position of posterior frontal puncture (in Q. mutilatus and Q. kalabi located closer to nuchal ridge than to postero-median margin of eye). Compared to the former species, Q. roma has quite different structure of the aedeagus. Quedius roma differs from Q. fonteius in habitus and in lack of additional puncture between posterior frontal puncture and postero-median margin of eye.

Unlike hypogean Microsaurus from Japan or Taiwan (referred as members of abnormalis -group) Q. roma has glabrous non-punctate scutellum and different type of the aedeagus (in the abnormalis -group aedeagus is usually symmetrical; with apically broad deeply bilobed paramere having numerous sensory peg setae; and with two carinae near apex on the anteparameral side). From the Chinese members of kiangsiensis - and mnemon -groups collected in caves, Q. roma differs in its brachypterous habitus (shorter elytra, lacking palisade fringe on abdominal tergite VII), brownish coloration, and in very different shape of the aedeagus. From the Turkish hypogean endemic Q. weiratheri , Q. roma differs both in habitus (in particular more narrow head with temples not diverging towards more distinct posterior angles) and very different shape of the aedeagus. Likewise, Q. roma appears very distinct in comparison with the North American Q. infernus , in particular in its clearly brachypterous habitus and aedeagus having median lobe with differently shaped apex, relatively broader paramere, and other arrangement of sensory peg setae.

Distribution and ecology. The new species is known only from the type locality at Mt. Ko. All specimens were hand collected at one talus field ( Fig. 1 ). When such talus is formed on a slope, continuous erosion transports smaller rocks and debris to its lower levels, filling its internal cavities. Our specimens were collected under smaller rocks of the upper levels of the talus that we could access and manually lift. We were collecting there from evening dusk to about midnight with spotlights. Quedius were easily spotted in the layer of wet humus accumulated under those rocks by their shiny appearance. Unlike various carabids, weevils, spiders and opilionids that were actively crawling on the boulders in these night hours, all Q. roma specimens were collected from the humus under rocks. Internal crevices between rocks were often filled with ice and snow that was still abundant and formed large patches in the shadowy spots in the forest at this elevation.

Etymology. The new species is dedicated to our friend and colleague Roman ( Roma ) Dudko who collected several specimens that formed the type series, and introduced us to talus, a very interesting and still poorly explored habitat for diverse beetles in Siberia and Russian Far East. The species name is a noun in apposition.

Figures

FIGURE 1. Talus-associated habitat of Quedius roma sp. n. at the type locality at Mt. Ko.

FIGURE 4. Quedius roma sp. n., details of morphology: head dorsally (A); pronotum dorsally (B); male sternite VIII (C); male sternite IX (D); male tergite X (E); aedeagus, parameral side (F); aedeagus, laterally (G); paramere, side facing median lobe (H); female tergite X (I); d—dorsal puncture, f—frontal puncture, s—sublateral puncture, v—vertical puncture. Scale bars 1 mm.