Quedius repentinus, Salnitska & Solodovnikov, 2018

Salnitska, Maria & Solodovnikov, Aleхey, 2018, Hypogean presumably sister species Quedius repentinus sp. n. from Altai and Q. roma from Sikhote-Alin (Coleoptera: Staphylinidae): a disjunct distribution or poorly sampled Siberia?, Zootaxa 4394 (1), pp. 95-104 : 99-102

Quedius repentinus sp. n.

Type material: Russia, Altai Republic, Turochaksky District: Holotype (♂): “SE Altai 35-40 km SSE Artybash, Evretchala Mt , 1850–2050 m a.s.l., 51°28’N, 87°26’E, 02–03.VI.2004, R. Yu. Dudko, I.I. Lyubechanskiy leg.” ( ISEA) ; paratypes: 2 males, 2 females, same data as in the holotype (1 male and 1 female at ISEA, 1 male and 1 female at ZIN) .

Description. Measurements and ratios (range, arithmetic mean; n = 5): HL: 1.30–1.45 (1.37); HW: 1.30–1.41 (1.34); PL: 1.55–1.66 (1.60); PW: 1.64–1.86 (1.76); EL: 1.64–1.82 (1.71); EW: 1.80–1.98 (1.87); FB: 4.48–4.91 (4.68); TL: 9.4–11.5 (10.5); HL/HW: 0.97–1.05 (1.02); PL/PW: 0.88–0.94 (0.91); EL/EW: 0.89–0.94 (0.92); PL/ EL: 0.90–0.96 (0.93); PW/EW: 0.91–0.97 (0.94).

Body dark brown to reddish brown; head and abdomen dark brown; pronotum, elytra and appendages lighter; legs rather long; body flattened dorso-ventrally.

Head about as long as wide or slightly longer with barely distinct, broadly arcuate posterior angles; surface with microsculpture of transverse waves on disk and isodiametric between eyes. Eyes small and flat, not or only slightly protruding over lateral contour of head; temples about 1.93–2.46 (2.18) times as long as longitudinal diameter of eye.

Head disk with the following punctation: anterior frontal puncture situated somewhat remotely from inner margin of eye, posterior frontal puncture between posterior margin of eye and nuchal ridge, the pair of smaller vertical punctures closer to nuchal ridge than to posterior frontal puncture. Each temple with two temporal punctures, posterior one closer to posterior margin of head than to posterior margin of eye; temples additionally with some fine setiferous punctures bearing short yellowish setae.

Antennae moderately long: second and third segments combined distinctly longer than first; third slightly longer than second, fourth and fifth as long as wide, sixth to tenth wider than long, gradually increasing in width towards apex of antenna, last segment slightly longer than preceding segments.

Pronotum barely wider than long, widest at about middle; gradually narrowing anteriad and vaguely posteriad; posterior lateral portions only slightly explanate. Dorsal rows of setae each with three punctures (anterior puncture distinctly smaller and less distinct than second and third), third (basalmost) puncture situated slightly before the level of large lateral puncture; sublateral group with one to two punctures; basal margin with row of 3–5 distinct, variably sized setae on each side; microsculpture as on posterior part of head.

Scutellum impunctate, with faint transversal microsculpture.

Elytra distinctly widening posteriad, rather short, on average shorter than wide, slightly wider and longer than pronotum; punctation fine and moderately dense, with interspaces between setiferous punctures larger than punctures diameter; interspaces shiny, with minute irregularities; pubescence yellowish to brownish. Wings vestigial.

Abdomen: sparsely punctate, interspaces between punctures larger than diameter of punctures, with minute irregularities; posterior margin of tergite VII without palisade fringe.

Male. First four segments of front tarsus dilated; second segment as wide as, or slightly narrower than apex of tibia. Sternite VIII with subangulate triangular medio-apical emargination ( Fig. 3H ). Sternite IХ asymmetrical, moderately elongate, with wide and glabrous basal portion, and with sparsely setose and vaguely bilobed apical portion ( Fig. 3G ). Tergite Х gradually narrowed apicad with few strong apical setae at apical margin and with numerous smaller setae in apical portion ( Fig. 3F ). Aedeagus ( Figs. 3C–E ): median lobe (in parameral or anteparameral view) slightly asymmetrical, apically broad, blunt ( Fig. 3D ); (in lateral view) with slightly arcuate and narrow apical portion, with obtuse apex, minute tooth situated very close to apex and carina under tooth ( Fig. 3C ). Paramere (in parameral view) slightly narrower than median lobe, asymmetrical, obtusely narrowed apicad, with slight but distinct apical emargination ( Figs. 3D, E ); with two pairs of apical setae on each side of emargination and ca. 1–3 of lateral setae; (underside) with 10–12 sensory peg setae arranged in two dense groups on each side of apical emargination; (in lateral view) nearly reaching apex of median lobe ( Figs. 3C, D ). Internal sac without large sclerotized structures.

Female. Tarsomeres 1–4 of protarsi dilated, but slightly narrower than in males. Tergite Х pigmented, medioapically with long setae in apical portion.

Comparison. Quedius repentinus sp. n. appears most closely related to the recently described Q. roma based on the following characters: sparse punctation of abdomen; apical portion of the median lobe of the aedeagus (in parameral or anteparameral view) broad and not pointed, (in lateral view) with minute tooth and carina basally from the tooth; wide paramere with 10–12 sensory peg setae divided in two elongate groups by apical emargination. Nevertheless, Q. repentinus can be easily distinguished from Q. roma externally by a relatively wider head and the shape of the pronotum with less pronounced posterior angles and the lateral contours less narrowing anteriad before anterior angles. Also, compared to Q. roma , the aedeagus of Q. repentinus has a narrower apex of the median lobe (in lateral view), a deeper apical emargination of the paramere (in parameral view), and a less defined arrangement of sensory peg setae extending to the lateral margins of the paramere (in Q. roma forming compact groups at apex only).

Both Q. repentinus and Q. roma share some characters with Q. przewalskii : posterior frontal puncture situated at about the same distance from posterior margin of eye and nuchal ridge; three punctures in each dorsal row of the pronotum and one to two in the sublateral row; posteriorly explanate lateral portions of pronotum; impunctate glabrous scutellum; an asymmetrical aedeagus (best seen in parameral view) with the median lobe (in lateral view) having a subapical tooth and the paramere (in parameral view) with a shallow apical emargination and a similar pattern of peg setae. Since the diagnosis and composition of the Q. przewalskii species group remain unclear ( Solodovnikov & Hansen, 2016), both species can be affiliated with this group only tentatively. Both Q. repentinus and Q. roma can be easily distinguished from Q. przewalskii by longer elytra, sparse punctation of the abdomen, and by the structure of aedeagus, in particular by a wider paramere with more stretched arrangement of peg setae and a blunt median lobe with a carina basally from the subapical tooth facing the paramere.

Even though Q. repentinus also resembles the Q. mutilatus species group due to shared adaptations to the hypogean biology and is generally similar to the latter in habitus and chaetotaxy of head and pronotum, Q. repentinus (and its presumed sister species Q. roma ) seem more remote from that group. Unlike the Q. mutilatus species group they have the posterior frontal puncture situated farther away from the nuchal ridge and a different structure of the aedeagus, which in Q. mutilatus group is symmetric, with a differently shaped apical portion of the median lobe and the paramere having four groups of sensory peg setae (two apical and two subapical).

Distribution and bionomics. So far Quedius repentinus sp. n. is known only from the type locality in Evrechala Mountain in the southeastern Altai. The specimens were collected at an elevation of 1850–2050 m in the old talus already covered by the ground or fine detrital rock with lichens ( Fig. 4 ).

Etymology. The name is the Latin adjective ‘ repentinus ’ (= unexpected) that refers to the fact that the new species appears phylogenetically close to the geographically remote Q. roma , which was unexpected.

Figures

FIGURE 3. Quedius repentinus sp.n.: A, C, D, F–H (holotype), B (paratype, female), E (paratype, male); A, B, habitus; C, aedeagus(laterally); D, same (in parameral view); E, paramere,underside (side facing medianlobe); F, tergite X; G,sternite IX; H, sterniteVIII. Scale bars:A–D, F–H = 1 mm, E = 0.2 mm.

FIGURE 4. Typical talus-associated habitat at Mt.Evrechala (SE Altai). Photo by I.I. Lubechanskiy.