Amphichroum ahrensi Shavrin, 2021

Shavrin, Alexey V., 2021, New species and records of the genus Amphichroum Kraatz, 1857 from the Himalayan Region and Tibet (Coleoptera: Staphylinidae: Omaliinae: Anthophagini), Zootaxa 5082 (1), pp. 1-14 : 2-4

Amphichroum ahrensi Shavrin , sp. n.

( Figs. 1 , 8–9 , 15 )

Type material examined: Holotype, ♂: ‘ INDIA, West Bengal | Darjeeling, Tonglu | 19.-23.V.1998 | 2600-3000m NN | leg. Fabrizi & Ahrens’ <printed>, ‘HOLOTYPE | Amphichroum | ahrensi sp. n. | Shavrin A.V. des. 2021’ <red, printed> (NME).

Paratypes: 7 ♂♂ (two specimens dissected), 11 ♀♀: same data as the holotype. (5 ♂♂, 7 ♀♀: NME; 2 ♂♂, 4 ♀♀: cSh). All paratypes with red label ‘ PARATYPE | Amphichroum | ahrensi sp. n. | Shavrin A.V. des. 2021’.

Description. Measurements (n=19): HL: 0.30–0.43; HW: 0.55–0.70; AL (holotype): 1.54; OL: 0.19–0.25; PL: 0.53–0.72; PW: 0.88–1.00; ESL: 1.05–1.25; EW: 1.18–1.32; AW: 1.16–1.30; MTbL (holotype): 0.57; MTrL (holotype): 0.52 (MTrL 1–4: 0.30; MTrL 5: 0.22); AedL: 0.70–0.75; TL: 2.65–3.75 (holotype: 3.70).

Habitus as in Fig. 1 . Head, mouthparts, antennomeres 4–11, disc of pronotum, scutellum, legs and abdomen yellow-brown; antennomeres 1–3, lateral and basal portion of pronotum, elytra and paratergites yellow. Forebody glossy; frontal portion of head with dense transverse microsculpture, middle portion of head without or with very fine transverse microreticulation, infraorbital ridges with fine, rounded or longitudinal meshes; neck with dense transverse microsculpture; pronotum with distinct isodiametric microreticulation, without meshes in mediobasal third; exposed part of scutellum with dense, transverse sculpture; abdominal tergites with very dense, fine, isodiametric microreticulation. Head with very fine and sparse punctation, slightly denser in middle portion and with several moderately large punctures between anteocellar foveae and eyes; punctation of pronotum distinctly larger, denser and deeper than that in middle portion of head, sometimes finer and sparser in medioapical portion or without punctures in middle and/or mediobasal portions; punctation of elytra large, distinctly denser, coarser and deeper in basal portion, finer and sparser in middle along suture; abdominal tergites with dense, fine punctures, coarser and denser on abdominal tergite VII. Forebody without setation except for head with several long setae on frontal portion and two to four moderately long and erect setae between anteocellar foveae and eyes, and lateral margins of pronotum with four moderately long setae; abdominal tergites with regular, short, moderately dense setation.

Head subtrapezoidal, transverse, 1.6–1.8 times as broad as long, flattened in middle and slightly convex on posterior portions of infraorbital ridges; anteocellar foveae narrow, deep and long, diagonally stretching toward antennal bases about to level of anterior margins of eyes. Eyes very large, convex. Ocelli large, located at level of posterior margins of eyes near deep occipital furrow, distance between ocelli as long as or slightly shorter than distance between ocellus and posterior margin of eye. Apical maxillary palpomere 1.3 times as long as preceding segment, gradually narrowed from basal third toward subacute apex. Antenna moderately long, reaching basal part of elytra when reflexed, from antennomere 5 progressively widened apicad; basal antennomere oblong, about three times as long as broad, antennomere 2 distinctly shorter than and about as broad as basal antennomere, 3 slightly longer than 2, 4 slightly shorter than 3, 5–6 slightly broader than 4, 7–8 slightly broader than 6, 9–10 slightly broader than 8, apical antennomere about 1.3 times as long as 10, sharply narrowed from apical third toward subacute apex.

Pronotum 1.3–1.6 times as broad as long, 1.4–1.6 times as broad as head, widest in middle, slightly more narrowed posteriad than anteriad; anterior angles widely rounded, slightly protruded anteriad; posterior angles widely rounded; laterobasal margins slightly sinuate in some specimens; lateral portions flattened, moderately wide, slightly explanate, explanate area sometimes gradually widened posteriad.

Elytra slightly broader than long and slightly widened apicad, reaching apical margin of abdominal tergite IV or V, slightly less than twice as long as pronotum, with widely rounded or straight apical margins. Hind wings fully developed.

Legs moderately long; metatibia slightly longer than metatarsus, with long strong thorns on inner and long setation on outer surfaces.

Abdomen slightly narrower than elytra, with a pair of very large transverse tomentose spots (wing-folding patches) in middle of tergite IV, with narrow palisade fringe on apical margin of tergite VII.

Male. Protarsomeres 1–4 very wide. Medial margin of inner side of protibia with two parallel rows of eight to twelve short peg setae; mesotibia strongly curved mediad, with dense row of numerous very short and wide thorns beginning from medial side of bend and stretching to apex of mesotibia; lateral margins of mesotibia with very long and strong, sparse thorns and apical margins with several strong and long thorns. Apical margin of abdominal tergite VIII straight or rounded. Apical margin of abdominal sternite VIII widely rounded. Aedeagus ( Fig. 8 ) with median lobe widest at basal bulb, gradually narrowed apicad; parameres moderately narrow, distinctly exceeding apex of median lobe, each with two moderately short preapical setae; internal sac long, with two fields of long thorns in apical and two complicated sclerotized structures in basal portions. Lateral aspect of aedeagus as in Fig. 9 .

Female. Protarsomeres 1–4 narrow. Medial margin of protibia without peg setae; mesotibia without modifications, slender, with long strong thorn along entire length of lateral margin. Abdominal tergite VIII and sternite VIII with small rounded or straight apical margin.

Comparative notes. Amphichroum ahrensi sp. n. differs from the remaining species of the Himalayan Region by the absence of pubescence on the disc of pronotum and elytra. Based on the shape of the median lobe, it somewhat similar to the Chinese A. maculosum Shavrin & Smetana, 2018 and A. subelongatum Shavrin & Smetana, 2018 , but differs from them by the paler coloration of the body and completely different morphology of the internal sac.

Distribution. The new species is at present known only from the type locality ( Fig. 15 ) in West Bengal, India.

Bionomics. Specimens were collected at elevations from 2600 to 3000 m a.s.l.

Etymology. Patronymic, the species is named to honor Dirk Ahrens (Bonn, Germany), one of the collectors of the type specimens.

Figures

FIGURES 1–7. Habitus of Amphichroum (males): 1—A. ahrensi (paratype), 2—A. altivagans (holotype), 3—A. anthobioides (lectotype), 4—A. monticola (holotype), 5—A. nepalicum (Nepal, Manaslu Himal), 6—A. pindarense (syntype), 7—A. telnovi (paratype). Scale bars: 1.0 mm.

FIGURES 8–14. Aedeagus of Amphichroum ahrensi (8–9: paratype), A. altivagans (10–11: Kashmir, Khelanmarg) and A. anthobioides (12, 14: syntype; 13: Nepal, Bajura): 8, 10, 12—parameral view, 9, 11, 14—lateral view, 13—apical portion of aedeagus, parameral view. Scale bars: 0.1 mm.

FIGURES 15–17. Distribution of Amphichroum species in the Himalayan Region and Tibet: 15—A. ahrensi (circle), A. altivagans (triangle), A. anthobioides (squares), 16—A. monticola (circles), A. pindarense (triangles), A. telnovi (diamond), 17—A. nepalicum.