Amphichroum discolor, Shavrin, 2022

Shavrin, Alexey V., 2022, New species and records of Amphichroum Kraatz, 1857 from China and the Himalayan Region (Coleoptera: Staphylinidae: Omaliinae: Anthophagini), Zootaxa 5190 (4), pp. 575-583 : 576-578

Amphichroum discolor sp.n.

( Figs. 1–5 )

Type material examined. Holotype ♂ ( Fig. 1 ): ‘ CHINA: YUNNAN PROv., | Gongshan Co., | Biluo Mts. Pass, 3890–3910 m, | 28°04.5′N, 098°45.6′E, | D. Král & J. Růžička leg.’ <printed>, ‘ 5.vii.2019, sift #06 [Y06], | mixed forest with dominant | Abies and Rhododendron shrubs, | litter under shrubs and along | fallen trunks’ <printed>, ‘HOLOTYPE | Amphichroum | discolor sp.n. | Shavrin A.V. des. 2022’ <red, printed> ( NMPC) .

Paratypes: 24 ♂♂ (four specimens dissected), 27 ♀♀: same data as the holotype, with additional red printed label: ‘ PARATYPE | Amphichroum | discolor sp.n. | Shavrin A. V. des. 2022’ <red, printed> (3 ♂♂, 3 ♀♀: cSh; 21 ♂♂, 24 ♀♀: NMPC).

Description. Measurements (n=52): HW: 0.47–0.60; HL: 0.27–0.35; AL(holotype): 1.12; OL: 0.15–0.17; PL: 0.47– 0.65; PW: 0.75–0.90; ESL: 0.88–1.20; EW: 0.95–1.02; AW: 0.94–1.07; MTbL(holotype): 0.57; MTrL(holotype): 0.32 (MTrL 1–4: 0.15; MTrL 5: 0.17); AedL: 0.45–0.60; TL: 2.35–3.35 (holotype: 2.70).

Habitus as in Figs. 1–2 . Body yellow-brown to brown; antennomeres 3–11 (brown specimens) or 5–11 (pale specimens) brownish; mouthparts, antennomeres 1–2 or 1–4 and legs yellow to yellow-brown (some specimens with yellow-brown forebody and narrow brown longitudinal spot along midline ( Fig. 2 ), brown abdomen and yellowish paratergites; pronotum of specimens with brown body ( Fig. 1 ) with yellow-brown lateral margins and slightly paler elytra). Body shiny; head with dense transverse microsculpture, denser and isodiametric on infraorbital ridges (some pale specimens without distinct meshes on infraorbital ridges); neck with distinct isodiametric or transverse microreticulation; pronotum with indistinct transverse microsculpure or without it; visible part of scutellum with very fine transverse meshes or without them; abdominal tergites with very dense isodiametric microsculpture. Head with several very fine and sparse punctures in middle; pronotum with moderately dense, large and deep punctation, sparser in middle and mediobasal portions; punctation of elytra distinctly larger, deeper and denser than that on pronotum, denser and coarser in mediobasal portion, finer and sparser along suture; abdominal tergites with indistinct and very sparse moderately fine punctation. Frontal portion of head with several long setae; pronotum and elytra with dense long setation; abdominal tergites with regular, short and moderately dense pubescence.

Head 1.7 times as broad as long, distinctly flattened in middle and slightly elevated on infraorbital ridges; anteocellar foveae (grooves in front of ocelli) narrow and very long, diagonally stretching toward antennal bases to about level of anterior margins of eyes. Ocelli large, located at level of posterior margins of eyes near occipital furrow, distance between ocelli about as long as distance between ocellus and posterior margin of eye or slightly longer. Eyes very large, convex. Apical segment of maxillary palpi 1.1–1.3 times as long as preceding segment, from basal portion gradually narrowed apicad. Antenna moderately long, reaching basal third of elytral length when reclined; basal antennomere moderately long, 1.4–1.6 times as long as broad, antennomere 2 about as broad as and distinctly shorter than basal antennomere, 3 about as long as and narrower than 2, 4 slightly shorter and broader than 3, 5–9 about as long as and distinctly broader than 4, 10 slightly shorter and broader than 9, apical antennomere about twice longer than 10, from apical third strongly narrowed toward subacute apex.

Pronotum convex, 1.3–1.5 times as broad as long, 1.5 times as broad as head, widest in middle, gradually or slightly more narrowed anteriad than posteriad; anterior angles rounded, distinctly protruded apicad; posterior angles widely rounded; lateral portions widely flattened and slightly explanate, gradually broadened posteriad.

Elytra about as broad as long, distinctly broadened apicad, reaching apical margin of abdominal tergite IV or V, 1.8 times as long as pronotum, with widely rounded apical margins.

Legs moderately long; metatibia 1.7 times as long as metatrasus, with long strong thorns on inner and outer surface.

Abdomen about as broad as elytra, with a pair of small transverse tomentose spots in middle of tergite IV, with narrow palisade fringe on apical margin of tergite VII.

Male. Protarsomeres 1–4 wide. Medial margin of apical half of protibia with two parallel rows of several short peg setae; mesotibia strongly curved mediad, with dense row of 17–21 very short thorns beginning from medial side of bend and stretching to apex of mesotibia. Apical margin of abdominal tergite VIII truncate. Apical margin of abdominal sternite VIII slightly concave. Aedeagus with very wide basal portion, strongly narrowed apicad toward very narrow and long apical portion of median lobe; parameres narrow, slightly exceeding apex of median lobe, with three short apical setae; internal sac long, with two fields of small thorns ( Fig. 3–4 ). Lateral aspect of the aedeagus as in Fig. 5 .

Female.Protarsomeres 1–4narrow.Medial margin of protibia without peg setae; mesotibia without modifications, slender, gradually slightly widened apicad. Abdominal tergite VIII and sternite VIII with truncate or rounded apical margin.

Comparative notes. Based on the general shape of the body and apical portion of the median lobe, it is similar to Chinese A. subaequale Shavrin & Smetana, 2018 (Shaanxi) , A. cuccodoroi Shavrin, 2022 (Yunnan) , and the Himalayan A. altivagans Cameron, 1941 ( India: Kashmir) and A. telnovi Shavrin, 2021 ( Nepal) . From A. subaequale it differs by the less transverse pronotum, and shorter and narrower parameres. From A. cuccodoroi , A. altivagans and A. telnovi it differs by the absence of the large sclerotized teeth in the internal sac. Additionally, it can be distinguished from:

A. cuccodoroi by the less transverse pronotum, longer elytra, and significantly shorter parameres;

A. altivagans by the longer antennomeres and shorter elytra;

A. telnovi by the smaller body, longer antennomeres 6–10, slightly broader pronotum and elytra.

From all these species it can be distinguished by the darker elytra, and the shape of very narrow and elongate apical portion of the median lobe.

Distribution. The species is at present known only from the type locality in Biluo Mts., Yunnan, China.

Bionomics. Specimens were collected at elevation from 3890 to 3910 m a.s.l. together with specimens of A. grandidentatum sp.n. (see below). They were taken by sifting litter under shrubs and along fallen trunks in mixed forest with Abies and Rhododendron .

Etymology. The specific epithet (Latin adjective: of different colours) refers to the different coloration of the body of specimens.

Figures

FIGURES 1–2. Habitus of Amphichroum discolor: 1–holotype, 2–paratype. Scale bar: 1.0 mm.

FIGURES 3–10. Aedeagus of Amphichroum (Figs. 3–5: A. discolor; Fig. 6 (apical portion): A. rotundatum; Figs. 7–8: A. grandidentatum; Figs. 9–10: A. reticulatum): 3–4, 6–7, 9–parameral view, 5, 8, 10–lateral view. Scale bar: 0.1 mm.