Amphichroum tibetanum Shavrin & Smetana, 2018

Shavrin, Alexey V. & Smetana, Aleš, 2018, New species of the genus Amphichroum Kraatz, 1857 (Coleoptera: Staphylinidae: Omaliinae: Anthophagini) from China, Zootaxa 4508 (3), pp. 377-402 : 399-401

Amphichroum tibetanum Shavrin & Smetana , sp.n.

( Figs. 34 , 39–41 )

Type material examined: Holotype ♂ [specimen without antennomeres 10–11]: ‘SE Tibet, “Chola Shan” pass | road Yanjing—Markam | 50 km S Markam, 4400m | 29°16'N, 98°38'E | mixed forest, 24-27.VI.1997 | Jaroslav Turna leg.’ <rectangular label, printed>, ‘ Sammlung | M. Schülke | Berlin’ <green rectangular label, printed >, ‘ HOLOTYPE | Amphichroum | tibetanum sp.n. | Shavrin A. & Smetana A. des. 2018’ <red rectangular label, printed> ( CSC) .

Paratypes: 1 ♂ [specimen without antennomeres 9–11], 2 ♀♀ [one specimen without antennomeres 7–11 and other specimen without left antennomeres 3–11 and right antennomeres 8–11]: same data as the holotype, with red rectangular label ‘ PARATYPE | Amphichroum | tibetanum sp.n. | Shavrin A. & Smetana A. des. 2018’ (1 ♂: CS; 2 ♀♀: CSC) .

Description. Measurements (n=4): HW: 0.65–0.70; HL: 0.35–0.39; OL: 0.19–0.20; PL: 0.57–0.62; PW: 0.97– 1.04; ESL: 1.17–1.40; EW: 1.27–1.42; AW: 1.22–1.35; MTbL(holotype): 0.72; MTrL(holotype): 0.54 (MTrL 1–4: 0.32; MTrL 5: 0.22); AedL: 0.72; TL: 3.20–3.85 (holotype: 3.30).

Forebody yellow-brown, with somewhat paler lateral and basal portions of pronotum; mouthparts, antennomeres 1–3 and legs yellow; apical segment of maxillary palp and antennomeres 4–11 brown; abdomen reddish-brown. Head with distinct, dense isodiametric microsculpture; microsculpture of middle part of neck as that on head but distinctly stronger; pronotum with distinct microsculpture as that on head; scutellum with distinct transverse meshes. Posterior portion of head between grooves and infraorbital ridges with several small punctures; pronotum with dense, irregular and very small punctation, distinctly sparser on medio-basal portion; punctation of elytra dense, moderately large and deep, markedly denser on prescutellar area.

Head 1.7–1.8 times as wide as long. Length × width of antennomeres (holotype): 1: 0.15 × 0.05; 2: 0.13 × 0.05; 3: 0.12 × 0.04; 4: 0.10 × 0.05; 5–6: 0.10 × 0.06;7–9: 0.11 × 0.06.

Pronotum 1.6–1.7 times as wide as long, 1.4 times as wide as head, widest in middle, evenly narrowed both posteriad and anteriad.

Elytra slightly wider than long and slightly widened apicad, twice as long as pronotum.

Metatibia 1.3 times as long as metatarsus.

Male ( Fig. 34 ). Protarsomeres 1–4 wide. Medial margin of apical part of protibia with two parallel rows of ten short peg setae; mesotibia moderately strongly curved mediad, with dense row of twenty short and wide thorns, slightly elongated toward apex. Abdominal tergite VIII and sternite VIII with straight apical margin. Aedeagus ( Fig. 39 ) with median lobe gradually narrowed toward rounded apex; parameres narrow, distinctly exceeding apex of median lobe, with two pairs of apical and preapical short setae; internal sac long, with extensive field of densely set fine thorns in apical and middle portion and with wide field of strongly sclerotized large thorns and oval structure in basal portion.Aedeagus laterally as in Fig. 40 .

Female. Protarsomeres 1–4 moderately narrow. Pro- and mesotibiae without modifications. Apical margin of abdominal tergite VIII and sternite VIII rounded.

Comparative notes. Based on the body size, shape of long parameres significantly exceeding median lobe and on the presence of fields of large thorns in the internal sac, A. tibetanum sp.n. is similar to A. assingi sp.n. and A. rotundatum sp.n. Based on the shape of apex of the median lobe, it’s most similar to A. rotundatum sp.n., from which it differs by the paler coloration of the body, and sparser and smaller punctation of the head. From A. assingi sp.n. it differs by the shape of anterior angles of the pronotum not protruded anteriad. From both species it differs by the details of the internal sac.

Distribution. The new species is at present known only from the type locality ( Fig. 41 ) in the Chola Mountains in Tibet, China.

Bionomics. All specimens were taken by sifting mixed forest floor litter at elevation 4400 m a.s.l.

Etymology. The specific epithet is the latinized adjective derived from the area the specimens were collected from.

Figures

FIGURE 41. Distribution of Amphichroum in China: A. angustilobatum sp.n. (black star), A. assingi sp.n. (white square with wide black margin), A. longilobatum sp.n. (white circle), A. maculosum sp.n. (white star), A. miaoershanum Watanabe, 1999 (circle with wide white margin), A. propinquum sp.n. (black square), A. rotundatum (white square), A. schuelkei sp.n. (black rhomb), A. squamosum sp.n. (black circle), A.subaequale sp.n. (white rhomb), A. subelongatum sp.n. (black triangle), A. tibetanum sp.n. (white triangle).

FIGURES 32–34. Habitus of Amphichroum (males): 32—A. subaequale sp.n. (paratype), 33—A. subelongatum sp.n. (paratype), 34—A. tibetanum sp.n. (holotype). Scale bar: 1.0 mm.

FIGURES 39–40. Aedeagus of Amphichroum tibetanum sp.n. (paratype): 39—parameral view, 40—lateral view. Scale bar: 0.1 mm.