Amphichroum grandidentatum, 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 : 578-580

Amphichroum grandidentatum sp.n.

( Figs. 7–8 , 11 )

Type material examined. Holotype ♂ ( Fig. 11 ; left antennomeres 10–11 missing): ‘ 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 | grandidentatum sp.n. | Shavrin A.V. des. 2022’ <red, printed> ( NMPC).

Paratypes: 3 ♂♂ (two specimens dissected; one specimen without left antennomeres 7–11), 5 ♀♀ (three specimens without left antennomeres 10–11, 7–11 or 11 respectively): same data as the holotype, with additional red printed label: ‘ PARATYPE | Amphichroum | grandidentatum sp.n. | Shavrin A. V. des. 2022’ <red, printed> (1 ♂, 1 ♀: cSh; 2 ♂♂, 4 ♀♀: NMPC).

Description. Measurements (n=9): HW: 0.64–0.68; HL: 0.41–0.44; AL(holotype): 1.68; OL: 0.16–0.20; PL: 0.56–0.67;PW:0.98–1.17; ESL:1.26–1.30;EW:1.31–1.37;AW:1.19–1.29;MTbL(holotype):0.72;MTrL(holotype): 0.61 (MTrL 1–4: 0.32; MTrL 5: 0.29); AedL: 0.55–0.58; TL: 2.95–3.70 (holotype: 3.32).

Habitus as in Fig. 11 . Head, antennomeres 4–11, pronotum and abdomen brown or reddish-brown (frontal portion and infraorbital ridges of head and sometimes paratergites distinctly paler); lateral and basal portions of pronotum and elytra yellow-brown; mouthparts, antennomeres 1–3 and legs yellow (two preapical segments of maxillary palpi darker, brown or reddish-brown). Head with very dense transverse microsculpture, sometimes finer in middle and coarser on infraorbital ridges; neck with dense isodiametric microreticulation; pronotum with dense isodiametric microsculpture, missing in mediobasal third in some paratypes; visible part of scutellum with dense isodiametric meshes. Head with sparse and moderately large punctation, denser and deeper in middle, finer, sparser and sometimes indistinct on infraorbital ridges; pronotum with moderately dense punctation, slightly finer than that in middle portion of head, sometimes sparser in middle and mediobasal portions; punctation of elytra denser, larger and deeper than that on pronotum, finer along suture.

Head 1.5 times as broad as long; anteocellar foveae narrow and very deep, diagonally stretching toward supraantennal elevation. Ocelli very large, distance between ocelli about as long as distance between ocellus and posterior margin of eye. Apical segment of maxillary palpi slightly longer than precending segment, from basal portion strongly narrowed toward acute apex.Antennomeres 5–7 about as long as and slightly broader than 4, 8–10 distinctly shorter and slightly broader than 7, apical antennomere 1.5–1.7 times as long as 10.

Pronotum transverse, 1.7 times as broad as long, 1.5–1.7 times as broad as head, disitnctly more narrowed anteriad than posteriad; widely rounded anterior angles distinctly protruded anteriad; lateral portions very wide, flattened and explanate.

Elytra wide, distinctly broader than long, reaching basal portion of abdominal tergite IV, about or more than twice as long as pronotum.

Metatibia 1.1 times as long as very long metatarsus.

Abdomen distinctly narrower than elytra, with a pair of indistinct and very wide transverse tomentose spots in middle of tergite IV.

Male. Medial margin of apical half of protibia with two parallel rows of several moderately long peg setae; mesotibia strongly curved mediad, with dense row of 18–20 short thorns. Apical margin of abdominal tergite VIII truncate. Apical margin of abdominal sternite VIII widely rounded. Aedeagus with very wide basal portion, strongly narrowed towards rounded apex; parameres moderately wide, long and slightly curved, significantly exceeding somewhat rounded apex of median lobe, with one short apical and one preapical setae; internal sac long, with a row of large sclerotized thorns in middle and four strongly sclerotized, very large teeth in basal portions ( Fig. 7 ). Lateral aspect of the aedeagus as in Fig. 8 .

Female. Medial margin of protibia and mesotibia without modifications. Apical margin of abdominal tergite VIII straight or rounded. Apical margin of abdominal sternite VIII rounded.

Comparative notes. Amphichroum grandidentatum sp.n. differs from remaining species of the genus by the presence of large sclerotized teeth in basal portion of the internal sac of the aedeagus. Regarding the shape of the median lobe with rounded apex and the length of the parameres considerably exceeding apex of median lobe, it is somewhat similar to A. rotundatum Shavrin & Smetana, 2018 and A. feldmanni Shavrin, 2019 (both from Sichuan), but can be distinguished from them by the different coloration of the body and the morphology of the aedeagus. Additionally, it differs from A. feldmanni Shavrin, 2019 by the smaller body, more transverse pronotum and slightly broader elytra.

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

Bionomics. Specimens were collected in the same locality together with A. discolor sp.n. (see above).

Etymology. The specific epithet is an adjective composed of the Latin adjectives grandis, - e (large) and dentatus, - a, - um (toothed). It alludes to the presence of large sclerotized teeth in basal portion of the internal sac of the aedeagus.

Figures

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.

FIGURES 11–12. Habitus of Amphichroum: 11–A. grandidentatum, 12–A. reticulatum. Scale bar: 1.0 mm.