Chasmogenus parorbus, Jia, Fenglong & Tang, Yu-dan, 2018

Jia, Fenglong & Tang, Yu-dan, 2018, A faunistic study of genus Chasmogenus Sharp, 1882 of China (Coleoptera, Hydrophilidae), ZooKeys 738, pp. 59-66 : 61

Chasmogenus parorbus sp. n. Figs 1-7, 8

Type material.

Holotype: CHINA. Yunnan: male (SYSU), CHINA: Yunnan Prov., Yingjiang, Tongbiguan, Kaibangyahu, 24.58°N, 97.67°E, 1289m, 25.V.2016, Yu-dan Tang & Rui-juan Zhang leg. [transcribed from Chinese]. Paratypes (3 males, SYSU): 2 males, same data as holotype; 1 male., Yunnan, Yingjiang, Nabang, 24.75°N, 97.56°E, 239m, 27.V.2016, Yu-dan Tang & Rui-juan Zhang leg. [transcribed from Chinese].

Diagnosis.

Body oblong (Fig. 1). Black, pronotum and elytra with paler margins. Head, pronotum and elytra with distinct systematic punctures. Ground punctures of pronotum and elytra finer laterally and posteriorly than on disc (Figs 1, 3). Mesoventrite with a longitudinal and moderate high ridge posteromedialy (Fig. 5). Hind femora pubescent on basal four-fifths. Parameres shorter than median lobe, inner margin with a subapical tooth, apex obtuse rounded. Median lobe broad, gradually narrowing from apical fourth to apex, moderately curved on apical fifth and strongly curved subapically, apex truncate (Fig. 8).

Description.

Length 3.4-3.7 mm, width 1.7-2.0 mm. Body oblong, moderately convex. Dorsum of head, pronotum and elytra black with paler margins. Maxillary and labial palpi, and antennae uniformly yellowish brown (Figs 1-4). Ventral surface and legs reddish brown or dark brown.

Head. Labrum sparsely and finely punctate, with slightly emarginate anterior margin and round arcuation on posterior margin. Clypeus emarginate anteriorly (Figs 6-7), systematic punctures distinct, ground punctures fine and sparse, with distance between punctures 1.5-3.0 × the width of one puncture. Frons with distinct systematic punctures, ground punctures as fine as those on clypeus but a little denser. Mentum transverse, ca. 2 × as wide as long, rugose, with distinct oblique sculptures and a few strong punctures, strongly depressed anteriorly, anterocentral notch developed (Fig. 4). Maxillary palpi obviously longer than width of head. Antenna with nine antennomeres, pedicel as long as antennomeres 3 to 6 combined.

Thorax. Pronotum with distinct systematic punctures, ground punctures on disc as fine as those on frons, with distance between punctures 1.5-3.0 × the width of one puncture; lateral portions with finer punctures. Prosternite slightly bulged in middle, not carinate, with sparse pubescence, with transverse groove anteriorly (Fig. 4). Elytra with fine punctures similar to those of pronotum, systematic punctures distinct; with distinct sutural stria on posterior three-quarters. Mesoventrite with a longitudinal carina posteromedially, completely fused with mesanepisterna. Metaventrite pubescent with an irregular glabrous area (Figs 2, 5). Meso- and metafemoral pubescence on basal four-fifths.

Abdomen. Abdominal ventrites densely pubescent. Apical margin of fifth ventrite with shallow emargination (Fig. 2).

Aedeagus. Parameres shorter than median lobe, inner margin with a tooth subapically, apex obtuse rounded. Median lobe broad, gradually narrowing from apical quarter to apex, moderately depressed on apical fifth and strongly curved subapically, apex truncate (Fig. 8).

Remarks.

This species is close to C. orbus Watanabe, 1987. It can be distinguished from C. orbus by parameres obtuse apically, subapical tooth sharper; median lobe slender, slightly but distinctly constricted in apical quarter (Fig. 8).

Etymology.

The species name is combined from Latin “para-“, similar, and orbus, a species name of the genus.

Biology.

Aquatic, living in stagnant pools.

Distribution.

Only known from type locality.