Coelostoma (s. str.) vitalisi Orchymont, 1923

Sheth, Sayali D., Ghate, Hemant V. & Fikáček, Martin, 2020, Review of Coelostoma of the Indian subcontinent (Coleoptera: Hydrophilidae) Part 1: Coelostoma s. str. and Holocoelostoma, European Journal of Taxonomy 690, pp. 1-32 : 17-19

Coelostoma (s. str.) vitalisi Orchymont, 1923

Fig. 7 A–K

Coelostoma vitalisi Orchymont, 1923a: 418 .

Coelostoma (s. str.) vitalisi – Orchymont 1925: 269 (faunistics); 1928: 57 (catalogue); 1936: 27 (faunistics). — Jia et al. 2017: 118 (faunistics).

Differential diagnosis

Coelostoma vitalisi is easy to recognize based on its aedeagus, with a very wide median lobe with a very large subapical gonopore. Thanks to the unique genital morphology, it cannot be confused with any other species of the genus.

Material examined

Holotype

Not examined.

Other material

INDIA • 1 ♂; “ Assam, Kohora (= Kaziranga village), Green Reed Hotel ; 27º35.93N, 93º26E ” [26º35ʹ21.81ʺ N, 93º24ʹ44.07ʺ E]; [1000 m a.s.l.]; 16–18 Apr. 2008; Fikáček, Podskalská and Šípek leg.; at light; NMPC .

Published records

NEPAL: Narayani Sauraha, bank of Rapti River ( Hebauer 2002; Jia et al. 2017); Seti distr., Bajhang, on the way from Chainpur to Sagu Bagar ( Jia et al. 2017); valley of Rapti river, Jhawani ( Jia et al. 2017); Narayani Prov., Sauraha SW Royal Chitwan Nat. Park ( Hebauer 2002); Kathmandu, Baneshwar ( Hebauer 2002). INDIA: Uttarakhand: Dehradun (Orchymont 1936). Chhattisgarh: ‘Barwayʼ [= Barway mission, Chainpur env., see Fikáček et al. 2012] (Orchymont 1925, 1936). Bihar: Pusa (Orchymont 1923b). Jharkhand: Mandar (Orchymont 1925). Kerala: ‘Calicut ' [= Kozhikode] (Orchymont 1936). SRI LANKA: without specified locality (Orchymont 1928, 1936) [specimens reported by Orchymont (1925) as C. vitalisi from India: West Bengal (‘Bengalʼ and ‘Calcuttaʼ) were found to belong to C. vividum by Orchymont (1936)].

Description

FORM AND COLOUR. Body length 4.0– 4.9 mm, body width 2.5–2.9 mm. Body oval in dorsal view, moderately convex in lateral view. Head black; pronotum and elytra uniformly black to dark brown with slightly paler margins; ventral surface uniformly dark brown. Tarsi pale brown. Mouthparts and antennae yellowish, antennal club brown.

HEAD. Dorsal punctation dense, consisting of simple punctures, few punctures at posterior-most portion with associated ridges; trichobothria present; surface between punctures smooth. Anterior margin of clypeus gently arcuate. Eyes large, interocular distance ca 4.3× the width of one eye in dorsal view; eye emarginate anteriorly. Labrum moderately sclerotized, largely exposed anterior of clypeus, sinuate

on anterior margin, brown. Antenna with 9 antennomeres, club loosely segmented. Second maxillary palpomere moderately broad.

PROTHORAX. Pronotum bisinuate anteriorly, anterolateral corners obtuse; posterior margin moderately bisinuate, posterolateral corners rectangular. Lateral margin with very indistinct sculpture; anterior and lateral margins with distinct bead not extending to posterior margin. Pronotal punctation similar to that on head, consisting of simple punctures without associated ridges; surface between punctures smooth. Prosternum straight on anterior margin, very weakly carinate mesally, anterior portion raised, producing tooth-like process seen in lateral view.

MESOTHORAX. Elytral punctation dense and moderately coarse, similar to that on pronotum, consisting of punctures without transverse ridges. Series of punctures absent. Sutural stria impressed, present in apical half. Mesoventral plate 1.1 × as long as wide, arrowhead-shaped, bluntly pointed anteriorly, posteriorly widely attached to metaventrite.

METATHORAX. Metaventrite raised medially, posterior third and anterior portion of median elevation bare, remaining median surface with sparse regular setae; lateral portions densely pubescent. Anterior

metaventral process narrowly projecting between mesocoxae; posterior process bifid. Wings welldeveloped (macropterous).

LEGS. Profemur with dense pubescence except in apical fifth; mesofemur with sparsely arranged stout setae only, metafemur with sparse pubescence.

ABDOMEN. All ventrites densely pubescent. First ventrite without carina. Posterior margin of last ventrite entire, without stout spines mesally.

AEDEAGUS ( Fig. 7 J–K). 0.75–0.85 mm long. Median lobe triangular, broad at middle, tapering towards apex; gonopore situated at apex, widely semicircular. Parameres longer than median lobe; rounded or obtusely pointed at apex. Phallobase small, slightly wider than long.

Biology

Aquatic species, Nakajima et al. (2020) reported it from shallow wetlands in lowland to hilly areas. Most specimens available in the collections were collected at light.

Distribution

Widespread species, known from Nepal ( Jia et al. 2017), India (Orchymont 1925, 1936; this paper), Sri Lanka (Orchymont 1936), Cambodia, Thailand, Vietnam ( Jia et al. 2017), Indonesia (Borneo, Java, Sumatra; Orchymont 1923a, 1925), Malaysia (Sabah; Orchymont 1925), Singapore (Orchymont 1925; Jia et al. 2014), southern China ( Jia et al. 2014), Taiwan ( Liu et al. 2020) and Japan (Minoshima 2017; Nakajima et al. 2020).

Figures

Fig. 7. Coelostoma (s. str.) vitalisi Orchymont, 1923, ♂ specimen from Assam: Kohora (NMPC). A. Dorsal habitus. B. Lateral habitus. C. Frontal view. D. Thorax in ventral view. E. Dorsal punctation of head. F. Dorsal punctation of pronotum. G. Dorsal punctation of elytron. H. Abdominal ventrites. I. Detail of abdominal apex. J–K. Aedeagus: ventral (J) and dorsal (K).