Coelostoma (s. str.) lyratum, Sheth & Ghate & Fikáček, 2020

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 : 15-17

Coelostoma (s. str.) lyratum sp. nov.

urn:lsid:zoobank.org:act:6E05380A-D3AA-410E-A974-D1CED984068A

Fig. 6 A–K

Differential diagnosis

The species is easily recognized based on its aedeagus which resembles those of C. bhutanicum and C. stultum in its apically situated gonopore and parallel-sided median lobe. In contrast to both latter species, the outer margin of the parameres in strongly bisinuate in C. lyratum sp. nov. (in contrast to a nearly continuously arcuate outer margin in C. bhutanicum and C. stultum ) and the abdominal apex is simple, without emargination and stout setae.

Etymology

The species name refers to the lyriform shape of the aedeagus; adjective.

Type material

Holotype

INDIA • ♂; “ Maharashtra, ca. 15 km of Savantvadi; 15º55ʹN 75º53ʹE ” [15º55ʹ3.72ʺ N, 73º48ʹ56.67ʺ E]; ca 40 m a.s.l.; 22 May 2006; Z. Kejval leg.; riverside; NMPC.

Paratypes

INDIA • Maharashtra • 3 specs; same collection data as for holotype; NMPC • 2 specs; same collection data as for holotype; BMNH • 1 spec.; same collection data as for holotype; SMNS • 1 spec.; same collection data as for holotype; ZSI • 2 specs; same collection data as for holotype; NCBS-BL018–019 • 2 specs; same collection data as for holotype; UASB 01923068–69 .

Description

FORM AND COLOUR. Body length 4.2–4.7 mm (holotype 4.5 mm), body width 2.7–3.1 mm (holotype 3.0 mm). Body narrowly oval in dorsal view, moderately convex in lateral view. Head black, reddish brown near clypeus and anterior to eyes; pronotum and elytra uniformly dark brown to black with slightly paler margins, ventral surface blackish brown, legs reddish brown. Mouthparts and antennae pale brown, antennal club brown.

HEAD. Dorsal punctation dense, consisting of simple punctures without associated ridges; trichobothria present; surface between punctures smooth.Anterior margin of clypeus arcuate, indistinctly emarginated medially. Eyes large, interocular distance ca 4.0 × the width of one eye in dorsal view; eye emarginate anteriorly. Labrum moderately sclerotized, largely exposed anterior of clypeus. 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.Anterior and lateral margins with distinct bead not extending to posterior margin. Pronotal punctation denser and finer than on head, consisting of simple punctures without associated ridges; surface between punctures smooth. Prosternum straight on anterior margin, weakly carinate mesally.

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

METATHORAX. Metaventrite raised medially, median part sparsely pubescent except posterior third and anterior part, which are bare; lateral portions pubescent. Anterior metaventral process narrowly projecting between mesocoxae; posterior process bifid. Wings well-developed (macropterous).

LEGS. Profemur with dense pubescence except in apical fifth; mesofemur and metafemur with very sparsely arranged short setae only.

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

AEDEAGUS ( Fig. 6 J–K). 0.84 mm long. Median lobe of nearly the same width throughout; apex roundly cut off; gonopore situated at apex, widely semicircular. Parameres slightly longer than median lobe; heavily tri-sinuate on outer margin; apex acute at inner margin, rounded laterally. Phallobase small, slightly wider than long.

Biology

Unknown. The labels of the type specimens indicate that they were found at the riverside.

Distribution

Known from the type locality in southern Maharashtra.

Figures

Fig. 6. Coelostoma (s. str.) lyratum sp. nov., holotype, ♂ (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).