Oocyclus madidus, Short, 2009

Short, Andrew Edward Z., 2009, Two new species of the hygropetric genus Oocyclus from eastern India (Coleoptera: Hydrophilidae), Acta Entomologica Musei Nationalis Pragae 49 (2), pp. 625-630 : 628-630

Oocyclus madidus sp. nov.

( Figs. 2 , 4 )

Type material. HOLOTYPE: male, ‘ INDIA, Meghalaya State (10) / E Khasi Hills, 11km SW Cherra- / punjee, Laitkynsew, 21-24.iv. / 2008, 25°13’N 91°39’E, 810m / Fikáček, Podskalská, Šípek lgt.’ // ‘seepage: wet rocks algae / blue algae/moss ca. 1.5-2 km / via rd. from ‘Cherrapunjee Holid. / Resort’ in direct. Cherrapunjee, / exposed’ ( NMPC) . PARATYPES: 24 spec., same data as holotype ( KSEM, NHMW, NMPC, USNM).

Diagnosis. Posterolateral corners of pronotum evenly rounded. Procoxae without distinct spines. Abdominal ventrites finely and evenly pubescent. Elytra without detectable rows of systematic punctures. This species is externally very similar to O. bhutanicus SATÔ, 1979 but differs in several subtle characters: although the dorsal punctation on the elytra of both species consists of punctures of mixed sizes, in O. madidus sp. nov. the smallest punctures are much finer and smaller than the smallest punctures seen on O. bhutanticus . The largest punctures on both species are relatively similar in size. Consequently, the size range of the punctures observed in O. madidus sp. nov. is more extensive. In addition, the metafemora in O. madidus sp. nov. are slightly broader (ca. 2.1× as long as wide, compared to ca. 2.3× for O. bhutanicus ). Additionally, the anteromedial tooth of the prosternal carina, while still small in O. madidus sp. nov., is larger than in the holotype of O. bhutanicus . Unfortunately, the aedeagus of the holotype of O. bhutanicus has been missing for more than 25 years (see SHORT & SWANSON 2005 for discussion) and so I was not able to compare these structures directly; based on the figure by SATÔ (1979: Fig. 16), the inner margin of the parameres are sinuate in that species (straight in O. madidus ). SATÔ’ s (1979) drawing is not symmetrical, with the left paramere indicating a small apical constriction and the right evenly rounded; thus, I cannot determine which is correct for comparison with O. madidus sp. nov., which is closer to the former condition.

Description. Size and form. Total body length = 3.7–4.2 mm. Oval, moderately convex. Elytra longer than wide.

Color. Dorsum black; head, pronotum, and elytra with distinct greenish sheen. Maxillary and labial palps yellow; apex of maxillary palps dark brown. Mentum and stipes light to reddish brown, distinctly paler than ventral face of head. Legs, epipleura, lateral margins of prosternum, and posterior margin of each ventrite yellow to light brown, with remainder of venter slightly to moderately darker reddish brown.

Head. General punctation on labrum, clypeus and frons slightly variable in size from very fine to moderately fine; densely distributed, distance between punctures 1.0–1.5× the width of one puncture. Systematic row of punctures on labrum moderately dense, forming a nearly continuous lateral row set with moderately long setae, but each puncture still fairly distinguishable, not forming a groove. Frons with an irregular row of systematic punctures mesad of each eye, bearing fine erect setae. Clypeus with a few very indistinct systematic punctures along anterolateral margins, slightly larger than surrounding punctation and bearing short setae. Antennae with scape subequal in length to segments 2–5; first two segments of club subequal in length and apical segment subequal in length to the two preceding segments combined. Maxillary palps short, about as long as width of labrum; segment 2 slightly bulbous, apical segment slightly longer than penultimate. Labial palps one-half to three-fourths as long as width of mentum. Mentum quadrate, anterior margin slightly convex, bearing very fine and scattered punctures.

Thorax. General punctation on pronotum and elytra composed of extremely fine and coarse punctures, evenly mixed and distributed. Pronotal systematic punctures present, ca. 1.5× the size of general punctation and set with a fine seta, sometimes partially blending with larger general punctures; anterior and posterior series each forming an irregular row. Lateral margins of pronotum set with a few sparsely distributed setiferous punctures; with punctures very small as to almost appear absent. Posterolateral corners of pronotum evenly rounded. Sutural punctation on elytra absent or unmodified from general punctation. Elytra without distinct rows of larger punctures, as they blend uniformly with general punctation; some of these rows (of systematic punctures) can be detected by the presence of fine, short setae. Prosternum with median carina along entire length, with small anteromedial tooth; without long spines or hairs anteriorly. Process of the mesoventrite with lateral extensions sloping evenly downward; apex set with a few long fine setae. Metaventrite with small oval glabrous area posteromedially, slightly longer than wide, length of glabrous area about half the total length of metaventrite. Pro- and mesocoxae densely pubescent; without distinct spines. Protibiae with 10 spines on dorsal face. Protarsal segments 1–4 small, subequal in length; apical segment ca. as long as segments 1–4 combined.

Abdomen. Ventrites 1–5 with uniform pubescence, longest setae about as long as the setae around the metasternal glabrous area. Fifth ventrite entire. Aedeagus with parameres slightly attenuated apically; inner margins straight. Median lobe ( Fig. 4 ) not reaching the apex of the parameres.

Etymology. Madidus, Latin , meaning soaked or drenched, referring to the wet habitats of the species.

Biology. Collected with and presumed identical to O. armstrongorum sp. nov. (see above).

Distribution. Known only from the type locality in Meghalaya state of India.

Figures

Figs. 1–2. Dorsal habitus. 1 – O. armstrongorum sp. nov., 2 – O. madidus sp. nov.

Figs. 3–4. Aedeagus, dorsal view. 3 – Oocyclus armstrongorum sp. nov., 4 – O. madidus sp. nov. Scale bar = 0.33 mm.