Oocyclus namtok Short & Swanson

Short, A. E. Z. & Swanson, A. P., 2005, A revision of the Oocyclus Sharp of Thailand with description of six new species (Coleoptera: Hydrophilidae), Zootaxa 1078, pp. 1-24 : 12-13

Oocyclus namtok Short & Swanson , sp. n.

( Fig. 3 )

Type Locality. Thailand: Kanchanaburi Province, Ampur Thong Pha Phum, 6.3 km W of boarder police station at Ban Padsadoo Klang, 14°32N 98°32E, 568 m.

Type Material. Holotype: Male. “ THAILAND: Kanchanaburi Prv. Amphur / Thong Pha Phum sml. wtrfl 6.3 km W of / Boarder Police Stn. at Ban Padsadoo Klang / rock face 568 m L­463 14°32N 98°32E / 10.IV.2003, UMC & CMU teams”, “ HOLOTYPE / Oocyclus / namtok / Short & Swanson” ( USNM). Paratypes (50): THAILAND: Kanchanaburi Province: same data as holotype (49: AEZS, BMNH, CUIC, ISU, EMBT, MCZ, NWM, UMRM, USNM). Ranong Province: Thung Raya­Na Sak Wildlife Sanctuary, Chumsang waterfall on rockface, 20.v.2003, Vithaeepradit & Ferro leg., L­550 (1: UMRM).

Diagnosis. Posterolateral corners of pronotum weakly spinose. Procoxae covered with coarse spines. Ventrites not uniformly pale in coloration. Metasternal glabrous area one half the length of metasternum. Most similar to O. thailensis , but smaller in size.

Description. Size and Form. Length=4.0– 4.5mm. EL/EW=1.03. Broadly oval, moderately convex. Elytra slightly longer than wide. Color. Dorsum black. Head and pronotum with very distinct mottled green iridescence; usually also very distinct on elytra, especially laterally. Maxillary and labial palpi uniformly yellow. Mentum and stipes reddish brown, distinctly paler than ventral face of head. Most of venter, including legs, sterna, and ventries reddish to dark brown, with lateral margins of prosternum and epipleura slightly pale. Head. General punctation on labrum, clypeus and frons very fine; distance between punctures 2–2.5x the width of one puncture. Systematic punctures on labrum composed of a dense median row of coarse punctures bearing fine, long erect setae, less than one puncture width between punctures. Frons with an irregular row of systematic punctures mesad of each eye, bearing fine recumbent to erect setae. Clypeus with a few very indistinct systematic punctures along anterolateral margin, almost undetectable; slightly larger than surrounding punctation and usually bearing a short seta. Antennae with scape subequal in length to segments 2–5; first two segments of club subequal in length and apical segment slightly shorter in length than two preceding segments combined. Maxillary palpi short, slightly shorter in length than width of labrum; apical segment 1.5x as long as penultimate. Labial palpi three­fourths as long as width of mentum. Mentum quadrate, anterior margin slightly convex; bearing nearly obsolete scattered punctures, some of which bear fine setae. Thorax. General punctation of pronotum and elytra extremely fine, almost undetectable at 50x magnification, especially on pronotum. Pronotal punctation similar but distinctly less impressed. Pronotal systematic punctures distinct, each bearing a short recumbent seta; anterior series each forming an irregular row; posterior series more diffused into a short, wide field. Lateral margins of pronotum with a few sparse setiferous punctures. Posterolateral corners of pronotum weakly but distinctly spinose. Sutural punctation on elytra unmodified from general punctation. Elytra with five diffuse rows of coarse setiferous punctures: rows 1–3 with punctures spaced irregularly but linearly and bearing recumbent setae; row 4 more or less a field of irregularly spaced punctures with recumbent to erect setae; row 5 along extreme lateral margin, bearing erect fine setae. Prosternum with median carina along entire length, with a moderately acute tooth anteriorly; without long spines or hairs anteriorly. Mesosternal process with lateral extensions sloping evenly downward; apex set with a few fine setae. Metasternum with small oval glabrous area posteromedially, ca. twice as long as wide, length of glabrous area about half the total length of metasternum. Procoxae covered with short, coarse spines; mesocoxae with 2–4 short but distinct spines. Protibiae with 7–9 spines on dorsal face. Protarsal segments 1–4 small, subequal in length; apical segment ca. as long as segments 1–4 combined. Abdomen. Ventrites with moderately dense pubescence, with longest setae shorter to subequal in length to longest setae around mesosternal glabrous area. Fifth ventrite entire, with pubescence slightly denser than ventrites 1–4. Aedeagus ( Fig. 3 ) with outer margin of parameres evenly arcuate, with apex of each paramere narrowing to a blunt point; median lobe appearing triangular.

Distribution. Thailand.

Etymology. The species name is derived from “ Nam Tok ”, meaning waterfall in Thai.

Figures

FIGURES 1 – 6. Oocyclus aedeagi, dorsal views. 1. O. viridescens sp. n. 2. O. sitesi sp. n. (holotype). 3. O. namtok sp. n. 4. O. thailensis sp. n. (holotype). 5. O. sumatrensis d’Orchymont (specimen from Thailand). 6. O. melinoventris sp. n. Scale Bar = 0.18 mm.