Oocyclus brunneus

Short, Andrew Edward Z., Greene, Luke & Garcia, Mauricio, 2013, New species and new records of the hygropetric water beetle genus Oocyclus Sharp from South America (Coleoptera: Hydrophilidae), Zootaxa 3741 (3), pp. 349-358 : 350-352

Oocyclus brunneus SHort, Greene & García sp. n.

Figs. 1 A, 2A.

Type material. Holotype (male): “ BOLIVIA; Santa Cruz/ Amboro National Park/ Los Volcanes, c. 1000m / S 18°06': W 63°36'/ 20/xi-12/xii/2004 ”, “Ex flood debris/ Barclay, M.V.L. &/ Mendel, H./ BMNH(E)2004-280” (BMNH). Paratypes (3): Same data as holotype (3; BMNH, SEMC).

Diagnosis. Medium-sized species ( Fig. 1 A); dorsum entirely brown. Posterolateral corners of pronotum rounded. Procoxae set with a few spine-like setae basally. Elytra with distinct rows of systematic punctures, and set with short row of erect setae medially. Elytral suture not raised. Elytral margins weakly explanate in posterior half and without a fringe of yellow setae.

The distinctly brown coloration of this species is unique among all known species of Oocyclus , which are otherwise black and often have iridescent markings. Given the level of apparent scleritization and the series of specimens, this coloration is not due to them being teneral. The lack of an elytral pale posteromedial spot and rounded posterolateral corners of the pronotum further serve to characterize this species from many of those in neighboring Brazil.

Description. Size and Form. Length = 4.1–4.3 mm. Broadly oval. Color. Dorsum of head, pronotum, and elytra brown to dark brown, the former two with very faint and patchy iridescence. Anterolateral margins of pronotum pale to very light brown, moderately paler then rest of the pronotum. Maxillary and labial palps yellow, the apex of the former darkened. Mentum dark brown to black, similar in color to the venter of the head; cardo and stipes light brown, distinctly paler than the venter of the head. Legs, epipleura, and lateral margins of prosternum pale yellow to light brown. Remainder of venter, including the abdominal ventrites, brown to dark brown. Head. Ground punctation on labrum, clypeus and frons coarse, distance between punctures 2.0–3.0× the width of one puncture. Systematic punctures on labrum consisting of several indistinct punctures. Frons with an irregular row of systematic punctures mesad of each eye, bearing coarse setae. Clypeus with a sparse row of systematic punctures along anterior margin, subequal in size as surrounding punctation. Maxillary palps short, about as long as width of labrum; segment 2 slightly bulbous, apical segment slightly longer than penultimate. Labial palps three-fourths as long as width of mentum. Mentum quadrate, anterior margin slightly convex, smooth, with two course punctures medially. Thorax. Ground punctation on pronotum moderately impressed and evenly distributed. Ground punctation on elytra consisting of dual punctation, with very fine and coarse punctures evenly distributed. Pronotal systematic punctures with short fine setae, distinctly larger than ground punctures. Lateral margins of pronotum with a very sparse row of setiferous punctures; with punctures almost appearing absent, and bearing a very fine, short seta. Posterolateral corners of pronotum rounded. Sutural punctation represented by a single row of dense, irregularly spaced, extremely fine; sutural interval distinct raised in posterior quarter. Elytra with distinct but irregular rows of systematic punctures; the first row represented by a combination of large punctures each bearing a single decumbent seta and two short series of dense punctures bearing an erect setae ( Fig. 1 A). The remaining rows are represented by irregularly spaced punctures usually bearing a recumbent seta; the punctures significantly larger that surrounding punctation. Elytral margin weakly explanate in posterior half, and without fringe of long yellow setae. Prosternum with a weakly raised median carina; with two short spine-like setae at anterior margin. Elevated process of the mesoventrite narrow, elongate; set with 4–7 thickened, coarse spines. Metaventrite with oval glabrous area posteromedially, distinctly longer than wide, length of glabrous area three-quarters the length of metaventrite. Procoxae covered with dense, fine short pubescence, set spine-like setae basally. Protibiae each with 12–14 spines on dorsal face. Abdomen. Ventrites covered with very dense, short to moderately long setae, the longest setae not longer than the longest setae surrounding the glabrous area of the metaventrite. Aedeagus as in Figure 3 A.

Etymology. Named for the distinctly brown dorsal coloration, which is unique among all described members of the genus.

Distribution. Known only from the type locality.

Biology. The label data indicates the series was taken from “flood debris”.

Remarks. While the brown coloration of this species separates it from all other known Oocyclus in both the Old and New Worlds and it is not known from Brazil, the key to the Brazilian species in Clarkson & Short (2012) may be modified as follows to accommodate O. brunneus :

1’ Dorsum brown. Posterolateral corners of the pronotum rounded................................... O. brunneus sp. n.

- Dorsum black. Posterolateral corners of the pronotum of various shapes.......................................... 1

Figures

FIGURE 1. Habitus photos of Oocyclus spp. A) O. brunneus sp. n. (dorsal and lateral), B) O. maluz sp. n. (dorsal), C) O. miza, sp. n. (dorsal). All specimens are paratypes.

FIGURE 3. Elytral detail of Oocyclus spp. A) O. maluz sp. n., B) O. andinus.