Berosus castaneus Oliva & Short

Oliva, Adriana & Short, Andrew E. Z., 2012, Review of the Berosus Leach of Venezuela (Coleoptera, Hydrophilidae, Berosini) with description of fourteen new species, ZooKeys 206, pp. 1-69 : 17-19

Berosus castaneus Oliva & Short sp. n. Fig. 9

Type material.

Holotype (male): "VENEZUELA: Bolivar State/ 5°44'28.7"N, 61°30'54.3"W, E. of/ Kavanayen; 1.viii.2008; 1290 m/ leg. A. Short & M. Garcia; large/ vegetated marsh; AS-08-063", "HOLOTYPE/ BEROSUS/ castaneus sp. n./ des. Oliva & Short 2010" (MIZA). Paratypes (2): VENEZUELA: Bolívar State: 5°37'53.8"N, 61°41'12.8"W, 1330 m, E. of Kavanayen, 1.viii.2008, leg. Short & García, small stream, AS-08-061 (1 male, SEMC); 48 km WSW Luepa, Salto Apanguao, 1220 m, 1.vii.1987, leg. M.A. Ivie, "stream-side wrack" (1 female, MTEC).

Diagnosis.

This species appears close to Berosus sinigus Oliva, 1989 (Argentina, Brazil) and Berosus hispidulus Oliva, 1993 (Brazil), in the general shape of the genitalia and th e color pattern. It differs from both in having spine-like hairs on the outer interstria only ant in the characters of the male genitalia, noticeably the very long basal piece (Fig. 9).

Description.

Body length 4.3 mm (holotype: total length: 4.3 mm; humeral width: 1.8 mm). Shape depressed. Labrum testaceous; clypeus testaceous with a very small dark median triangle medially, frons testaceous in lateral quarters, with central half darkened. Pronotum testaceous with a median melanic parallel sided stripe divided into two lateral halves by a thin testaceous median line. Scutellum dark brown. Elytra testaceous with dark spots in the usual pattern. Venter of thorax and abdomen very dark brown. Maxillary palpi yellow with apical segment darkened at apex. Femora with pubescent portion darkened, glabrous portion testaceous.

Clypeus with fine punctures (rather smaller than ommatidia), distance between punctures 1-2 times their diameter. Frons with punctures subequal in size to an ommatidion, distance between punctures 2-3 times their diameter. Maxillary palpi slender, not elongate. Pronotal disc with fine round punctures spaced by 2-4 times their diameter; surface shining, not microreticulate. Scutellum with dense punctures the same size as those on pronotum, surface shining. Elytral striae fine, on disc bearing punctures spaced by 1-2 times their diameter; outer striae more densely punctuated. Outer stria obsolete on apical fifth. Interstriae flat, with uniseriated punctures about the same size as those on striae, outer ones with obsolete punctures, on striae 9 and 11 a few larger punctures. Elytral apices separately rounded; with spine-like hairs on interstria 11 only.

Mesoventral process with small, straight anterior tooth directed posteroventrally, behind ventral margin weakly convex, then gradually depressed to posterior end which is not raised. Metaventral process narrow, finely carinate on front of medial depression, posterolateral angles produced into triangular laminae, posterior angle not raised. First ventrite carinate only between metacoxae, and without lateral depressions. Fifth ventrite with shallow apical notch, which is set with two triangular teeth. Meso- and metafemora with pubescence on basal two-thirds, the limit transverse, convex. Protarsus of male weakly thickened at base, with basal two tarsomeres expanded and with ventral pads, first tarsomere about twice as long as second. Claws weakly curved.

Male genitalia with basal piece extending three-quarters of total length. Parameres acuminate, unencased portion divided into a sternal membranous part, which has a weakly convex sternal margin, and a more strongly sclerotized tergal part, narrow, acuminate, straight.

Row of hairs rather short, extending along subapical third. Median lobe a little shorter than parameres, straight, acuminate at the apex.

Etymology.

The name alludes to the brown coloring of the dorsum, from the Latin nux castanea, “chestnut”, given adjectival form.

Distribution.

Venezuela ( Bolívar).

Remarks.

All three known specimens were collected in the Gran Sabana region (at elevations of>1000 m): one each in a large marsh, a stream, and 'stream-side wrack’.