Berosus tramidrum 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 : 46-50

Berosus tramidrum Oliva & Short sp. n. Figs 14D, 15E

Type material.

Holotype (male): "VENEZUELA: Guarico State/ 8°59'1.0"N, 65°44'18.8"W, 110 m/ nr. Socorro; 29.vii.2008/ leg. A. Short & M. Garcia/ AS-08-050; Muddy ditch", "[barcode]/ SM0827667/ KUNHM-ENT", "HOLOTYPE/ BEROSUS / tramidrum sp. n./ des. Oliva & Short 2010" (MIZA). Paratypes (3):VENEZUELA: Bolívar State: ca. 20 km E. Maripa, 7°26'23.2"N, 64°57'5.6"W, 45 m, grassy flooded area, 5.viii.2008, leg. Short & García, AS-08-074 (2 exs., MIZA, SEMC). Guárico State: nr. Socorro, 8°59'1.0"N, 65°44'18.8"W, 100 m, muddy ditch, 29.vii.2008, leg. Short & García, AS-08-050 (1 ex., SEMC).

Diagnosis.

This species keys to Berosus marquardti Knisch, 1921 in the key by Oliva (1993). It differs by the genitalia, especially the median lobe, which in the new species is longer than the parameres and very strongly thickened at the apex (Fig. 15D), and also by the shape of the carina on the first apparent ventrite, which in the new species is much more strongly raised, very strongly convex on anterior two-thirds, behind lower but raised into a separate curve, and by the margins of the fifth ventrite, crenulate in Berosus marquardti , coarsely dentate in the new species (Fig. 15D). Otherwise the two species are much alike.

Description.

Body length 3.3-3.9 mm. Shape short, broad, convex. Labrum, clypeus and small area of frons close to suture testaceous; most of frons melanic, in typical series reddish. No metallic luster. Pronotum testaceous with narrow median melanic spot divided by a median testaceous line. Scutellum melanic. Elytra testaceous with small spots following the usual pattern. Venter weakly melanic (light reddish in typical series). Femora with pubescent portion darkened, glabrous portion testaceous. Palpi with apical palpomere strongly melanic on distal one-fourth.

Clypeus with dense punctures about the size of one ommatidion, in lateral aspect convex, swollen. Frons even more densely punctured, the punctures twice the size of those on clypeus. Pronotum narrower than humeral humps, bearing contiguous puncture 2-3 times as large as ommatidia, round to polygonal in shape; between these a few deep micropunctures. Elytral striae with deep punctures, on elytral disc about twice as large as those on pronotum, on the sides larger and squarish. Interstriae narrower than striae, convex, the eleventh costate on most of the length, even at the elytral apex. Micropunctation fine but distinct. Humeral angle serrate. Elytral apices narrowly rounded. Spine-like hairs absent.

Mesoventral process short, strongly raised, with hood-like anterior tooth, strongly curved, directed downwards. Posterior angle raised, blunt, more weakly raised than anterior tooth. Metaventral process very wide, posterolateral angles produced into rounded laminae, posterior angle a little less strongly raised, in lateral aspect rounded. First ventrite carinate in its whole length, carina very strongly raised, convex, in anterior two-thirds of sternite further raised, therefore describing a double curve in lateral aspect. Fifth ventrite raised at each side of the deep, narrow apical notch, bidentate at bottom. Ventrites first to fourth crenulate at the sides, fifth coarsely serrate.

Maxillary palpi short, thick. Basal pubescence on two-thirds to three-quarters of mesofemora and two-thirds to three-fifths of metafemora, limit oblique. Protarsus of male almost linear, first and second tarsomeres with small tufts of adhesive hairs; first slightly longer than second. Claws slender, weakly arched, weakly toothed at base.

Male genitalia remarkably small, compressed: basal piece about twice as long as wide. Parameres broadly acuminate, apices strongly curved towards the sternal side. Row of hairs very long, extending along most of the part of the parameron not encased in the basal piece. Median lobe longer than the parameres, strongly curved towards the tergal side, with apex very abruptly and strongly thickened into a rounded club which protrudes entirely from the parameres.

Etymology.

The name is an arbitrary association of letters, derived from an anagram of “marquardti”.

Distribution.

Venezuela.

Remarks.

This species resembles Berosus marquardti Knisch, 1921 from which it may be distinguished by the remarkably high, very convex carina on the first apparent ventrite, which in lateral aspect describes a double curve, and by the male genitalia with the median lobe longer than the parameres. In Berosus marquardti , the carina is convex only on its middle portion and the median lobe is rather shorter than the parameres, with the apical swelling weaker.