Berosus asymmetricus 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 : 12-13

Berosus asymmetricus Oliva & Short sp. n. Figs 6A, 7A, 27

Type material.

Holotype (male): "VENEZUELA: Bolivar State/ 6°35.617'N, 66°49.238'W, 80 m, Los Pijiguaos; 6.viii.2008/ leg. A.Short, M. García, L.Joly/ AS-08-076; morichal/rock outcrop", "HOLOTYPE/ BEROSUS/ asymmetricus sp. n./ des. Oliva & Short 2010" (MIZA). Paratypes (112): VENEZUELA: Amazonas State: nr. Iboruwa, “Tobogancito”, 5°48.414'N, 67°26.313'W, 80 m, rock pool with detritus, 7.viii.2008; leg. Short, García, & Joly, AS-08-078 (2 exs., SEMC); ca. 15 km S. Puerto Ayacucho, 5°30.623'N, 67°36.109'W, 100 m, 'rock pools et al.' on granite outcrop, 14.i.2009, leg. Short, VZ09-0114-03B (1 ex., SEMC). Bolívar State: Same data as holotype (55 exs., MIZA, MALUZ, SEMC); same locality as holotype but 7.vii.2010, leg. Short, Tellez & Arias, rock pools, VZ10-0707-01A (24 exs., MIZA, SEMC); same locality as holotype but 8.vii.2010, leg. Short, Tellez, & Arias, rock pools, VZ10-0708-01A (25 exs., MIZA, SEMC); same locality but 8.vii.2010, leg. Short, Tellez & Arias, small stream on outcrop, VZ10-0708-01B (6 exs., SEMC).

Diagnosis.

The males of this species resemble Berosus festivus Berg in the thin carina in front of the apical notch. They differ in the unique asymmetrical genitalia and in the coarsely serrate edge of the mesoventral process.

Description.

Body length 2.1-2.6 mm; (holotype: total length: 2.3 mm; humeral width: 1.0 mm). Shape depressed. Head testaceous with a melanic triangle taking up a small part of the clypeus and the greater part of the frons. Pronotum testaceous with a strongly melanic band on the anterior margin behind the head; a pair of elongate paramedial discal spots; a less deeply melanic posterior band taking up one-third of the pronotum excepting the lateral margins. Scutellum dark. Elytra testaceous with small dark spots. Venter of thorax and abdomen dark brown in typical series. Maxillary palpi with distal palpomere darkened on apex. Femora with pubescent portion darkened, glabrous portion testaceous.

Punctures on clypeus fine and regular, coarser on frons, irregularly spaced, polygonal rather than round, rather sparse except along inner margin of the eyes, where they are contiguous. Pronotum with moderate-sized punctures (about twice the size of ommatidia), elliptical, with irregular spaces 1-4 times their diameter, which are shining, not micropunctate. Scutellum shining, with a few punctures similar in size to those on the pronotum. Elytral striae with round punctures, twice as large as those on the pronotum, contiguous, on the basal stria spaced by a whole diameter or a little more. Interstriae flat on elytral disc, not step-shaped, 1.5-2 times as wide as striae, sparsely and finely punctate (punctures smaller than those on pronotum); between punctures shining, not micropunctate. Interstriae 10 convex, overhanging the eleventh between humeral humps and stridulatory patch. Eleventh interstria flat, about 1.5 times as wide as the tenth. Spine-like hairs absent.

Mesoventral process with curved anterior tooth directed downwards and backwards; behind this, the ventral margin concave and irregularly serrate, in some specimens forming a small, acute second tooth; posterior angle weakly raised. Metaventral process rather wide, posterolateral angles raised into rounded lamellae, posterior angle carinate, not raised. First ventrite with carina thick between metacoxae, behind thin, reaching the posterior margin of the ventrite. Lateral depressions absent. Fifth ventrite with shallow apical notch, the bottom of the latter with two contiguous rounded teeth, in front of these a thin carina.

Maxillary palpi short and thick in both sexes, darkened at apex of fourth palpomere. Basal pubescence on half of mesofemora and three-fifths of metafemora, limit transverse. Protarsus of male short and thick, with basal tarsomere about 1.5 times as long as second, both weakly thickened, bearing small soles of adhesive hairs. Claws weakly arched.

Male genitalia (Fig. 7A): basal piece four-fifths of total length, three times as long as wide. Parameres with basal two-thirds encased in apical half of basal piece, asymmetrical. In lateral aspect, the unencased part of the parameres evenly curved towards the sternal side, describing nearly a quarter of a circle; apices narrowed. Row of hairs rather long. In tergal aspect, parameres strongly and regularly curved inwards. Median lobe longer than parameres, but strongly curved towards one side, subcylindrical, acuminate at the apex which is directed to one side.

Etymology.

The name alludes to the asymmetrical genitalia.

Distribution.

Venezuela (Amazonas, Bolívar).

Remarks.

This species, remarkable for its unusual genitalia, is apparently restricted to granite outcrops. All specimens have been collected in rock pools and small streams that occur on the bare rock of the numerous outcrops along the northwestern margin of the Guiana Shield region of Venezuela (Fig. 27). Several longer series have been collected in small seasonal streams that form on the outcrops which drain water during the wet season, as well as in small rock pools adjacent to the streams.