Berosus humeralis 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 : 28-33

Berosus humeralis Oliva & Short sp. n. Figs 16A, 17A, 27

Type material.

Holotype (male): "VENEZUELA: Amazonas State/ 5°30.623'N, 67°36.109'W, 110 m/ ca. 15 km S. Puerto Ayacucho/ 14.i.2009; rock pools et al./ leg. A.Short; VZ09-0114-03B", "[barcode]/ SM0843787/ KUNHM-ENT", "HOLOTYPE/ BEROSUS/ humeralis sp. n./ des. Oliva & Short 2010" (MIZA). Paratypes (12): VENEZUELA: Amazonas State: ca. 15 km S. Puerto Ayacucho, 5°30.623'N, 67°36.109'W, 100 m, pool at base of outcrop, 14.ix.2007, leg. Short, AS-07-011a (1 ex., SEMC); same data as holotype (5 exs., SEMC, MIZA); at river near confluence of Orinoco/Sipapo rivers, rock pool, 15.i.2009, leg. García, VZ09-0115-01D (1 ex., SEMC). Bolívar State: Los Pijiguaos, 6°35.617'N, 66°49.238'W, 80 m, morichal/rock outcrop, 6.iii.2008, leg. Short, García, & Joly, AS-08-076 (2 exs., SEMC); same locality but 8.vii.2010, stream on side, leg. Short, Tellez, & Arias, VZ10-0708-01B (3 exs., SEMC).

Diagnosis.

Moderate-sized, broad-shaped, not very convex species with strong metallic luster on dorsum of head and often with weak metallic sheen on medial spot on pronotum. Elytra with small, well-defined black spots, including an additional pair below the humeral humps (Fig. 16A). Mesoventral process entirely laminar. First ventrite carinate in anterior half. Male genitalia as in Fig. 17A. The extended subhumeral spots distinguish Berosus humeralis from the closely related Berosus ornaticollis sp. n., besides the other characters listed in the key. There are hardly any species that may be confused with these two.

Description.

Body length: 3.7-4.0 mm. Shape short and broad, with prominent humeral humps, but rather depressed. Eyes moderately prominent in both sexes. Labrum melanic at base, testaceous on the distal margin. Dorsum of head melanic with strong metallic luster. Pronotum testaceous with a median melanic spot covering approximately two-fifths of total pronotal width, without testaceous median line, in most specimens with metallic sheen. Scutellum melanic. Elytra testaceous with small melanic spots as in Berosus ornaticollis sp. n., but the additional subhumeral spots more extensive, taking up the interstriae 8 and 9 and about half of 10. Venter of thorax and abdomen brown to dark brown. Maxillary palpi with apical palpomere darkened on distal quarter. Femora with pubescent portion darkened, glabrous portion testaceous.

Head densely punctured, punctures on clypeus about the size of an ommatidion, on frons slightly larger. Pronotal punctures slightly larger than ones on head, round, moderately dense, spaced by the equivalent of 2-4 times their diameter; surface sparsely and finely micropunctate, shining. Scutellum with a few deeply impressed punctures, smaller than pronotal ones; surface shining. Elytral striae fine on disc, the external ones a little more shallow, with dense punctures about the same size as the pronotal ones, not overflowing except on a short stretch of striae 6-8 on the posterior half of the elytra. Interstriae wide, flat, bearing punctures smaller than those on striae, irregularly uniseriated; outer interstriae slightly convex; background smooth. Elytral apices simple, slightly more pointed and outwardly deflexed in females; spine-like hairs absent.

Mesoventral process small, laminar, with curved anterior tooth pointing downwards, a little thickened; posterior tooth raised but less prominent than anterior one. Metaventral process as in Berosus ornaticollis . First ventrite carinate medially in the anterior half, carina broadened and lowered behind metacoxae; without lateral depressions. Ventrites 2-4 not carinate. Fifth ventrite with shallow apical notch, set with two straight, sharp teeth.

Maxillary palpi short, thick. Meso- and metafemora with pubescence on basal half and three-fifths respectively, limit oblique. Protarsus of male with basal tarsomeres strongly enlarged, with adhesive sole; second without sole. Claws fine, toothed.

Male genitalia (Fig. 17A): basal piece about two-fifths of total length. Parameres narrow, rounded at apex, in tergal aspect elbowed and curved inwards. Row of hairs rather long. Median lobe a little shorter than parameres, complex.

Etymology.

The name refers to the characteristic subhumeral spots, taking up part of the striae 8-10.

Distribution.

Venezuela (Amazonas, Bolívar).

Remarks.

This species is known only from granite outcrops in along the northwestern fringe of the Guiana Shield. It has only been found in distinctive "rock pools" that collect rainwater or in small streamlets that drain such pools (Fig. 27).