Berosus megaphallus 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 : 36-38

Berosus megaphallus Oliva & Short sp. n. Fig. 21B

Type material.

Holotype (male): "GUYANA, Karanambo/ 3°45.1'N, 59°18.6'W / 2Apr1994, Buffalo Pond/ PJSpangler, colln #11", "HOLOTYPE/ BEROSUS/ castaneus sp. n./ des. Oliva & Short 2010" (USNM). Paratypes (97): GUYANA: Karanambo, 3°45.1'N, 59°18.6'W, 31.iii.1994, 'on bank of Rupununi’, blacklight, leg. P.J. Spangler, Collection #2 (11 exs., USNM); same locality but 2.iv.1994, 'buffalo pond’, collection #11 (31 exs., USNM, SEMC); same locality but 2.iv.1994, Simoni Lake, collection #10 (1 ex., USNM); same locality but 2.iv.1994, Rupununi River, collection #8 (1 ex., USNM); same data but 2.iv.1994, pool in sandbar of Rupununi River, collection #9 (5 exs., USNM). VENEZUELA: Apure State: Fundo Mata Palito, Laguna Larga, 6°59'N, 67°17'W, 26.i.1999, leg. E. Osuna (5 exs., MIZA, SEMC). Bolívar State: Cuchivero, 30 km SE Caicura, 4.viii.1987, leg. S. & J. Peck, woodland UV light, SBP87-108 (1 ex., SEMC); 4°37.362'N, 61°5.679'W, 876 m,Gran Sabana, N. Santa Elena, Rio Guara at Rt. 10, 17.vii.2010, leg. Short, Tellez, & Arias, marshy area, VZ10-0717-02A (9 exs., MIZA, MALUZ, SEMC). Delta Amacuro State: Transect 2, Agua Negra Farm, 08°32'48.1"N, 62°09'29.6"W, 15 m, Seasonal pond, 17.viii.2009, leg. R. Cordero, VZ09-817-17A, (4 exs., SEMC); Transect 2, Agua Negra Farm, 08°32'47.5"N, 62°09'37.11"W, 15 m, Seasonal pond, 17.viii.2009, leg. R. Cordero, VZ09-817-17B, (16 exs., MIZA, MALUZ, SEMC); Transect 2, Agua Negra Farm, 08°32'47.5"N, 62°09'39.4"W, 15 m, Seasonal pond, 21.viii.2009, leg. R. Cordero, VZ09-821-17C, (6 exs., MIZA, SEMC); Transect 2, Agua Negra Farm, 08°32'47.5"N, 62°09'38.9"W, 15 m, Seasonal pond, 21.viii.2009, leg. R. Cordero, VZ09-821-17D, (5 exs., SEMC). Monagas State: Uverito, 24.v.1990, "En la luz", leg. C.J. Rosales (2 exs., MIZA).

Diagnosis.

Large, elongate, depressed species. Resembling large individuals of Berosus truncatipennis but with micropunctation finer (micropunctures about one-quarter of punctures in Berosus truncatipennis , one-sixth in the new species) and with sutural angle of elytra in males broadly rounded, not bearing spines. Male genitalia much larger with respect to total body size in the new species; parameres bearing a subapical tuft of hairs instead of a row; membranous appendices a little longer than the median lobe (Fig. 21B).

Description.

Body length: 6.0-7.7 mm. Shape elongate, depressed, not very narrow. Eyes prominent, a little more in males. Maxillary palpi slender, rather long, a little more so in males because the apical segment is longer and more slender than in females. Dorsum of head, pronotum, scutellum, and elytra testaceous, except slightly darkened on base of frons, a pair of narrow paramedial bands on pronotal disc, and small elytral spots in the usual pattern. Venter of thorax and abdomen dark brown; maxillary palpi darkened at tip of apical segment; femora with pubescent portion darkened, glabrous portion testaceous.

Dorsal sculpture moderate to fine, regular; punctures round, only on the base of frons a little elliptical. Head and pronotum with punctures about twice the size of an ommatidion; micropunctures about one-sixth the size of punctures. Elytral striae deep, well-im pressed, finely punctured. Interstriae flat, wide, with moderate-sized punctures disposed in several series, on posterior half of elytra a little coarser and bearing spine-like hairs. Elytral micropunctures fine, on posterior half obsolete. Elytral apices emarginate, with acute parasutural spine; in males sutural angle broadly rounded, comprising the three inner striae; in females the emargination a little broader and the sutural angle produced into a short straight spine. Mesoventral process laminar, with large, curved, but not acute, anterior tooth, behind the margin obliquely lowered. Metaventral process narrow, with small median depression; posterolateral angles produced into triangular laminae, posterior angle not raised. First ventrite carinate medially only between metacoxae, with deep, moderately large lateral depressions. Fifth ventrite with shallow apical notch in females, in males raised into a disc around a narrow, very deep notch (Fig. 21B). Lateral margins of abdominal ventrites smooth. Meso- and metafemora with pubescence on basal three-fifths and three-quarters respectively. Male protarsi with the two basal tarsomeres thickened, bearing adhesive soles; first about twice as long as second, fourth slender, longer than 3 basal segments taken together. All claws long, slender, very weakly curved.

Male genitalia: Basal piece about two-fifths of total length. Parameres complex, in lateral aspect with wide blunt apices, with membranous appendices in a ventral position. Median lobe much shorter than parameres, a little shorter than the appendices (Fig. 21B).

Etymology.

Named after the comparatively large aedeagus.

Distribution.

Guyana andVenezuela (Apure, Bolívar, Delta Amacuro, Monagas).

Remarks.

All known collecting events for Berosus megaphallus represent standing waters, both permanent and temporary. Oliva (1989) probably handled this species (from Venezuela [Barinas] and Nicaragua [Zelaya]), but believed at the time that there was a gradient in the size of male genitalia of Berosus truncatipennis Castelnau, "with shorter, thicker organs in specimens of the Antilles area and Orinoco basin, and longer, more slender organs in those of the middle and lower Paraná.”