Hydrochus denarius, Perkins, 2019

Perkins, Philip D., 2019, Taxonomy of Venezuelan water beetles in the genus Hydrochus Leach, 1817, and an analysis of male genitalia morphology (Coleoptera: Hydrochidae), Zootaxa 4708 (1), pp. 1-59 : 46-48

Hydrochus denarius new species

Figs. 2 , 26

Type Material. Holotype (male): “ Venezuela: Bolivar State: 6° 35.617’ N, 66° 49.238’ W, 80m, Los Pijiguaos: out-

crop/morichal, 12.i.2009, leg. Miller & Short, detrital pools VZ09-0112-01C” ( MIZA). Paratypes (8): Venezuela: Bolivar: Same data as holotype (7 SEMC, MIZA) ; VZ09-0112 - 02 B (1 SEMC) .

Differential Diagnosis. Among Venezuelan species, recognized by the combination of small size (ca. 2.18–2.46 mm), the elytra having 10 costate interstriae and with unusual, large translucent punctures at apices, the densely punctate pronotum with deep depressions and convex reliefs, the black dorsal color, and the male genitalia ( Fig. 26 ; described below). Differentiation from other similarly small sized Venezuelan species easily made because of the costate elytra.

Description. Habitus as illustrated ( Fig. 26 ). Size: holotype (length/width, mm): body (length to elytral apices) 2.18 /0.88; head width 0.58; pronotum l/w 0.46/0.50; PA 0.50; PB 0.40; elytra 1.38 /0.88. Body size small (ca. 2.18–2.46 mm). Dorsum black, with very weak iridescence. Legs brown, with tibiofemoral joints darker. Punctation on elytra ca. 3– 4x that of pronotum. Elytra with odd numbered interstriae costate, costae ca. 0.5– 1x strial puncture diameter; 5 th costate, usual area of callus not otherwise raised.

Pronotum slightly wider than long (as ca. 46/50), widest at anterior margin, markedly narrowed at base, sides very slightly sinuate, minutely denticulate, each denticle with a short seta; anterior margin weakly bisinuate, and with border of short, closely spaced setae; depressions deep and densely punctate, pits near anterior and posterior angles large and deep.

Elytra with spaces between strial punctures ca. 0.5x their diameter, to narrow ridges; apices widened and with submarginal groove having row of large, translucent punctures, another row of translucent punctures above groove.

Ventral characters: Mentum coarsely punctate, with shallow median fovea. Submentum with two very large, confluent or nearly confluent, foveae.

Male genitalia ( Fig. 26 ) general characters: paramere tips pointed, straight in dorsal and ventral views, slightly arcuate in lateral view, extending well beyond aedeagal apex; basal piece long, in dorsal/ventral views oriented at an angle to parameres, very arcuate in lateral view; aedeagus simple, lanceolate shaped.

Dorsal surface: pdmm very slightly overlapping aedeagus lateral margins; adbl lacking.

Ventral surface: pvmm very slightly overlapping aedeagus lateral margins.

Etymology. Named in reference to the ten elytral costae.

Figures

FIGURE 2. Dorsal habitus of Hydrochus species.

FIGURE 26. Hydrochus denarius n. sp., habitus and male genitalia of holotype.