Hydrochus pictus, 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 : 43-45

Hydrochus pictus new species

Figs. 1 , 24

Type Material. Holotype (male): “ Venezuela: Sucre State, 10° 31.419’ N, 63° 7.070’ W, 2 m, ca. 5 km SE El Pilar , 29.i.2010, leg. Short & Garcia; forested swamp by road; VZ10-0129-04A” ( MIZA).

Differential Diagnosis. Among Venezuelan species, recognized by the combination of small size (ca. 2.31

mm), the pronotum with very shallow impressions and rather uniform punctation, the pronotal shape, the very large black spots on the elytra, and the male genitalia ( Fig. 24 ; described below). Differentiation from other similarly small sized species with similarly shaped pronotum will require dissection of males.

Description. Habitus as illustrated ( Fig. 24 ). Size: holotype (length/width, mm): body (length to elytral apices) 2.31/0.86; head width 0.60; pronotum l/w 0.55/0.60; PA 0.60; PB 0.43; elytra 1.38/0.86. Body size small (ca. 2.31 mm). Dorsum grey, with moderately strong iridescence, elytra with several large black spots. Legs testaceous, with tibiofemoral joints darker. Punctation on elytra ca. 2– 3x that of pronotum. Elytra interstriae ca. 1–1.5x strial puncture diameter. Interstria 9 th more convex than others, overhanging 10 th interstria. Usual area of callus on 5 th not raised.

Pronotum slightly wider than long (as ca. 55/60), widest at anterior margin, markedly narrowed at base, sides straight, smooth; anterior margin bisinuate; depressions very shallow, or absent; punctation quite uniform over pronotum

Elytra with spaces between strial punctures ca. 0.5x their diameter, to narrow ridges; apices rather sharply conjointly rounded in dorsal view, in lateral view outer margin with slight angulation.

Ventral characters: Mentum moderately coarsely punctate, median fovea shallow; submentum without foveae.

Male genitalia ( Fig. 24 ) general characters: parameres long, tapering to very fine apices, very narrow and extending well beyond distal end of aedeagus, tips in dorsal/ventral views very thin and sharply pointed, in lateral view tips very thin and arcuate ventrad; basal piece shorter than parameres, in lateral view markedly arcuate, orifice with rim sclerotized.

Dorsal surface: adtl lacking; pdmm slightly overlapping alm; adbl small.

Ventral surface: avtl near basal 1/3 of aedeagus; pvmm overlapping alm, medial margins very narrowly separated.

Etymology. Named in reference to the numerous large black spots of the elytra.

Figures

FIGURE 1. Dorsal habitus of Hydrochus species.

FIGURE 24. Hydrochus pictus n. sp., habitus and male genitalia of holotype.