Hydrochus hellmani, 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 : 40-42

Hydrochus hellmani new species

Figs. 1 , 22

Type Material. Holotype (male): Venezuela: “ Bolivar: Upata (69 km SE), 31 Oct. 1982, John L. Hellman ” ( NMNH).

Differential Diagnosis. Among Venezuelan species, recognized by the combination of small size (ca. 2.37 mm), the pronotum with moderately deep impressions separated by narrow reliefs, the elytra with large and deep strial punctures, interstriae and spaces between punctures narrow ridges, and the male genitalia ( Fig. 22 ; described below). Completely reliable determinations will include dissection of males.

Description. Habitus as illustrated ( Fig. 22 ). Size: holotype male (length/width, mm): body (length to elytral apices) 2.37/0.92; head width 0.60; pronotum l/w 0.53/0.57; PA 0.55; PB 0.47; elytra 1.50/0.92. Body size small (ca. 2.37 mm). Dorsum black, with slight iridescence, elytra without black spots. Legs dark brown. Punctation on elytra large, deep, ca. 2– 3x that of pronotum. Elytra interstriae much narrower than strial puncture diameter, narrow ridges. Interstria 9 th more convex than others, weakly overhanging 10 th interstria. Usual area of callus on 5 th very weakly raised.

Pronotum slightly wider than long (as ca. 53/57), widest at anterior margin, narrowed at base, sides very weakly arcuate, smooth; anterior margin very weakly bisinuate; depressions moderately deep, reliefs narrow.

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

Ventral characters: Mentum moderately coarsely and moderately densely punctate, with shallow median fovea. Submentum with two small shallow foveae.

Male genitalia ( Fig. 22 ) general characters: genitalia stout; paramere tips tapering and arcing slightly toward midline, extending slightly beyond distal end of aedeagus, parameres in lateral view arcuate, and wider than dorsal/ ventral views; basal piece much shorter than parameres, tapering from distal end to base, orifice sclerotized, asymmetrical; aedeagus lanceolate, lateral margins moderately widely sclerotized, greatest width at about midlength, tapering apically, with internal lumen in basal ½, gonopore apical.

Dorsal surface: adtl subapical; pdmm widely overlapping alm, especially in distal 1/2; adbl moderately large.

Ventral surface: avtl subbasal; pvmm approximating alm.

Etymology. Named for John Leroy Hellman, who collected the only known specimen.

Figures

FIGURE 1. Dorsal habitus of Hydrochus species.

FIGURE 22. Hydrochus hellmani n. sp., habitus and male genitalia of holotype.