Hydrochus piroei Makhan

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 : 36-39

Hydrochus piroei Makhan

Figs. 2 , 21

Hydrochus piroei Makhan, 1992: 97 .

Material examined (10). Venezuela: Sucre: VZ10-0129-04A (2 SEMC) . Anzoategui: VZ10-0204-01A (3 SEMC, MALUZ) . Merida: Palmarito, Lake Maracaibo , 1m, 3.VIII.1989, S.&J. Peck, lakeshore, ex: UV, 89-285 (2 CMN) . Trujillo: VZ12-0128-06A (3 SEMC, MIZA) .

Differential Diagnosis. Among Venezuelan species, recognized by the combination of moderate size (ca. 2.54– 2.86 mm), the moderately low and relatively punctate pronotal reliefs, and the male genitalia ( Fig. 21 ; described below). This species has a generalized Hydrochus habitus; reliable determinations will require dissection of males.

Description. Habitus as illustrated ( Fig. 21 ). Size of imaged specimen (length/width, mm): body (length to elytral apices) 2.86/1.03; head width 0.70; pronotum l/w 0.65/0.68; PA 0.65; PB 0.48; elytra 1.73/1.03. Body size moderate (ca. 2.54–2.86 mm). Dorsum grey, with slight iridescence, elytra with black spots. Legs testaceous, with tibiofemoral joints darker. Punctation on elytra ca. 1.5– 2x 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 very slightly raised, indistinct, moderately elongate.

Pronotum slightly wider than long, widest slightly behind anterior margin, narrowed at base, sides arcuate or very weakly sinuate, smooth; anterior margin slightly bisinuate; depressions shallow, much more densely punctate than low reliefs between depressions.

Elytra with spaces between strial punctures ca. 0.5– 1x their diameter; apices rather sharply conjointly rounded in dorsal view, in lateral view outer margin with slight angulation.

Ventral characters: Mentum moderately coarsely punctate, with median fovea. Submentum with two very large, almost confluent, foveae.

Male genitalia ( Fig. 21 ) general characters: genitalia rather narrow, elongate; parameres slightly but distinctly longer than basal piece, narrow in dorsal/ventral views, in lateral view much wider and slightly arcuate, tips extending very slightly beyond distal apex of aedeagus, tips rounded, medial margins straight, almost parallel; aedeagus lanceolate, with sclerotized lateral margins; basal piece distinctive appearing laterally compressed over distal ½, lateral margins strongly sclerotized in this area, rim of orifice strongly sclerotized and apicoventrally produced.

Dorsal surface: adtl subbasal, hence membranous area of aedeagus large; pdmm slightly overlapping aedeagus in basal 1/3; adbl large.

Ventral surface: avtl subbasal, hence membranous area of aedeagus large; pvmm more or less contiguous with alm.

Remarks. The specimen imaged ( Fig. 21 ) is from locality VZ10-0129-04A. I was not able to examine the holotype of H. piroei ; its location is unknown. My concept is based on the examination of paratypes.

Figures

FIGURE 2. Dorsal habitus of Hydrochus species.

FIGURE 21. Hydrochus piroei Makhan, habitus and male genitalia.