Hydrochus shorti, 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 : 25-26

Hydrochus shorti new species

Figs. 2 , 16

Type Material. Holotype (male): “ Venezuela: Amazonas State: 5° 20.497’ N, 67° 45.358’ W, 72m, ca. 12km N. Sa- mariapo, small stream @ rd x-ing; 06.i.2006, AS-06-013, leg. A.E.Z. Short” ( MIZA) . Paratypes (31): Venezuela: Amazonas: Same data as holotype (21 SEMC, MIZA, MALUZ); VZ09-0115 - 03 A (10 SEMC) .

Differential Diagnosis. Among Venezuelan species, recognized by the combination of moderate size (ca. 3.00– 3.39 mm), the relatively high and relatively punctate pronotal reliefs, and the male genitalia ( Fig. 16 ; described below). The general shape of the outline of the male genitalia show some similarity to that of H. formosus n. sp., but the shape of the aedeagi markedly differ in the two species, among other genitalic differences. H. shorti n. sp. is smaller than H. formosus n. sp. (ca. 3.32 vs. 4.04 mm), and males lack the abdominal tubercles present in that species. This species has a generalized Hydrochus habitus; reliable determinations will require dissection of males.

Description. Habitus as illustrated ( Fig. 16 ). Size: holotype (length/width, mm): body (length to elytral apices) 3.32/1.23; head width 0.81; pronotum l/w 0.71/0.81; PA 0.81; PB 0.65; elytra 2.06/1.23. Body size moderate (ca. 3.00– 3.39 mm). Dorsum grey, with slight to moderately strong iridescence, elytra with black spots. Legs testaceous, with tibiofemoral joints darker. Punctation on elytra only slightly larger that of pronotum. Elytra interstriae ca. 1.5– 2x strial puncture diameter. Interstria 9 th more convex than others, overhanging 10 th interstria. Callus on 5 th moderately raised, moderately elongate.

Pronotum length less than width (as ca. 71/81), widest slightly behind anterior margin, narrowed at base, sides sinuate, smooth; anterior margin slightly bisinuate; depressions rather deep, slightly more densely punctate than 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 moderate angulation.

Ventral characters: Mentum moderately coarsely punctate, with median fovea. Submentum with two foveae.

Male genitalia ( Fig. 16 ) general characters: paramere tips in dorsal/ventral views arcuate toward midline, in lateral view narrow and tapering and arcing slightly ventrad, very lightly sclerotized; alm bisinuate.

Dorsal surface: adtl near midlength, not distinctive; pdmm sinuate and at points slightly separated from or beneath alm; adbl small.

Ventral surface: pvmm approximating alm; pseudoparameres extending past midlength of parameres, m rather large in lateral view; avtl very indistinct.

Etymology. Named for Andrew E. Z. Short, an outstanding water beetle collector who has netted many new species of Hydrochus .

Figures

FIGURE 2. Dorsal habitus of Hydrochus species.

FIGURE 16. Hydrochus shorti n. sp., habitus and male genitalia of holotype.