Hydrochus argutissimus, 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: 45

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Hydrochus argutissimus

new species

Hydrochus argutissimus   new species

Figs. 2 View FIGURE 2 , 25 View FIGURE 25

Type Material. Holotype (male): “ VENEZUELA: Tachira State, 7° 35.038’ N, 72° 10.340’ W, El Tama National Park , 16.vii. 2009, 472m, leg. Short, Sites, Garcia, Inciarte, Gustafson & Camacho ,, HG-vapor light; VZ09-0716- 07A” ( MIZA) GoogleMaps   . Paratypes (41): Venezuela: Bolivar: El Dorado (65 km S), 1 Nov. 1982, John L. Hellman (33 NMNH)   . Portuguesa: Guanare , at light, Borys Malkin, leg. (1 NMNH)   ; Guanare , IX-10 to 13-1957, Borys Malkin Collector (1 NMNH)   . Tachira: VZ09-0716-07A (6 SEMC)   .

Differential Diagnosis. Among Venezuelan species, recognized by the combination of small size (ca. 2.29– 2.85 mm), the pronotum with moderately deep, densely punctate depressions, the pronotal shape, the elytral disc with very large punctures and very narrow, zig-zag shaped interstriae, the large punctures of the elytral apices, and the male genitalia ( Fig. 25 View FIGURE 25 ; described below). Differentiation from other similarly small sized species with similarly shaped pronotum should include dissection of males.

Description. Habitus as illustrated ( Fig. 25 View FIGURE 25 ). Size: holotype (length/width, mm): body (length to elytral apices) 2.29 /0.81; head width 0.54; pronotum l/w 0.52/0.54; PA 0.54; PB 0.42; elytra 1.48 /0.81. Body size small (ca. 2.29–2.85 mm). Dorsum dark brown to reddish brown, with very slight iridescence, elytra without black spots. Legs testaceous, with tibiofemoral joints darker. Punctation on elytra deep, ca. 2– 4x that of pronotum. Elytra interstriae narrow ridges to ca. 1x strial puncture diameter, often with zig-zag pattern due to large, alternately spaced punctures. 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. 54/52), widest at anterior margin, markedly narrowed at base, sides straight, not denticulate; anterior margin bisinuate; depressions shallow, densely punctate; reliefs very low, generally punctate.

Elytra with spaces between strial punctures narrow ridges; suture raised, especially at summit of posterior declivity; apices slightly widened, with submarginal groove having large translucent punctures and, apically, one large elongate puncture.

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

Male genitalia ( Fig. 25 View FIGURE 25 ) general characters: paramere tips appearing sagittate, but only in lateral view; in dorsal/ ventral views tips have contiguous medial margins, which extend beyond distal end of aedeagus; basal piece long, proximal 1/2 strongly arcuate ventrad, with terminal sclerotization.

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

Ventral surface: pvmm closer to one another than are pdmm.

Etymology. Named in reference to the relationship with Hydrochus argutus Knisch.  

Remarks. Images of the lectotype of Hydrochus argutus Knisch   can be seen in Perkins (2019).


Museo del Instituto de Zoologia Agricola Francisco Fernandez Yepez


Smithsonian Institution, National Museum of Natural History


University of Kansas - Biodiversity Institute