Hydrochus lobatus, 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 : 42

Hydrochus lobatus new species

Figs. 2 , 23

Type Material. Holotype (male): “ Venezuela: Bolivar State: 6.58694° N, 67.02912° W, Rio Caripito, nr. Rio Orinoco , 12.i.2009, leg. Short & Miller, VZ 09-0112-02A: river margin” ( MIZA) . Paratypes (17): Venezuela: Apure: AS-06-019 (1 SEMC) . Bolivar: Same data as holotype (1 SEMC) ; VZ09-0112 - 01 A (4 SEMC) ; VZ09-0112 - 01 C (11 SEMC, MIZA) .

Differential Diagnosis. Among Venezuelan species, recognized by the combination of small size (ca. 2.31–2.69 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. 23 ; described below). Differentiation from other similarly small-sized species with similarly shaped pronotum will require dissection of males.

Description. Habitus as illustrated ( Fig. 23 ). Size: holotype (length/width, mm): body (length to elytral apices) 2.33/0.90; head width 0.60; pronotum l/w 0.52/0.55; PA 0.52; PB 0.43; elytra 1.40/0.90. Body size small (ca. 2.31–2.69 mm). Dorsum grey to silver, with moderately strong iridescence, elytra with several large black spots. Legs with pro- and mesofemora dark brown in basal ¾, remainder lighter; metafemora dark brown; tibiae reddish brown. Punctation on elytra deep, ca. 3– 4x that of pronotum. Elytra interstriae ca. 0.5x strial puncture diameter. Interstria 9 th more convex than others, overhanging 10 th interstria. Usual area of callus on 5 th low, small.

Pronotum slightly wider than long, widest at anterior margin, narrowed at base, sides straight, smooth; anterior margin arcuate or very slightly bisinuate; depressions very shallow; punctation quite uniform over pronotum

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

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

Male genitalia ( Fig. 23 ) general characters: genitalia very small; paramere tips comparatively large, each nearly as wide as widest part of aedeagus, very lightly sclerotized, tips rounded and curving toward midline, but not contacting one another; basal piece shorter than parameres, in lateral view with rim of large orifice produced apicoventrally, arcuate toward dorsad.

Dorsal surface: adtl subbasal; adbl lacking.

Ventral surface: pvmm slightly overlapping basal part of aedeagus; each paramere, in basal ¼, with thin, finely striated ridge; pseudoparameres appearing to be adjacent to aedeagus, behind parameres.

Etymology. Named in reference to the lobate paramere apices.

Figures

FIGURE 2. Dorsal habitus of Hydrochus species.

FIGURE 23. Hydrochus lobatus n. sp., habitus and male genitalia of holotype.