Hydrochus cracentis, Perkins, 2020

Perkins, Philip D., 2020, Taxonomy of Peruvian water beetles in the genus Hydrochus Leach, 1817 (Coleoptera: Hydrochidae), Zootaxa 4868 (1), pp. 61-89 : 71-72

Hydrochus cracentis , new species

Figs. 1 , 7

Type Material. Holotype (male): “ PERU: Tambopata Prov., Madre de Dios Dpto, 15km NE Puerto Maldonado, Reserva Cuzco Amazonico , 12°33’S, 69°3’W, 200m, camp, 21 June 1989, J. S. Ashe, R. A. Leschen, #213, ex., at light” ( SEMC).

Differential Diagnosis. Differentiated from other Peruvian species by the combination of the small body size (ca. 2.11 mm), the narrow body form (width/length ca. 0.33), the numerous dorsal microsetae, and the male genitalia ( Fig. 7 ; described below). Completely reliable determinations will include dissection of males.

Description. Habitus as illustrated ( Fig. 7 ). Size: holotype (length/width, mm): body (length to elytral apices) 2.11/0.71; head width 0.54; pronotum l/w 0.49/0.47; PA 0.47; PB 0.40; elytra 1.33/0.71. Body size small (ca. 2.11 mm), very narrow. Dorsum brown to copper (holotype teneral), with slight to moderately strong iridescence, elytra with black spots. Dorsum with numerous microsetae. Legs testaceous, with tibiofemoral joints and basal ½ of femora darker. Punctation on elytra ca. 2–3x that of pronotum. Elytra interstriae ca. 0.5–1x strial puncture diameter. Interstria 9 th more convex than others, overhanging 10 th interstria. Usual area of callus on 5 th very weakly if at all raised.

Pronotum very slightly longer than wide, widest at anterior margin, narrowed at base, sides very weakly arcuate, almost straight, smooth; anterior margin arcuate; depressions moderately deep, coarsely densely punctate, reliefs between depressions less punctate.

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 without angulation.

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

Male genitalia ( Fig. 7 ) general characters: genitalia very small, wider in dorsal/ventral views than lateral view; paramere tips extending slightly beyond tip of aedeagus, in dorsal/ventral views slightly widened, arcuate toward midline, with apical portions separated one from the other, in lateral view tips straight, distal end rounded; aedeagus broad in both dorsal/ventral and lateral views, in distal ½ much wider than parameres in dorsal/ventral views; basal piece longer and slightly wider than parameres; basal piece much wider in dorsal/ventral views than lateral view.

Dorsal surface: pdmm slightly separated from alm in distal portion, contiguous or nearly so for remainder of length.

Ventral surface: ventrally parameres in distal ½ distinctly wider than dorsal part of parameres, pvmm in this area very thin and nearly straight, overlapping alm; pvmm in proximal ½ becoming narrowly separate one from the other and with thin, finely striated ridge; pseu small, appear to be between parameres and aedeagus.

Etymology. Named in reference to the slender body form.

Figures

FIGURE 1. Dorsal habitus of Hydrochus species.

FIGURE 7. Hydrochus cracentis n. sp., habitus and male genitalia of holotype.