Hydrochus perpunctatus, Perkins, 2021

Perkins, Philip D., 2021, Taxonomy of Central American water beetles in the genus Hydrochus Leach, 1817 (Coleoptera: Hydrochidae), Zootaxa 4974 (3), pp. 459-503 : 470-471

Hydrochus perpunctatus , new species

Figs. 1 , 11 , 28

Type material. Holotype (male): “ Mexico: Veracruz, Jalapa , 24-V-1984, J. Pena ” ( UNAM).

Differential diagnosis. Among Central American species, recognized by the combination of moderate size (ca. 3.10 mm), the densely coarsely punctate pronotum, the large and closely spaced strial punctures of the elytra, the three callosities of each elytron, and the male genitalia ( Fig. 11 ; described below). The male genitalia can be differentiated from others by the aedeagus greatest width being near the base, and tapering toward the apex, plus the shape of the paramere tips.

Description. Habitus as illustrated ( Fig. 11 ). Size: holotype (length/width, mm): body (length to elytral apices) 3.10/1.22; head width 0.76; pronotum l/w 0.67/0.76; PA 0.73; PB 0.61; elytra 2.04/1.22. Body size moderate (ca. 3.10 mm). Dorsum grey to greenish grey, with moderately strong iridescence, elytra with large black spots. Punctation on elytra ca. 3–5x that of pronotum. Elytra interstriae ca. 1–1.5× strial puncture diameter. Interstria 9 th more convex than others, overhanging 10 th interstria. Elytra with three calluses: usual area of callus on 5 th strongly raised, elongate, ca. 7 punctures in row on each side; additional callus of about same size on 5 th, located slightly before midlength; third callus, smaller than others, on 7 th interstria, ca. opposite gap between calluses on 5 th interstria.

Pronotum slightly wider than long, widest slightly behind anterior margin, narrowed at base, sides arcuate, very minutely denticulate; anterior margin bisinuate; pronotum densely coarsely punctate; depressions large and deep; reliefs very narrow.

Elytral punctures large and deep, spaces between strial punctures narrow walls to ca. 0.5x their diameter; apices rather sharply conjointly rounded in dorsal view, in lateral view outer margin with very slight angulation.

Ventral characters: Mentum coarsely moderately densely punctate, with large median fovea. Submentum with two foveae. Legs testaceous, femora and tibiofemoral joints slightly darker than tibiae.

Male genitalia ( Fig. 11 ) general characters: paramere tips slender and pointed, narrower in lateral view than in dorsal/ventral views, in dorsal/ventral views with medial margins at apex parallel or nearly so, plsa very slight; parameres distinctly sinuate in lateral view; aedeagus in dorsal/ventral views much wider in proximal ½ than distal ½, agw very near base; in lateral view narrower, without emargination where adbl and shaft meet; basal piece shorter than parameres.

Dorsal surface: pdmm separated slightly at adtl, then overlapping one another in ca. middle ½, then separating before adbl; adbl large; adtl at about distal 1/6; paramere tips without sclerotized ridge.

Ventral surface: pvmm widely separated in proximal ½, but overlapping alm; avtl not apparent.

Etymology. Named in reference to the densely and deeply punctate dorsum.

Figures

FIGURE 1. Dorsal habitus of Central American Hydrochus species.

FIGURES 11–12. Habitus and male genitalia of holotypes. 11. Hydrochus perpunctatus n. sp. 12. Hydrochus panamensis n. sp.

FIGURES 28–30. Geographical distribution maps.