Hydrochus laevigatus, 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 : 467

Hydrochus laevigatus , new species

Figs. 1 , 7 , 28

Type material. Holotype (male): “ Mexico: Oaxaca Toltepec 2.xi.1987 F. Arias R. Barba E. Barrera” ( UNAM) . Paratypes (4): Honduras: Francisco Morazan, 15km N. Zamorano, San Juan del Rancho , 14.0090° N, 86.9899° W, (14°0’32.4’’N, 86°59’23.64’’W), 26.v.1994, leg. H. & A. Howden (2 CMN) ; Ocotepeque, 11 mi. S. Nueva Ocotepeque, small stream, mostly bedrock, in pine forest, 14.4345° N, 89.1837° W, (14°26’4.2’’N, 89°11’1.32’’W), 17.vi.1974, leg. M. E. & P. D. Perkins (1 MCZ) ; Mexico: Same data as holotype (1 UNAM) ; Veracruz, 30 mi. south Acayucan , 21.iv.1962, leg. F. D. Parker, L. A. Stange (1 MCZ) .

Differential diagnosis. Among Central American species, recognized by the combination of moderate size (ca. 2.60 mm), the very smooth and relatively impunctate pronotal reliefs, the deep pronotal depressions, the mentum and submentum without foveae, and the male genitalia ( Fig. 7 ; described below). This species has a generalized Hydrochus habitus; reliable determinations will require dissection of males. The male genitalia are somewhat similar to that of H. beeneni , but differ in the shape of the paramere tips and lack the paramere dorsal ridge present in H. beeneni ( Figs. 7 , 21 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 2.60/0.96; head width 0.65; pronotum l/w 0.60/0.67; PA 0.65; PB 0.52; elytra 1.65/0.96. Habitus as illustrated ( Fig. 7 ). Size moderate (ca. 2.60 mm). Dorsum grey to bluish grey, with strong to moderately strong iridescence, elytra with black spots. Pronotal punctation fine, moderately dense in foveae, much sparser on very smooth reliefs. 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. Usual area of callus on 5 th weakly raised.

Pronotum slightly wider than long, widest slightly behind anterior margin, narrowed at base, sides sinuate, smooth; anterior margin bisinuate; depressions deep.

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 very slight angulation.

Ventral characters: Mentum coarsely densely punctate, without median fovea. Submentum punctate, without foveae. Legs testaceous.

Male genitalia ( Fig. 7 ) general characters: genitalia very narrow; paramere tips slender and pointed, very slightly longer than aedeagus, at apex narrower in lateral view than in dorsal/ventral views, in dorsal/ventral views with medial margins at apex parallel or nearly so, then arcuate away from midline, narrow proximal to weak plsa; aedeagus in dorsal/ventral views very slender; in lateral view slightly wider, with no emargination where adbl and shaft meet; lateral margins of aedeagus weakly sclerotized; basal piece shorter than parameres, orifice sclerotized.

Dorsal surface: pdmm narrowly separated, overlapping aedeagus; adtl at about distal 1/5; adbl moderately large; paramere tips without sclerotized ridge.

Ventral surface: pvmm approximating lateral margin of aedeagus; avtl not apparent.

Etymology. Named in reference to the smooth pronotal reliefs.

Figures

FIGURE 1. Dorsal habitus of Central American Hydrochus species.

FIGURES 7–8. Habitus and male genitalia. 7. Hydrochus laevigatus n. sp. holotype. 8. Hydrochus laevigatus n. sp. paratype.

FIGURES 28–30. Geographical distribution maps.

FIGURES 21–22. Habitus and male genitalia. 21. Hydrochus beeneni Makhan, non-type Panama. 22. Hydrochus beeneni Makhan, non-type Mexico.