Hydrochus choennii Makhan, 1992

Perkins, Philip D., 2020, Taxonomy of Ecuadorian water beetles in the genus Hydrochus Leach, 1817 (Coleoptera: Hydrochidae), Zootaxa 4790 (2), pp. 358-374 : 370-373

Hydrochus choennii Makhan

Figs. 1 , 8

Hydrochus choennii Makhan 1992: 96

Originally described from Suriname, based on one male. Only one male is now known from Ecuador. I have examined the holotype of H. choennii Makhan 1992 , kindly loaned by the RBINS. Labels on the holotype of H. choennii : “Coll. R. I. Sc. N. B. // Suriname District Commewijne 4.viii.1984 leg. D. Makhan // Hydrochus choenii” [sic] “det. D. Makhan 1990 // Holotype [red].”

Material examined. ECUADOR, Napo Limoncocha 11 June 1977, P. J. Spangler & D. R. Givens, #115 (1 NMNH) .

Differential Diagnosis. Among Ecuadorian species, recognized by the combination of moderate size (ca. 3.21 mm), the moderately low and relatively impunctate pronotal reliefs, and the male genitalia ( Fig. 8 ; described below). This species has a generalized Hydrochus habitus; reliable determinations will require dissection of males.

Redescription. Habitus as illustrated ( Fig. 8 ). Size (specimen from Ecuador; length/width, mm): body (length to elytral apices) 3.21/1.21; head width 0.77; pronotum l/w 0.69/0.74; PA 0.69; PB 0.62; elytra 2.08/1.21. Body size moderate (ca. 3.21 mm, Ecuadorian specimen). Dorsum grey, with slight to moderately strong iridescence, elytra with black spots. Punctation on elytra ca. 2–3x that of pronotum. Elytra interstriae ca. 1–1.5x strial puncture diameter. Interstria 9 th more convex than others, overhanging 10 th interstria. Usual area of callus on 5 th moderately raised, moderately elongate, ca. 5 punctures in row on each side.

Pronotum length greater than width, widest at anterior margin, narrowed at base, sides weakly arcuate or very weakly sinuate, smooth; anterior margin slightly bisinuate; depressions moderately deep, much more densely punctate than low reliefs between depressions, latter almost entirely impunctate.

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 slight angulation.

Ventral characters: Mentum coarsely punctate, with median fovea. Submentum with two foveae. Legs testaceous, with tibiofemoral joints darker.

Male genitalia ( Fig. 8 ) general characters: Genitalia large, strongly sclerotized, with margins between strongly sclerotized areas and weakly or non-sclerotized areas very distinct; parameres much longer than aedeagus, plsa large, parameres in dorsal/ventral views with middle 1/3 widened and strongly sclerotized, in lateral view parameres much wider, pointed apically, with two small, indistinct pwsa; pseudoparameres large, as long as or slightly longer than aedeagus; aedeagus distal ½ widened, with alsm, apex sharply pointed, agw at about same level as adtl; basal piece ca. same length as parameres, orifice strongly sclerotized.

Dorsal surface: adbl moderately large; adtl at about distal 1/3.

Ventral surface: pvmm in basal ¼ approximating alm.

Figures

FIGURE 1. Dorsal habitus of Hydrochus species.

FIGURE 8. Hydrochus choennii Makhan, habitus and male genitalia.