Hydrochus latipennis, Perkins, 2020

Perkins, Philip D., 2020, Taxonomy of Ecuadorian water beetles in the genus Hydrochus Leach, 1817 (Coleoptera: Hydrochidae), Zootaxa 4790 (2), pp. 358-374 : 362-365

Hydrochus latipennis , new species

Figs. 1 , 4

Type Material. Holotype (male): “ Ecuador: Napo, Limoncocha , 14 June 1977 BLT. W. E. Steiner ” ( NMNH).

Differential Diagnosis. Among Ecuadorian species, recognized by the combination of small size (ca. 2.54 mm), the shallow pronotal impressions, the wide elytra with arcuate lateral margins and large serial punctures, and the male genitalia ( Fig. 4 ; described below).

Description. Habitus as illustrated ( Fig. 4 ). Size: holotype (length/width, mm): body (length to elytral apices) 2.54/0.94; head width 0.62; pronotum l/w 0.60/0.60; PA 0.56; PB 0.48; elytra 1.54/0.94. Body size small (ca. 2.54 mm). Dorsum black, with slight iridescence, elytra without black spots. Punctation on elytra ca. 2–4x that of pronotum. Elytra interstriae narrow walls to ca. 0.5x strial puncture diameter. Interstria 9 th more convex than others, overhanging 10 th interstria. Usual area of callus on 5 th very weakly raised.

Pronotum length and width equal, widest slightly behind anterior margin, narrowed at base, sides arcuate or very weakly sinuate, smooth; anterior margin slightly bisinuate; depressions moderately deep.

Elytra widest at ca. posterior 1/3, where lateral margin notably arcuate; spaces between strial punctures narrow walls to ca. 0.5x their diameter; apices separately rounded in dorsal view, in lateral view outer margin without angulation.

Ventral characters: Mentum coarsely punctate, with large and deep median fovea. Submentum with two large foveae, separated by narrow midlongitudinal ridge. Legs brown to testaceous, femora darker than tibiae.

Male genitalia ( Fig. 4 ) general characters: genitalia small; paramere tips moderately large, each as wide, or almost as wide, as widest part of aedeagus, very lightly sclerotized, tips rounded and curving toward midline, but not contacting one another, tips wider on ventral than on dorsal surface, on dorsal surface pdmm arcuate away from midline, parameres more evidently sclerotized for short distance just proximal to tips; aedeagus widest at about distal ¼; basal piece as long as parameres, widest at about distal 1/3 to ¼, orifice weakly sclerotized.

Dorsal surface: adtl lacking; adbl very small.

Ventral surface: pvmm slightly overlapping basal part of aedeagus; pseudoparameres extending to about ¾ length of parameres.

Etymology. Named in reference to the wide, arcuate lateral margins of the elytra.

Figures

FIGURE 1. Dorsal habitus of Hydrochus species.

FIGURE 4. Hydrochus latipennis n. sp., habitus and male genitalia of holotype.