Hydrochus sinuatus, Perkins, 2020

Perkins, Philip D., 2020, Taxonomy of Guatemalan water beetles in the genus Hydrochus (Coleoptera: Hydrochidae), Acta Entomologica Musei Nationalis Pragae 60 (1), pp. 291-301: 299-300

publication ID

http://doi.org/ 10.37520/aemnp.2020.016

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scientific name

Hydrochus sinuatus

sp. nov.

Hydrochus sinuatus   sp. nov.

( Figs 1 View Fig , 6 View Fig )

Type material. HƟĿƟŦYPൾ:male ( NMNH):‘ GUATEMALA, 20 Mi. SW Puerto Barrios VIII-16-1965 Paul J. Spanglerʼ.

Differential diagnosis. Among Guatemalan species, H. sinuatus   is recognized by the combination of moderately small size (ca. 2.39 mm), the densely coarsely punctate pronotum, and the male genitalia ( Fig. 6 View Fig ; described below). This species has a generalized Hydrochus   habitus; reliable determinations will require dissection of males.

Description. Habitus as in Fig. 6 View Fig . Size (in mm): holotype: body (length to elytral apices / width) 2.39 / 0.89; head width 0.58; pronotum length / width 0.53 / 0.55; PA 0.53; PB 0.48; elytra 1.52 / 0.89. Body size moderate. Dorsum black, with moderately strong iridescence, elytra with non-iridescent black spots. Legs dark brown, with tibiofemoral joints slightly darker. Punctation on elytra ca. 2–4× that of pronotum. Elytra interstriae ca. 0.5–1.0× strial puncture diameter. Interstria 9 th more convex than others, overhanging 10 th interstria. Callus on usual area of 5 th interstria small, weakly raised.

Pronotum length slightly less than width, widest just behind anterior angles, narrowed at base, sides very slightly sinuate, minutely denticulate; anterior margin bisinuate; depressions, especially anteromedian, deep, reliefs sharply raised, depressions more densely punctate than reliefs.

Elytra with spaces between strial punctures ca. 0.5–1.0× their diameter; 3 rd interseries slightly raised over basal fourth; 4 th interseries raised in area anterior to callus of 5 th; apices rather sharply conjointly rounded in dorsal view, in lateral view with submarginal row of large punctures, bordered above by low ridge, outer margin with strong angulation.

Male genitalia ( Fig. 6 View Fig ). General characters: paramere tips slightly widened, distal ends pointed, lateral margins arcuate, medial margins of tips emarginate and well separated from lateral margins of aedeagus, distal end of tips extending very slightly beyond aedeagus, in lateral view tips narrow, sharply pointed; pwsa distinctive; aedeagus moderately narrow in both dorsal/ventral and lateral views, in dorsal/ventral views margins sinuate, distinctly narrowed slightly past midlength in dorsal/ventral views, with narrowly sclerotized lateral margins; basal piece shorter than parameres, with rim of orifice strongly sclerotized.

Dorsal surface: adtl located slightly distal to midlength; pdmm narrowly overlapping alm over basal two-thirds, then markedly arcuate where paramere tips begin; adbl large, distinctively shaped.

Ventral surface: pvmm very slightly overlapping alm at base.

Etymology. Named in reference to the shape of the parameres and aedeagus, which have sinuate lateral margins. Adjective.


Smithsonian Institution, National Museum of Natural History