Taxonomy of Guatemalan water beetles in the genus Hydrochus (Coleoptera: Hydrochidae) Author Perkins, Philip D. text Acta Entomologica Musei Nationalis Pragae 2020 2020-04-23 60 1 291 301 journal article 21739 10.37520/aemnp.2020.016 6f4e1328-0bba-4f1c-aa66-4c1fe1fda040 1804-6487 3879760 45563A23-8582-4C53-81F3-591948E7A74D Hydrochus directus sp. nov. ( Figs 1 , 3 ) Type material. HƟĿƟŦYPൾ:male ( NMNH ): ‘ GUATEMALA , 20 Mi. SW Puerto Barrios VIII-16-1965 Paul J. Spanglerʼ. PARAŦYPൾඌ ( 13 spec. ): GUATEMALA : same data as holotype (4 NMNH ); ‘ 28mi. SW Puerto Barrios, VIII-16-1965 , Paul J. Spanglerʼ (1: NMNH ); ‘15 Mi. W. Pijije, VIII-5-1965 , P. J. Spanglerʼ (1: NMNH ); ‘ Peten , Tikal, 28 June 1974 , W. E. Steinerʼ (7: NMNH ). Differential diagnosis. Among Guatemalan species, H. directus is recognized by the combination of moderate size (ca. 2.54–3.00 mm), the densely punctate pronotum with the reliefs slightly less punctate than the depressions, and the male genitalia ( Fig. 3 ; described below). This species has a generalized Hydrochus habitus; reliable determinations will require dissection of males. Description. Habitus as illustrated in Fig. 3 . Size (in mm): holotype : body (length to elytral apices / width) 2.76 / 1.02; head width 0.67; pronotum length / width 0.62 / 0.65; PA 0.62; PB 0.56; elytra length / width 1.73 / 1.02. Body size moderate (ca. 2.54–3.00 mm). Dorsum grey, with moderately strong gold iridescence, elytra with black spots. Legs testaceous, with tibiofemoral joints slightly darker. Punctation on elytra ca. 2× that of pronotum. Elytra interstriae ca. 1.0–1.5× strial puncture diameter. Interstria 9 th more convex than others, overhanging 10 th interstria. Callus on usual area of 5 th interstria weakly raised, moderately long. Pronotum length slightly less than width, widest at about anterior 1/3, narrowed at base, sides sinuate, smooth; anterior margin bisinuate; depressions shallow, reliefs low, depressions more densely punctate than reliefs. Elytra with spaces between strial punctures narrow ridges; apices rather sharply conjointly rounded in dorsal view, in lateral view outer margin with very slight angulation. Male genitalia ( Fig. 3 ). General characters: paramere tips elongate, slightly widened, distal ends pointed, lateral margins straight from plsa to distal tip, medial margins of tips emarginate and well separated from lateral margins of aedeagus, distal end of tips extending slightly beyond aedeagus, in lateral view tips narrow, pointed; aedeagus lanceolate in dorsal/ventral views, widest at ca. midlength, ca. same width as adbl , from which point markedly tapering to sharp distal end, with narrowly sclerotized lateral margins; basal piece slightly shorter than parameres, tapering from distal end to orifice, with rim of orifice strongly sclerotized. Dorsal surface: adtl located slightly distal to midlength of aedeagus; pdmm narrowly overlapping alm over basal two-thirds then arcuate where paramere tips begin; adbl moderately large, ca. same width as greatest width of aedeagus shaft. Ventral surface: pvmm very slightly overlapping alm at base; avtl at about proximal fourth. Etymology. Named in reference to the male genitalia, which have the paramere tips elongate, with straight lateral margins, and the aedeagus sharply pointed. Adjective.