Taxonomy of water beetles in the genus Hydrochus Leach, 1817, from Bolivia, Brazil and Paraguay (Coleoptera: Hydrochidae) Author Perkins, Philip D. text Zootaxa 2021 2021-06-28 4994 1 1 93 journal article 10.11646/zootaxa.4994.1.1 1175-5326 5043261 107FCA64-345F-40A4-99D3-5C1441EEAD93 Hydrochus personatus , new species Figs. 2 , 15 , 55 Type Material. Holotype (male): “ Paraguay : 23.vii.1998 , Dep. Cordillera , San Bernadino, leg. U. Drechsel ” ( NMW ) . Paratypes (15): Bolivia : Santa Cruz , 60 mi. N. Santa Cruz , Saavedra Exp. Sta. , 27–30.xii.1959 , leg. Robert Cumming (6 NMNH ) ; Okinawa , 6.vi.1958 , leg. E. Pinckert (6 CAS ) ; Prov. Sara , 2 km NW of Santa Rosa , 21.ii.1969 , leg. A. Martinez & R.E. Woodruff (3 NMNH ) . Differential Diagnosis. TO MODIFY: Among Bolivian species, recognized by the combination of moderate size (ca. 3.18), the grey dorsum with a large black area on each elytron, the pronotum with depressions shallow, reliefs very weakly raised, if at all, depressions moderately densely punctate, reliefs very sparsely punctate, and the male genitalia ( Fig. 15 ; described below). This species has a generalized Hydrochus habitus; reliable determinations will require dissection of males. Description . Size: holotype (length/width, mm): body (length to elytral apices) 3.18/1.08; head width 0.73; pronotum l/w 0.70/0.73; PA 0.70; PB 0.63; elytra 1.98/1.08. Habitus as illustrated ( Fig. 15 ). Dorsum grey, with very slight to moderate iridescence, elytra with large medial mask-like black maculae. Legs brown to testaceous, with tibiofemoral joints darker. Punctation on elytra ca. 2–3x that of pronotum. Elytra interstriae ca. 1–2x strial puncture diameter. Interstria 9 th more convex than others, overhanging 10 th interstria. Callus on usual area of 5 th interstria moderately raised, moderately long. Pronotum length and width ca. equal, widest at about anterior 1/3, narrowed at base, sides sinuate, smooth; anterior margin very slightly bisinuate; depressions shallow, reliefs very weakly raised, if at all, depressions moderately densely punctate, reliefs very sparsely punctate. Elytra with spaces between strial punctures ca. 1.0–1.5xpd; apices rather sharply conjointly rounded in dorsal view, in lateral view outer margin with angulation. Ventral characters: Mentum punctate, with central depression; submentum with two large, narrowly separated foveae. Male genitalia ( Fig. 15 ) general characters: genitalia narrow (l/w ratio ca. 49/9); paramere tips distal ends pointed, lateral margins emarginate from rounded plsa to distal tip, medial margins of tips parallel, distal end of tips extending slightly beyond aedeagus, in lateral view parameres ca. as wide as basal piece; aedeagus lanceolate in dorsal/ventral views, widest at ca. midlength; basal piece slightly longer than parameres (ratio ca. 27/22), in dorsal/ ventral views nearly parallel-sided for most of length, tapering near orifice, with rim of orifice weakly sclerotized. Dorsal surface: adtl near distal end; pdmm widely overlapping alm except at paramere tips; adbl small. Ventral surface: pvmm approximating alm; avtl at about proximal 1/4. Etymology. Named in reference to the large, mask-like black maculae on the elytra.