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 H. sculptissimus species group Figs. 1 , 3 , 45 , 48, 49 , 55 , 57 , 70 Members of the H. sculptissimus species group are recognized by the combination of the following characteristics: 1) small size, ca. 2.25–2.45 mm ; 2) black dorsal color; 3) elytral with costate or raised interseries; 4) pronotum deeply sculptured; 5) male genitalia lacking parameres, and lacking distal piece. Currently, three species are recognized: H. ampliarmus , H. casuarius , and H. sculptissimus . All three species are known only from Brazil ( Figs. 55 , 57 ).