Review of the Helochares (Hydrobaticus) MacLeay of the New World (Coleoptera: Hydrophilidae: Acidocerinae) Author Short, Andrew Edward Z. Author Girón, Jennifer C. text Zootaxa 2018 2018-04-09 4407 1 29 50 journal article 22806 10.11646/zootaxa.4407.1.2 8e0aac3a-6556-4b96-a67e-fce9f0db0ba9 1175-5326 3766290 B45E9ABD-CB52-4EE7-91D6-783E8E958AC5 Key to the New World species of the Helochares subgenus Hydrobaticus 1. Elytra with distinct rows of serial punctures, sometimes deeply impressed into grooves (e.g., Fig. 2A , C–E). Size variable ( 4.2– 6.6 mm ). Widely distributed............................................................................. 2 - Elytra without rows of serial punctures ( Figs. 2B , 4 ). Size larger than 5.5 mm . Mexico and Central America.............. 8 2. Abdominal pubescence sparse and not uniformly distributed on each ventrite ( Fig. 6A ). Abdominal ventrites uniformly very dark brown to almost black in coloration. Elytra with rows of serial punctures not impressed into striae............................................................................................ H. normatus (LeConte) (in part) - Abdominal pubescence dense and uniform, not appearing sparse or absent on anterior half of each ventrite (e.g. Fig. 6 B–D). Abdominal ventrites variously colored. Elytra with rows of serial punctures impressed into striae or not................. 3 3 Size larger (> 5.8 mm ). Elytral serial punctures not impressed into striae or only very weakly so; absent or almost appearing absent anteromedially ( Fig. 2A ).............................................................. H. trujillo n. sp. - Size variable (4.2–6.0 mm). Elytra with rows of serial punctures impressed into striae or not; rows distinctly present anteromedially............................................................................................... 4 4 Abdominal ventrites pale in color, either uniformly yellowish brown or yellowish brown on lateral thirds with median third darker brown......................................................................................... 5 - Abdominal ventrites uniformly dark brown to almost black in color..............................................6 5 Parameres of aedeagus truncate at apex, with outer corners widely rounded ( Fig. 7 F–H). More southern distribution ( Panama , Ecuador , Venezuela )....................................................................... H. nexus n. sp. - Parameres of aedeagus with apex oblique to truncate, with outer corners widely rounded ( Fig. 8 ). More northern distribution (this rarer form known from Mexico )............................................ H. normatus (LeConte) (in part) 6 Clypeus pale in coloration, not darkened medially ( Fig. 5A ). Eastern North America............. H. maculicollis Mulsant - Clypeus distinctly darkened medially ( Fig. 5E, H ). South America............................................... 7 7 Pronotum almost entirely darkly colored ( Fig. 2D ). Size smaller ( 4.7–4.8 mm ). Ecuador ................ H. zamora n. sp. - Pronotum only darkened on central disc ( Fig. 2E ). Size larger ( 5.2–5.5 mm ). Peru ............................ H . sp. A 8 Clypeus pale in coloration, not darkened medially ( Fig. 5G ). Aedeagus with median lobe broadly rounded, with only a small “pinched” apex ( Fig. 7K )............................................................... H. championi Sharp - Clypeus distinctly darkened medially ( Fig. 5I ). Aedeagus with median lobe tapered to a point at apex ( Fig. 7 I– J)......... 9 9 Aedeagus with apex of parameres rounded ( Fig. 6I ); lateral outer margins of parameres parallel, slightly constricted near midlength; maximum width of aedeagus at basal half, nearly as wide as maximum width of aedeagus at apical half................................................................................................... H. politus n. sp. - Aedeagus with apex of parameres truncate ( Fig. 6J ); lateral outer margins of parameres parallel along basal two thirds, slightly constricted at two thirds, diverging along apical third; maximum width of aedeagus at basal half, clearly narrower than maximum width of aedeagus at apical half........................................................... H. laevis n. sp.