Three new genera of acidocerine water scavenger beetles from tropical South America (Coleoptera, Hydrophilidae, Acidocerinae) Author Giron, Jennifer C. https://orcid.org/0000-0002-0851-6883 Department of Ecology & Evolutionary Biology, and Division of Entomology, Biodiversity Institute, University of Kansas, Lawrence, KS 66045, USA entiminae@gmail.com Author Short, Andrew Edward Z. Department of Ecology & Evolutionary Biology, and Division of Entomology, Biodiversity Institute, University of Kansas, Lawrence, KS 66045, USA text ZooKeys 2018 2018-06-19 768 113 158 http://dx.doi.org/10.3897/zookeys.768.24423 journal article http://dx.doi.org/10.3897/zookeys.768.24423 1313-2970-768-113 399BCC3E9D6F4231870E05C79B9FD4B0 CB01CA30FFB4F96DFFA2FF86FFAEFFB6 1298776 Crucisternum sinuatus sp. n. Figs 3A-D ; 6G, H ; 7 Type material examined. Holotype (male): BRAZIL: Minas Gerais : Lassance, -17.83384, -44.50515, 568 m, Cachoeira da Palmeira, flotation of root mats and moss from side of waterfall and seepage, 2.iii.2018, leg. Benetti & team; BR18-0302-04A (INPA). Paratypes (10): BRAZIL: Para : Rio Xingu Camp 52°22'W , 3°39'S , Altamira, ca 60km S., 3.x.1986, leg. P. Spangler & O. Flint, Colln. #6, 1st jungle stream on trail 1 (1, USNM); same, except 14.x.1986, Colln. #23, stream on left branch of trail 1 (3; SEMC, USNM); Minas Gerais : same data as holotype (2 INPA, 4 SEMC). Differential diagnosis. Crucisternum sinuatus is very similar to C. escalera and C. xingu in the shallowness of the punctation. In addition, it can be distinguished from C. xingu by the aedeagus with median lobe constricted at midlength, continuing as a narrow and roundly pointed bar (see Fig. 6G, H ; as opposed to gradually narrowing towards the apex, see Fig. 6E, F ), and the outer margins of the parameres, which are strongly constricted at apical third, continuing nearly parallel (as opposed to nearly straight to sinuate). Description. Body length 2.0-2.4 mm, width 1.1-1.4 mm. General coloration variable, either orange brown or uniformly dark brown (Fig. 3A-D ). Elytra with punctures shallowly marked. Aedeagus with outer margins of parameres strongly constricted at apical third, continuing nearly parallel towards apex; inner margins of parameres slightly concave only along apical sixth; median lobe constricted at midlength, continuing as a narrow and roundly pointed bar (Fig. 6G, H ). Etymology. Named in reference to the abrupt constriction of the outer margins of the parameres at their apical third, with the Latin word sinuatus meaning bent, curved. Distribution. Brazil (Minas Gerais, Para ). See Fig. 7 . Biology. The series from Lassance was collected by floating root mats and detritus that were on rock at the margin of a river and waterfall. The specimens from Altamira were collected in streams.