Revision of the water scavenger beetle genus Notionotus Spangler, 1972 in the Neotropical Region (Coleoptera, Hydrophilidae, Enochrinae) Author Gonzalez-Rodriguez, Liza M. Department of Ecology & Evolutionary Biology, and Division of Entomology, Biodiversity Institute, University of Kansas, Lawrence, KS 66045, USA lizmgr287@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 2022 2022-07-01 1109 141 191 http://dx.doi.org/10.3897/zookeys.1109.80775 journal article http://dx.doi.org/10.3897/zookeys.1109.80775 1313-2970-1109-141 A418DA2C02DD4023A9F841FA0AEAAC83 2CB5DB1837165454A3C0E833ACD79CA7 Notionotus mexicanus Perkins, 1979 Figs 2D-F , 7B , 14 Notionotus mexicanus Perkins, 1979: 306. Type material examined. Holotype (male) : "MEXICO, Oaxaca, 8 mi. E./Tapanatepec, tropical/stream with lg. boulders/3-VII-1974/ME&PD Perkins", "Type No/76326/U S N M", "HOLOTYPE/ Notionotus / Notionotus mexicanus /P.D.Perkins" (USNM). Differential diagnosis. Notionotus mexicanus is very similar morphologically to N. tricarinatus sharing characters such as body length, yellow dorsal coloration, pronotum and elytra with fine ground punctation, and elevation of the mesoventrite with a transversal and a longitudinal ridge. It can be distinguished by the shape of the aedeagus, specifically the shape of the parameres: inner margins straight and sinuate reaching the apex, parameres narrowing along apical third, and narrower than N. tricarinatus . Description. Size and form : Body length 1.8 mm. Body form elongate oval, convex in lateral view (Fig. 2D ). Color and punctation : Dorsally yellow, head mostly yellow, frons pale brown; pronotum with two small black round spots along posterior margin (Fig. 2D ). Ventrally brown; maxillary palps, mouthparts, antennae, pro and meso legs yellow, meta legs pale brown (Fig. 2E ). Clypeus and labrum with dense, fine, and weakly impressed ground punctation (punctures separated by 2 x their width); pronotum and elytra ground punctation fine, weakly impressed and sparser than on head (punctures separated by 3 x their width). Head : Clypeus and labrum shallowly emarginate anteromedially, lateral margins of the labrum bearing setae. Thorax : Prosternum carinate medially, strongly raised, pointing anteriorly and acute. Elevation of mesoventrite with one transversal ridge, elevated medially, lateral sides concave; longitudinal ridge sharp, the point where the two ridges merged rounded and obtuse (e.g., Fig. 10A, B ); elevation concave in lateral view; mesoventrite with triangular shape in ventral view. Metaventrite convex in the median region, pubescent with narrow glabrous patch on the medial and posterolateral area; anterior margin extending to mesoventrite elevation. Metafemora densely covered with hydrofuge pubescence on basal three-quarters (Fig. 2E ). Abdomen : Abdominal ventrites very densely pubescent. Aedeagus (Fig. 7B ) with basal piece 1.1 x the length of a paramere. Base of the parameres broader than the base of the median lobe; outer margin slightly convex along basal two-thirds, then slightly sinuate apically, inner margins nearly straight along basal two-thirds and then sinuate apically; apex of parameres rounded. Median lobe shorter than the parameres, approximately triangular, with acute apex. Distribution. Only known from the type locality in Mexico (Fig. 14 ). Life history. The type series was collected "from plant debris which had become trapped between stones in a rapid stream" ( Perkins 1979 ).