Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae) Author Perkins, Philip D. text Zootaxa 2019 2019-11-27 4701 2 149 167 journal article 24789 10.11646/zootaxa.4701.2.2 2254e402-c6b6-4b90-95d8-587e979af76f 1175-5326 3557927 69045F2D-1E16-427B-939E-9F0A6D047D05 Hydrochus metallipes Knisch Figs. 6 , 13A Hydrochous metallipes Knisch 1920: 56 . The RBINS kindly provided eighteen syntypes of Hydrochus metallipes Knisch , which are part of the Orchymont/ Knisch types collection. The syntypes consist of both males and females. I have selected one of the males, a specimen in good condition, to serve as lectotype , have labeled it such, and have imaged the habitus, male genitalia and labels of this specimen ( Figs. 6 , 13A ). The seventeen non-lectotype syntypes have been labeled as paralectotypes . Lectotype labels ( Fig. 13A ): “Bras.Corumba [Matto Grosso] // det. Kniž metallipes m. // Coll. A.Knisch TYPUS // coll. A. d’Orchymont: Hydrochus R.M.H.N.B. 15.962 // TYPE // HABITUS/GENIT. DIGITAL IMAGES captured 2019 P.D. Perkins // [red] LECTOTYPE Hydrochus metallipes Knisch desig. P. D. Perkins // Hydrochus tarsalis Chevrolat, 1863 , det. P. D. Perkins, 2019.” The male genitalia of the lectotype of Hydrochus metallipes Knisch 1920 does not differ significantly from the male genitalia of the neotype of Hydrochus tarsalis Chevrolat 1863 . H. metallipes is therefore reduced to status of junior synonym of H. tarsalis Chevrolat. Remarks. Oliva (1992) published a drawing of the male genitalia of, supposedly, H. metallipes . The parameres are depicted as having a more pronounced enlargement of the medial margin than is present in the lectotype , or in all specimens of H. tarsalis for which the male genitalia have been examined. Oliva (1992) did not give the locality data of the specimen that was used to make the drawing.