taxonID	type	description	language	source
C17B87FF3C3C1235C0E6FD50FE63F307.taxon	description	Figs. 1, 12 E	en	Perkins, Philip D. (2019): Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae). Zootaxa 4701 (2): 149-167, DOI: 10.11646/zootaxa.4701.2.2
C17B87FF3C3C1235C0E6FD50FE63F307.taxon	description	The male genitalia illustrations (Fig. 1) are from a non-type specimen with the following labels: “ BRAZIL, State of Mato Grosso, Cuiaba, Parque de Exposicao // HABITUS / GENIT. DIGITAL IMAGES captured 2019 P. D. Perkins // Hydrochus argutus Knisch 1921, det. P. D. Perkins 2019. ” This specimen is deposited in the NMNH.	en	Perkins, Philip D. (2019): Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae). Zootaxa 4701 (2): 149-167, DOI: 10.11646/zootaxa.4701.2.2
C17B87FF3C3C1235C0E6FD50FE63F307.taxon	discussion	Remarks. Oliva (1992) provided a male genitalia drawing supposedly of H. argutus, but unfortunately does not specify any data of the specimen that was used. The drawing is very different from the male genitalia of specimens examined in this study, or in any other published figures of Neotropical Hydrochus male genitalia: the parameres in the drawing are very short, only about ½ the length of the aedeagus. I conclude that this drawing was made with inadequate magnification, using the damaged specimen noted above, which has the distal portions of both parameres sheared-off. I have examined the holotype, and the holotype male genitalia, of Hydrochus johannapietersenae Makhan 1995, deposited in the NMW, and concur with Oliva (1996) that it is a junior synonym of Hydrochus argutus Knisch. Labels on holotype of H. johannapietersenae: “ PARAGUAY, 16.20.10 Dep. Guaira, 1992 Zorilla leg. U. Drechsel // Hydrochus johannapietersenae det. D. Makhan 1995 // Holotype [red] // Hydrochus argutus Knisch, 1921 det. P. D. Perkins, 2019 ”.	en	Perkins, Philip D. (2019): Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae). Zootaxa 4701 (2): 149-167, DOI: 10.11646/zootaxa.4701.2.2
C17B87FF3C3D1235C0E6FEC3FCE9F1CC.taxon	description	Figs. 2, 12 D	en	Perkins, Philip D. (2019): Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae). Zootaxa 4701 (2): 149-167, DOI: 10.11646/zootaxa.4701.2.2
C17B87FF3C3D1235C0E6FEC3FCE9F1CC.taxon	description	The RBINS kindly provided eight syntypes of Hydrochus corruscans Bruch, which are part of the Orchymont / Knisch types collection. The syntypes consist of six females, one specimen of unknown gender (unknown because a prior worker dissected the specimen, but there are no genital segments or male genitalia with the specimen), and one male. I have selected the male to serve as lectotype and labeled it as such, and provide images of the habitus, male genitalia, and labels of that specimen (Figs. 2, 12 D). Lectotype labels (Fig. 12 D): “ Hydrochus corruscans Bruch // Coll. A. d’Orchymont // Cotypus // Rep. ARGENTINA Prov. Buenos Aires 1. 1. 1915 C. Bruch // HABITUS / GE- NIT. DIGITAL IMAGES captured 2019 P. D. Perkins // [red] LECTOTYPE Hydrochus corruscans Bruch desig. P. D. Perkins. ” The seven other syntypes have been labeled paralectotypes.	en	Perkins, Philip D. (2019): Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae). Zootaxa 4701 (2): 149-167, DOI: 10.11646/zootaxa.4701.2.2
C17B87FF3C3D1235C0E6FEC3FCE9F1CC.taxon	discussion	Remarks. Oliva (1992) placed Hydrochus corruscans Bruch as a junior synonym of Hydrochus obscurus Sharp, 1882. However, the dorsal habitus and male genitalia of the lectotype of Hydrochus corruscans Bruch differ significantly from that of specimens of Hydrochus obscurus Sharp. Consequently, Hydrochus corruscans Bruch is hereby removed from synonymy with Hydrochus obscurus Sharp.	en	Perkins, Philip D. (2019): Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae). Zootaxa 4701 (2): 149-167, DOI: 10.11646/zootaxa.4701.2.2
C17B87FF3C3D1232C0E6FD04FC65F52B.taxon	description	Figs. 3, 12 B	en	Perkins, Philip D. (2019): Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae). Zootaxa 4701 (2): 149-167, DOI: 10.11646/zootaxa.4701.2.2
C17B87FF3C3D1232C0E6FD04FC65F52B.taxon	discussion	Remarks. One of the syntypes bears a lectotype label, by J. L. Hellman, but this designation was never published. This label has been reversed and “ unpub. ” written on the reverse side.	en	Perkins, Philip D. (2019): Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae). Zootaxa 4701 (2): 149-167, DOI: 10.11646/zootaxa.4701.2.2
C17B87FF3C3B1231C0E6FC88FA14F7CB.taxon	description	Figs. 4, 5, 12 A	en	Perkins, Philip D. (2019): Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae). Zootaxa 4701 (2): 149-167, DOI: 10.11646/zootaxa.4701.2.2
C17B87FF3C3B1231C0E6FC88FA14F7CB.taxon	description	type labels (Fig. 12 A): “ Bras. Corumba [Matto Grosso] // Coll. A. Kniž COTYPUS // det. Kniž ducalis m. // coll. A. d’Orchymont: Hydrochus R. M. H. N. B. 15.962 // HABITUS / GENIT. DIGITAL IMAGES captured 2019 P. D. Perkins // [red] LECTOTYPE Hydrochus ducalis Knisch desig. P. D. Perkins. ” The three non-lectotype syntypes have been labeled paralectotypes.	en	Perkins, Philip D. (2019): Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae). Zootaxa 4701 (2): 149-167, DOI: 10.11646/zootaxa.4701.2.2
C17B87FF3C3B1231C0E6FC88FA14F7CB.taxon	discussion	Remarks. One of the male paralectotypes has a distinctly more ovoid basal piece, while the structures of the aedeagus and the parameres do not significantly differ from those of the lectotype. Images of this specimen are given as an example of some of the infraspecific variation to be expected in species of Hydrochus (Fig. 5). The drawing of Hydrochus ducalis Knisch male genitalia by Oliva (1992) is unfortunately very inaccurate in several aspects, including general proportions, shapes of the parameres, size of the basal piece, etc. I have also examined the holo- type of Hydrochus desenderi Makhan 1992 (which is one of the syntypes of Hydrochus ducalis), including the male genitalia. I concur with Oliva (1996) that Hydrochus desenderi Makhan is a junior synonym of Hydrochus ducalis Knisch. The holotype of H. desenderi Makhan, deposited in the RBINS, has the same label data as the lectotype.	en	Perkins, Philip D. (2019): Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae). Zootaxa 4701 (2): 149-167, DOI: 10.11646/zootaxa.4701.2.2
C17B87FF3C39123EC0E6FC33FC82F69F.taxon	description	Figs. 6, 13 A	en	Perkins, Philip D. (2019): Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae). Zootaxa 4701 (2): 149-167, DOI: 10.11646/zootaxa.4701.2.2
C17B87FF3C39123EC0E6FC33FC82F69F.taxon	discussion	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.	en	Perkins, Philip D. (2019): Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae). Zootaxa 4701 (2): 149-167, DOI: 10.11646/zootaxa.4701.2.2
C17B87FF3C36123FC0E6FD14FEB3F553.taxon	description	Figs. 7, 13 B	en	Perkins, Philip D. (2019): Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae). Zootaxa 4701 (2): 149-167, DOI: 10.11646/zootaxa.4701.2.2
C17B87FF3C34123DC0E6FC34FAACF5B7.taxon	description	Figs. 8, 13 C	en	Perkins, Philip D. (2019): Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae). Zootaxa 4701 (2): 149-167, DOI: 10.11646/zootaxa.4701.2.2
C17B87FF3C34123DC0E6FC34FAACF5B7.taxon	discussion	Remarks. The lectotype, plus the second male from Mato Grosso, one of the females from Mato Grosso, and the syntype of unknown gender distinctively differ from the other syntypes in having a deep cervical sulcus, a groove behind the eyes into which fits the arcuate anterior margin of the pronotum (for descriptions of other species with this character see Perkins, in press). This rather obvious character has not been mentioned by previous authors, including Makhan (1992). Oliva (1992), in the “ Material examined ” section listed six syntypes, but did not designate a lectotype. The description in Oliva (1992) cannot be conclusively evaluated because it is unknown which syntype was used for the description, or if the description is a composite based on two or more specimens.	en	Perkins, Philip D. (2019): Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae). Zootaxa 4701 (2): 149-167, DOI: 10.11646/zootaxa.4701.2.2
C17B87FF3C35123DC0E6F884FF48F2FC.taxon	description	Figs. 9, 13 E	en	Perkins, Philip D. (2019): Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae). Zootaxa 4701 (2): 149-167, DOI: 10.11646/zootaxa.4701.2.2
C17B87FF3C35123DC0E6F884FF48F2FC.taxon	discussion	Remarks. Oliva (1996) placed Hydrochus mahunkai Makhan 1993 as a junior synonym of Hydrochus secretus Knisch. I have examined the holotype and male genitalia of Hydrochus mahunkai Makhan, provided through the courtesy of the HMNH, and concur with the synonymy. Labels on holotype of H. mahunkai: “ Soil Zoological Exp. BOLIVIA, Guayaramerin / Beni / outskirts of town BALOGH, MAHUNKA, ZICSI // No. 424 lamping 1. XII. 1966 // Hydrochus mahunkai det. D. Makhan 1993 // Holotype [red] // Hydrochus secretus Knisch, 1921 Det. A. Oliva 1996 ”. The drawing of the male genitalia in Makhan (1993) is grossly inaccurate, especially in the shape of the basal piece.	en	Perkins, Philip D. (2019): Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae). Zootaxa 4701 (2): 149-167, DOI: 10.11646/zootaxa.4701.2.2
C17B87FF3C35123AC0E6FC53FAA3F62F.taxon	description	Figs. 10, 13 D	en	Perkins, Philip D. (2019): Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae). Zootaxa 4701 (2): 149-167, DOI: 10.11646/zootaxa.4701.2.2
C17B87FF3C35123AC0E6FC53FAA3F62F.taxon	discussion	Remarks. Hydrochus tarsalis is a large species. Chevrolat (1863) gives the size of the unique type as “ long. 4 ½ mill., lat. 1 3 / 4 mill. ” There is only one currently known species of Hydrochus in Cuba that is this large. The external characters, and the male genitalia, of the lectotype of H. metallipes Knisch do not differ significantly from those of the neotype of H. tarsalis. Hydrochus metallipes is therefore hereby placed as a junior synonym.	en	Perkins, Philip D. (2019): Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae). Zootaxa 4701 (2): 149-167, DOI: 10.11646/zootaxa.4701.2.2
C17B87FF3C331239C0E6FD2FFD70F657.taxon	description	Figs. 11, 12 C	en	Perkins, Philip D. (2019): Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae). Zootaxa 4701 (2): 149-167, DOI: 10.11646/zootaxa.4701.2.2
C17B87FF3C331239C0E6FD2FFD70F657.taxon	discussion	Remarks. The male genitalia of the lectotype appears to have a very large gonopore; this is, based on other specimens of this species examined, because the male genitalia had dried out, and the membranous area surrounding the gonopore had consequently retracted toward the lateral margins. Images of a specimen of H. variabilis with the gonopore of usual size is given in Perkins (in press).	en	Perkins, Philip D. (2019): Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae). Zootaxa 4701 (2): 149-167, DOI: 10.11646/zootaxa.4701.2.2
