Hydrochus argutus Knisch, 1921

Perkins, Philip D., 2019, Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae), Zootaxa 4701 (2), pp. 149-167 : 151-152

Hydrochus argutus Knisch

Figs. 1 , 12E

Hydrochus argutus Knisch 1921: 3 .

Hydrochus johannapietersenae Makhan 1995 ; Oliva (1996). The RBINS kindly provided eight syntypes of Hydrochus argutus Knisch , which are part of the Orchymont / Knisch types collection. Five of the syntypes are females, one of which is in three pieces. This specimen has been dissected by a prior worker, but the genital segments are not with the specimen. One syntype , labeled as male by a prior worker, is missing the head and prothorax, has been dissected, but the genital segments and male genitalia are not with the specimen. One syntype , gender unknown, is in two pieces. The genital segments are not with the specimen, hence the gender is unknown. One male syntype , dissected by a prior worker, is in six pieces. The male genitalia is partially crushed, and approximately the distal ½ of both parameres are missing, making the aedeagus appear to be much longer than the parameres. A complete male specimen, with complete male genitalia, is not available to serve as lectotype. Therefore, I have chosen a relatively good syntype female to serve as lectotype, and have labeled it such. This specimen is imaged ( Fig. 1 ). The lectotype has the following labels ( Fig. 12E ): “ Bras.Corumba [Matto Grosso] // Kniž det. argutus m. // Coll. A.Knisch COTYPUS // Ex coll. A.d’Orchymont // HABITUS/GENIT. DIGI- TAL IMAGES captured 2019 P.D. Perkins // [red] LECTOTYPE Hydrochus argutus Knisch desig. P. D. Perkins. ” The seven other syntypes have been labeled paralectotypes.

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.

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”.

Figures

FIGURE 1. Hydrochus argutus Knisch, habitus of lectotype, and male genitalia of specimen from Brazil.

FIGURES 12A–E. Labels of lectotypes. (A) Hydrochus ducalis Knisch; (B) Hydrochus drakei Knisch; (C) Hydrochus variabilis Knisch; (D) Hydrochus corruscans Bruch; (E) Hydrochus argutus Knisch.