Hydrochus ducalis Knisch

Perkins, Philip D., 2019, Type designations for Neotropical water beetles in the genus Hydrochus Leach 1817 (Coleoptera: Hydrochidae), Zootaxa 4701 (2), pp. 149-167 : 154-155

Hydrochus ducalis Knisch

Figs. 4 , 5 , 12A

Hydrochous ducalis Knisch 1921: 1 .

Hydrochus desenderi Makhan 1992 ; Oliva (1996).

The RBINS kindly provided four syntypes of Hydrochus ducalis Knisch , which are part of the Orchymont/Knisch types collection. All four syntypes are conspecific males. I have selected one to serve as lectotype and labeled it as such, and provide images of the habitus, male genitalia, and labels of this specimen ( Figs. 4 , 12A ). Lecto- type labels ( Fig. 12A ): “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.

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.

Figures

FIGURE 4. Hydrochus ducalis Knisch, habitus and male genitalia of lectotype.

FIGURE 5. Hydrochus ducalis Knisch, habitus and male genitalia of paralectotype.

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.