Taxonomy of Central American water beetles in the genus Hydrochus Leach, 1817 (Coleoptera: Hydrochidae) Author Perkins, Philip D. text Zootaxa 2021 2021-05-21 4974 3 459 503 journal article 6214 10.11646/zootaxa.4974.3.2 5b4eaeb3-5722-4021-84ad-125ccd80855f 1175-5326 4777839 1BD6220B-7540-4A12-B3D2-5EDC1A3B7DD8 Hydrochus variolatus LeConte Figs. 2 , 17, 18 , 26 , 34 Hydrochus variolatus LeConte 1852: 211 . Hydrochus otvosi Makhan 1993: 67 . New Synonymy. Type material. There is only one specimen of Hydrochus variolatus LeConte , a male, in the LeConte collection at the MCZ. It is therefore the holotype , by monotypy. Images of the habitus, male genitalia, and labels of this specimen given herein ( Figs. 18 , 26 ). Originally described from San Diego , California , the following new records are from Mexico . Material examined (19): Mexico : Baja California , 17 mi. S. of Ensenada , 14.vi.1938 , leg. Michelbacher & Ross (9 CAS ) ; Norte , Arr. Santo Domingo , 5.7 mi. E. Hamilton Ranch , 23.iv.1963 , leg. H. B. Leech , P.H. Arnaud , Jr. (4 CAS ) ; Norte , Sa. Juarez , 1 mi. S. Laguna Hanson , elev. 5000 ft , 19.vii.1970 , leg. P. D. Perkins (1 MCZ ) ; San Jose del Castillo , 15.vi.1961 , leg. E. L. Sleeper - 1 male (1 TAMU ) ; Campeche , Escarcega , 18.v.1962 , leg. F. Islas S. (1 NMNH ) ; Jalisco , Chamela , Rio Chamela , 4.vi.1989 , leg. G. Ortega (1 UNAM ) ; Veracruz , 9 mi. W. Poza Rica , 27.viii.1965 , leg. Paul J. Spangler (1 NMNH ) ; Rio Metlao nr. El Fortin , 17.xii.1948 , leg. H. B. Leech (1 CAS ) . Differential diagnosis. Among Central American species, recognized by the combination of moderate size (ca. 3.10–3.46 mm ), the deep pronotal depressions, the well raised and relatively impunctate pronotal reliefs, and the male genitalia ( Figs. 17, 18 ; described below). This species has a generalized Hydrochus habitus; reliable determinations will require dissection of males. The male genitalia have a very large adbl, and a unique character: the adbl and the continuing shaft of the aedeagus are on the same plane for about 1/3 the length of the aedeagus; this is best seen in lateral view. Male genitalia ( Figs. 17, 18 ). General characters: paramere tips slender and pointed, narrower in lateral view than in dorsal/ventral views, in dorsal/ventral views with medial margins at apex parallel or nearly so, then weakly arcuate away from midline, plsa absent or very slight; aedeagus in dorsal/ventral views moderately wide, parallelsided or nearly so; in lateral view wider, especially basally, adbl and continuing shaft of aedeagus on same plane for about 1/3 length of aedeagus, after which shaft dorsal margin is sinuate; lateral margins of aedeagus sclerotized; basal piece shorter than parameres, orifice strongly sclerotized. Dorsal surface: pdmm sinuate, slightly overlapping aedeagus; adbl very large, ca. ½ as wide as total genitalia width at that level; adtl at about midlength of shaft; paramere tips without sclerotized ridge. Ventral surface: pvmm approximating lateral margin of aedeagus; avtl near base. Remarks . I have examined the holotype of Hydrochus otvosi Makhan (HNHM) , including the male genitalia, and have determined that it is a synonym of Hydrochus variolatus LeConte. The H. otvosi holotype specimen is supposedly from Costa Rica . The non-type specimen of H. variolatus imaged ( Fig. 17 ) has this locality data: Baja California, Norte, Sa. Juarez, 1 mi. S. Laguna Hanson, elev. 5000 ft , 19.vii.1970 , leg. P. D. Perkins.