Canthydrus testaceus

Canthydrus testaceus (Boheman, 1858) Hydrocanthus testaceus Boheman, 1858: 19 (Type locality: “ China ”). Canthydrus testaceus (Boheman, 1858): Branden 1884: 18 (n. comb.). Hydrocanthus ritsemae Régimbart, 1880: 213 (Type locality: “ Sumatra, Loeboekh [Lubuk] Gadang ”); syn. nov. Type material. Hydrocanthus testaceus: Lectotype ♀ (NHRS), by present designation. The specimen has been dislodged from its original, small, pointed card (Fig. 1) to check its sex and re-glued on a new, rectangular one. It is labelled as follows (Fig. 2): “ China [small, printed] / Kinb. [=Hjalmar Kinberg (1820-1908); small, printed] / Typus [small, printed] / testaceus Boh. [larger, handwritten, folded paper strip] / 3390 E91 + [light blue, printed] / NHRS-JLKB 000076466 [unique specimen catalogue number]” plus our red lectotype label. Notes on the lectotype of Canthydrus testaceus. The only known type specimen, a female (Fig. 1), has a rather weakly convex body (dorso-ventrally), sides of elytra (in lateral view) almost straight, very weak pronoto-elytral sinuation, and no traces of paler submedian markings on the elytra. Measurements are: total length 2.8 mm, maximum width 1.4 mm. Although the body length and maximum width are closer to the upper limit, all the other characters align fully with C. ritsemae, as defined by Toledo & Negri (2024), and exclude Canthydrus flavus (Motschulsky, 1855) as well as the two other larger, light-colored species of Canthydrus from Asia (C. birmanicus Guignot, 1956 and C. rocchii Wewalka, 1992). In light of this, we confirm that Canthydrus testaceus (Boheman, 1858) and C. ritsemae (Régimbart, 1880) are synonyms and the first name has priority over the second.