Peltonotus karubei was described based on seven male specimens (holotype and six paratypes) (Fig. 4, paratype) from the Dambri waterfall near Bao Loc in Lam Dong Province, southern Vietnam (Muramoto 2000). Females are not known for the species. An additional male specimen of P. karubei broadens the concept of the species based on its entirely black elytral coloration (Fig. 5). Elytral coloration is reddishorange for all specimens in the type series. A single male specimen was collected in April 2004, 45 km east of Bao Loc on Mount Braian (specimen deposited in FUJI). Only three species of Peltonotus are known to occur in Vietnam: P. nasutus Arrow (elytral coloration black to castaneous with dorsum shining), P. favonius, n. sp. (elytral coloration black with iridescent bloom), and P. karubei (elytral coloration reddishorange or black with iridescent bloom). The form of the labrum (deeply, narrowly emarginated), bidentate protibia, form of the maxilla (Fig. 11), and form of the male genitalia (Fig. 14 a-b) easily separate P. karubei from other species in the genus. Despite the variation in color, the species is readily identified using the key in Jameson and Wada (2004).