Diabrotica circulata Harold 1875: 91
MNHN, lectotype, female, verified
nummularis Harold 1877: 110 (type locality: Mexico; type depository: MfN, lectotype, male, verified)
Body length 6.7-7.3 mm, width 3.4-3.5 mm. Head basic color black. Antennae filiform, uniformly yellow. Maxillary palpi yellow or yellow ocher, labrum black or chestnut. Pronotum yellow, mustard yellow, light cadmium or yellow ocher, subquadrate, weakly bifoveate with wide shallow foveae, not shagreened, sometimes with minute wrinkles. Scutellum yellow. Elytra yellow or rufous, with two black bands. One yellow macula of the variable size may present in the center of basal band on each elytron. Posterior band may be reduced to oculate or sickle-shaped maculae. Bands black, metallic black blue or chestnut. Epipleura completely yellow, sutural angle of elytron round, punctation scattered, fine. Abdomen yellow or yellow ocher. Legs yellow or yellow ocher. Aedeagus symmetric, with five internal sac sclerites.
Mexico, Guatemala, Costa Rica, Panama, Colombia
Unknown. Two specimens in the USNM collection were collected on the milkweeds (AsclepiasL.)
Smith and Lawrence (1967) designated the lectotype of D. circulata and two paralectotypes (the paralectotype labels with question-marks) in the Allard collection in MNHN. One of the paralectotypes, a male, is morphologically identical with the type. We presume this male to be the male of D. circulata. Genitalia of this male were examined and no any substantial differences were found in internal sac structure between it and the type male of D. nummularis. The currently known range of both species is about the same. Except the very variable macula shape, no any substantial morphological differences occur in both species. Thus, we placed D. nummularis into synonymy of D. circulata.
Potential problems with identification
Diabrotica circulata is very similar to many of the "oculate" species such as D. gratiosa Baly, D. adelpha Harold, D. biannularis Harold, D. bioculata Bowditch and D. godmani Jacoby.
They can be separated by the following features: tibiae of D. gratiosa and D. bioculata are black or darkened by brown, but yellow in D. circulata; pronotum is nonfoveate D. adelpha, but very convex, bifoveate in D. circulata; elytrae of D. adelpha are more convex than in D. circulata; scutellum of D. biannularis is black, but yellow in D. circulata. Diabrotica godmani is smaller in size, its antennae are thinner and longer, slightly moniliform, usually bearing the longitudinal costae on the inner margin of antennomeres. Internal sac in D. circulata is very similar to D. pulchella (Jacquelin-du-Val). The internal sac sclerites 5B in D. circulata are elongate, handlelike hooks slightly widened and bearing 5-8 big teeth apically, while in D. pulchella they are elongate, handlelike hooks bearing 2-3 big teeth apically. Antennae are yellow in D. circulata, but bicolored in D. pulchella; posterior maculae on elytra are sickle-shaped or oculate in in D. circulata, but usually round in D. pulchella.