Goniaspis opaca Mlynarek and Wheeler, sp. n. (Figs. 14–15) Description: As in G. obscurata except as follows: male postabdomen (Figs 14–15): epandrium barely wider than high; sides of epandrium parallel in posterior view; cerci somewhat wide; separated by semi-circular ventral excavation. Type material: Holotype 3: “ COSTA RICA: San José: Santo / Domingo de Heredia / InBioParque, sweep veg. / 14.ii.2003, J. Savage”, “ HOLOTYPE / Goniaspis / opaca / Mlynarek & Wheeler” (LEM). Paratypes: ARGENTINA: Tucuman: Lacavera, 23–28.xi.1951, Aczel & Golbach (13, USNM); BRAZIL: Nova Teutonia, 27˚11’S, 52˚23’W, vi.1937, F. Plaumann (13, USNM); COSTA RICA: Puntarenas, San Vito, Estacion Biologica Las Alturas, 1500m, Malaise trap, i.1992, P. Hanson (13, LEM); San Jose, 15.v.1907, H. Schmidt (23, USNM); La Suiza, iv.1922, P. Schild (23, USNM); Turrialba, xi.1922, P. Schild (23, USNM); PERU: Madre de Dios, Manu, Rio Manu, Cocha Salvador, 240m, 14.ix.1988, A. Freidberg (13, USNM). Etymology: From the Latin opacus (dim, obscure), referring to the cryptic characters that distinguish this species from the appropriately named G. obscurata. Remarks: Goniaspis opaca differs from G. obscurata only in the shape of the male epandrium and cerci. Although the morphological differences are minor, they are consistent and we found no intermediates between the two species. The geographic ranges of the two species overlap broadly. Examination of additional specimens of this species complex from across their geographic range would be helpful in resolving their status.

Published as part of Mlynarek, Julia J. & Wheeler, Terry A., 2009, Revision of the Neotropical genus Goniaspis Duda (Diptera: Chloropidae), pp. 26-40 in Zootaxa 2033 on page 33, DOI: 10.5281/zenodo.186327