First tropical American species of the "relict" genus Litoleptis, and relationships in Spaniinae (Diptera, Rhagionidae)

Abstract

The genus Litoleptis has consisted of nine described species, seven of them Asian and only two in the New World: L. alaskensis Chillcott, known from two specimens from northwest Alaska, and L. chilensis Hennig, known from a male specimen from near Santiago, Chile. A third New World species is described here, Litoleptis tico, n. sp., based on a single female from Costa Rica. The species is unique for the genus in having a vestigial proboscis and lacking spermathecal accessory ducts and glands. Female terminalia are unknown for the other two New World species. A morphologically based, preliminary phylogeny of spaniines is provided, indicating Litoleptis is recently derived among spaniines and thus Rhagionidae; the Early Cretaceous Litoleptis fossilis is a stem group to the living species. A derived position of the genus, its apparently broad distribution, and an abundance in Japan where Litoleptis has been bred from liverworts (Imada and Kato, 2016a), all indicate that these flies are probably not at all relict, simply vastly undersampled because of a reliance on mass-collecting techniques.