A new apterous species of Platypalpus Macquart (Diptera: Hybotidae, Tachydromiinae) from Ecuador.

Tachydromiinae is a very diverse subfamily of Hybotidae that comprises quite small predaceous flies. It is clearly monophyletic and its species are distinguished from other subfamilies by the apomorphic loss of vein M2 and cell dm, neither pterostigma nor pseudotracheae, phallus with the apex not articulated and ejaculatory apodeme not fused to the base of phallus (Sinclair & Cumming 2006). Platypalpus Macquart belongs to the tribe Tachydromiini and it is defined by the following characters: eyes bare, separated in both sexes, postpronotal lobe differentiated, scutum longer than broad (except in P brevicornis species-group), mid leg raptorial, mid femur thickened and armed with rows of spine-like ventral setae, mid tibia usually with a somewhat prominent apical projection, wing with veins A1 and CuA2 present (cell cup present) (Grootaert & Shamshev 2012). The genus is the most diverse of those in the Tachydromiinae, with approximately 550 species found almost worldwide, but preferentially inhabiting cold and temperate regions in the Nearctic and Palaearctic; it is particularly diverse in the latter region with 295 described species, whereas only 22 species are known from the Neotropics (Yang et al. 2007). In the tropics it is more diverse at higher altitudes and in cold regions, with few species known at lower altitudes and in tropical areas, where they likely compete with species of Elaphropeza Macquart that occupy similar habits and niches (Grootaert & Shamshev 2012). This apparent competitive exclusion is the probable reason the genus is not very diverse in tropical regions (op. cit.). This paper describes a very curious new wingless species of Platypalpus from the Parque Nacional Cajas, Ecuador. It is the first wingless species described in the genus and is the 23rd species known from the Neotropical Region.