Description of a peculiar new species of the genus Platypalpus Macquart, 1827 (Diptera: Hybotidae) from the Caucasus

Platypalpus pilifer Grootaert et van der Weele, sp. n. is described from the Caucasus region in Azerbaijan, Georgia and Russia. The species belongs to the Platypalpus pallidiventris-cursitans group and is characterised by very long ventral bristles on the spindle-shaped dilated fore tibia in the male. Mid femur in both male and female has a ventral black stripe over the entirely length. An extended diagnosis of the related species Platypalpus infectus (Collin, 1926) is given with new illustrations of the male terminalia. It lacks long bristles on the fore tibia. The left epandrial lamella bears a lobe at the right side facing the left cercus and a long lobe at the left side. These distinct lobes are lacking in the new species. In addition numerous spinules are present on the right surstylus in P. infectus lacking in the new species.