Philippine damselfly subgenus Risiocnemis (Igneocnemis)

Risiocnemis Cowley, 1934 is the largest genus of the zygopteran subfamily Calicnemiinae in the Indo-Pacific region. The group is endemic to the Philippines, except for the Sulu Archipelago and the Palawan island chain. Members of the group are confined to small, clear creeks in shady rainforest environment, occurring from lowland up to mid-montane forest.

Two subgenera within the genus Risiocnemis are currently recognized: Risiocnemis Cowley, 1934 s. str., and Igneocnemis Hämäläinen, 1991. A revision of the subgenus Risiocnemis was presented by Hämäläinen (1991). Mainly based on the large Roland A. Müller collection from the Philippines, which is now housed by the Natural History Museum in Leiden, a complete taxonomic revision of the subgenus Igneocnemis has recently been completed by Gassmann & Hämäläinen (2002). In total, 20 species of sg. Igneocnemis have been recognized, of which five were newly described.

Several putative synapomorphies of Igneocnemis species point to the monophyly of the group.However, the monophyly of the whole genus, i.e. Risiocnemis Cowley sensu lato, is less certain.Within the scope of a phylogenetic-biogeographical study on the Indo-Pacific Platycnemididae, thephylogeny of the Igneocnemis species was reconstructed based on morphological characters. Thedistribution patterns of the species can be explained by Tertiary island arc connections as well as by the existence of larger islands during the Pleistocene.