New species of Metagonia Simon with directionally asymmetric male and female genitalia (Araneae, Pholcidae)

Genital asymmetry is a rare phenomenon in spiders, and directional asymmetry, where all specimens are same-sided, is particularly scarce. In the New World genus Metagonia, only M. mariguitarensis (González-Sponga, 1998) was previously known to be directionally asymmetric. Here we describe three further species in the genus Metagonia that all share directionally asymmetric male and female genitalia: M. embera Huber sp. nov. (Colombia and Panama), M. uca Huber sp. nov. (Colombia), and M. wayuu Huber sp. nov. (Colombia and Venezuela). Metagonia uca is the species with the most extreme asymmetry and also the only species where female asymmetry is not limited to internal structures but extends to the epigynal scape. Interspecific CO1 distances among these four species ranged from 15.5 to 20.9%. Intraspecific distances mostly ranged from 0.0–1.7%, but higher values were found for M. mariguitarensis (up to 9.1%). While the available evidence suggests that directional asymmetry in Metagonia arose only once (in the last common ancestor of the four species above), the origin of the more widespread asymmetry in Metagonia (female antisymmetry) is less clear. We briefly discuss the phylogenetic pattern of antisymmetry in Metagonia, concluding that further focused research is necessary to provide the basic data for such an analysis.