Previously, the spiders assigned to the genus Leptopholcus were thought to be largely restricted to the Old World, with the exception of some species from the Antilles, where these spiders are quite common. Then, in 2002 and 2003, three species apparently attributable to this genus were found in South America: two in Brazil and one in Venezuela. Why are these spiders so rare on the mainland? The answer lies possibly in another genus that occupies exactly the same microhabitat (the underside of large leaves): Metagonia is common on the mainland but largely absent from the Antilles (except for one blind species in a cave in Cuba).
In the meantime, morphological and molecular evidence has led us to transfer all New World Leptopholcus to Micropholcus (see Huber et al. 2014). So, Leptopholcus is now considered to be restricted to the Old World, and Micropholcus is one of the very few Pholcidae genera with autochthonous species in both New and Old Worlds.
Photos: B.A. Huber