Metagonia on Galapagos: blind cave dwellers and their epigean relatives
Published in Invertebrate Systematics, 2022; https://doi.org/10.1071/IS21082
 
Two blind Metagonia species in Galápagos lava tubes have long been thought to be relicts whose epigean ancestors had disappeared from the archipelago. At our collecting trip in 2019 we found two epigean species on Galápagos, but it was unclear whether these were closely related to the cave-dwelling species or distantly related species recently introduced from the mainland.

Here we describe the two new epigean species, a new bling species that it among the smallest pholcids known, and redescribe both previously known cave species. We add all five species to the recently published molecular phylogeny of Pholcidae, together with more than 30 further congeners from the mainland.


The newly described, entirely blind Metagonia zatoichi, from lava tubes in the highland of Santa Cruz Island.

Our analyses of molecular data consistently resolve all Galápagos Metagonia together as a monophyletic group, divided into an epigean clade and a hypogean clade. Each species is restricted to an individual island (Isabela or Santa Cruz; with one possible exception), suggesting that the epigean Metagonia species are native rather than introduced.