USA 2016
 
In June 2016, just before the International Congress in Colorado, I took the opportunity and visited Big Bend National Park in southern Texas. The main motivation to go there was a unique and mysterious, tiny pholcid species endemic to this Park. It was originally described as Pholcophora diluta, based on female specimens collected in 1938. Almost thirty years later, in 1967, Willis Gertsch, visited the locality again, and found two male specimens, that he described in 1982. Since 1967, no further specimens seem to have been collected.

In 2000, I transferred the species to a new genus, Chisosa, considered to belong to Ninetinae. In the meantime I tend to see Chisosa as a miniaturized member of Arteminae, but without molecular data the evidence for this is weak. Therefore, I needed fresh specimens.






Most of Big Bend National Park is desert and shrubland, but a few places up in the mountains contain small pockets of oak forest with running water.



These are two of the first and only existing photos of Chisosa diluta. They may not be perfect, but the spider has a body length of just 1.5 mm!

Apart from Chisosa, I found two truly surprising species: the first representatives of the genera Metagonia (below left) and Anopsicus (below right) in the USA. These genera were previously thought to have their northern limits in Mexico, and Big Bend N.P. extends their distributions by about 400-450 km.

I thank the National Park Service for issuing a collecting permit, and the staff at Big Bend National Park for their kind support.