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. Later I tended to see Chisosa as a miniaturized member of Arteminae, but without molecular data the evidence for this was 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. We have since sequenced the species and confirmed my suspicvion that it is a miniaturized member of Arteminae rathat than a Nientinae (Eberle et al. 2018; Huber et al. 2018).

Apart from Chisosa, I found some other nice surprises: below on the left is the first representatives of the genera Metagonia in the USA. Metagonia was previously thought to have its northern limits in Mexico, and Big Bend N.P. extends the distribution by over 400 km. On the right is a tiny Modisimus, representing a species group that is species-rich in Mexico but has never been found in the USA.

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