Taxonomic revision of fossil Psilodercidae and Ochyroceratidae spiders (Araneae: Synspermiata), with a new species of Priscaleclercera from mid-Cretaceous Burmese amber, northern Myanmar

Abstract

Psilodercidae contains some 200 known extant species of small spiders that live in tropical rainforests and caves and is mainly restricted to the Oriental biogeographic realm. Interestingly, at least ten different fossil species have been described from inclusions in Upper Cretaceous Burmese amber. This suggests the family has been diversifying in the region for at least ~100 million years. In this paper, we revise the taxonomy of fossil species of this family and the closely related Ochyroceratidae, based on the re-examination of type specimens of described species. We find that ten Cretaceous species described in the psilodercid genera Priscaleclercera and Aculeatosoma are valid, and present new illustrations of their type material. The genus Propterpsiloderces apparently does not belong to Psilodercidae, but rather to a family representing a stem lineage within Scytodoidea. Ochyroceratidae is represented in the fossil record by a single ochyroceratine genus from Miocene Dominican amber, Arachnolithulus. The original combination of the extant species Leclercera spinata Deeleman-Reinhold, 1995 is reinstated by transferring it from Priscaleclercera, leaving this latter genus as a strictly fossil taxon. Finally, we present the description of a hitherto unknown species of Priscaleclercera from mid-Cretaceous Burmese amber, Priscaleclercera christae sp. nov., bringing the total number of congeners to ten. By studying its morphological features, we argue that Priscaleclercera is a crown-group Psilodercidae, closely related to the Althepus–Leclercera lineage. The high species diversity of Priscaleclercera indicates that Psilodercidae was already a diverse component of the Oriental tropical forests during the Cretaceous.