The synziphosurine horseshoe crab Pasternakevia was until now known only from a single specimen. Herein we describe three new specimens from the outcrop close to the type locality of monotypic P. podolica that show several features that were unknown or only assumed in this genus. These characters include: a smooth surface of the carapace; an opisthosoma composed of ten segments, the first one being a microtergite (strongly reduced first opisthosomal segment usually hidden under the carapace), two or three last segments fused into a metasoma, and the telson. Pasternakevia is included in Bunodidae due to a hypertrophied tergite 2, but it is linked to the Pseudoniscidae by the shape of the opisthosoma.

Key words: Arthropoda, Xiphosura, Bunodidae, Pasternakevia, microtergite, phylogeny, Silurian, Ukraine.

Wiesław Krzemiński, Ewa Krzemińska [krzeminska@isez.pan.krakow.pl], and Dariusz Wojciechowski, Institute of Systematics and Evolution of Animals, Polish Academy of Sciences; ul. Sławkowska 17, 31-016 Kraków, Poland.