Abstract

The Upper Ordovician (Sandbian–Katian) bathyurid trilobite Raymondites Sinclair is revised using new collections from Missouri and Ontario, and archival material from Illinois, Wisconsin, New York, and Ontario. Phylogenetic analysis supports monophyly of Raymondites, but recognition of this genus renders Bathyurus Billings paraphyletic. We treat Raymondites as a subgenus of Bathyurus and label the paraphylum of species traditionally assigned to the latter as Bathyurus sensu lato. Bathyurus (Raymondites) is composed of five previously named species, B. (R.) spiniger (Hall), B. (R.) longispinus (Walcott), B. (R.) ingalli (Raymond), B. (R.) bandifer Sinclair, and B. (R.) trispinosus (Wilson), and two new species, B. (R.) clochensis, and B. (R.) missouriensis; an eighth species is placed in open nomenclature. All species share tuberculate sculpture on the glabella, a relatively short palpebral lobe whose length is less than half of preoccipital glabellar length, and a pygidial outline that is well rounded posteriorly. Aside from the most basal species, B. (R.) longispinus, they also possess occipital spines and, where the pygidium is known, axial pygidial spines.