PHYLOGENY AND SYSTEMATICS OF THE TELEPHINID TRILOBITE OPIPEUTERELLA, WITH NEW SPECIES FROM THE WESTERN USA AND NEWFOUNDLAND, CANADA

The telephinid trilobite genus Opipeuterella historically consisted of a group of rather poorly known species from Laurentia and western Australia. Several additional Australian species known from abundant and well-preserved material were described in the late 1990s, while reexamination of available North American material has remained lacking until now. New sampling efforts by the authors in the Great Basin, western USA, and in western Newfoundland, Canada, have revealed numerous well-preserved specimens of Opipeuterella, including several new species. Six new species, as well as, new material of two previously described species were recovered from southeastern Idaho, western Utah, and eastern Nevada, and range in age from the Tulean to Blackhillsian (Ibexian). A single new species was identified from the Shallow Bay Formation (Cow Head Group) in western Newfoundland. The Newfoundland species also occurs in the latest Tulean of the Great Basin. This wide occurrence of a pelagic species is of critical importance for correlation of faunas on either side of the Transcontinental Arch, as no benthic trilobite taxa from the Newfoundland Opipeuterella fauna are known from the Great Basin. Correlations between western and eastern Laurentia have been so difficult to establish that some workers have advocated separate stadial schemes for either region.

No part of the speciose and geographically widespread family Telephinidae has ever been subject to modern, quantitative phylogenetic analysis. With the discovery of this new material a morphologic parsimony analysis examining ingroup relationships of this clade and the potential synonymy of Ompheter with Opipeuterella is now possible. The putatively closely related Stairsian species Goniophrys prima was used as the outgroup, and the results demonstrate a much higher degree of congruence between phylogenetic and stratigraphic order than is typical of analyses of benthic trilobite clades.