Search

The Cephalaspidea is a diverse marine clade of euthyneuran gastropods with many groups still known largely from shells or scant anatomical data. The definition of the group and the relationships between members has been hampered by the difficulty of establishing sound synapomorphies, but the advent of molecular phylogenetics is helping to change significantly this situation. Yet, because of limited taxon sampling and few genetic markers employed in previous studies, many questions about the sister relationships and monophyletic status of several families remained open. In this study 109 species of Cephalaspidea were included covering 100% of traditional family-level diversity (12 families) and 50% of all genera (33 genera). Bayesian and maximum likelihood phylogenetics analyses based on two mitochondrial (COI, 16S rRNA) and two nuclear gene markers (28S rRNA and Histone-3) were used to infer the relationships of Cephalaspidea. The monophyly of the Cephalaspidea was confirmed. The families Cylichnidae, Diaphanidae, Haminoeidae, Philinidae, and Retusidae were found non-monophyletic. This result suggests that the family level taxonomy of the Cephalaspidea warrants a profound revision and several new family and genus names are required to reflect the new phylogenetic hypothesis presented here. We propose a new classification of the Cephalaspidea including five new families (Alacuppidae, Colinatydidae, Colpodaspididae, Mnestiidae, Philinorbidae) and one new genus ( Alacuppa ). Two family names (Acteocinidae, Laonidae) and two genera ( Laona , Philinorbis ) are reinstated as valid. An additional lineage with family rank (Philinidae “Clade 4”) was unravelled, but no genus and species names are available to reflect the phylogeny and formal description will take place elsewhere. [ABSTRACT FROM AUTHOR]

Three new species in two new genera of cornuate Osteostraci are described here based on specimens from the Early Devonian (Lochkovian) Man on the Hill (MOTH) locality in the Mackenzie Mountains, Northwest Territories, Canada. The new taxa share several characteristics withSuperciliaspis gabrielsei.Glabrapeltagen. nov., and its two species,G. cristatasp. nov. andG. minimasp. nov., are based on four previously undescribed specimens.Dentapelta loeffleraegen. et sp. nov. is based on one newly recovered specimen, along with another specimen originally referred by earlier workers to ‘Cephalaspidinae indet.’ Together withSuperciliaspis, these new genera are subjected to a phylogenetic analysis, building on earlier work by R. Sansom. The results indicate that all four species in three genera belong to a single clade that is here named as the new family Superciliaspididae. The Superciliaspididae are characterized by a long, narrow median field with a border of raised ridges of fused plates, by narrow and posteriorly pointing cornua, and by orbits close together. A laterally expanded pineal opening and raised orbital rims place the Superciliaspididae as sister to the clade Scolenaspididae + Zenaspididae in the Order Zenaspidida. Internal anatomy of the nasohypophysial opening confirms separate internal nasal and hypophysial ducts. To date, the Superciliaspididae have been found only at the MOTH locality in the Mackenzie Mountains of northern Canada, whereas related taxa are distributed more widely in North America, Spitsbergen and Europe. http://zoobank.org/urn:lsid:zoobank.org:pub:F69DDE22-311A-4F2A-9B5D-8E59D13341E2 [ABSTRACT FROM PUBLISHER]