The phylogenetic relationships between actinolepids (Placodermi: Arthrodira) and other arthrodires (phlyctaeniids and brachythoracids)

Abstract

The phylogenetic relationships between actinolepids (Placodermi, Arthrodira) and other arthrodires (Phlyctaenii and Brachythoraci) are re-evaluated in connection with a study in progress on some Podolian and Spitsbergen actinolepid material. The species Kujdanowiaspis podolica (Brotzen, 1934) is briefly redescribed, and its characters discussed in relation to a recent cladistic analysis of the actinolepids. An enlarged phylogenetic analysis using a data matrix of 55 characters for 31 taxa reveals that the actinolepids may be a paraphyletic group; their taxonomic and nomenclatural status is briefly discussed. Within the actinolepids, the genus Kujdanowiaspis does not have the basal position proposed by previous authors. A proposed new phylogeny shows Wuttagoonaspis as the sister group to all other arthrodires, and the Phyllolepida as the sister group to the Phlyctaenioidei (Phlyctaenii plus Brachythoraci).