Cladistic analysis of the ‘trepostome’ Suborder Esthonioporina and the systematics of Palaeozoic bryozoans

Esthonioporina is a suborder of Trepostomata known mainly from the Ordovician - Usually regarded as containing fewer than ten genera, this suborder has particular importance as it has been interpreted to be phylogenetically basal among stenolaemates (cyclostomes excluded). Cladistic analysis of the suborder has been undertaken: 1. to infer the relationships between esthonioporine genera, 2. to assess whether the suborder is monophyletic, and 3. to determine its sister-group. The results indicate that the genera Esthoniopora, Esthonioporella, Dianulites, Orbipora, Chondraulus, Nekhorosheviella, Revalotrypa and Ibexella can all be included within a monophyletic suborder Esthonioporina, here raised to ordinal level as Esthonioporata. However, Orbiramus and Kanoshopora, which have ramose colonies with branches differentiated into endozone and exozone, although previously assigned to Esthonioporina, appear to belong elsewhere in the Trepostomata. Using a small range of exemplar genera, cladistic analysis found Esthonioporina to form a monophyletic clade with Cystoporata, which together constitute the sister-group of the other Trepostomata (i.e. Amplexoporina and Halloporina) + Cryptostomata. The new superorder Palaeostomata is introduced for the free-wa Cladistic analysis of the ‘trepostome’ Suborder Esthonioporina and the systematics of Palaeozoic bryozoans.