Phylogenetic tree based on complete 18S rDNA sequence. © A Waeschenbach
Tennysonia stellata is the only known species of the genus Tennysonia. It has not been found as a fossil, despite having a hard skeleton that should fossilize well.
A survey using scanning electron microscopy reveals a high level of variability in the skeleton of Tennysonia stellata.
This variability within a single species has been confirmed by DNA sequencing revealing only minor genetic differences between specimens of contrasting morphology, such as those shown above.
Molecular phylogenetic analysis of Tennysonia in the context of other cyclostome bryozoans, places Idmidronea atlantica (suborder Tubuliporina) as T stellata’s closest relative.