In search of phylogenetic congruence between molecular and morphological data in bryozoans with extreme adult skeletal heteromorphy

The taxonomy of cyclostome bryozoans, both recent and fossil, is founded almost entirely on characters of the mineralized skeleton. However, the adequacy of these characters is now being questioned by molecular sequence data. In this study we construct a molecular tree using ssrDNA and lsrDNA sequences and identify a clade of New Zealand cyclostomes containing species exhibiting widely different morphologies. In particular, Diaperoecia purpurascens (Hutton), a species assigned to the suborder Tubuliporina on the basis of adult skeletal morphology, is shown to be closely related to New Zealand species assigned to Heteropora, including H. neozelanica (Busk), which has a very different adult skeleton and is traditionally placed in the suborder Cerioporina. A new species resembling the Antarctic genus Hastingsia, ‘H’. whitteni sp. nov., from North Island, New Zealand, is found to belong to the same clade, despite being placed conventionally in a different family (Hastingsiidae) from both Diaperoecia (Diaperoeciidae) and Heteropora (Cerioporidae). These results challenge the utility of adult skeletal morphology in cyclostome taxonomy. In contrast to the striking dissimilarity between the adult skeletons of D. purpurascens and ‘Hastingsiawhitteni compared with New Zealand species of Heteropora, morphological similarities in early colony development, as well as possibly the presence of a gizzard, corroborate the molecular interpretation of their close relationships. Greater attention should be paid in the future to early astogenetic characters in cyclostome taxonomy.