The origins of major sessile cirripede groups; a revision of Cretaceous Brachylepadomorpha and Verrucomorpha

The taxonomy of Cretaceous cirripedes referred to the sessile orders Brachylepadomorpha and Verrucomorpha is revised. New taxa include the brachylepadid genera Crithmumlepas (type species C. hoensis sp. nov., C. aycliffensis sp. nov.) and Calvatilepas (type species C. recurvus sp. nov.). The family Pycnolepadidae nov. is established (constituent genera Pycnolepas, Faxelepas) and Pycnolepas batchelorum sp. nov. is described; a new eoverrucid species, E. barringtonensis sp. nov. is erected. Cladistic analysis of 48 characters of 18 operational taxonomic units, including 16 in-group sessile taxa yielded a consensus tree showing the strongly supported monophyly of Brachylepadomorpha + Verrucomorpha + Balanomorpha. It is recommended that the Order Brachylepadomorpha is abandoned, and its constituent families are identified as, respectively, stem group Verrucomorpha (Pycnolepadidae) and stem group Balanomorpha (Brachylepadidae). The sister-group relationship of Verrucomorpha and Balanomorpha, identified from many molecular studies, is confirmed from shell morphological data. The Neolepadoidea are shown to closely parallel the sessile adaptations of verrucomorphs and balanomorphs. The fossil record of key segments of cirripede evolution is demonstrated to be remarkably, and surprisingly, complete.