The Cephalaspidea is a diverse marine clade of euthyneuran gastropods with many groups still known largely from shells or scant anatomical data. The definition of the group and the relationships between members has been hampered by the difficulty of establishing sound synapomorphies, but the advent of molecular phylogenetics is helping to change significantly this situation. Yet, because of limited taxon sampling and few genetic markers employed in previous studies, many questions about the sister relationships and monophyletic status of several families remained open. In this study 109 species of Cephalaspidea were included covering 100% of traditional family-level diversity (12 families) and 50% of all genera (33 genera). Bayesian and maximum likelihood phylogenetics analyses based on two mitochondrial (COI, 16S rRNA) and two nuclear gene markers (28S rRNA and Histone-3) were used to infer the relationships of Cephalaspidea. The monophyly of the Cephalaspidea was confirmed. The families Cylichnidae, Diaphanidae, Haminoeidae, Philinidae, and Retusidae were found non-monophyletic. This result suggests that the family level taxonomy of the Cephalaspidea warrants a profound revision and several new family and genus names are required to reflect the new phylogenetic hypothesis presented here. We propose a new classification of the Cephalaspidea including five new families (Alacuppidae, Colinatydidae, Colpodaspididae, Mnestiidae, Philinorbidae) and one new genus (Alacuppa). Two family names (Acteocinidae, Laonidae) and two genera (Laona, Philinorbis) are reinstated as valid. An additional lineage with family rank (Philinidae "Clade 4") was unravelled, but no genus and species names are available to reflect the phylogeny and formal description will take place elsewhere.

A molecular phylogeny of the Cephalaspidea sensu lato (Gastropoda: Euthyneura): Architectibranchia redefined and Runcinacea reinstated. -Zoologica Scripta , 38 , 23-41. The monophyly and phylogenetic relationships of the Cephalaspidea sensu lato ( sensu Burn and Thompson 1998) have been investigated by means of Bayesian, parsimony and distance analyses of nuclear (18S rRNA and 28S rRNA) and mitochondrial cytochrome oxidase I (COI) genes.Results revealed the presence of three monophyletic groups among the Cephalaspidea s. l. (i) Architectibranchia ( sensu Haszprunar 1985, in part: including Acteonidae and Aplustridae, but excluding Diaphanidae), (ii) Cephalaspidea including Diaphanidae but not Runcinidae (both previously of uncertain systematic affinity), and (iii) Runcinacea.The monophyly of the architectibranch families Acteonidae (represented by Acteon and Pupa ) and Aplustridae ( Hydatina and Micromelo ); of the runcinacean family Runcinidae ( Runcina ); and of the cephalaspidean families Aglajidae ( Chelidonura , Aglaja , Odontoglaja , Navanax and Philinopsis ), Bullidae ( Bulla ), Gastropteridae ( Siphopteron and Sagaminopteron ), Haminoeidae ( Atys , Haminoea , Phanerophthalmus and Smaragdinella, but not Ventomnestia ), and Retusidae ( Retusa and Pyrunculus , but not Volvulella ) is suggested. The families Scaphandridae ( Scaphander ) and Rhizoridae ( Volvulella ) are reinstated as valid. A new phylogenetic classification of the Cephalaspidea is proposed.

Aim Our aims were: (1) to reconstruct a molecular phylogeny of the cephalaspidean opisthobranch genus Bulla, an inhabitant of shallow sedimentary environments;(2) to test if divergence times are consistent with Miocene and later vicariance among the four tropical marine biogeographical provinces; (3) to examine the phylogenetic status of possible Tethyan relict species; and (4) to infer the timing and causes of speciation events.Location Tropical and warm-temperate regions of the Atlantic, Indo-West Pacific, Australasia and eastern Pacific.Methods Ten of the 12 nominal species of Bulla were sampled, in a total sample of 65 individuals, together with cephalaspidean outgroups. Phylogenetic relationships were inferred by Bayesian analysis of partial sequences of the mitochondrial cytochrome c oxidase I (COI) and 16S rRNA and nuclear 28S rRNA genes. Divergence times and rates of evolution were estimated using uncorrelated relaxed-clock Bayesian methods with fossil calibrations (based on literature review and examination of fossil specimens), implemented in beast. The geographical pattern of speciation was assessed by estimating the degree of overlap between sister lineages.Results Four clades were supported: Indo-West Pacific (four species), Australasia (one species), Atlantic plus eastern Pacific (three species) and Atlantic (two species), with estimated mean ages of 35-46 Ma. Nominal species were monophyletic, but deep divergences were found within one Indo-West Pacific and one West Atlantic species. Species-level divergences occurred in the Miocene or earlier. The age of a sister relationship across the Isthmus of Panama was estimated at 7.9-32.1 Ma, and the divergence of a pair of sister species on either side of the Atlantic Ocean occurred 20.4-27.2 Ma.Main conclusions Fossils suggest that Bulla originated in the Tethys realm during the Middle Eocene. Average ages of the four main clades fall in the Eocene, and far pre-date the 18-19 Ma closure of the Tethys Seaway. This discrepancy could indicate earlier vicariant events, selective extinction or errors of calibration. Similarly, the transisthmian divergence estimate far pre-dates the uplift of the Panamanian Isthmus at about 3 Ma. Speciation events occurred in the Miocene, consistent with tectonic events in the central Indo-West Pacific, isolation of the Arabian Sea by upwelling and westward trans-Atlantic dispersal. Differences in habitat between sister species suggest that ecological speciation may also have played a role. The basal position of the Australasian species supports its interpretation as a Tethyan relict.

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Bullidae are a worldwide family of marine shelled cephalaspidean gastropods with a mainly tropical distribution, but also with some representatives in temperate waters. The taxonomy of the group has in the past been based only on shell characters, and the few anatomical accounts available have not addressed more than one to three species, so there has been no agreement about the number of valid species. Seventy-two specific names and 16 varietal names have been proposed worldwide. The systematics of the family Bullidae are revised, based not only on shells but also on anatomy of all extant species and on DNA sequence data. Twelve species are recognized worldwide, including one new species here described, and all are assigned to the genus Bulla. Bullidae show a general morphological stasis, with anatomy being very similar between species. However, there are high levels of intraspecific variability in the shell, radula and male genital system. In some cases species could only be separated based on molecular data . After defining the characters and geographical range of each species it became clear that sympatric species (a maximum of three) show distinctive shells and reproductive structures, which makes identification straightforward. This study employs an integrative approach, combining information on shells, anatomy, DNA and geographical distribution, in order to resolve the systematics of a difficult taxonomic group.