Molecular systematics of the marine gastropod families Trochidae and Calliostomatidae (Mollusca: Superfamily Trochoidea).

This study is the most extensive molecular study of the gastropod families Trochidae and Calliostomatidae published to date, in terms of both numbers of taxa and of gene sequences. As a result of Bayesian phylogenetic analyses of molecular sequence data from one nuclear gene and three mitochondrial genes, we propose dramatic changes to Trochidae family systematics, present the first molecular phylogeny for Calliostomatidae and include the first published sequence data for the enigmatic subfamily Thysanodontinae. Our phylogeny demonstrates that within the family Trochidae there is strong support for three subfamilies new to traditional classifications: Alcyninae subfam. nov., Fossarininae and Chrysostomatinae subfam. nov. As proposed, Alcyninae consists only of the nominotypical genus Alcyna, which is sister to all other trochids. The subfamily Fossarininae, as defined here, includes Fossarina, Broderipia, Synaptocochlea and "Roya"eximia and probably also Clydonochilus and Minopa. The subfamily Chrysostomatinae comprises the genera Chrysostoma and Chlorodiloma. Additional molecular support is also obtained for recently redefined Trochinae, Monodontinae, and Cantharidinae and for the traditionally recognised subfamilies Umboniinae and Stomatellinae. The subfamily Lirulariinae is not supported by the molecular data, but rather is incorporated into Umboniinae. We also demonstrate that the current concept of the subfamily Margaritinae (previously a trochid subfamily, but recently and provisionally assigned to Turbinidae) is not monophyletic. We provide preliminary evidence that whereas Margarella rosea (previously a member of Margaritinae) belongs in the trochid subfamily Cantharidinae, its presumptive congener M. antarctica is not a trochid, but instead clusters with the thysanodontine genus Carinastele. Based on the phylogenetic placement of C. kristelleae, we agree with previous proposals based on morphological data that Thysanodontinae are more closely related to Calliostomatidae than Trochidae. Both Calliostoma and Carinastele are carnivorous and if a sister relationship can be confirmed between Carinastele and Margarella antarctica it might mean that carnivory evolved twice in Trochoidea. The direction of dietary changes was not investigated in this study, but mapping diet onto the phylogeny suggests that true herbivory is predominantly a derived character. The new classification system also means that five trochid subfamilies are predominantly associated with hard substrata, one with soft substrata (Umboniinae) and two with algae and seagrass (Alcyninae and Cantharidinae). There has been a shift back to hard substrata in one umboniine clade. Two of three clades within Calliostomatidae were predominantly associated with hard substrata, but one Japanese clade is associated with sand. The finding of three new, unidentified species from very deep water means that Trochidae, like Calliostomatidae, now includes species found at bathyal depths. More deep-water species may be found as increased sampling leads to the discovery of new species.

Williams ST ，Donald KM ，Spencer HG ，Nakano T ... -  《-》

Molecular phylogeny suggests polyphyly of both the turban shells (family Turbinidae) and the superfamily Trochoidea (Mollusca: Vetigastropoda).

Williams ST ，Ozawa T 《MOLECULAR PHYLOGENETICS AND EVOLUTION》

The first molecular phylogeny of cladobranchian opisthobranchs (Mollusca, Gastropoda, Nudibranchia).

The first molecular phylogeny is presented for the highly diverse, opisthobranch molluscan Cladobranchia. This study, the most comprehensive for Cladobranchia to date, used new sequences of two mitochondrial and one nuclear genes for 95 specimens from 22 families and 38 genera with a species of Pleurobranchoidea as outgroup. Although our results do not resolve all the relationships within the Cladobranchia, there are significant findings that have implications for the systematics of the Cladobranchia. Cladobranchia represents a monophyletic group within the Nudibranchia with the exception of a clade containing species of Melibe. These species share a deletion of four codons in the COI gene that may account for their strong divergence from the remainder of the Cladobranchia. Bornellidae is the sister group to the rest of Cladobranchia, but this relationship is weakly supported. A series of well-supported clades within Cladobranchia show little structure as to their relationships to each other in the current analysis. The relationships of Tethys and Hancockidae to other Cladobranchia remain unresolved. Pseudobornella orientalis is here transferred to Dendronotus as D. orientalis. With this systematic change Bornellidae and Dendronotidae are now monophyletic. Lomanotus appears as the sister group to a monophyletic Aeolidida, but this relationship is not strongly supported. Scyllaeidae is monophyletic in this study with Scyllaea being sister taxon to Notobryon. The Proctonotidae are monophyletic and are clearly nested in the Cladobranchia. Dotoidae is monophyletic when Pinufius is included in this clade. Doriodomorpha is sister taxon to the Arminidae. Within Arminidae, Dermatobranchus and Armina, as they are presently constructed, are not monophyletic. There is an interesting potential sister group relationship between Dirona albolineata and Lemina millecra that requires additional exploration with expanded taxon sampling. In this study, Marianina rosea is nested within Tritoniidae, thus we consider Aranucidae, and its synonym Marianinidae, as a junior synonym of Tritoniidae to preserve the monophyly of Tritoniidae.

Pola M ，Gosliner TM 《-》

Phylogenetic relationships of Mediterranean and North-East Atlantic Cantharidinae and notes on Stomatellinae (Vetigastropoda: Trochidae).

The subfamily Cantharidinae Gray, 1857 (Trochoidea: Trochidae) includes 23 recognized genera and over 200 known living species. These marine top shell snails are microphagous grazers that generally live in shallow rocky shores and in macroalgae and seagrass beds of sub-tropical and temperate waters from the Central and Western Indo-Pacific biogeographic regions to the Mediterranean Sea and the Eastern Atlantic Ocean. Recent molecular phylogenetic studies revising the family Trochidae supported the monophyly of the subfamily Cantharidinae and its sister group relationship to the subfamily Stomatellinae. These studies and others has thus far mostly focused on Indo-Pacific members of the subfamily Cantharidinae whereas here, we investigated phylogenetic relationships among their counterparts from the Mediterranean Sea and the North-eastern (NE) Atlantic Ocean including 33 species of genera Gibbula, Jujubinus, Phorcus, Clelandella, and Callumbonella. The Mediterranean and NE Atlantic taxa were supplemented with 30 Indo-Pacific Cantharidinae species plus 19 members of the sister group subfamily Stomatellinae. Phylogenetic trees were constructed using Bayesian inference and maximum likelihood with two datasets comprised of partial sequences of four or six mitochondrial (cox1, rrnL, rrnS, and cob) and nuclear (28S rRNA and histone H3) genes. A clade comprised of all Mediterranean and NE Atlantic taxa was recovered with high support, but its sister group among the Indo-Pacific lineages could not be determined with confidence (although the assignment of "Trochus" kotschyi to Priotrochus could be rejected). Within the Mediterranean and NE Atlantic clade, genera Phorcus and Jujubinus were recovered as reciprocally monophyletic, and the deep-sea genera Clelandella and Callumbonella were placed with high support as sister to Jujubinus. However, the genus Gibbula as currently defined was not monophyletic and constituent species were divided into three major clades and two independent lineages. Phylogenetic relationships among Phorcus, Jujubinus (plus Clelandella and Callumbonella), and the different clades of Gibbula were not fully resolved but received higher support in the phylogenetic analyses based on six genes. A first approach to resolve phylogenetic relationships within Stomatellinae was conducted showing that the diversity of the subfamily is highly underestimated at present, and that Calliotrochus is possibly a member of this subfamily. A chronogram was reconstructed using an uncorrelated relaxed lognormal molecular clock and the origin of the Mediterranean and NE Atlantic clade was dated right after the Azolla phase in the Middle Eocene about 48 million years ago whereas diversification of major clades (genera) followed the eastern closure of the Tethys Ocean in the Middle Miocene about 14 million years ago.

Uribe JE ，Williams ST ，Templado J ，Buge B ，Zardoya R ... -  《-》

The phylogeny and taxonomy of austral monodontine topshells (Mollusca: Gastropoda: Trochidae), inferred from DNA sequences.

Donald KM ，Kennedy M ，Spencer HG 《MOLECULAR PHYLOGENETICS AND EVOLUTION》