A molecular framework for the phylogeny of Coralliophila and related muricoids

Coralliophilid gastropods include a large number of described species, grouped in at least seven to 10 ‘genera’ according to their shell morphology. They are considered closely related to Muricidae and ranked as a family on its own or as a subfamily of muricids. Their phylogenetic position and relationships are still not defined. The little anatomical work so far done on this group seems to indicate a relatively high level of homogeneity, at least in the alimentary system. There is a need for an independent phylogenetic framework to understand their position and relationship within the muricoideans, and their internal systematics and phylogeny. We have addressed this problem by means of parsimony analysis of 609 aligned positions of the sequences coding for the 12S rDNA. Four coralliophilid sequences representing the same number of commonly recognized lineages (Babelomurex, Latiaxis, Coralliophila, Galeropsis � Quoyula) were analysed, along with three sequences of muricoid genera (Stramonita, Phyllonotus, Nucella) representing as many subfamilies of Muricidae, plus the sequence of the buccinoidean Fasciolaria as outgroup. Maximum parsimony and neighbour-joining analysis of the dataset, with increasing weighing of transversions versus transitions, yielded similar topologies. Two major outcomes resulted from the analyses: first, the coralliophilid sequences included herein are always monophyletic, with very high bootstrap support in all analyses. This is in agreement with the few anatomical data gathered so far that suggest coralliophilids are relatively homogeneous. Secondly, the sister-group of the coralliophilids among the analysed sequences is represented by Stramonita, with high bootstrap support in all analyses. This is in a good agreement with previous molecular analyses and with the morphological evidence that Rapaninae are the closest sister group of coralliophilids. According to the present results, the rank of the coralliophilids should be the same as Rapaninae, therefore a subfamilial status (Coralliophilinae) seems reasonable.