World Congress of Malacology Antwerp ... - Unitas Malacologica

Although the Indo-Pacific has been regarded as a single biogeographic unit there is increasing
evidence that this is not the case and that within the Indian Ocean there are distinct regional faunas;
Red Sea, Northern Arabian Sea, Gulf of Aden, Mascarenes, Bay of Bengal. Much debate remains
over the interpretation of geographical variation versus speciation but this will only be solved by
systematics research.
Current data suggests that species-richness does not reach that discovered in the Indo-west Pacific but
no similar surveys have been undertaken. Very little data is available for outer shelf and continental
margin zones but collections made by the RS “Meteor” in the Red Sea and Gulf of Aden indicate a
diverse and largely undescribed fauna.
The coralliophilines radiation: repeated dives into the deep?
Oliverio, Marco 1 ; Richter, Alexandra 1,2 ; Barco, Andrea 1 ; Modica, Maria Vittoria 1
1. Dipartimento di Biologia Animale e dell'Uomo, “La Sapienza” Rome University, Viale
dell'Università 32, I-00185 Roma, Italy,
Email: marco.oliverio@uniroma1.it, setteottavi@gmail.com, mariavittoria.modica@uniroma1.it
2. Laboratorio de Biología Marina, Departamento de Biología, Universidad Autónoma, Madrid,
España,
Email: alexandra@acett.org
Coralliophila and related genera (e.g. Babelomurex, Latiaxis, Leptoconchus and Quoyula) form a
highly diverse group of neogastropods of ca. 250 described species. They are distributed worldwide
in warm temperate and tropical oceans, and are traditionally grouped in at least 7-10 "genera" based
on their shell morphology. Coralliophilinae are known in the fossil record since at least the Middle
Eocene (ca 40 MYbp). All species with known ecology are symbionts (ecto or endobiotically) of
anthozoans (including sea-anemones, gorgonians and reef-building corals species), on which they
feed.
An extensive phylogenetic study based on two mitochondrial sequences (12S and 16S) and 58
anatomical characters is performed to uncover relationships of the Coralliophilinae within the family
Muricidae, and of a large representation of species within the subfamily. A close phylogenetic
relationships with the Rapaninae s.l. within Muricidae is confirmed. Yet, coralliophiline digestive
anatomy is strongly modified in relation to their feeding habit, and other anatomical traits are unique
within Neogastropoda having evolved broodcare and protandry.
Two main lineages are highlighted in our analyses. At least two of the main “genera” of traditional
taxonomy, namely Coralliophila and Babelomurex, are evidently polyphyletic. Relationships among
the species emerging from both datasets (molecular and anatomical, analysed separately and
combined) are surprisingly in contrast with most of the traditional taxonomic arrangements.
Coralliophiline diversity is presently higher in deep waters (>100 m depth: 65-85% of the species)
than in shallow waters. Along with the phylogenetic patterns depicted here, this seems to indicate that
coralliophiline radiation probably started in shallow waters, but has been more successful in deeper
environments. There is evidence that from a shallow water stem group, several colonization of deep
waters resulted in as many radiations in those habitat.
It will be interesting to analyse in parallel the vertical patterns of diversity in coralliophilines (and
other coral feeding gastropods) and in their anthozoans “hosts”. The lack of information on host
association for most deep water species has been so far a serious problem for these analyses, which
could be partly resolved by applying a sort of ecological DNA-barcoding of the gut contents.
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