Traditional Taxonomic Groupings Mask Evolutionary History: A Molecular Phylogeny and New Classification of the Chromodorid Nudibranchs

Chromodorid nudibranchs (16 genera, 300+ species) are beautiful, brightly colored sea slugs found primarily in tropical coral reef habitats and subtropical coastal waters. The chromodorids are the most speciose family of opisthobranchs and one of the most diverse heterobranch clades. Chromodorids have the potential to be a model group with which to study diversification, color pattern evolution, are important source organisms in natural products chemistry and represent a stunning and widely compelling example of marine biodiversity. Here, we present the most complete molecular phylogeny of the chromodorid nudibranchs to date, with a broad sample of 244 specimens (142 new), representing 157 (106 new) chromodorid species, four actinocylcid species and four additional dorid species utilizing two mitochondrial markers (16s and COI). We confirmed the monophyly of the Chromodorididae and its sister group relationship with the Actinocyclidae. We were also able to, for the first time, test generic monophyly by including more than one member of all 14 of the non-monotypic chromodorid genera. Every one of these 14 traditional chromodorid genera are either non-monophyletic, or render another genus paraphyletic. Additionally, both the monotypic genera Verconia and Diversidoris are nested within clades. Based on data shown here, there are three individual species and five clades limited to the eastern Pacific and Atlantic Oceans (or just one of these ocean regions), while the majority of chromodorid clades and species are strictly Indo-Pacific in distribution. We present a new classification of the chromodorid nudibranchs. We use molecular data to untangle evolutionary relationships and retain a historical connection to traditional systematics by using generic names attached to type species as clade names

First evaluation of the cookie-cutter sharks (Isistius sp.) predation pattern on different cetacean species in Martinique

International audienceCookie-cutter sharks (Isistius sp.) are small squaloid sharks that live in tropical and sub-tropical oceans. Their name comes from their unique tactic of feeding, which enables them to parasitize marine mega-fauna, like cetaceans. Due to their morphological and anatomical characteristics, they are responsible of crater-like wounds on the skin of marine mammals. Little is known on Isistius sp. around the globe especially in Martinique, which represents a potential habitat. The main goal of this study was to assess the impact of cookie-cutter sharks on cetaceans by determining (1) seasonal changes in the occurrence of bites, (2) intra- and interspecific differences in frequencies and locations of bites among the different species of cetaceans, and (3) link behavior patterns of both cookie-cutter sharks and cetaceans. Data were collected from a 3-year photo-identification database of Cetaceans in Caribbean coast of Martinique. 431 wounds of various stages on 396 individuals from nine species of marine mammals were recorded. Results did not show any significant variation in the occurrence of wounds between seasons. Intermediate state was more important, most injuries were observed on the SCF (Superior Central Flank) (62.40%) and in a lesser extent on young individuals (3.25%). The predation of cookie-cutter sharks on different cetacean species has been confirmed consistently in Martinique. Further studies are required with both scientists and fishermen to better understand their specific role in this marine ecosystem