Focus on the Bramble Shark Echinorhinus brucus conservation status and first evaluation of possible sub-species presence

Abstract

The IUCN red list is constantly updated in relation to fishing pressure and climate change and new marine species are added to it. Despite conservation researchers are working hard to implement knowledge about them, the biology, ethology, reproduction, distribution or genetic structure of many species are still scattered. Echinorhinus brucus is a deep benthic shark evaluated as endangered species on which little information is available, particularly about its genetic variability. Echinorhinus brucus belongs to the Echinorhinidae family and its sister species is Echinorhinus cookei. The main morphological diagnostic character for these two species is the presence of denticles with different shape and pattern on derma. In 2014 in the Venezuelan Caribbean Sea, a shark identified as E. brucus by genetic markers presented intermediate denticles characteristics. Some COI sequences were downloaded from Bold System and five and four sequences attributed respectively to E. brucus and E. cookei. They were aligned with ClustalW and three phylogenetic analyses were conducted. The first one was a Maximum Likelihood analysis handled with default parameters, other two were Bayesian analyses handled respectively with relaxed and strict model. Apparently, Atlantic E. brucus sequences did not cluster with Indian E. brucus sequences and all analyses showed a similar topology, supported by high value nodes (more than 85%). On the contrary, Indian sequences clustered with E. cookei sequences and ML analysis shows a small distance between them. Our results confirm how still poorly known is the variability into E. brucus species and in Echinorhinidae family. In fact, despite the few individuals sequenced and only one genetic marker available, the evolutionary history of this group is controversial, suggesting that more data should be investigated for this species.