Phylogenetic Diversity of Cephalopoda (Animalia:Mollusca) Along the Saudi Arabian Red Sea Coastline

Abstract

Although the Red Sea presents a unique environment with high temperature and salinity, it remains an area that is understudied. This lack of information is reflected in many areas, one which is biodiversity. Despite increasing work on biodiversity throughout the Red Sea and an increase in Cephalopoda studies, Cephalopoda in the Red Sea remain underrepresented, which is especially pronounced in molecular analyses. Members of the class Cephalopoda are considered to be major contributors to coral reef ecosystems, serving as part of the food chain and exhibiting population increases due to targeted teleost fisheries and global climate change. In order to assess the biodiversity of Cephalopoda in the Saudi Arabian Red Sea, 87 specimens were collected from 25 reef locations between 17°N and 28°N latitude, as well as from the largest fish market in the Kingdom of Saudi Arabia. Taxonomic identification of specimens was determined using morphological comparisons with previously reported species in the Red Sea and the molecular barcoding region Cytochrome Oxidase I. 84 Red Sea sequences were compared with sequences from GenBank and analyzed using a complement of Neighbor-Joining, Maximum-Likelihood, and Bayesian inference trees. Species complexes were also investigated for Sepia pharaonis and Sepioteuthis lessoniana, which had been previously reported. From 17 cuttlefish, our study yielded three species, two of which matched previously reported species in GenBank. In addition, two distinct clades of Sepia pharaonis were identified. Of 35 squid collected, four species were identified, one of which did not match any other accepted species in literature, while Sepioteuthis lessoniana in the Red Sea formed a distinct clade. From 30 different specimens a total of five genera of Octopoda were present, forming six distinct species. Five Octopoda species collected did not match previously reported species, although many specimens were paralarvae or juveniles, so morphologically we could not compare to previously described species in the Red Sea. Cephalopoda fisheries in the Red Sea is low, and as their populations increase worldwide, this could be a viable fishery for Saudi Arabia. As such, further investigation into the role which cephalopods play in supporting biodiversity in the Red Sea is essential.