Occurrence of Octopus insularis Leite and Haimovici, 2008 in the Tropical Northwestern Atlantic and implications of species misidentification to octopus fisheries management

Abstract

The genus Octopus has been treated as a “catch all” taxon because many species have morphological similarities. To investigate the taxonomic status of the Octopus species in the Tropical Northwestern Atlantic (TNA) and the Tropical Southwestern Atlantic (TSA), we sampled Octopus insularis Leite and Haimovici, 2008 in three areas of the northeastern Brazilian coast, four Brazilian oceanic islands and one island in Western Caribbean, Mexico. Samples of Octopus maya Voss and Solís, 1966 were obtained from the cultivation center of the Universidad Nacional Autónoma de México (UNAM) in Sisal city. Specimens previously identified as Octopus vulgaris Cuvier, 1797 were collected in two regions of southeast Brazil, in an industrial port in Progreso city (southern Gulf of Mexico) and from a fish market in Isla Mujeres, Mexico (Western Caribbean). Molecular species attribution was completed based on morphology of fresh specimens identified by an octopus specialist and then checked against previous identification (cultivation center and GenBank sequences). Molecular analysis of both mitochondrial (cytochrome oxidase I) and nuclear genes (elongation factor-1α), including GenBank data, confirmed that one specimen collected at the Western Caribbean from Mexico and identified as O. insularis, shared the same haplotype of the species from the type locality, indicating the occurrence of this species in the Caribbean Sea. Phylogenetic analyses indicated that 21 GenBank sequences from TNA identified as O. vulgaris grouped within the O. insularis clade and are most likely to be to the latter species. The COI analysis also showed that 18 individuals collected in fishing landings and fish markets, previously identified as O. vulgaris, had the identical haplotype of O. maya collected in the UNAM cultivation center. These results corroborate the misidentification of species in Mexican fisheries. Based on molecular and morphological data we extended the distribution of O. insularis to the TNA and revealed cases of misidentification among the most commercially exploited octopus species in this region.