First molecular approach to the octopus fauna from the southern Caribbean

Abstract

The octopus fauna from the southern Caribbean is an understudied field. However, recent taxonomic work in the Colombian Caribbean has led to the discovery of several new species in the family Octopodidae. To provide molecular evidence for recent descriptions in the area (i.e., Octopus taganga, O. tayrona and Macrotritopus beatrixi) and contribute to the systematics of the family, we reconstructed the first molecular phylogenies of the family including Colombian Caribbean octopus species. Using cytochrome c oxidase subunit I and rhodopsin sequences from specimens collected in three sites (Santa Marta, Old Providence and San Andrés Islands) we inferred maximum-likelihood trees and delimited species with PTP. Our mitochondrial analysis supported the monophyly of species found in the area (i.e., O. taganga, O. hummelincki and O. briareus). The genetic distinction of the species O. tayrona and O. insularis was not resolved, as these were found in one clade together with Caribbean O. vulgaris and O. aff. tayrona species (O. spB) and delimited as a single species. Additionally, our results suggest a distant relationship of the Type I O. vulgaris group (Caribbean region) from the other forms of the species complex (Old World and Brazil). Lastly, the third newly described species M. beatrixi emerged as an independent lineage and was delimited as a single species. However, its relationship to other species of its genus remains unknown due to the lack of sequences in databases. Altogether, our molecular approach to the octopus fauna from the southern Caribbean adds on information to the relationship of Octopodidae species world-wide by providing sequences from recently described species from an understudied region. Further studies employing higher taxon sampling and more molecular information are needed to fill taxonomic gaps in the area and account for single-locus resolution on the systematics of this group.

Traditional Knowledge Aids Description When Resolving the Taxonomic Status of Unsettled Species Using Classical and Molecular Taxonomy: The Case of the Shallow-Water Octopus Callistoctopus furvus (Gould, 1852) From the Western Atlantic Ocean

“…On the continental scale, combining genetic studies in southern Caribbean (Ritschard et al, 2019) and northeastern Brazil (Lima et al, 2020 and our results), plus published occurrences in the western Atlantic (Hanlon, 1988;Voss and Toll, 1998;Cedillo-Robles and Pliego-Cardenas, 2018;Flores-Valle et al, 2018) results in a broad, cross-hemisphere distribution range for the species on the western Atlantic Ocean, including the Caribbean Sea (∼19 • N-28 • S). However, Schwartz (1992) reported the occurrence of "Octopus macropus" off North Carolina (34 • N; United States), implying that C. furvus northernmost range limit may extend farther north than the Gulf of Mexico (Figure 1).…”

“…Accounts of Callistoctopus reported by SCUBA divers and spearfishers alike are relatively rare along the entire studied area, which may be due to the shallow-water and nocturnal habits of these octopuses (Norman, 2000), as both recreational and professional/fishing dives are often conducted during daylight hours in deeper (>10 m) waters. The same is true for northwestern Atlantic records, as published accounts invariably describe C. furvus as a shallow-water species (e.g., Ritschard et al, 2019).…”

“…The taxonomic status of the western Atlantic Callistoctopus has long been problematic and, along with C. furvus, at least two other described species [i.e., Callistoctopus bermudensis (Hoyle, 1885) and Callistoctopus chromatus (Heilprin, 1888)] were initially recognized in the region but later synonymized within C. macropus (Voss and Toll, 1998). However, earlier authors did not have access to modern multivariate statistics and molecular tools that allowed us to recognize C. furvus as a valid species distinct from C. macropus, a conclusion also supported by genetic studies of tropical western Atlantic shallowwater octopus fauna recently conducted by Ritschard et al (2019) and Lima et al (2020).…”

“…Two newer lots (one from the same region and another from Fernando de Noronha Island) were deposited at the University of Rio Grande Oceanographic Museum (Leite and Haimovici, 2006). Leite et al (2008) urged a critical revision on the taxonomic status of "Brazilian" C. macropus, and recent genetic analysis suggest that the western Atlantic Callistoctopus is distinct form C. macropus stricto sensu (Ritschard et al, 2019;Lima et al, 2020).…”

“…During recent morphological and genetic studies on shallowwater octopuses off the Mexican and Colombian Caribbean coasts, samples representing this genus have been variably named as C. cf. macropus (Flores-Valle et al, 2018), C. furvus (Cedillo-Robles and Pliego-Cardenas, 2018), or as an undefined species of Callistoctopus requiring description (Ritschard et al, 2019).…”