DNA Barcoding and Species Delimitation for Dogfish Sharks Belonging to the Squalus Genus (Squaliformes: Squalidae)

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Ariza, Ailton A. ; Adachi, Aisni M. C. L. ; Roque, Pollyana ; Hazin, Fabio H., V ; Vianna, Marcelo ; Rotundo, Matheus M. ; Delpiani, Sergio M. ; de Astarloa, Juan M. Diaz ; Delpiani, Gabriela ; Oliveira, Claudio ; Foresti, Fausto ; Cruz, Vanessa P.

• Document type: Journal article
• Source: DIVERSITY-BASEL; v. 14, n. 7, p. 13-pg., 2022-07-01.

Abstract

The Squalus genus comprises a group of small demersal sharks occurring circumglobally, popularly known as dogfish sharks. This genus exhibits a conserved morphology, thus making correct morphological identification difficult. Considering these taxonomic problems and the scarcity of molecular data, the present study aimed to identify Squalus genus MOTUs, using DNA barcoding for species delimitation via ABGD (automatic barcode gap discovery), PTP (Poisson tree process), and GMYC (general mixed Yule coalescent) employing the mitochondrial COI gene. A total of 69 sequences were generated from samples obtained from the American coast in both the Atlantic and Pacific Oceans. The ABGD analysis was the most conservative among the three applied delimitations, indicating three taxonomic units, while the PTP analysis revealed nine MOTUs, with two conflicting units noted between S. clarkae + S. mitsukurii and S. albicaudus + S. cubensis. The GMYC analysis indicated an excessive division, with S. acanthias and S. mitsukurii subdivided into six MOTUs each and S. blainville, into four. These findings demonstrated that Squalus presents a complex of previously defined species, with misidentified samples deposited in databases leading to difficulties in analyzing the real distribution and diversity of species belonging to this genus. Thus, further efforts to highlight possible new species are recommended. (AU)

• FAPESP's process: 14/26508-3 - Phylogeny of the hyperdiverse order Characiformes (Teleostei: Ostariophysi) using ultraconserved elements
• Grantee: Claudio de Oliveira
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 18/20610-1 - Study of the biogeography of the Brazilian coast using data population genetic data of marine catfish of the genera Cathorops and Genidens
• Grantee: Claudio de Oliveira
• Support Opportunities: Regular Research Grants
• FAPESP's process: 16/09204-6 - Biodiversity and Biogeography in marine-estuarine fishes (Teleostei) from Brazil
• Grantee: Claudio de Oliveira
• Support Opportunities: Regular Research Grants