DNA barcoding of the western South Atlantic deep-sea fishes (Actinopterygii:Teleostei)

• Autor(a) principal: Caixeta, Heloísa De Cia
• Data de Publicação: 2023
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: https://www.teses.usp.br/teses/disponiveis/21/21134/tde-28022024-132939/
• topic: Brazilian Exclusive Economic Zone; citocromo c oxidase I; citocromo c oxidase I; deep-sea diversity; delimitação de espécies; diversidade de oceano profundo; species delimitation; taxonomia; taxonomy; Zona Econômica Exclusiva Brasileira

The deep sea is the largest and most extreme ecosystem on Earth, and harbors approximately 15% of all fishes which have a variety of adaptations to extreme conditions of incipient or absent light, high hydrostatic pressure, low temperatures, among other biotic and abiotic factors. The difficulty to obtain samples makes there exist large geographical gaps and several groups still lacking extensive taxonomic revisions. During the DEEP-OCEAN project, two oceanographic cruises were conducted aboard the N/Oc Alpha Crucis to collect deep-sea fish between 250 and 1,520 m on the continental slope of Southern and Southeastern Brazil, including 1,400 tissue samples for molecular analysis of bony fish (Actinopterygii). Thus, it became possible to use the molecular tool of DNA barcoding for the identification of deep-sea fishes of the western South Atlantic. DNA extraction was performed using extraction kits and fragments of the cytochrome c oxidase I gene were amplified using universal primers. The products were sequenced bidirectionally, and the sequences were compared with sequences available in digital databases, confronting the morphological identification performed in the laboratory. Phylogenetic trees of maximum likelihood and bayesian were constructed using the RAxML and MrBayes software, respectively. To access the diversity of deep-sea fishes in the region were calculated the species richness, alpha and beta phylogenetic diversity between the depth range. A total of 144 sequences of 82 species belonging to 41 families and 18 orders were generated, including a species insertae sedis in Epercaria. The results contributed to the first available sequences of 15 species, for the western South Atlantic of 29 species, South Atlantic of 16 species and for the Atlantic the first sequences of 12 species. A new species of Polymixia (Polymixiidae: Polymixiiformes) was identified, presented here, in addition to three putative new species of the genera Bassozetus (Ophidiidae: Ophidiiformes), Aristostomias e Photonectes (Stomiidae: Stomiiformes), under investigation. Additionally, the new occurrences of Coryphaenoides subserrulatus Makushok, 1976 in the Brazilian Exclusive Economic Zone and of Coryphaenoides striaturus Barnard, 1925 (Macrouridae: Gadiformes) in the Atlantic were recorded. Intermediate depths presented both a high species richness and a high phylogenetic diversity, observed by three peaks of diversity according to the increase in depth, beiging with 400500 m, followed by 700800, and 9001,000 m. The greatest diversity of fish was found between 9001,000 m deep, composed mainly by pelagic stomiiforms and the benthopelagic gadiforms and anguilliforms. The DNA barcoding revealed a high diversity of deep-sea fish for the western South Atlantic, possible new species and synonyms and new occurrences; as well as indicated a high phylogenetic diversity around 1,000 m deep.