DNA Barcoding Southwestern Atlantic skates: assessing its effectiveness for species identification and highlighting cryptic species.

MABRAGAÑA E.; GABBANELLI, V.; VAZQUEZ, D. M.; DELPIANI, S. M; JURADO, C.; HANNER, R; DÍAZ DE ASTARLOA J. M.

Conferencia; Sharks International Conference; 2018

Skates are a common component of the demersal sh community along the South American continentalshelf and slope, and have become a concernbecause of the considerable and increasing catchesin recent decades due to international demand. eskate fauna in the Southwest Atlantic (34°-55°S) isrepresented by ~30 species grouped in two families,Arhynchobatidae and Rajidae. Several species shareexternal characters, especially when juvenile, thatmay lead to misidenti cation and therefore sherystatistics may be error-prone or de cient. In thissense, molecular approach may be a complementaryuseful tool for helping in both, species identi cationand flagging of potential cryptic species. In thisstudy, we explore on the use of DNA barcoding todiscriminate skates species from the SouthwestAtlantic (SWA) Ocean. We also compile our resultsplacing them into a comparative framework withother studies to provide a comprehensive reviewof available barcodes for SWA skates. A total of 208specimens belonging to 22 di erent species fromfamilies Arhynchobatidae and Rajidae were successfullybarcoded in our survey. e Kimura 2-parametergenetic distances averaged 0.19% withinspecies and 3.65% within genera. Nearly all speciesexhibit unique barcodes or clusters of closely relatedhaplotypes, showing a strong concordance betweenmorphological identification and COI sequencesclustering. The only exception were samples ofPsammobatis normani and P. rudis, which sequencescould not be separated each other. However, the useof nucleotic diagnostic character (NDC) allowedus to discriminate them. Character-based analysisalso showed that species were clustered in two mainclades corresponding to the families Arhynchobatidaeand Rajidae according to current classi cationscheme. Compiling our results with available dataon the Barcode of Life Data System, about 27 speciesinhabiting SWA have barcodes, representing 90 %of the species occurring in the area. Some speciesexhibited low interspecific divergence, which isre ected in the Barcode Index Number analysis: aconservative approach that clusters sequences datainto Operational Taxonomic Units called BINs. Indeed,some species were assigned to the same BIN.However, these species do not shared haplotypesand presented unique NDC that allow to di erentiatethem. Finally, the presence of two di erent BINsfor the same nominal species, highlights a potentialcryptic skate in the SWA.