Analysis of the morphological variation of Doryteuthis sanpaulensis (Cephalopoda: Loliginidae) in Argentinian and Brazilian coastal waters using geometric morphometrics techniques

BRAGA, RAMIRO; CRESPI-ABRIL, AUGUSTO CÉSAR; VAN DER MOLEN, SILVINA; RODRIGUES SILVEIRA BAINY, MARA CRISTIANE; ORTIZ, NICOLÁS

Marine Biodiversity

Springer

Lugar: Berlín; Año: 2017

1867-1616

Shape variation of individuals from three locations,two from Argentina and one from Brazil, was analysed by geometricmorphometrics techniques. Individuals were weighed,measured, sexed, assigned to a maturity stage and photographed.For the analysis, two landmark configurations were used: one ofnine landmarks (9L) and another of 25 landmarks (25L). Tovisualise shape variation, a principal component analysis(PCA) on Procrustes coordinates was conducted. The percentageof total shape variation explained by the 9L configurationwas 80.5% (PC1: 61% and PC2: 19.5%), while the percentagefor the 25L configuration was 76.4% (PC1: 54.8% and PC2:21.6%). Based on this, shape analyses were performed usingonly the 9L configuration. The PCA results indicated thatspecimens show a large overlap between the categories basedon sex and maturity stage. When location is considered, squidshape from São Sebastião and Rawson Port were very similar,while in Nuevo Gulf, the presence of two different morphologicalgroups were observed: one similar to São Sebastião andRawson Port, and the other with a morphology typical ofNuevo Gulf. Thus, two different morphotypes were defined:(i) morphotype of the continental shelf and (ii) morphotype typicalof the gulf. The continental shelf morphotype ischaracterised by larger fins and wider mantle than the gulfmorphotype. These results suggest that the morphotypes ofDoryteuthis sanpaulensis are adaptations to oceanographicregimens.