Discriminação de espécies do gênero Selene (Carangidae) da costa Nordeste do Brasil,utilizando técnicas de morfometria geométrica

Abstract

Species of the Carangidae family are important components of fish fauna during all phases of the life span. Both Selene spixii (full moon fish) Spix and Agassiz (1831) and Selene Vomer (Atlantic look down) Linnaeus (1758) range in the Western Atlantic Ocean from New Scotia (Canada) to South America including the Gulf of Mexico. They are found in coastal shallow waters, either on hard or sandy bottoms. They usually establish schoals, but are also observed in small groups or pairs. They feed on small crustaceans, shrimps, fish and worms. Their flesh tastes good; these species are trade fresh. They can also be reared, they are highly prized in sport fishing. Both species are very similar in early phases of their life cycle, which renders the identification at the species level quite difficult. The aim of the present study was to carry out analyses of the pattern of morphological differentiation between the above mentioned species of Selene genre, using as method 1, techniques of multivariate analysis of the 16 distances between landmarks, defined in the truss net; and as method 2, the relative warps analysis (thin plate spline function) on the coordinates of 9 landmarks. Morphometric data were obtained from scanner digitalized images and the coordinates of the landmarks by using tpsdigw program, the distances were obtained from a program developed in language C and the relative warps analysis from tpsRelw program. Similarities were discriminated between the studied species using both Principal Components Analysis, Canonic as well as Discriminant Analyses based on morphometric features. The landmarks usedwere: 1. tip of the nose, 2. base of pelvic fin, 3. beginning of the first dorsal fin, 4. beginning of anal fin, 5. beginning of the second dorsal fin, 6. end of anal fin, 7.end of the second dorsal fin, 8. beginning of lower caudal fin, 9. beginning of upper caudal fin. According to method 1, measures D 1-3 and D 3-4 were the most important whereas for method 2, among shape variations, the one which contributes the most was the component x.