Identification des deux espèces jumelles Beryx mollis Abe 1959 et B. splendens Lowe 1834, à l'aide de caractères morphologiques et méristiques simples

Abstract : Identification of two sibling species of alfonsino, Beryx mollis Abe 1959 and B. splendens Lowe 1834, using simple morphological and meristic measurements - Two sibling species, Beryx mollis and B. splendens, are potentially the main fish species of commercial interest for a bottom-line fishery in the deep waters of New Caledonia's EEZ. Two datasets, morphological and meristic (one from Japan, the other one from New Caledonia) were obtained from specimen samples of the two species, which were species-identified by either the number of pyloric caeca (which allows total discrimination of the two species), or DNA markers, or a posteriori by the outcome of principal component analysis (PCA). Four morphological variables were measured (body height, head length, snout length, orbit diameter) and transformed to take standard length into account. None of these morphological variables, either single or combined to another, allowed sufficient discrimination between the two species. PCA on the four morphological variables led to a slightly better result, but still insufficient. Six meristic variables were utilized (numbers of soft rays in the dorsal, pectoral, pelvic, and anal fins, number of branchiospines on the lower half of the first branchial arch, number of scales on the lateral line). All these variables except the number of scales on the lateral line, proved useful to statistically distinguish the two species. However, none was diagnostic when taken separately from the other variables and the combination of two variables was only slightly better for this purpose. Canonical discriminant analysis helped determine which meristic characters could be used in priority to identify individuals: these were the numbers of soft rays on the dorsal, pectoral, and pelvic fins, and the number of branchiospines. In practice, if the fish is disembowelled or filetted, it takes only counting the number of pyloric caeca for identification to species. If the fish is preserved whole before being marketed, then we recommend to count the numbers of soft rays on the dorsal, pectoral, and pelvic fins for a reasonably reliable identification
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Philippe Borsa, Seiji Akimoto, Aude Pasco, Manina Tehei, Shugo Watabe. Identification des deux espèces jumelles Beryx mollis Abe 1959 et B. splendens Lowe 1834, à l'aide de caractères morphologiques et méristiques simples. 2011. ⟨ird-00798612⟩

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