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Morphometry of the shell in Scaphopoda (Mollusca): a tool for the discrimination of taxa

Published online by Cambridge University Press:  29 December 2020

Leonardo Santos de Souza*
Affiliation:
Departamento de Invertebrados, Museu Nacional, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
Carlos Henrique Soares Caetano
Affiliation:
Laboratório de Zoologia de Invertebrados Marinhos, Departamento de Zoologia, Instituto de Biociências, Universidade Federal do Estado do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
*
Author for correspondence: Leonardo Santos de Souza, E-mail: leosouza2301@gmail.com

Abstract

The alpha taxonomy of scaphopods is based mainly on the shell morphology, as it is for most molluscs. In the last three decades, the employment of morphometric variables of the shell in combination with statistics has considerably increased to aid species discrimination, but this has not been used above species level. In this study, a traditional morphometric approach was used to distinguish congeners, genera and families within the orders Dentallida and Gadilida. We studied 28 species of scaphopods from Brazil, belonging to 12 genera and five families. Twelve morphometric variables were measured, and a correlation test was done to select a set of variables without correlation as input data to perform a discriminant analysis. In the analysis of congeners, the discrimination power was high in both orders. Among the genera studied, the robustness of the analysis was drastically reduced in Dentaliida, while Gadilida maintained a high percentage of correct classifications. At the family level, both orders presented high percentages of correct classification, but the imbalance of cases for each taxon masks an inconsistent result. Based on our results, the morphometric approach was a useful tool to discriminate congeneric species of both orders and to discriminate the genera of Gadilida.

Type
Research Article
Copyright
Copyright © The Author(s), 2020. Published by Cambridge University Press on behalf of Marine Biological Association of the United Kingdom

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