Native and non-native species of Litopenaeus Pérez-Farfante, 1969 (Crustacea: Penaeidae) from the East Atlantic: Geometric morphometrics as a tool for taxonomic discrimination.

Alex B De Moraes,Fúlvio A.M Freire,Daniele C.S De Moraes,Carlos Eduardo R.D Alencar

doi:10.1590/0001-3765202120200107

Abstract

The shape of the secondary sexual characters is, traditionally, used to discriminate the marine shrimps at the species level. However, the qualitative evaluation of structures that are morphologically variable in the taxonomy of species can favor misunderstandings and misidentifications. These possibilities of taxonomic inaccuracies are especially alarming when there is a need to evaluate the invasion of introduced species. The present study used geometric morphometric analyses to identify differences in the cephalothorax shape that would help discriminate the native and non-native species of Litopenaeus of the South American coast. The comparative morphology analysis was conducted using the right profile of adult males' cephalothorax of L. schmitti, captured in the natural environment, and L. vannamei captured in the natural environment or grown in shrimp farms. In intraspecific evaluation, it was not possible to distinguish the specimens of L. vannamei that were grown in shrimp farms from those acclimated to the natural environment. However, significant interspecific differences in shape were found in the shape of this body structure. Additionally, the base position of the first rostral spine to the tip of the hepatic spine is indicated as a characteristic that can be used to distinguish these two species by eye in the field.

Highlights

The species identification of many Penaeidae shrimps, within the same genus, is primarily characterized by the shape of the secondary sexual characters, due to their great anatomical diversity between the species and the tremendous morphological conservation of the other characters (Dall et al 1990, Lavery et al 2004, Pérez-Farfante & Kensley 1997)
The Canonical Variates Analysis (CVA) provided a visual display of the morphospace considering the two groups of L. vannamei and L. schmitti, with component 1 representing 92.31% of the total variance (Fig. 2)
The results of the CVA are reaffirmed by the Discriminant Function Analysis (DFA), which confirms both the statistical difference of shape between L. schmitti and L. vannamei, and the statistical similarity in shape between the groups of L. vannamei from the natural environment and cultivated in shrimp farms

Summary

Introduction

The species identification of many Penaeidae shrimps, within the same genus, is primarily characterized by the shape of the secondary sexual characters, due to their great anatomical diversity between the species and the tremendous morphological conservation of the other characters (Dall et al 1990, Lavery et al 2004, Pérez-Farfante & Kensley 1997). These structures are easy to visualize and to distinguish interspecifically, they may be variable within species, since their shape changes along the ontogenetic development There are numerous escape cases, the population status of L. vannamei in the natural environment in the Atlantic coastline of South America is still uncertain

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