Morphological differentiation in the cave shrimps Troglocaris (Crustacea: Decapoda: Atyidae) of the Dinaric karst - a consequence of geographical isolation or adaptation?

Abstract

Three Dinaric subgenera of cave shrimps from the genus Troglocaris s. l.: T. sg. Troglocaris Dormitzer, 1853 (= Troglocaris s. str.), T. sg. Spelaeocaris Matjašič, 1956 and T. sg. TroglocaridellaBabić, 1922 comprise 12 currently known species and phylogenetic lineages. On the basis of the results of previous molecular studies and the extensive morphometric analysis, appropriateness of several former and the existence of some new metric descriptors are examined by multivariate statistical methods. In discriminant function analyses (DFA), all subgenera are distinctly separated even when only sexually non-dimorphic characters are used. Since considerable number of these characters is acknowledged, a joined analysis of both sexes is proven to be appropriate for the identification of the subgenera. Characters for the species recognition of Spelaeocaris and Troglocaridella females are provided. In the subgenus Troglocaris s. str., molecularly recognized phylogroups are separated by DFA despite the expressed clinal variation. Also, minimum spanning tree (MST) demonstrates the existence of considerable morphological differences. The amounts of morphological difference (indicated by the length of the MST lines) and genetic difference are concordant i.e. morphological differences among the subgenera exceed the ones within the subgenera. © 2011 Blackwell Verlag GmbH.