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 Matjasˇicˇ, 1956 and T. sg. Troglocaridella Babic´, 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.

COXI based phylogenetic analysis of Caucasian clade of European Troglocaris (Crustacea: Decapoda: Atyidae) with the suggestion of a new taxonomic group structure

“…Thus, the armature of the rostrum and the presence of supraorbital or suborbital teeth on the carapace could not be considered as morphological features of the generic level. Moreover, extreme variations of the length of the rostrum and supraorbital teeth within the genera Troglocaris and Xiphocaridinella and even populations of Troglocaris-related shrimps has been shown (Zakšek et al, 2007;Jugovic et al, 2010Jugovic et al, , 2011Jugovic et al, , 2012, even suggesting the theory of the influence of predators such as cave salamander Proteus anguinus Laurenti, 1768 (Amphibia: Caudata: Proteidae) (Jugovic et al, 2011). The obtained genetic data clearly support the monophylety of Xiphocaridinella and Troglocaris while Spelaeocaris represent a paraphyletic taxon (Fig.…”

Cave shrimps Troglocaris s. str. (Dormitzer, 1853), taxonomic revision and description of new taxa after phylogenetic and morphometric studies

“…Additionally, eye pigmentation, presence of supraorbital, antennal and pterygostomial spine, as well as presence of exopodites on pereopod V were considered. The descriptions, as well as the taxonomic decisions presented herein follow the results of discriminant function analysis (Jugovic et al 2011) conducted in accordance with Zakšek et al (2009: p. 933-934, Table 1; see also Appendix C) molecular analysis.…”

“…The phylogenetic framework published by Zakšek et al (2007Zakšek et al ( , 2009 provided a solid basis for the detailed morphometric studies (Jugovic et al, 2010a(Jugovic et al, , 2011. Only the adult animals were included in the analyses to exclude main sources of ontogenetic variation.…”

“…Only the adult animals were included in the analyses to exclude main sources of ontogenetic variation. Beside 71 metric also 17 meristic characters were recorded (all listed in Jugovic et al, 2011), describing body proportions and elaboration of cuticular structures. Additionally, eye pigmentation, presence of supraorbital, antennal and pterygostomial spine, as well as presence of exopodites on pereopod V were considered.…”

Wing pattern morphology of three closely related Melitaea (Lepidoptera, Nymphalidae) species reveals highly inaccurate external morphology-based species identification

“…Some taxa remain morphologically unidentifiable despite detailed morphometric analysis, hence a consideration of a large set of morphometric characters from different anatomical regions may greatly increase the chances of revealing taxonomic differences within seemingly cryptic or morphologically highly variable species (e.g. Jugovic et al 2011).…”