Contribution
Systematic revision of the Caucasigenini (Gastropoda: Hygromiidae) from the Caucasus region
Walther, Frank; Neiber, Marco T.; Hausdorf, Bernhard
Archiv für Molluskenkunde International Journal of Malacology Band 147 Heft 1 (2018), p. 129 - 169
98 références bibliographiques
publié: Jun 29, 2018
publication en ligne: Jun 29, 2018
DOI: 10.1127/arch.moll/147/129-169
Open Access (article peut être télechargé gratuitement)
Abstract
The species systematics of the tribe Caucasigenini (Gastropoda: Hygromiidae) from the Caucasus region is revised based on recently collected specimens as well as material from all major research collections. Shells and genitalia of the 14 species assigned to the genera Caucasigena, Anoplitella, Hygrohelicopsis, Diodontella, Dioscuria, Teberdinia, and Lazicana are described and figured. Caucasigena armeniaca, C. rengarteni, C. schileykoi and the form from the Fiagdon valley labelled erroneously as C. tschetschenica, are classified as subspecies of C. eichwaldi because transitional forms among these taxa exist. Anoplitella antonwagneri is separated from A. schaposchnikovi as a distinct species. Diodontella nubigena is placed in the synonymy of D. stschukini, and Kokotschashvilia eberhardi as well as K. tanta are placed in the synonymy of Lazicana suanetica. Lazicana makvalae, Dioscuria thalestris, Dioscuria abchasica, Dioscuria caucasicola, Dioscuria prometheus, Teberdinia flavolimbata, and T. phaeolaema are confirmed as distinct. The anatomy of Dioscuria prometheus is described for the first time. The name Helix thalestris is fixed by the designation of a neotype for the taxon for which it is in current usage. The geographic ranges of the species are summarized based on a comprehensive compilation of locality records and illustrated in distribution maps. The morphological variability of the Caucasigenini species corresponds to their phylogenetic patterns. The Fruticocampylaea species are separated by long branches, probably caused by bottlenecks as a result of the Pleistocene ice ages, and diversified only recently. This is reflected in little intraspecific morphological variation. In contrast, Circassina, Caucasigena, and Lazicana show a continuous branching pattern, and the greater diversity of genetic lineages in these groups is reflected by more extensive intraspecific morphological variability. The contrast between the patterns found in Fruticocampylaea versus Circassina, Caucasigena and Lazicana demonstrates the importance of extinction in the speciation process. The differentiation of Fruticocampylaea into sharply delimited species was not an adaptive radiation into different niches, but was initiated by the extinction of intermediate populations. Such non-adaptive radiations are more likely in organisms with limited dispersal abilities, whereas ecological differentiation might play a more important role in the speciation of organisms with better dispersal abilities.
Mots-clefs
Russia • Georgia • Azerbaijan • Armenia • biogeography • taxonomy