Taxonomic harmonization of Neogene and Quaternary candonid genera (Crustacea, Ostracoda) of the Paratethys

摘要

During the Cenozoic, the constant northward movement of the African plate led to the division of the Tethys Ocean into two: the Palaeomediterranean and the Paratethyan branches. The latter was represented by a huge epicontinental sea and brackish to freshwater lakes that extended across central Europe and western Asia. Neogene and Quaternary ostracods from the Paratethys originated through major adaptive radiations, which gave rise to endemic brackish taxa. Unfortunately, much confusion surrounds their taxonomy, due to the quality of descriptions and images in the original literature and the incompleteness of the type material, making necessary a taxonomic revision. In this paper, we propose a systematic revision of several Paratethyan endemic candonid genera based on the analysis of the type material, new material collected from the type localities, and new fossil material from the Ponto-Caspian area. The study focuses on the description of the valve morphology and particularly on the geometric morphometric analysis of the valve outline. Thirty-three genera were taken into account of which four (Advenocypris, Candoniella, Graviacypris, Telekia) were considered to be junior synonyms of Typhlocypris, Pseudocandona or Candona. Moesiella is considered a nomen nudum. In the case of Caspiollina, Dacicandona, Liventalina and Turkmenella the scarcity of material and/or the poor descriptions reported in the literature prevented us from performing a full revision. The monospecific genus Thaminocypris possibly includes a teratological form. The remaining 23 genera were merged into nine valid, endemic, genera (Bakunella, Camptocypria, Caspiocypris, Hastacandona, Lineocypris, Pontoniella, Propontoniella, Typhlocyprella and Zalanyiella). Emended diagnoses and descriptions are proposed for these genera and a new species, Bakunella anae sp. nov., is described. This study considerably reduces the taxonomic uncertainty within the Paratethyan candonids, providing new data for the evaluation of the palaeobiodiversity of the Paratethyan domain. Finally, the palaeobiogeography of Paratethyan candonids during the Neogene and Quaternary is also discussed.