HEMICYTHERINAE SUBFAMILY (OSTRACODA, CRUSTACEA) AND ITS SPECIES IN PARATETHYS BRACKISH-WATER FACIESES (NEOGENE, CARPATHIAN AREAS). THEIR MORPHOLOGY AND TAXONOMY

摘要

This paper summarizes some of the problems, points of view and results of a series of studies on the phylogenetic and environmental events of Upper Neogene Ostracoda from Carpathian areas, mainly from the Meotian and the Pannonian-Pontian interval of time, focussed on Hemicytheria group. Why it and why here? Both stages are full of Hemicytheria species, more than 25 species within Meotian sediments and about 20 species within Pannonian-Pontian sediments. During Pontic Cycle (Pontian and Dacian), Hemicytheria, inexplicable dissapeared from game, being substituted by Tyrrhenocythere (in fact, another kind of Hemicytheria). After the end of the Sarmatian cycle of faunas, appeared and exuberantly developped two types of ostracode-fauna, one in Pannonian area and another contemporary of it, in Dacian basin. The first is so-called "Congerian Beds" or Pannonian stage, the second is the Meotian stage, both covered by Pontian sediments. In other words, two bioprovinces more or less separated one from each other. The species are completely different and yet there are no little homologous processes, similarities in the morphological elements, suggesting both the same origins, but similar tendencies of modifications. Through studies of the gradual or stepped apparition of new forms (as paleontological taxa), accepting of single adaptative directions along the time, would be recognized a causally interrelated ecological condition (in the case of accepting as the cause of the directional changes, the ecological determinism).%Genul Hemicytheria este un tip morfologic plasat pe linia de curent Pokorniella-Mutilus (Aurila)-Hemicytheria-Tyrrhenocythere, acoperind un uriaş interval temporal (Eocen-Recent). Prima specie „autentică" a genului este Hemicytheria omphalodes omphalodes (Reuss) din Badenianul mediu (am găsit-o la Coştei, în Badenianul mediu). Ea se transformă în timp oferind o succesiune graduală, lipsită de sincope. Astfel, în Sarmaţian se desprind speciile „sarmatica" şi "loerenthey", ambele regăsite şi în post-Sarmaţianul arealului pannonic. Urmează o adevărată „explozie" morfologică în timpul Pannonian-Ponţianului (din Bazinul Pannonic) şi în timpul Meoţianului (din Bazinul Dacic). Deşi speciile sunt diferite, procesul în sine este considerat un factor de corelare între aceste bioprovincii. Aproape 20 de specii în primul şi cam tot atâtea în al doilea. Aici însă gradul de dispersie morfologică atinge parametrii de gen (Drobetiella, Severinella, Heterocythereis în Meoţianul inferior, Getocytheria, Hemicytheria s str., în Meoţianul superior).