介形类Denticulocythere和Potamocythere在柴达木盆地晚新生代地层中的发现——对区内Leucocythere属的再鉴定

DISCOVERY OF DENTICULOCYTHERE AND POTAMOCYTHERE(OSTRACODA)FROM THE QAIDAM BASIN,QINGHAI——REIDENTIFICATION OF LEUCOCYTHERE APPEARED IN THE AREA

本文对区内晚新生代地层中被归入Leucocythere属名下、以L.mirabilis为代表的所有已知种进行了重新审视,发现它们具有一个共同的特征:右壳铰合构造有发育良好的前铰齿。这一特征与以L.mirabilis为模式种的Leucocythere属的属征不一致。这些种的左壳铰棒呈现两种类型:一种具锯齿或刻痕,另一种则是光滑或近于光滑。前者与Denticulocythere的属征相符,后者则与Potamocythere的属征一致。以铰合构造的特点为主,结合壳体形态,对研究区内原定Leucocythere属名下各个种再次进行鉴定后,改划出Denticulocythere属两个已知种,两个亲近种,一个新种,Potamocythere属两个巳知种,一个新种。现存的资料表明,研究区及其毗邻地区内迄今并未发现有可靠Leucocythere产出的证据。Denticulocythere化石种的沉积环境水质以半咸水为主,Potamocythere化石种为淡水-半咸水。

After the revision of all the known species of the genus Leucocythere,occurred in the late Cenozoic strata from the Qaidam Basin（Qinghai）,their common character has been found：There are developed and often furcated anterior cardinal tooth on the right valves.It differs from the diagnosis of the genus Leucocythere.Among these species,two form of the intercardinal bar are present,one of them with crenulated or notched intercardinal bar,and the another one with the intercardinal bar really smooth.The former are allocated to the genus Denticulocythere,with one new species and four species under new combination,while the latter are allocated to the genus Potamocythere,with one known species,one new species and one species of new combination.In the hinge of the type-species of Leucocythere（L.mirabilis Kaufmann）,the anterior cardinal tooth ＂weak or even hardly developed＂（Danielopol et al.,1990）.Up to now,no such tooth could be detected in the literature published by Chinese ostracodologist though some species were allocated to Leucocythere.It seems advisable to allocate these species to genera Denticulocythere or Potamocythere separably.Paleoenvironmental distribution of Denticulocythere and Potamocythere in Eurasia suggests that most Denticulocythere are brackish water species,while Potamocythere live in the fresh or brackish water.