Hydrobiologia 382: 175–181, 1998. © 1998 Kluwer Academic Publishers. Printed in the Netherlands. 175 Two new species of Keratella (Rotifera: Monogononta: Brachionidae) from Inner Mongolia, P.R. China Hendrik Segers 1 & Su Rong 2 1 Laboratory for Animal Ecology, Zoogeography and Nature Conservation, Department of Biology, University of Ghent, K.L. Ledeganckstraat 35, B-9000 Gent, Belgium; 2 Fisheries Research Institute of Inner Mongolia, 010031 Huhehot Shi Xi Lu, Inner Mongolia, P.R. China Received 3 February 1998; in revised form 8 September 1998; accepted 8 September 1998 Key words: Keratella new species, taxonomy, Rotifera, zoogeography Abstract Two new morphospecies of Keratella Bory de St. Vincent (Rotifera: Brachionidae) are described from Inner Mongolia, P.R. China. Keratella mongolianum n. sp. is related to K. cruciformis and K. eichwaldi, while Keratella zhugeae n. sp. belongs to the K. quadrata group. K. mongolianum n.sp. is known from a single locality only, but K. zhugeae n.sp. was found in several ponds and had previously been recorded from Tibet. Both taxa are restricted to the eastern Palaearctic region. Introduction The genus Keratella Bory de St. Vincent, 1822 of Brachionidae is a genus with a predominantly tem- perate distribution (Dumont, 1983; Pejler, 1977), and contains a relatively large number of species with a restricted geographic distribution. Until recently, no species were known to be endemic to the North-East Palaearctic region, which was remarkable considering most other zoogeographical regions.The first descrip- tions of endemic Keratella from the region are very recent (Segers & Wang, 1997; Zhuge & Huang; 1997, in press). During a survey of the Brachionidae of Inner Mon- golian waters (Rong et al., 1998), we came across populations of two unnamed Keratella species. These constitute a significant addition to the record of en- demic Rotifera for the region, and are herein described and named. Material and methods Specimens were picked under a Wild M5 dissec- tion microscope, and examined and drawn under a Olympus CH2 compound microscope with a draw- ing tube. Scanning Electron Microscopy (SEM) was performed using a JEOL-JSM 840 microscope, on critical-point dried and gold-coated specimens or on trophi processed following Segers & Dumont (1993) and Segers (1993). Type specimens are in permanent glycerine slides. Repositories are abbreviated as fol- lows: FRIIM: Fisheries Research Institute of Inner Mongolia; KBIN: Royal Belgian Institute for Nat- ural Sciences; UA: Department of Biology, University of Antwerp, Belgium; UG: Department of Biology, University of Ghent, Belgium. All measurements are in μm. Keratella mongolianum new species (Figures 1–3) Material examined Holotype (in KBIN, reg. nr. IG 28555 RIR 96), three slides with one paratype (one in FRIIM, one in KBIN (RIR 97), one in UA), two slides with three paratypes (one in KBIN (RIR 98), one in UG). Type locality Haidaihaga, Xingan Meng, Inner Mongolia, P.R. China (45 ◦ 41 ′ N, 121 ◦ 04 ′ E). Coll. 27 May 1985.