Morphological description of two new ciliates (Ciliophora, Karyorelictea, Cryptopharyngidae): Apocryptopharynx discoidalis spec. nov. and Cryptopharynx minutus spec. nov.

The karyorelictids, a highly specialized group of ciliates, mostly inhabit marine biotopes, and there is very little information about their diversity, taxonomy, and systematics. The present paper investigates two new cryptopharyngid ciliates, Apocryptopharynx discoidalis spec. nov. and Cryptopharynx minutus spec. nov., which were isolated from the intertidal zone of Diaosuyuan Beach in Qingdao, China. Apocryptopharynx discoidalis spec. nov. can be distinguished from related species by its oval discoid body shape and highly structured epipellicular scales covering the left lateral surface. Cryptopharynx minutus spec. nov. can be recognized by its small body length (30–50 μm), seven to 15 dikinetids in intrabuccal kinety, and two to five macronuclei. Based on our comparison, we believe that Cryptopharynx sp. 1 described by Foissner in 1996 represents a population of C. minutus spec. nov.