Morphology and Small Subunit (SSU) rRNA Gene Sequence of the New Brackish Water Ciliate Neobakuella flava n. g., n. sp. (Ciliophora, Spirotricha, Bakuellidae) and SSU rRNA Gene Sequences of Six Additional Hypotrichs from Korea

Abstract

The morphology and the small subunit (SSU) rRNA gene sequence of the hypotrich Neobakuella flava n. g., n. sp. from the estuary of the Taehwagang River (Ulsan, South Korea) were investigated. The three frontal cirri, the composition of the midventral complex of cirral pairs and rows, and the simple dorsal kinety pattern of three bipolar kineties assign it to the urostyloid taxon Bakuellidae. The increased number of buccal and parabuccal cirri, the presence of transverse cirri, and more than one left marginal row, as well as the lack of caudal cirri separate Neobakuella n. g. from the other bakuellids. Neobakuella flava n. sp. has many 0.3 μm sized green and/or yellow usually dark-green cortical granules and some sparsely distributed, 2 × 1 μm sized grass green with yellowish shimmer granules. The gene sequence data indicate a close relationship with Diaxonella and a distinct separation from the bakuellid Metaurostylopsis and parabirojimid Parabirojimia. The SSU rRNA gene sequences of four further urostyloids (i.e. Diaxonella pseudorubra, Anteholosticha monilata, Metaurostylopsis struederkypkeae, Pseudourostyla cristata) and two stylonychines (i.e. Sterkiella cavicola, Sterkiella histriomuscorum) from Korea were analyzed. Anteholosticha monilata, type of the genus, is clearly separated from the Holosticha clade, supporting the morphological separation from Holosticha. Sterkiella cavicola, type of Sterkiella, clusters within the stylonychines and is obviously closely related with S. histriomuscorum.