Morphology, Morphogenesis, and Molecular Phylogeny of Neobakuella aenigmatica n. sp. (Ciliophora, Spirotrichea, Bakuellidae).

The morphology and morphogenesis of a new ciliate species, Neobakuella aenigmatica n. sp., which was discovered in an estuary in Korea, were investigated, using live observation, protargol impregnation, and scanning electron microscopy. This new species is characterized by a large (185-300 × 55-105 μm in vivo), elongate-ellipsoidal, flexible but not contractile body. It has ellipsoidal, yellowish cortical granules, 1.3 × 1.0 μm in size. The species has invariably 3 frontal and 2 frontoterminal cirri, about 5-10 buccal and 1-6 parabuccal cirri, 7 midventral rows, and 1 right and 2-4 left marginal rows. The outer left marginal row(s) consists of 1-7 short rows of cirri. The nuclear apparatus comprises 130 macronuclear nodules and 2 spherical micronuclei on average. The dorsal ciliature consists of 3 dorsal kineties. The leftmost left marginal row(s) likely develops from anlagen originating from both the rightmost and leftmost left marginal row(s). The molecular phylogenetic tree based on SSU rDNA suggests the nonmonophyly of the genus Neobakuella.