Abstract
The morphology, morphogenesis, and molecular phylogeny of Bakuella (Pseudobakuella) guangdongica n. sp., isolated from southern China, were investigated. The new species is characterized by a body length of 150–225 μm in vivo; 35–42 adoral membranelles; 3–5 buccal, two frontoterminal, 7–12 transverse and two pretransverse ventral cirri; midventral complex comprised of 10–20 pairs and two rows extending to transverse cirri; posterior part of marginal rows slightly overlapping; colorless cortical granules about 1 μm across, arranged in small groups; soil habitat. Its main ontogenetic features are: (1) in the proter, the parental adoral zone of membranelles is completely renewed by new structures; (2) in the opisthe, the oral primordium originates apokinetally, some old midventral cirri join the formation of frontoventral-transverse cirral anlagen; (3) the anlagen for marginal rows and dorsal kineties develop intrakinetally; and (4) the numerous macronuclear nodules fuse into a single mass before dividing. Phylogenetic analyses based on the SSU rDNA sequence suggest the non-monophyly of the genus Bakuella.