Abstract
Background: Ciliated protists, a huge assemblage of unicellular eukaryotes, are extremely diverse and play important roles in ecosystem in almost all kinds of habitats. Even though there is a growing recognition that those organisms associate with many ecological or environmental processes, their biodiversity, due to many reasons, is poorly understood and many biotopes (e.g. the soil in desert area in Asia) remain largely unknown or unconsidered. Here we document an undescribed form found in sludge soil in a halt-desert inland in China and the taxonomic/ morphogenetic surveys indicate that it represents a new genus and new species, Parasincirra sinica n. g., n. sp. which is supported also by molecular data.Results: This new, monotypic genus Parasincirra n. g. is defined by having three frontal cirri, an amphisiellid median cirral row about as long as the adoral zone, one short frontoventral cirral row, cirrus III/2 and transverse cirri present, buccal and caudal cirri absent, one right and one left marginal row and three dorsal kineties. The main morphogenetic features of the new taxon are: (1) frontoventral-transverse cirral anlagen II to VI are formed in primary mode; (2) the amphisiellid median cirral row is formed by anlagen V and VI, while the frontoventral row is generated from anlage IV; (3) cirral streaks IV to VI generate one transverse cirrus each; (4) frontoventral-transverse cirral anlage II generates one or two cirri, while the posterior one will be absorbed in late stages, that is, no buccal cirrus is formed; (5) the posterior part of the parental adoral zone of membranelles is renewed; (6) dorsal morphogenesis follows a typical Gonostomum-pattern; and (7) the macronuclear nodules fuse to form a single mass. Based on the SSU rDNA information, analyses of the phylogenetic relationship inferred from Bayesian inference and maximum likelihood analyses were unable to outline the exact position of this new form among some other species of related genera which are generally assigned in the family Amphisiellidae Jankowski, 1979. The morphological/ morphogenetical differences between the new genus/species and Uroleptoides Wenzel, 1953/ Parabistichella Jiang et al., 2013, as well as other amphisiellids, clearly support the validity of the establishment of this new genus Parasincirra.