Morphology and molecular phylogeny of three heterotrichid species (Ciliophora, Heterotrichea), including a new species of Anigsteinia.

Heterotrichs are generally larger than ciliates of other groups with a seemingly cosmopolitan distribution, and recent studies have demonstrated that they exhibit great biodiversity. In the present work, we investigated the morphology and small subunit rRNA (SSU rRNA) gene sequences of three heterotrichous species, including that of a new one, Anigsteinia paraclarissima spec. nov. The new organism is morphologically very similar to A. clarissima, however, it can be distinguished from the latter by the larger dimensions and more somatic kineties (25-32 vs. 18-26), and its sequence similarity of SSU rRNA gene is 97.14% which indicate that it is a distinct species. Detailed morphological and molecular data for Blepharisma bimicronucleatum are supplied together for the first time in this study. In addition, the morphology of a poorly known species, Spirostomum yagiui is redescribed and an improved species diagnosis is provided. Finally, based on phylogenetic analyses of SSU rRNA gene sequences data, the Spirostomum group contains two main clades based on the type of the macronucleus. Spirostomum yagiui was newly sequenced here and clustered with the other S. yagiui populations and positioned within the Spirostomum assemblage. The Anigsteinia clade, including A. paraclarissima and A. clarissima, clustered within the family Spirostomidae.

Morphology and molecular phylogeny of a new haptorian ciliate, Chaenea mirabilis sp. n., with implications for the evolution of the dorsal brush in haptorians (Ciliophora, Litostomatea).

We discovered a new haptorian ciliate, Chaenea mirabilis sp. n., in brackish water collected near the town of Busan, Korea. Its morphology was studied using standard taxonomical methods and its phylogenetic relationships were assessed by phylogenetic analysis of the 18S rRNA gene. Chaenea mirabilis is distinguished from all congeners by the combination of the following traits: (i) a narrowly bursiform to flask-shaped, 60-100 µm long body; (ii) 11-21 doughnut-shaped or sometimes horseshoe-shaped macronuclear nodules; (iii) two types of extrusomes: type I is rod-shaped and 6-8 µm long, while type II is narrowly to broadly teardrop-shaped and only 1.5-2 µm long; (iv) highly refractive special granules tightly arranged between the first and second brush row, forming a conspicuous bulge; and (v) 12-13 somatic kineties. In the 18S rRNA gene phylogeny, C. mirabilis clustered with full support with other congeners. However, there was no statistical support for classification of Chaenea into the families Fuscheriidae, Acropisthiidae, or Trachelophyllidae, but a sister relationship with the Lacrymariidae could not be excluded. Therefore, we establish a new family, Chaeneidae, within the order Lacrymariida. This affiliation is strongly corroborated by the distinctly subapical dorsal brush bearing cilium-like bristles.