Incorporating mitogenome sequencing into integrative taxonomy: The multidisciplinary redescription of the ciliate Thuricola similis (Peritrichia, Vaginicolidae) provides new insights into the evolutionary relationships among Oligohymenophorea subclasses

A Reassessment of Phylogenetic Relationships in Class Oligohymenophorea (Protista, Ciliophora) Based on Updated Multigene Data

Within the ciliate class Oligohymenophorea, many evolutionary relationships among taxa remain unresolved. This study incorporates 97 new sequences from 30 oligohymenophorean populations, including nuclear small subunit ribosomal (SSU-rRNA) genes, nuclear ITS1-5.8S-ITS2 rRNA regions, nuclear large subunit ribosomal (LSU-rRNA) genes, mitochondrial cytochrome oxidase c subunit I (cox 1) genes, and mitochondrial small subunit ribosomal RNA (mtSSU-rRNA) genes. With the addition of these new sequences, we performed comprehensive multigene phylogenetic analyses of Oligohymenophorea. The main findings are: (1) Utilizing multiple genes is instrumental in improving phylogenetic relationships within class Oligohymenophorea; (2) class Oligohymenophorea is divided into two distinct groups: (i) encompassing the subclass Hymenostomatia, Scuticociliatia, Apostomatia, Astomatia, and Urocentria; and (ii) comprising the subclasses Peniculia and Peritrichia; (3) Revising the phylogenetic placement of the subclass Urocentrida reveals its transitional role as a taxon between Group I and Group II. It emerges as a sister clade to Hymenostomatia; (4) the phylogenetic positions of Astomatia and Apostomatia within the clade 'SAA' become clearer; and (5) the order Loxocephalida represents an early member of Scuticociliatia and serves as a potential prototype for this taxonomic group. This study provides more information for understanding the evolutionary relationships within Oligohymenophorea.

High infestation and phylogenetic position of Epistylis sp. (Ciliophora, Peritrichia) on Aegla serrana Buckup & Rossi (Crustacea, Anomura) from southern Brazil

High infestations of epibiont ciliates on vertebrates or invertebrates are normally related to aquaculture tanks or similar environments, and the importance of this relationship in natural habitats is often disregarded. Here, we describe the first record of high infestation of ciliates on Aegla serrana in South America and conduct a brief morphological and phylogenetic characterization of these ciliates. Our findings confirm that cases of high infestation of ciliates on metazoans can indeed occur in natural environments.

Morphology and phylogeny of four trachelocercid ciliates (Ciliophora, Karyorelictea, Trachelocercidae) from North China Sea, with description of a new species

Trachelocercids are common ciliates in marine sandy intertidal zones, however, only few species have been described using modern taxonomic techniques, with several earlier descriptions still lacking primary data, such as a detailed description of the oral ciliature. For this reason, systematics of the family Trachelocercidae Kent, 1881 resulted in paraphyletic genera and needs a critical revision. As an attempt to fill the gap of knowledge for this group, this study presents one new species description, Tracheloraphis apodiscolor n. sp., along with redescriptions of three lesser-known trachelocercid species, Trachelocerca bodiani (Dragesco, 1963) Dragesco, 2002, Trachelocerca ditis (Wright, 1982) Foissner & Dragesco, 1996 and Prototrachelocerca fasciolata (Sauerbrey, 1928) Foissner, 1996, collected from coastal marine habitats at Qingdao (China), using live and protargol-stained specimens. Tracheloraphis apodiscolor n. sp. can be distinguished from its closest related congener, T. discolor, by a shorter body length and fewer somatic kineties. Molecular data of T. apodiscolor n. sp. and T. bodiani were provided for the first time. Additionally, based on the Qingdao populations, we provide improved diagnoses for T. ditis and P. fasciolata. Phylogenetic analyses were performed and discussed, as there is strong support for paraphyly of the genera Tracheloraphis and Trachelocerca. In general, more integrative studies based on taxonomy, ultrastructure as well as molecular data are needed to properly shed light on the systematics of trachelocercids.

On four epibiotic peritrichous ciliates (Protozoa, Ciliophora) found in Lake Weishan Wetland: morphological and molecular data support the establishment of a new genus, Parapiosoma gen. nov., and two new species

During a study on the diversity of ciliated protists in Lake Weishan Wetland, the largest wetland in northern China, four epibiotic sessilid peritrichs were isolated from aquatic host animals. Two of them, i.e., Epistylis cambari Kellicott, 1885 and Epistylis lwoffi Fauré-Fremiet, 1943, were known species whereas the other two, i.e., Parapiosoma typicum gen. nov., sp. nov. and Orborhabdostyla gracilis sp. nov., are new to science. The new genus Parapiosoma gen. nov. is characterized by its branched non-contractile stalk, everted peristomial lip, obconical macronucleus and transverse silverlines. Two species are assigned to the new genus, namely Parapiosoma typicum sp. nov. and Parapiosoma gasterostei (Fauré-Fremiet, 1905) comb. nov. Morphologically, P. typicum sp. nov. is recognized by its goblet-shaped zooids, single-layered peristomial lip, dichotomously branched stalk, and infundibular polykinety 3 (P3) containing three equal-length rows. Orborhabdostyla gracilis sp. nov. is characterized by its slender zooid, curved macronucleus, and three equal-length rows in infundibular P3. Improved diagnoses and redescriptions of E. cambari and E. lwoffi are provided including, for the first time, data on the ciliature of E. cambari. Phylogenetic analyses based on SSU rDNA, ITS1-5.8S rDNA -ITS2, and LSU rDNA sequence data strongly support the assertion that the family Epistylididae comprises morphospecies with different evolutionary lineages and indicate that Parapiosoma gen. nov. may represent a new taxon at family level.