\u3cem\u3eAgolohymena aspidocauda\u3c/em\u3e nov. gen., nov. spec., a Histophagous Freshwater Tetrahymenid Ciliate in the Family Deltopylidae (Ciliophora, Hymenostomatia), from Idaho (Northwest U.S.A.): Morphology, Ontogenesis and Molecular Phylogeny

Morphology, ontogeny and the molecular phylogeny of Agolohymena aspidocauda nov. gen., nov. spec., a new freshwater tetrahymenid ciliate from Idaho, U.S.A, are described. The ontogeny and histophagous mode of nutrition are similar to those of Deltopylum rhabdoides Fauré-Fremiet and Mugard, 1946. The new genus is placed with Deltopylum in the resurrected family Deltopylidae Song & Wilbert, 1989. We emend the diagnostic features of the family to include division by polytomy, right and left somatic kineties extending into the preoral suture, crook-shaped or sigmoid adoral membranelles 1 and 2, markedly reduced adoral membranelle 3 and a tetrahymenid silverline pattern. The main diagnostic features of the new genus are a disc-shaped caudal ciliary array and formation of two types of resting cysts, one smooth and the other bearing tangled tubular or cylindrical lepidosomes. Nuclear small subunit ribosomal RNA gene and mitochondrial cytochrome oxidase subunit 1 gene sequences place the new genus basal within the order Tetrahymenida, well separated from members of the family Tetrahymenidae (Lambornella and Tetrahymena) and also from other tetrahymenids (Colpidium, Dexiostoma, Glaucoma). The genetic divergences between this species and other genera in Tetrahymenida are large enough to suggest placement of the new genus in a separate family. This corroborates the morphological data, since the elaborate caudal ciliary array and the lepidosome-covered resting cyst of this species are not found in other Tetrahymenidae

What Morphology and Molecules Tell Us about the Evolution of Oligotrichea (Alveolata, Ciliophora)

The evolution of the dominant marine plankton ciliates, the oligotrichids and choreotrichids, is analysed for morphologic and genetic convergences and apomorphies based on literature and our own data. These findings have taxonomic implications. Within the oligotrichid genus Parallelostrombidium two subgenera, Parallelostrombidium Agatha, 2004 nov. stat. and Asymptokinetum nov. subgen., are established, using the courses of the ventral and girdle kineties as a distinguishing feature. Likewise, a different arrangement of extrusome attachment sites is used for a split of the oligotrichid genus Novistrombidium into the subgenera Novistrombidium Song and Bradbury, 1998 nov. stat. and Propecingulum nov. subgen.; Novistrombidium (Propecingulum) ioanum (Lynn and Gilron, 1993) nov. comb. and Novistrombidium (Propecingulum) platum (Song and Packroff, 1997) nov. comb. are affiliated. Based on discrepancies in the somatic ciliary pattern and the presence of conspicuous argyrophilic inclusions, the aloricate choreotrichid species Pelagostrobilidium kimae nov. spec. is distinguished from P. conicum. The diagnosis for the tintinnid family Eutintinnidae Bachy et al., 2012 is improved by including cell features. The co-operation of taxonomists and molecular biologists is strongly recommended to prevent misinterpretations of gene trees due to incorrectly identified species and for better species circumscriptions

Parallel evolution of histophagy in ciliates of the genus Tetrahymena

BACKGROUND: Species of Tetrahymena were grouped into three complexes based on morphological and life history traits: the pyriformis complex of microstomatous forms; the patula complex of microstome-macrostome transformers; and the rostrata complex of facultative and obligate histophages. We tested whether these three complexes are paraphyletic using the complete sequence of the small subunit rDNA (SSrDNA). RESULTS: In addition to the 16 species of Tetrahymena whose SSrDNA sequences are known, we sequenced the complete SSrDNA from the following histophagous Tetrahymena species; Tetrahymena bergeri, Tetrahymena mobilis, Tetrahymena rostrata, and Tetrahymena setosa as well as the macrostome species Tetrahymena vorax. We also included a ciliate tentatively identified as Lambornella sp., a parasite of the mosquito Aedes sp. We confirmed earlier results using SSrDNA, which showed two distinct clusters of Tetrahymena species: the australis group and borealis group. The genetic distances among Tetrahymena are in general very small. However, all nodes were supported by high bootstrap values. With the exception of T. bergeri and T. corlissi, which are both histophagous and group as sister species, all other histophagous Tetrahymena species are most closely related to a bacterivorous species. Furthermore, Lambornella sp. and T. empidokyrea, both mosquito parasites, are sister species, although there is a considerable genetic distance between them. CONCLUSIONS: There has been parallel evolution of histophagy in the genus Tetrahymena and the three classical species complexes are paraphyletic. As the genus Lambornella arises within the Tetrahymena clade, it is not likely a defensible one

What Morphology and Molecules Tell Us about the Evolution of Oligotrichea (Alveolata, Ciliophora)

The evolution of the dominant marine plankton ciliates, the oligotrichids and choreotrichids, is analysed for morphologic and genetic convergences and apomorphies based on literature and our own data. These findings have taxonomic implications. Within the oligotrichid genus Parallelostrombidium two subgenera, Parallelostrombidium Agatha, 2004 nov. stat. and Asymptokinetum nov. subgen., are established, using the courses of the ventral and girdle kineties as a distinguishing feature. Likewise, a different arrangement of extrusome attachment sites is used for a split of the oligotrichid genus Novistrombidium into the subgenera Novistrombidium Song and Bradbury, 1998 nov. stat. and Propecingulum nov. subgen.; Novistrombidium (Propecingulum) ioanum (Lynn and Gilron, 1993) nov. comb. and Novistrombidium (Propecingulum) platum (Song and Packroff, 1997) nov. comb. are affiliated. Based on discrepancies in the somatic ciliary pattern and the presence of conspicuous argyrophilic inclusions, the aloricate choreotrichid species Pelagostrobilidium kimae nov. spec. is distinguished from P. conicum. The diagnosis for the tintinnid family Eutintinnidae Bachy et al., 2012 is improved by including cell features. The co-operation of taxonomists and molecular biologists is strongly recommended to prevent misinterpretations of gene trees due to incorrectly identified species and for better species circumscriptions