The morphology and ontogenesis of a new psilotrichid ciliate, Hemiholosticha pantanalensis, were studied using live observation, protargol impregnation, and scanning electron microscopy. Diagnostic features of the new species include: a medium-sized, almost circular to broadly obovate body with a short anterior projection; two macronuclear nodules with a single micronucleus in between; a total of about 35 cirri arranged in three ventral, one postoral, one right and one left marginal row; three dorsal kineties extending along prominent ribs; an adoral zone occupying about 60% of body length; and intracellular, eyespot-bearing, green algae almost filling the body. The ontogenesis of H. pantanalensis follows the psilotrichid mode, being a mixture of features found not only in various hypotrich taxa but also in other spirotrich groups. Specifically, the oral primordium develops in a deep pouch as in euplotids and oligotrichs, the anlage for the undulating membranes does not produce cirri as in euplotids and some schmidingerothrichids, and the longitudinal ventral cirral row R3 develops from two anlagen as in some amphisiellids and kahliellids. Since psilotrichids are classified in a polytomy of main hypotrich lineages in 18S rRNA gene phylogenies, some of their ontogenetic features might be ancient spirotrich plesiomorphies while others might be homoplasies.

The molecular phylogeny of the sand-dwelling dinoflagellate Planodinium striatum was investigated from isolates collected in the NE English Channel. In the SSU rRNA gene phylogeny, the sequences of Planodinium clustered with the type species of Plagiodinium, P. belizeanum, and more distantly related to Plagiodinium ballux. Although the SSU rRNA gene sequences of Planodinium showed a high percentage of identity (96%) with partial sequences of species of Podolampas (~1200 base pairs), the SSU rRNA gene phylogenies did not show a relationship with the clade of the Podolampadaceae (Podolampas, Blepharocysta, Roscoffia), neither with the sequences of the sanddwelling genus Cabra. The SSU rRNA gene sequences of Plagiodinium belizeanum and P. ballux showed a low percentage of identity (96%) clustering in separate clades in the SSU rRNA gene phylogeny with Planodinium. The morphology of P. ballux and its generic type differed in the plate arrangement and the morphology of the cingulum, amongst other features. Based on the morphological and molecular differences, we propose the new genus Chrysodinium gen. nov. for P. ballux, with the re-interpreted thecal plate formula Po 3’ 1’’ 7c 2s 5’’’ 1’’’’.

Trichodina heterodentata was first described from fish breeding farms in the Philippines by Bryan Duncan in 1977 as ectoparasites of imported cichlids, more specifically the southern African Oreochromis mossambicus (Peters, 1852) from the Limpopo River System. This trichodinid has subsequently been described from almost every continent, bar North America. Being a cosmopolitan species, with a preference for cichlid hosts, it has unambiguous morphological features, but with distinct variances between and within populations. After reviewing previous descriptions of North American trichodinids, analysing the morphological data (both generally published information along with the original type material from the Smithsonian Museum, Washington, U.S.A.) and investigating the distribution patterns of the southern African introduced O. mossambicus throughout the North American water systems, three of the four studied trichodinids (T. hypsilepis Wellborn, 1967, T. salmincola Wellborn, 1967 and T. vallata Wellborn, 1967) are proposed to represent the same species as T. heterodentata. According to nomenclature rules T. hypsilepis henceforth represents the valid taxon (synonyms: T. salmincola, T. vallata and T. heterodentata). This not only questions the validity of several trichodinid species, but also indicates the probability of an African alien introduction into North America.

Mobiline taxonomic data is mostly inferred from populations collected in and on hosts associated with aquaculture. Even though these conditions may be conducive for studies relating to the hosts, accurate taxonomic inferences of the symbionts will be problematic. The site for the present study was the Okavango Panhandle region in Northern Botswana, an isolated, natural area with minimal anthropogenic influences. Morphometric and molecular evidence revealed that anuran tadpole trichodinids, up to now reported as Trichodina heterodentata Duncan 1977 and T. hypsilepis Wellborn 1967 from multiple host types, are in fact a new, more host specific species. This study includes comprehensive denticle descriptions of both the anuran hosted trichodinid and the morphologically similar T. hypsilepis restricted to teleost hosts (previously T. heterodentata).

To understand distributional and ecological aspects of ciliates living in tank bromeliads, we analyzed the ciliate community structure in fifteen different epiphytic and terrestrial bromeliad species from different types of vegetation. Sixty-nine samples were collected from plants of genera Aechmea, Bromelia, Pseudalcantarea and Tillandsia in seven localities in eastern Mexico during 2014 and 2015. The sampling localities covered an altitude gradient from 0 till 2 210 m ASL. We found 24 ciliate species and through the application of a principal component analysis, three clusters that correspond to several types of vegetation were obtained with regard to ciliate and bromeliad species. We recorded the largest number of ciliate species in localities of montane cloud forest, and also the largest number of ciliate species endemic to tank bromeliads, like Glaucomides bromelicola, inhabiting bromeliads from this forest. We observed the presence of ciliates in Bromelia pinguin that possesses a weakly developed phytotelm. The results of our study indicate that the species composition of ciliates inhabiting tank bromeliads depends on such correlated environmental factors like altitude ASL, temperature and type of vegetation.