Insights into the phylogeny of systematically controversial haptorian ciliates (Ciliophora, Litostomatea) based on multigene analyses

The ciliate subclass Haptoria is a diverse taxon that includes most of the free-living predators in the class Litostomatea. Phylogenetic study of this group was initially conducted using a single molecular marker small-subunit ribosomal RNA (SSU rRNA genes). Multi-gene analysis has been limited because very few other sequences were available. We performed phylogenetic analyses of Haptoria incorporating new SSU rRNA gene sequences from several debated members of the taxon, in particular, the first molecular data from Cyclotrichium. We also provided nine large-subunit ribosomal RNA (LSU rRNA) gene sequences and 10 alpha-tubulin sequences from diverse haptorians, and two possible relatives of controversial haptorians (Plagiopylea, Prostomatea). Phylogenies inferred from the different molecules showed the following: (i) Cyclotrichium and Paraspathidium were clearly separated from the haptorids and even from class Litostomatea, rejecting their high-level taxonomic assignments based on morphology. Both genera branch instead with the classes Plagiopylea, Prostomatea and Oligohymenophora. This raises the possibility that the well-known but phylogenetically problematic cyclotrichiids Mesodinium and Myrionecta may also have affinities here, rather than with litostomes; (ii) the transfer of Trachelotractus to Litostomatea is supported, especially by the analyses of SSU rRNA and LSU rRNA genes, however, Trachelotractus and Chaenea (more uncertainly) generally form the two deepest lineages within litostomes; and (iii) phylogenies of the new molecular markers are consistent with SSU rRNA gene information in recovering order Pleurostomatida as monophyletic. However, Pleurostomatida branches cladistically within order Haptorida, as does subclass Trichostomatia (on the basis of SSU rRNA phylogenies). Our results suggest that the class-level taxonomy of ciliates is still not resolved, and also that a systematic revision of litostomes is required, beginning at high taxonomic levels (taxa currently ranked as subclasses and orders).     

Phylogeny and biogeography of the "Australian" trichostomes (Ciliophora: Litostomata)

The phylogenetic relationships of members of the ciliate class Litostomatea were determined by a molecular phylogeny using the small subunit of the ribosomal RNA (ssu-rRNA) gene and a morphological phylogeny based on ultrastructural analyses of the group. Molecular analyses consistently supported the monophyly of Trichostomatia, Entodiniomorphida and the "Australian" trichostomes but provided limited support for a monophyletic Vestibuliferida and Haptoria. The results of the morphological analyses depended on the way in which the dataset was treated: "unordered" and "ordered" recovered a monophyletic Trichostomatia, Haptoria and the "Australian" trichostomes but challenged the monophyly of Entodinimorphida and Vestibuliferida; "dollo" recovered a monophyletic Trichostomatia and Entodiniomorphida but at the cost of a greatly longer tree than either "unordered" or "ordered" datasets. The monophyly of each "Australian" trichostome family was supported in all analyses and by both approaches. These results suggest that the trichostome ciliates may have become associated with mammals in Gondwana with the "Australian" trichostome ciliates entering Australia with primitive herbivorous marsupials. Subsequent diversification of the "Australian" families was probably a result of dietary specialization and oral and cortical synapomorphies define each family. We decline at this time to erect a formal taxon name for the "Australian" trichostomes due to the instability of other superfamilial taxa within the Litosomatea and concerns about the stability of tree topology until a better taxon sample of litostome ciliates is available.     

Morphological and molecular phylogeny of dileptid and tracheliid ciliates: resolution at the base of the class Litostomatea (Ciliophora, Rhynchostomatia)

Dileptid and tracheliid ciliates have been traditionally classified within the subclass Haptoria of the class Litostomatea. However, their phylogenetic position among haptorians has been controversial and indicated that they may play a key role in understanding litostomatean evolution. In order to reconstruct the evolutionary history of dileptids and tracheliids, and to unravel their affinity to other haptorians, we have used a cladistic approach based on morphological evidence and a phylogenetic approach based on 18S rRNA gene sequences, including eight new ones. The molecular trees demonstrate that dileptids and tracheliids represent a separate subclass, Rhynchostomatia, that is sister to the subclasses Haptoria and Trichostomatia. The Rhynchostomatia are characterized by a ventrally located oral opening at the base of a proboscis that carries a complex oral ciliature. We have recognized two orders within Rhynchostomatia. The new order Tracheliida is monotypic, while the order Dileptida comprises two families: the new, typically bimacronucleate family Dimacrocaryonidae and the multimacronucleate family Dileptidae. The Haptoria evolved from the last common ancestor of the Litostomatea by polarization of the body, the oral opening locating more or less apically and the oral ciliature simplifying. The Trichostomatia originated from a microaerophylic haptorian by further simplification of the oral ciliature, possibly due to an endosymbiotic lifestyle.     

Further insights into the highly derived haptorids (Ciliophora,Litostomatea): Phylogeny based on multigene data

Evolutionary relationships of taxa within the ciliate subclass Haptoria are poorly understood. In this study, we broaden the taxon sampling by adding 14 small subunit ribosomal RNA gene sequences, 13 large subunit ribosomal RNA gene sequences and 13 ITS1‐5.8S‐ITS2 gene sequences of haptorians. This includes the first molecular data from two genera, Pseudotrachelocerca Song, 1990, and Foissnerides Song & Wilbert, 1989. Phylogenies inferred from the three individual genes and concatenated data sets show that: (i) the subclass Haptoria could be a multiphyletic complex with about up to four main clades while “interrupted” by some intermingled with the related subclasses Rhynchostomatia, Trichostomatia and some incertae sedis; (ii) the genus Pseudotrachelocerca Song, 1990, is clearly separated from Litostomatea and clusters within an assemblage comprising the classes Prostomatea, Colpodea and Plagiopylea; (iii) both morphological evidence and molecular evidence indicate that the genus Foissnerides should be transferred from family Trachelophyllidae to Pseudoholophryidae; (iv) the validity of the order Helicoprorodontida Grain, 1994, and its monophyly is strongly supported; (5) the family Chaeneidae does not belong to the order Lacrymarida but represents a distinct clade in the subclass Haptoria.     

Phylogeny and classification of the Litostomatea (Protista, Ciliophora), with emphasis on free-living taxa and the 18S rRNA gene

The class Litostomatea is a highly diverse ciliate taxon comprising hundreds of species ranging from aerobic, free-living predators to anaerobic endocommensals. This is traditionally reflected by classifying the Litostomatea into the subclasses Haptoria and Trichostomatia. The morphological classifications of the Haptoria conflict with the molecular phylogenies, which indicate polyphyly and numerous homoplasies. Thus, we analyzed the genealogy of 53 in-group species with morphological and molecular methods, including 12 new sequences from free-living taxa. The phylogenetic analyses and some strong morphological traits show: (i) body polarization and simplification of the oral apparatus as main evolutionary trends in the Litostomatea and (ii) three distinct lineages (subclasses): the Rhynchostomatia comprising Tracheliida and Dileptida; the Haptoria comprising Lacrymariida, Haptorida, Didiniida, Pleurostomatida and Spathidiida; and the Trichostomatia. The curious Homalozoon cannot be assigned to any of the haptorian orders, but is basal to a clade containing the Didiniida and Pleurostomatida. The internal relationships of the Spathidiida remain obscure because many of them and some "traditional" haptorids form separate branches within the basal polytomy of the order, indicating one or several radiations and convergent evolution. Due to the high divergence in the 18S rRNA gene, the chaeneids and cyclotrichiids are classified incertae sedis.     

Phylogeny of trichostome ciliates (Ciliophora, Litostomatea) endosymbiotic in the Yakut horse (Equus caballus)

Ciliates of the subclass Trichostomatia inhabit the fermentative regions of the digestive tract of herbivores. Most available small subunit ribosomal RNA (SSrRNA) gene sequences of trichostomes are from species isolated from the rumen of cattle or sheep and from marsupials. No ciliate species endosymbiotic in horses has yet been analyzed. We have sequenced the SSrRNA genes of five ciliate species, isolated from the cecum and colon of four Yakut horses: Cycloposthium edentatum, Cycloposthium ishikawai, Tripalmaria dogieli, Cochliatoxum periachtum, and Paraisotricha colpoidea.

Based on their morphology, Cycloposthium, Tripalmaria, and Cochliatoxum are classified as Entodiniomorphida, while Paraisotricha is considered a member of the Vestibuliferida. Phylogenetic analyses using Bayesian inference, distance, and parsimony methods confirm these placements. The two Cycloposthium species cluster together with the published Cycloposthium species isolated from a wallaby in Australia. Tripalmaria and Cochliatoxum branch as a sister group to or basal within the Entodiniomorphida. The Vestibuliferida remain paraphyletic with Paraisotricha and Balantidium branching basal to all other trichostome species, but not closely related to Isotricha and Dasytricha.     

Phylogeny of the Rumen Ciliates Entodinium, Epidinium and Polyplastron (Litostomatea: Entodiniomorphida) Inferred from Small Subunit Ribosomal RNA Sequences

ABSTRACT. Three complete 18S ribosomal RNA gene sequences from the rumen ciliates, Entodinium coudatum (1,639 bp), Epidinium caudarum (1,638 bp), and Polyplastron multivesiculatum (1,640 bp) were determined and confrimed in the opposite direction. Trees produced using maximum parsimony and distance-matrix methods (lest squares and neighbour-joining). with strong bootstrap support, depict the rumen ciliates as a monophyletic group, Entodinium caudatum is the earliest branching rumen ciliate. However, Entodiniwn simplex does not pair with En. caudatum , but rather with Polyplastron multivesiculatum. Signature sequences for these rumen ciliates reveal that the published SSrRNA gene sequence from En. simplex is in fact a Polyoplastron species. The free-living haptorian ciliates, Loxophyllum, Homalozoon and Spathidium (Subclass Hoptoria), are monophyletic and are the sister group to the rumen cilates. The litostomes (class Litostomatea), consisting of the haptorians and the rumen ciliates, are also a monophyletic group.     

Synergistic effects of combining morphological and molecular data in resolving the phylogenetic position of Semispathidium (Ciliophora,Haptoria) with description of Semispathidium breviarmatum sp. n. from tropical Africa

We describe a new species, Semispathidium breviarmatum sp. n., from tropical Africa and analyse its phylogenetic position within the subclass Haptoria, using live observation, various silver impregnation methods, SEM and the 18S rRNA gene. Semispathidium breviarmatum differs from its congeners by the much higher number of ciliary rows and by the shape and size of the extrusomes, that is, extrusive organelles that kill the prey. The phylogenetic position of Semispathidium is controversial due to its ‘hybrid’ morphology. Specifically, the cylindroidal body has a more or less discoidal oral bulge indicating an enchelyodonid origin, while the anteriorly curved somatic kineties suggest a spathidiid ancestor. In order to reconstruct the evolutionary history of Semispathidium and to unravel its affinity to other haptorians, we used synergistic effects of combining morphological and molecular data coming from 34 haptorian taxa. These analyses show that Semispathidium belongs to the order Spathidiida representing a basal lineage that is far from ordinary Spathidium species, but very likely related to Protospathidium and Enchelys. Any closer phylogenetic relationship between Semispathidium and Enchelyodon spp. is not recognized in morphological and molecular phylogenies and is consistently excluded by statistical tree topology tests.     

The symbiotic intestinal ciliates and the evolution of their hosts

The evolution of sophisticated differentiations of the gastro-intestinal tract enabled herbivorous mammals to digest dietary cellulose and hemicellulose with the aid of a complex anaerobic microbiota. Distinctive symbiotic ciliates, which are unique to this habitat, are the largest representatives of this microbial community. Analyses of a total of 484 different 18S rRNA genes show that extremely complex, but related ciliate communities can occur in the rumen of cattle, sheep, goats and red deer (301 sequences). The communities in the hindgut of equids (Equus caballus, Equus quagga), and elephants (Elephas maximus, Loxodonta africanus; 162 sequences), which are clearly distinct from the ruminant ciliate biota, exhibit a much higher diversity than anticipated on the basis of their morphology. All these ciliates from the gastro-intestinal tract constitute a monophyletic group, which consists of two major taxa, i.e. Vestibuliferida and Entodiniomorphida. The ciliates from the evolutionarily older hindgut fermenters exhibit a clustering that is specific for higher taxa of their hosts, as extant species of horse and zebra on the one hand, and Africa and Indian elephant on the other hand, share related ciliates. The evolutionary younger ruminants altogether share the various entodiniomorphs and the vestibuliferids from ruminants.     

Genealogical analyses of multiple loci of litostomatean ciliates (Protista, Ciliophora, Litostomatea)

The class Litostomatea is a highly diverse ciliate taxon comprising hundreds of free-living and endocommensal species. However, their traditional morphology-based classification conflicts with 18S rRNA gene phylogenies indicating (1) a deep bifurcation of the Litostomatea into Rhynchostomatia and Haptoria+Trichostomatia, and (2) body polarization and simplification of the oral apparatus as main evolutionary trends in the Litostomatea. To test whether 18S rRNA molecules provide a suitable proxy for litostomatean evolutionary history, we used eighteen new ITS1-5.8S rRNA-ITS2 region sequences from various free-living litostomatean orders. These single- and multiple-locus analyses are in agreement with previous 18S rRNA gene phylogenies, supporting that both 18S rRNA gene and ITS region sequences are effective tools for resolving phylogenetic relationships among the litostomateans. Despite insertions, deletions and mutational saturations in the ITS region, the present study shows that ITS1 and ITS2 molecules can be used to infer phylogenetic relationships not only at species level but also at higher taxonomic ranks when their secondary structure information is utilized to aid alignment.     

An approximation to the phylogeny of Sclerotinia and related genera

Phylogenies are constructed based on nuclear ribosomal internal transcribed spacer (ITS) DNA sequences from an ingroup consisting of 50 isolates representing 24 species of the discomycete family Sclerotiniaceae and an outgroup consisting of five related taxa of the same family. The ingroup taxa are: three Botrytis spp., two Botryotinia spp., one Ciborinia sp., one Dumontinia sp., one Grovesinia sp., six Myriosclerotinia spp., nine Sclerotinia spp. and one Sclerotium sp. The outgroup taxa are: one Ciboria sp., one Encoelia sp. and three Monilinia spp. The type species is included for all taxa except for Ciborinia and Encoelia. Several of the included taxa are important plant pathogens. The resulting phytogenies are discussed with regard to morphology, life history and taxonomy. A suspected relationship between Sclerotinia borealis and S. tetraspora , and Myriosclerotinia is rejected, while a suspected relationship between Ciborinia ciborium and Myriosclerotinia is strongly supported. Sclerotinia ulmariae , previously synonymized with Dumontinia tuberosa , is reinstated as an independent species of Dumontinia. Two new combinations, Dumontinia ulmariae and Myriosclerotinia ciborium , are proposed. The imperfectly known taxon Sclerotium cepivorum seems most closely related to Dumontinia. We conclude that Dumontinia , and Myriosclerotinia , as currently conceived, are monophyletic, and that Botryotinia along with Botrytis anamorphs probably also constitute a monophyletic lineage. The genus Sclerotinia is probably polyphyletic and characterized by symplesiomorphies rather than synapomorphies. Two putatively new taxa, Sclerotinia sp. 1, and Sclerotinia sp.2 are most closely related to S. minor, S. sclerotiorum and S. trifoliorum , and to S. borealis , respectively.     

Phylogeny of Six Genera of the Subclass Haptoria (Ciliophora,Litostomatea) Inferred from Sequences of the Gene Coding for Small Subunit Ribosomal RNA

ABSTRACT. The small subunit ribosomal RNA genes of nine species belonging to six genera of litostome ciliates, namely Amphileptus aeschtae, Chaenea teres, Chaenea vorax, Lacrymaria marina, Litonotus paracygnus, Loxophyllum sp.‐GD‐070419, Loxophyllum jini, Loxophyllum rostratum, and Phialina salinarum, were sequenced for the first time. Phylogenetic trees were constructed using different methods to assess the inter‐ and intra‐generic relationships of haptorians, of which Chaenea, Lacrymaria, Litonotus, and Phialina were analyzed for the first time based on molecular data. Monophyly of the order Pleurostomatida was strongly confirmed, and the two existing families of pleurostomatids, created on the basis of morphology, were confirmed by molecular evidence. Within the Pleurostomatida, Siroloxophyllum utriculariae occupied a well‐supported position basal to the Loxophyllum clade, supporting the separation of these genera from one another. Both the subclass Haptoria and the order Haptorida were partially unresolved, possibly paraphyletic assemblages of taxa in all analyses, creating doubts about the traditional placement of some haptorid taxa. The existing sequence of L. rostratum in GenBank (DQ411864) was conspicuously different from that of the isolate from Qingdao, China sequenced in the present work, indicating that they are different species. The isolate from Qingdao was verified as L. rostratum by morphological analysis, and the published morphology of existing GenBank record of L. rostratum is different from it. Based on both morphological and molecular evidence, the latter may be congeneric with an undescribed species of Loxophyllum from Guangdong Province, China.     

A molecular phylogeny of heterodont bivalves (Mollusca: Bivalvia: Heterodonta): new analyses of 18S and 28S rRNA genes

A new molecular phylogeny is presented for the highly diverse, bivalve molluscan subclass Heterodonta. The study, the most comprehensive for heterodonts to date, used new sequences of 18S and 28S rRNA genes for 103 species from 49 family groups with species of Palaeoheterodonta (Trigoniidae, Margaritiferidae and Unionidae) as outgroups. Results confirm previous analyses that the Carditidae/Astartidae/Crassatellidae clade is basal to all other heterodonts including Anomalodesmata (often classified as a separate subclass or order). Thyasiroidea occupy a near basal position between the Crassatelloidea and Anomalodesmata. Lucinidae form a well‐supported monophyletic group distinct from Thyasiridae and Ungulinidae. The Solenoidea and Hiatelloidea link as sister groups distant from the Tellinoidea and Myoidea, respectively, where they had been previously associated. The position of the Gastrochaenidae is unstable but does not group with myoidean taxa. Species of four families of Galeommatoidea form a clade that also includes Sportellidae of the Cyamioidea. The Cardioidea and Tellinoidea form highly supported, long branched, individual clades but group as sister taxa. A major clade including Veneroidea, Mactroidea, Myoidea and other families is given the unranked name Neoheterodontei. There is no support for a separate order Myoida (Myoidea and Pholadoidea). Dreissenidae group within the clade including Myidae, Corbulidae, Pholadidae and Teredinidae. The Corbiculoidea is confirmed as polyphyletic with the Sphaeriidae and Corbiculidae forming separate clades within the Neoheterodontei; Corbiculidae grouping with the Glauconomidae. Hemidonacidae are unrelated to the Cardiidae, as previously proposed, but nest within the Neoheterodontei. The Gaimardiidae group near to the Ungulinidae and not with Cyamioidea where most recently classified. The family Ungulinidae, previously classified in the Lucinoidea, forms a well‐supported clade within the Neoheterodontei and is elevated to superfamily rank — Ungulinoidea. The monophyletic status of Glossoidea, Arcticoidea and Veneroidea is unconfirmed. A brief review of the fossil record of the heterodonts indicates that the basal clades of Crassatelloidea, Anomalodesmata and Lucinoidea diverged very early in the Lower Palaeozoic. Other groups such as the Hiatelloidea, Solenoidea, Gastrochaenidae probably were of late Palaeozoic origins. The Cardioidea and Tellinoidea originated in the Triassic while major groups of Neoheterodontei radiated in the Late Mesozoic. The phylogenetic position of the Thyasiroidea and Galeommatoidea suggests a longer fossil history than has so far been recognized.     

ORIGINS AND AFFINITIES OF THE FILAMENTOUS GREEN ALGAL ORDERS CHAETOPHORALES AND OEDOGONIALES BASED ON 18S rRNA GENE SEQUENCES

The order Chaetophorales includes filamentous green algae whose taxonomic relationships to other chlorophycean orders is uncertain. Chaetophoralean taxa include filamentous species which are both branched and unbranched. Ultrastructural studies of zoospores have revealed similar flagellar apparatuses in a number of genera, including Uronema, Stigeoclonium, and Fritschiella, suggesting a close phylogenetic relationship among these taxa. The order Oedogoniales represents a second group of branched and unbranched filamentous green algae whose relationships to other chlorophycean orders also has been unclear. A possible close relationship between the Chaetophorales and Oedogoniales has been suggested. Using DNA sequences from the small-subunit ribosomal RNA gene (SSU rRNA) of several members of each order, we have examined the monophyly of the Chaetophorales and Oedogoniales, as well as the nature of their relationship to other chlorophycean orders. Our results show that chaetophoralean and oedogonialean taxa form separate monophyletic groups. Results also suggest that the two orders are not closely related to each other.     

Monophyly of the family Desmoscolecidae (Nematoda,Demoscolecida) and Its Phylogenetic position inferred from 18S rDNA sequences

To infer the monophyletic origin and phylogenetic relationships of the order Desmoscolecida, a unique and puzzling group of mainly free-living marine nematodes, we newly determined nearly complete 18S rDNA sequences for six marine desmoscolecid nematodes belonging to four genera (Desmoscolex, Greeffiella, Tricoma and Paratricoma). Based on the present data and those of 72 nematode species previously reported, the first molecular phylogenetic analysis focusing on Desmoscolecida was done by using neighbor joining (NJ), maximum parsimony (MP), maximum likelihood (ML) and Bayesian inference (BI) methods. All four resultant trees consistently and strongly supported that the family Desmoscolecidae forms a monophyletic group with very high node confidence values. The monophyletic clade of desmocolecid nematodes was placed as a sister group of the clade including some members of Monhysterida and Araeolaimida, Cyartonema elegans (Cyartonematidae) and Terschellingia longicaudata (Linhomoeidae) in all the analyses. However, the present phylogenetic trees do not show any direct attraction between the families Desmoscolecidae and Cyartonematidae. Within the monophyletic clade of the family Desmoscolecidae in all of the present phylogenetic trees, there were consistently observed two distinct sub-groups which correspond to the subfamilies Desmoscolecinae [Greeffiella sp. + Desmoscolex sp.] and Tricominae [Paratricoma sp. + Tricoma sp].     

Bozasella gracilis n. sp. (Ciliophora,Entodiniomorphida) from Asian elephant and phylogenetic analysis of entodiniomorphids and vestibuliferids

Bozasella gracilis n. sp. in the order Entodiniomorphida was found in fecal samples of an Asian elephant kept in a zoo. The ciliate has general and infraciliary similarities to the families Ophryoscolecidae and Cycloposthiidae. Phylogenetic trees were inferred from 18S rRNA gene sequences of B. gracilis, 45 entodiniomorphids, 10 vestibuliferids, 5 macropodiniids, and an outgroup, using maximum likelihood, Bayesian inference, and neighbor joining analyses. Of them, there were 32 new sequences; 26 entodiniomorphid species in the genera, Bozasella, Triplumaria, Gassovskiella, Ditoxum, Spirodinium, Triadinium, Tetratoxum, Pseudoentodinium, Ochoterenaia, Circodinium, Blepharocorys, Sulcoarcus, Didesmis, Alloiozona, Blepharoconus, Hemiprorodon, and Prorodonopsis, and 6 vestibuliferid species in the genera, Buxtonella, Balantidium, Helicozoster, Latteuria, and Paraisotricha. Thirty additional sequences were retrieved from the GenBank database. Phylogenetic trees revealed non-monophylies of the orders Entodiniomorphida and Vestibuliferida, the suborders Entodiniomorphina and Blepharocorythina, and the families Cycloposthiidae and Paraisotrichidae. Bozasella gracilis was sister to Triplumaria. In addition, to avoid homonymy, we propose Gilchristinidae nom. nov., Gilchristina nom. nov. and Gilchristina artemis (Ito, Van Hoven, Miyazaki & Imai, 2006) comb. nov.     

Notes on the soil ciliate biota (Protozoa, Ciliophora) from the Shimba Hills in Kenya (Africa): diversity and description of three new genera and ten new species

A very diverse ciliate community was found in nine soil samples from the Shimba Hills Nature Reserve in Kenya, equatorial Africa. The ciliates, respectively, their resting cysts, were re-activated from air-dried samples using the non-flooded Petri dish method. Species were determined from life and by silver impregnation. 34 (27%) of the 125 taxa identified had not yet been described in 1985, when the samples were collected and investigated. The richest samples, each containing 59 species, were those from a deciduous primary forest and a young secondary pine forest. The most remarkable species discovered in the Shimba Hills were Krassniggia auxiliaris, Bresslauides terricola, Gigantothrix herzogi, and Afrothrix darbyshirei. They are flagships with a very distinct morphology and easy to recognise due to their extraordinarily large body size. Krassniggia auxiliaris occurs also in Australia and probably has a restricted Gondwanan distribution, like some other ciliates. Bresslauides terricola was later found in soils from all main biogeographical regions, except for Antarctica. Gigantothrix herzogi and Afrothrix darbyshirei are still unique to the Shimba Hills. The following taxa are described in detail: Sikorops woronowiczae nov. gen., nov. spec., Arcuospathidium multinucleatum nov. spec., Dileptus similis Foissner, 1995, Plagiocampa bitricha nov. spec., Drepanomonas exigua exigua Penard, 1922, D. exigua bidentata nov. sspec., Parafurgasonia protectissima (Penard, 1922) nov. comb., P. terricola nov. spec., Brachyosoma brachypoda mucosa nov. sspec., Gigantothrix herzogi nov. gen., nov. spec., Afrothrix darbyshirei nov. gen., nov. spec., Oxytricha africana nov. spec., and O. elegans nov. spec.     

In situ nutrient enrichment experiments with periphyton in agricultural streams

The abundance, composition and seasonal distribution of planktonic protozoans and physical and chemical variables such as temperature, dissolved oxygen content, pH, and chlorophyll a concentration were analyzed monthly from February 1985 to January 1986 in eutrophic Rio Grande Reservoir. Analyses were performed on water samples collected at the surface and bottom (0.5 m above the sediment) in three stations, and individual distribution profiles were constructed for the major species. Dominant protozoan taxa included Codonella cratera, Coleps amphacantus, Coleps hirtus, Halteria grandinella, Mesodinium pulex, Tintinnidium sp., Urotricha spp., Vorticella spp., and Difflugia sp.. The distribution of some species was probably related to temperature and dissolved oxygen content.     

Genetic heterogeneity in internal transcribed spacer genes of Balantidium coli (Litostomatea, Ciliophora)

The species Balantidium coli is the only ciliate that parasitizes humans. It has been described in other primates, and it has been proposed that the species B. suis from pigs and B. struthionis from ostriches are synonyms of B. coli. Previous genetic analysis of pig and ostrich Balantidium isolates found a genetic polymorphism in the ITS region but its taxonomic relevance was not established. We have extended the genetic analysis to Balantidium isolates of pig, gorilla, human and ostrich origin. We have PCR-amplified and sequenced the ITS region of individual Balantidium cells. The predicted ITS secondary structures of the sequences obtained were transferred by homology modelling to the sequences of other Trichostomatia ciliates (Isotricha, Troglodytella, Lacrymaria and Spathidium) and compared to determine the importance of the differences in the primary sequences. The results show that the ITS2 secondary structure of the species considered follows the general pattern of other ciliates, although with some deviations. There are at least two main types of ITS sequence variants in B. coli which could be present in the same cell and they are common to the mammal and avian hosts studied. These data do not support B. suis and B. struthionis as distinct species.