A new species of Uronychia (Spirotrichea: Euplotida) from Argentina.

Uronychia clapsae sp. n. was discovered in an artificial channel that drains an endorheic area from the "sandy Pampa" into the upper basin of Salado River, Buenos Aires, Argentina. This euplotid measures 56-112 µm × 42-70 µm in vivo, is oval in shape and the buccal field is enormous, occupying ca. 80% of body length. It is characterized by having two macronuclear nodules and one micronucleus; usually 10 anterior and invariably three posterior membranelles; right end of paroral hook-like; buccal cirrus base about 3.5-6.0 µm long; invariably four frontal, two ventral, three left marginal, four transverse, and three caudal cirri; six dorsal kineties, kinety 1 with 15-22 dikinetids. Most Uronychia species were recorded in marine habitats, while this new isolate was found in a slightly saline, inland water body. Taxonomic and nomenclatorial concerns on some species assigned to Uronychia are also discussed.

A new oligotrich (Ciliophora, Oligotrichia) from Argentina, with redefinition of Novistrombidium Song and Bradbury.

A new oligotrich similar to Novistrombidium was discovered in plankton samples from an artificial tributary of the Salado River, Buenos Aires province, Argentina, in summer 2010. Propecingulum fistoleramalliei sp. n. has an obovate and anteriorly truncated body, with a conspicuous ventral furrow, is flattened ventrally, and has a prominent right apical protrusion. It temporarily attaches to the substratum by a posterior mucous thread. Rod-shaped extrusomes arranged equidistantly and insert directly above the girdle kinety. The macronucleus is globular to ellipsoidal. The contractile vacuole is located in the left, anterior quarter of the cell and the adoral zone is composed of 30-35 collar, 9-14 buccal, and two thigmotactic membranelles. The girdle kinety is dextrally spiraled and ventrally open; the ventral kinety is posterior to anterior end of the girdle kinety. The oral primordium develops posterior to the right thigmotactic membranelle and anterior the stripe of extrusomes above left, lateral portion of the girdle kinety. The SSUrDNA phylogeny confirms one more time that Novistrombidium is not monophyletic; consequently, we elevate the subgenus Propecingulum up to genus rank and redefine the genus Novistrombidium.

Discomorphella pedroeneasi sp. nov. (Ciliophora, Odontostomatida): An anaerobic ciliate hosting multiple cytoplasmic and macronuclear endocytobionts.

Odontostomatids are among the less studied representatives of the Ciliophora. They are anaerobic microeukaryotes usually occurring as rare species in sapropelic environments. Here we describe a novel species of Discomorphella, named Discomorphella pedroeneasi sp. nov., using light and electron microscopy observations. Discomorphella pedroeneasi displays many complex morphological features, for which new terms are introduced, such as the auricules, epistomial fringe spacer, frontal awning, odontostomatid ciliary sockets, oral lips and ventral flap. Remarkably, D. pedroeneasi has at least six types of endocytobionts, including intramacronuclear ones, and organelles ultrastructurally similar to the M/H bodies of the odontostomatid Saprodinium dentatum. Based on the new data and revision of the literature, we propose two new diagnostic characters for species separation within Discomorphella: the fringe spacer ratio and the posterior fringe ratio. The taxonomy of Discomorphella is revised and an identification key is provided.

Ontogeny and Molecular Phylogeny of Apoamphisiella vernalis Reveal Unclear Separation between Genera Apoamphisiella and Paraurostyla (Protozoa, Ciliophora, Hypotricha).

Morphology and divisional morphogenesis of the hypotrich ciliate Apoamphisiella vernalis are investigated based on two populations from Brazil. Typical specimens of A. vernalis replicates its ventral ciliature from six fronto-ventral-transverse (FVT) anlagen independently formed for proter and opisthe, plus one or more short anlagen located between IV and V, which form surplus transverse cirri. Dorsal morphogenesis occurs as in typical oxytrichid dorsomarginalians, viz., with formation of three anlagen and fragmentation of the rightmost one. Dorsomarginal kineties are formed near anterior end of right marginal cirral row anlagen. Various anomalous specimens exhibiting more than two long ventral rows were found, which are explained by increasing the number of FVT anlagen and/or the number of cirri produced by anlagen. Comparative ontogeny and phylogenetic analyses based on the 18S rDNA reveal that Apoamphisiella vernalis is closely affine to North American and European strains of the Paraurostyla weissei complex. Their reduced genetic distances and conspicuous morphological variability show that both genera can overlap, which implies the necessity of re-evaluating the contextual relevance of some morphological characters commonly used for genus-level separation within hypotrich taxa.

Morphology of Clapsiella magnifica gen. n., sp. n., a new hypotrichous ciliate with a curious dorsal ciliary pattern.

The present work describes the morphology and infraciliature of a new hypotrichous ciliate, Clapsiella magnifica gen. n., sp. n., found in rewetted soil from a temporal pond in Argentina. It was studied by means of live observation and protargol impregnation. Its main diagnostic features are: Flexible hypotrich measuring 250-320 µm × 70-140 µm in vivo; two macronuclear nodules and 4-6 micronuclei. Single contractile vacuole. Cytoplasm transparent, cortical granules absent. Somatic ciliature composed of a tricorona of cirri, three buccal(?) cirri, 6-9 ventral rows, 3-5 right marginal(?) rows, one left marginal row, and 12-17 transverse cirri. Dorsal pattern rather complicated, with about 14 kineties and kinety fragments, with scattered kinetids among them; 17-28 caudal cirri arranged in three rows on dorsal kineties 1, 3, and 7. Remarkably, dorsal kinetids have two or four basal bodies, bearing a stiff bristle arising from left anterior basal body. Adoral zone composed of 70-92 membranelles, occupying about 40% of body length in protargol preparations; paroral and endoral curved, resembling a cyrtohymenid pattern. The peculiar dorsal ciliary arrangement and the unique combination of other characters require the establishment of a new genus for this new species, which is considered incertae sedis in the Hypotricha but possibly related to the oxytrichids.

Ciliates from eutrophized water in the northern Brazil and morphology of Cristigera hammeri Wilbert, 1986 (Ciliophora, Scuticociliatia).

Ciliates occur in all major aquatic and soil environments worldwide and are important links in the microbial food webs, which, along with other free-living protists, are generally overlooked in biodiversity conservation programs. In Brazil, the northern region comprises the Brazilian Amazonia, an area widely known for its huge biodiversity. However, the diversity of ciliates in that region is still almost unknown. As result of the present study, a total of 21 species of ciliates, distributed among 15 genera, were inventoried from samples of eutrophized water collected in the city of Belém, capital of the state of Pará, one of the states which comprise the Brazilian Amazonia. In addition, a local population of the rare scuticociliate Cristigera hammeri is described from optical and electron microscopy observations, and its synonymy with C. pleuronemoides is rejected based on new evidence.

An Antarctic hypotrichous ciliate, Parasterkiella thompsoni (Foissner) nov. gen., nov. comb., recorded in Argentinean peat-bogs: morphology, morphogenesis, and molecular phylogeny.

The ciliate Parasterkiella thompsoni (Foissner, 1996) nov. gen., nov. comb. was originally described from Antarctica. In the present study, we report the morphology, morphogenesis during cell division, and molecular phylogeny inferred from the 18S-rDNA sequence of a population isolated from the Rancho Hambre peat bog, Tierra del Fuego Province (Argentina). The study is based on live and protargol-impregnated specimens. Molecular phylogeny was inferred from trees constructed by means of the maximum parsimony, neighbor joining, and Bayesian analyses. The interphase morphology matches the original description of the species. During the cell division, stomatogenesis begins with the de novo proliferation of two fields of basal bodies, each one left of the postoral ventral cirri and of transverse cirri, which later unify. Primordia IV-VI of the proter develop from disaggregation of cirrus IV/3, while primordium IV of the opisthe develops from cirrus IV/2 and primordia V and VI from cirrus V/4. Dorsal morphogenesis occurs in the Urosomoida pattern-that is, the fragmentation of kinety 3 is lacking. Three macronuclear nodules are generated before cytokinesis. Phylogenetic analyses consistently placed P. thompsoni within the stylonychines. New data on the morphogenesis of the dorsal ciliature justifies the transference of Sterkiella thompsoni to a new genus Parasterkiella.