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A small, freshwater dinoflagellate with an incomplete cingulum, identified as Esoptrodinium gemma Javornický (5Bernardinium bernardinense sensu auctt. non sensu Chodat), was maintained in mixed culture and examined using light and serial section TEM. Vegetative flagellate cells, large cells with two longitudinal flagella (planozygotes), and cysts were examined. The cells displayed a red eyespot near the base of the longitudinal flagellum, made of two or three layers of pigment globules not bounded by a membrane. Yellow-green, band-shaped chloroplasts, bounded by three membranes and containing lamella with three thylakoids, were present in both flagellate cells and cysts. Most cells had food vacuoles, containing phagotrophically ingested chlamydomonads or chlorelloid green algae; ingestion occurred through the ventral area, involving a thin pseudopod apparently driven by the peduncle. The pusule was tubular, with numerous diverticula in its distal portion, and opened into the longitudinal flagellar canal. Three roots were associated with each pair of flagellar bases, both in vegetative cells and in a planozygote. The longitudinal microtubular root bifurcated around the longitudinal basal body. The planozygote contained a single peduncle and associated structures, and a single transverse flagellar canal with the two converging transverse flagella. Using two ciliates as outgroup species, phylogenetic analyses based on maximum parsimony, neighbor-joining and posterior probability (Bayesian analysis) supported a clade comprising Esoptrodinium, Tovellia, and Jadwigia.

Freshwater Diatoms Indices Predictive model a b s t r a c tDiatoms are widely used in stream bioassessment due to their broad distribution, extraordinary variability and the ability to integrate changes in water quality. The indices Specific Polluosensitivity Index (SPI), standardized Biological Diatom Index (BDI), European Economic Community Index (CEC) and Generic Diatom Index (GDI), originally developed in France, are often applied in Portugal to evaluate stream ecological quality based on diatom communities. Alternatively, predictive models resulting from the comparison between the communities of the study site and those of a set of reference sites representing undisturbed or the best available conditions of a given region have been proposed as valuable methods for evaluating the ecological status of streams. In the present study, we applied the four above-mentioned widely used diatom-based indices (SPI, BDI, CEC and GDI) and a predictive model (MoDi) to 54 sites located in central Portugal to assess the sensitivity of the five methods to a range of anthropogenic disturbances cumulatively affecting streams and represented by 27 variables (e.g., organic enrichment, changes in morphology of the channels, integrity of the riparian corridor, land use in the catchment). The results were analyzed comparatively through Spearman correlations, Boxplots and Stepwise Discriminant Analysis. This study confirmed the sensitivity of diatoms to organic and nutrient contamination (showed by the MoDi, BDI, CEC and SPI) and revealed the importance of suspended solids (through the MoDi, GDI, and SPI). The relevance of modifications in land use to diatoms was shown by all methods applied, except for the GDI. The MoDI also revealed the importance of changes in the structure and morphology of the reach and the channel, like the construction of artificial walls or embankments and connectivity; the BDI also related its assessments with the riparian zone integrity; and the SPI was not useful in detecting morphological pressures. The GDI produced the most divergent assessments and was less effective in revealing the anthropogenic disturbances. The use of the predictive model (MoDi) is therefore a good method for the assessment of streams in central Portugal because it expresses a great diversity of quantitative and qualitative changes in freshwater systems reflected in the structure (species richness and abundance) of diatom communities.

Amphidinium lacustre Stein, non sensu auctt. was identified by reference to original descriptions, which differ significantly from later interpretations. Mixed cultures containing A. lacustre, cryptomonads, Spermatozopsis exsultans Korshikov, and small chlorelloid cells were examined for feeding events. The dinoflagellate ingested the cytoplasm of cryptomonads, leaving the periplast, and completely ingested Spermatozopsis and chlorelloid cells. A peduncle was used in the initial stages of prey capture, although it was not visible during food uptake. The ultrastructure of A. lacustre was typical of unarmored dinoflagellates. A single pusule per cell, consisting of one long, convoluted tube, opened directly into one of the flagellar canals. An eyespot was present, composed of presumably crystalline, vesicle‐contained units, similar to those of Gymnodinium natalense Horiguchi et Pienaar. The main components of the flagellar apparatus resembled those of other Amphidinium species, but differences were noted. The transverse basal body overlapped the proximal end of the longitudinal one at an angle of about 120°. Three connectives were distinguished between basal bodies, one of which consisted of radiating fibers linking individual triplets of the longitudinal basal body to one triplet of the transverse. Some flagellar apparatus components were closely associated to a vesicle and to a mitochondrion. A ventral ridge extended from the (incomplete) longitudinal striated collar to the peduncular striated collar. The peduncle was supported by a single strand of microtubules, which were surrounded by numerous vesicles with electron‐opaque contents.