Archiv für Protistenkunde最新文献

Concentrations of rumen ciliate protozoa in 12 Australian red deer (Cervus elaphus L.) ranged from 15.0 to 50.9 × 10⁴ per g. Mean percentage generic distributions were: Entodinium, 83.6; Diplodinium, 3.0; Eudiplodinium, 9.6; Metadinium, 1.9; Elytroplastron, 0.9; Epidinium, 0.4 and Isotricha, 0.5. Twenty species were identified, nine of which represent a new host record. This brings the total number of ciliate species identified in red deer to 32. Most cells of Diplodinium rangiferi were spined, which has not been observed previously. Earlier reports on generic and species composition in red deer are summarized and compared to the present results.

This contribution to the revision of the genus Achnanthes sensu lato concerns a section of 38 apparently closely related taxa. Neither do they fit into Achnanthes sensu stricto with the type species A. adnata (syn. A. brevipes) nor into Achnanthidium with type species A. microcephalum (syn. A. minutissima). They also do not conform with the morphologic pattern of Eucocconeis or of the recently described Psammothidium. The proposed new genus Achnantheiopsis is characterized by a unique complex of distinct features. These are represented in particular by the most prominent species respectively species clusters around A. lanceolata and A. delicatula.

Mica material from the type locality “Lüneburg” (BM, Kützing collection, packet 906) of Stephanodiscus minutulus (sub Cylotella minutula) was reinvestigated using LM and SEM and shown to contain more than one taxon. This statement corresponds well with Kützing's lithographs but not with his description. In addition to Stephanodiscus minutulus (Kütz.) Grunow, the recently described new species Stephanodiscus kuetzingiiKlee et Casper, Cyclotella schumannii (Grunow) Håk., and Cyclotella cf. radiosaGrunow were found.

This is the third study on the cyanoprokaryotic (cyanophycean, cyanobacterial) epiphytes, colonizing submersed substrates (mainly other filamentous algae) in streaming waters in central Mexico. The species of the genus StichosiphonGeitler 1932 were all made synonyms of S. sansibaricus by Drouet & Daily (1956). We have found six morphotypes, which can be distinguished at the species level, five corresponding to species defined by previous authors and one new species, S. exiguus. The morphological variation of the Mexican populations was studied, and the comparison with the original descriptions of type specimens is presented. The characters applied in the taxonomy of the genus Stichosiphon are discussed. One other species, known from Burma (Skuja 1949), was redefined according to the present diacritical features for this genus (S. skujae).

The ultrastructure of two actinosporean stages, Aurantiactinomyxon sp. (A), and Raabeia (R) forming part of the life cycle of Myxobolus cultusYokoyama, Ogawa & Wakabayashi, 1995 has been studied. In both A and R, binucleate early stages were observed; their proliferation was not detected. In A, intracellular early stages were also found. Earliest stage of pansporocyst formation in R was a uninucleate cell enveloped by an outer one which revealed surface villosities. The latter may be instrumental in facilitating transport of nutrients to sporoblast cells. Cell junctions exist in A and R between pansporocyst cells (gap junctions), attaching vasogenic cells to capsulogenic cells (gap junctions) and between valvogenic cells (septate junctions). The very simplest myxozoan cells represent the “polar bodies” resulting from the meiotic process; in its course, synaptonemal complexes were recorded in R. The structural features, even those little known ones recorded in A and/or R (fibres spaced at 11 nm running on the surface of the immature polar filament, meridional ridges on the upper part of the capsular primordium, the apex of polar capsule consisting of inner dense cone covered by a layer of microtubules, malformations in the development of the capsule, close association of the sporoplasm vegetative nuclei and infective cells, iodinophilous vacuole-like agglomerations of glycogen in the sporoplasm) show the unity of cell structures in myxozoa expressed in the course of the actino-myxosporean alternation. The unique features observed were viral inclusions in A capsulogenic cells, special modifications of RER cisternae and vesicles with stacks of small discs. Infective cells in the sporoplasm can be compared with the inner cells of myxosporean proliferative cycles, both constituting stem cells endowed with extraordinary morphogenetic potential.

In Paramecium primaurelia food vacuole formation depends on membrane material supply. By using different solid particle concentrations in unbacterized culture medium it is shown that a given amount of membrane material is available for food vacuole formation. This membrane amount is utilized more rapidly if the concentration of particles is higher (where the size of food vacuoles is larger), than for a lower concentration (where the size of food vacuoles is smaller). After the utilization of the membrane which was available for the cell, a decrease of the number of food vacuoles occurs. Furthermore, the rate of food ingestion decreases when starved cells were pressed continuously to form food vacuoles, because of particles suspended in the culture medium.

Hermesinum adriaticumZach. is a rare non-photosynthetic flagellate with an internal siliceous skeleton. It is of uncertain taxonomic position and was, recently classified within dinoflagellates (Ebriales). Subsurface accumulation of H. adriaticumZach. (up to 380,000 cells - I₋) was found around the brackish/seawater interface (BSI), in a small, saline coastal lake (Lake Rogoznica, central Adriatic coast), from March to November 1994. Dense populations of this species may be found only in stratified ecosystems with a well defined oxic/hypoxic (anoxic) - H²S enriched boundary layer. In Lake Rogoznica such conditions coincided with the BSI. The increasing gradient of phosphate, nitrate, ammonia and silicate concentrations provided evidence of a sharp chemocline below the BSI. In winter, an advective transport of H. adriaticum population was evident in the southeastern Adriatic; by an inflowing northerly current from the eastern Mediterranean.