Archiv für Protistenkunde最新文献

The oxymonad flagellate Monocercomonoides termitisRadek, 1994, an intestinal symbiont of the dry-wood termite Kalotermes sinaicus, is renamed M. hausmanni nom. nov. because of preoccupation by M. termitisKrishnamurthy & Sultana, 1979.

The morphology and taxonomy of 15 marine ciliates (Chaenea vorax, Lacrymaria marinum*, Dysteria brasiliensis*, Uronema marinum*, Homalogastra binucleata, Fabrea salina, Strombidium platum nov. spec., Strombidium globosaneum nov. spec., Strombidium styliferum*, Euplotes charon*, Euplotes vannus, Euplotes rariseta*, Diophrys scutum*, Diophrys oligothrix*, Diophrys appendiculata*) from China were investigated. Nine species (marked with *) were recorded from this area for the first time. The infraciliature and the silverline system of all species reported here were investigated using various silver impregnation methods and, if possible, biometrically described. Two new species are described: Strombidium platum nov. spec.: Oblong to elliptical marine Strombidium with conspicuous collar and long-oval macronucleus; size in vivo 70-100x40-60 µm; dorso-ventrally 1:2 flattened; 8-11 buccal and 15-18 collar adoral membranelles, only one somatic kinety, extrusomes ca. 5 µm, irregularly arranged. Strombidium globosaneum nov. spec.: Colourless, small, ovoid-shaped marine Strombidium. Size in vivo 20-35×20-30 µm, 10-12 collar adoral membranelles, 5-6 buccal adoral membranelles; buccal lip inconspicuous, lorica absent.

The microsporidium Trichotuzetia guttata gen. et sp. n., a parasite of the copepod Cyclops vicinus in the Czech Republic, is described based on light microscopic and ultrastructural characteristics. All life cycle stages have isolated nuclei. In the merogonial reproduction multinucleate plasmodia divide by plasmotomy, yielding uninucleate merozoites. Sporonts develop into multinucleate plasmodia, which split in a rosette-like manner, initially into wide lobes with large nuclei, finally into narrow lobes with small nuclei. Sporoblasts are formed in individual sporophorous vesicles generated by the sporogonial plasmodium. Immature sporogonial stages are covered by fibrillar projections uniting the exospore with the envelope of the sporophorous vesicle. Mature spores, which are pyriform with pointed anterior end, normally lack projections. Unfixed spores measure 4.6-5.7x2.7-3.3 µm. The exospore is four-layered. The anterior lamellae of the polaroplast are wide. The posterior ones (present in a short zone) are narrow close to the filament, wider at the periphery. The polar filament is isofilar with 9-10, 102-131 nm wide, coils in a single layer close to the spore wall in posterior half of the spore. The angle of tilt is 60-65°. Isometric, 21-25 nm wide virus-like particles were observed in the nuclei of mature spores. Experimental transmission of the microsporidium per os has failed. The small subunit rRNA gene has been sequenced and the data have been used in a phylogenetic analysis (PAUP). The species is compared to previously described microsporida of copepods, and the taxonomy is discussed.

Rhizamoeba schnepfii was isolated in September 1994 in plankton samples from the German Bight, North Sea. It was an obligate algivorous amoeba with an unusual feeding mode. Host diatoms were not engulfed, but R. schnepfii pierced a pseudopodium into the frustule and gradually phagocytized the diatom protoplast. The host range was tested. Observation on the feeding success revealed that some diatom species could not be consumed unless the frustule was damaged. It is discussed whether the frustule might serve as a defence mechanism against attacks by invasive protozoans.

Gamonts and agamonts of the extant nummulitid Cycloclypeus carpenteri were collected from a depth between 45 and 61 m, near Okinawa (Ryukyu Islands, Japan) and maintained in the laboratory in Kiel (Germany) until they reproduced. All of them grew in the laboratory, including damaged specimens, which regenerated more or less regular tests. Like other nummulitids, they formed sheaths for attachment, complete in young and incomplete in adult specimens. Eighteen agamonts formed gamonts in the laboratory, the first reproducing after 5.5 months and the last after 9.2 months of maintenance. The process of multiple fission can be divided into 5 well defined periods. During the formation of the two-chambered embryonic apparatuses, the symbiotic diatoms are apportioned to the daughter cells by a highly organized process that is identical in all nummulitids. The number of gamonts provided by 3 agamonts was 1740, 1910 and 2540. The mean prolocular size in the two-chamber stage of the gamonts was 263 pm (minimum 200 µm, maximum 327 µm). The mean size of 5 gamonts from the natural habitat was 8.1 mm on the day of reproduction. The mean size of 39 gamonts from laboratory culture was 8.6 mm. Gamete formation began at an age of about 11 months and ended at an age of about 13 months. Gamonts released their 2.5-3.0 Nm biflagellated gametes over 0.7 to 15 hours mainly during the light period.