A total of 28,387 oligochaetes belonging to the families Tubificidae, Lumbriculidae, Naididae and Enchytraeidae were examined at regular intervals for actinosporean infections from October 1996 to August 1998 from a freshwater salmon farm in Northern Scotland. A total of 21 types of actinosporeans belonging to seven collective groups synactinomyxon (three types), aurantiactinomyxon (four types), echinactinomyxon (five types), raabeia (six types), triactinomyxon (one type), neoactinomyxum (one type) and siedleckiella (one type) were found. Synactinomyxon type 1, echinactinomyxon type 1 and raabeia type 4 were most abundant. The overall infection prevalence of oligochaetes was 2.9%. Aurantiactinomyxon, synactinomyxon and neoactinomyxum were most common in summer and autumn. Raabeia was most common in spring and summer and echinactinomyxon in winter and spring. Siedleckiella was found only in spring and triactinomyxon in all seasons except winter. A positive relationship between water temperature and the number of actinosporean types released was observed. Most actinosporean types were found in only one host species.
On a semiarid sand grassland (Festucetum vaginatae) colonised by juniper (Juniperus communis L.) shrubs terricolous lichens and mosses segregate strongly between microhabitats: certain species grow in the open grassland, others almost exclusively in the shade of junipers. The contrasting irradiances of these microhabitats influence much the metabolism of these organisms, and thus affect their small-scale distribution. This was confirmed by determining the efficiency of photochemical energy conversion by measuring chlorophyll a fluorescence parameters. In the open grassland maximum photochemical efficiency of photosystem 2 (PS2, Fv/Fm) declined from the humid spring to the hot and dry summer in all species, and this was caused by an increase in base fluorescence (F0), but not by the decrease in fluorescence maximum (Fm). In summer, mosses and lichens growing in the open grassland generally possessed lower Fv/Fm than cryptogams growing in the shade cast by juniper shrubs. Thus mosses and lichens in the open grassland suffer lasting reduction in photochemical efficiency in summer, which is avoided in the shade of junipers. Juniper shrubs indeed influence the composition and small-scale spatial pattern of sympatric terricolous lichen and moss communities by-among others-providing a shelter against high light in summer. and T. Kalapos, K. Mázsa.
The original description of Myxobolus longisporus Nie et Li, 1992, the species infecting gills of Cyprinus carpio haematopterus L., is supplemented with new data on the spore morphology and pathogenicity. Spores are elongate pyriform with pointed anterior end, 15.7 (15.5-16.5) µm long, 6.7 (6-8) µm wide and 5.5 µm thick. Sutural ridge is straight and narrow. Mucus envelope is lacking. Two equal-sized elongate pyriform polar capsules are 8.5 µm long and 2.5 µm wide with convergent long axes. Polar filament coiled perpendicularly to the long axis of the capsule makes 9 (8-10) turns. Posterior end of polar capsules exceeds mid-spore by 15-20%. Cyst-like plasmodia are localised in the gill secondary lamellae. The infection is described in adult big host specimens. Gross lesions manifested as dark red colouration of gill tissues were restricted to the ventral part of the first gill arches. Remarkable site specificity (apical part of secondary lamellae) was observed in the course of development of microscopic lesions. M. longisporus is characterised also on the molecular level using sequences of SSU rRNA gene. Phylogenetic analysis based on these sequences has allowed clearer phylogenetic relationships to be established with other species of the genus Myxobolus sequenced to date.