An unnamed microcercous cercaria (Digenea: Monorchiidae), a parasite of Amiantis purpurata (Lamarck, 1818) (Bivalvia: Veneridae) and its corresponding metacercaria from the province of Buenos Aires and the Patagonian coast of the Southwest Atlantic Ocean, are described. The cercaria described in this paper differs from the three other monorchiid microcercous cercariae, i.e., Lasiotocus minutus (Manter, 1931), Lasiotocus elongatus (Manter, 1931), and Cercaria caribbea XXXVI Cable, 1956, mainly because of the extension of the excretory vesicle and the location of the ventral sucker. Cercariae artificially extracted from sporocysts encyst in a dish and form metacercariae enveloped by a gelatinous sac with two prolongations, which are used to adhere to the substratum. The monorchiid described in this paper has a life cycle similar to those of L. minutus and L. elongatus, although the adult stage of the present species is still unknown. Their larvae are similar in morphology and have venerid clams as their first hosts. The presence of a monorchiid larva is reported for the first time in the Southern Hemisphere. Its monthly prevalence rates, ranging from 0 to 25% (mean: 8.3%), are given from the Patagonian coast. The infection seems to cause castration as it was observed that during March through to May, when most gametes were produced in uninfected individuals, 81% of the infected individuals did not produce gametes.
Parazitické stádium velkých mlžů (řád Unionida) vytváří velmi těsné spojení mezi těmito druhy a jejich rybími hostiteli. Tento článek představuje variabilitu mezidruhových interakcí na příkladech středoevropských druhů., The parasitic stage of freshwater mussels (order Unionida) constitutes a tight host-affiliate linkage between mussels and their host fish. This article presents the variability of interactions using the Central European species as a model group., and Karel Douda.
Zévy (Tridacnidae) jsou mezi mořskými mlži výjimečné velikostí i způsobem získávání potravy. V jejich plášti se vyskytují mikroskopické řasy zooxantely, které fotosyntézou produkují sacharidy, o něž se dělí s hostitelem. Za nápadné zbarvení pláště vděčí zévy zooxantelám a specializovaným buňkám iridocytům., Giant clams (Tridacnidae) are exceptional among sea clams for their size and the way they acquire food. On their shells microscopic zooxanthella algae occur, producing saccharides through photosynthesis, which they share with the host. The conspicuous coloring of the shells is due to the clams’ zooxanthellae and specialized iridocyte cells., and Nicole Černohorská.