Observations on Pyxidium tardigradum (Ciliophora), a protozoan living on Eutardigrada: infestation, morphology and feeding behaviour.
Pyxidium tardigradum is a protozoan that has been reported on a few occasions as an epizoan symphoriont living on eutardigrades. We report here the first records of this species from Kirghizia (the first Asian record), Poland and Portugal. The Portuguese population revealed the largest P. tardigradum infestation ever described in terms of both the whole tardigrade population, with 60% affected animals, as well as a single host, with 35 attached protozoan. The first ever Scanning Electron Microscope (SEM) photomicrographs and pictures of live P. tardigradum are also given. No considerable ultrastructural variability was detected within or between the populations, suggesting that P. tardigradum may be a true cosmopolitan species. Given that the ciliate imposed significant extra volumes on infested tardigrades (from 1% to as much as 136%), we also discuss possible negative effects of the protozoan on the fitness of the host and suggest that P. tardigradum should probably be considered as a eutardigrade parasite. Furthermore, some hypotheses about the life history strategies of the ciliate are proposed.
Vicente
Filipe
F
Centre for Environmental Biology and Department of Animal Biology, Faculty of Sciences, University of Lisbon, Campo Grande C2, 1749-016 Lisbon, Portugal. fjvicente@fc.ul.pt
Michalczyk
Lukasz
L
Kaczmarek
Lukasz
L
Boavida
Maria-José
MJ
D000818:Animals; D001522:Behavior, Animal; D016798:Ciliophora / Q000254:growth & development / Q000502:physiology / Q000648:ultrastructure; D005247:Feeding Behavior; D006790:Host-Parasite Interactions; D007448:Invertebrates / Q000469:parasitology*; D008855:Microscopy, Electron, Scanning