Morphological characteristics of Mesocestoides canislagopodis (Krabbe 1865) tetrathyridia found in rock ptarmigan (Lagopus muta) in Iceland

Genus Mesocestoides is a representative of the small cyclophyllidean family Mesocestoididae that is found parasitizing the small intestine of carnivores. The life cycle of cestodes from this genus is complex and requires two intermediate hosts. Cysticercoids are produced in the first intermediate host (oribatid mites), which when eaten by the second intermediate host (mainly rodents, but also other mammalian species, birds, reptiles, or amphibians) form tetrathyridia in the body cavity. Because of the rich history of nomenclatural evaluation of Mesocestoididae, the taxonomic status within the genus Mesocestoides is still unclear. Additional problem constitute the difficulty or even the impossibility in the determination of tetrathyridia based on morphological features. Thus, the aim of our study was to identify a molecular characteristic of the isolates of Mesocestoides from the second intermediate hosts (rodents) based on nuclear and mitochondrial ribosomal DNA data. We choose to analyze metacestodes isolated from two species of rodents (Apodemus agrarius and Myodes glarolus) from different sites. As a result of amplification of 18S rDNA, we obtained partial sequences from four isolates ranging from 1,116 to 1,162 bp. In relation to mitochondrial sequence, 354 bp product of 12S rDNA was obtained from one isolate. The neighbor joining and maximum parsimony trees were constructed in order to examine the phylogenetic relationship within Mesocestoides spp. occurring in rodents from central Europe. The results of our research on the larval stages from rodents, living in a periphery of urban agglomeration as well as in an area of reserve protection, confirm the data of more frequently occurring Mesocestoides litteratus.