A NEW DICROCOELIID FROM THE BANK VOLE CLETHRIONOMYS GLAREOLUS (RODENTIA: MICROTIDAE) FROM POLAND

Eurytrema coelomaticum: updated morphology of adult worms using advanced microscopy experiments

Eurytrema coelomaticum is a digenean flatworm of ruminants that is the causative agent of eurytrematosis, a disease of veterinary health concern. Although modern techniques of morphological analysis have provided new insights about the morphology and anatomy of parasitic helminths, most studies on E. coelomaticum adults are based on conventional light microscopy. In the present study, a combined approach using brightfield, fluorescence, confocal and scanning electron microscopies (SEMs), together with the cryofracture technique, have updated morphological data on E. coelomaticum recovered from cattle in Rio de Janeiro State, Brazil. Light microscopy confirmed the presence of several structures present in the current description, such as suckers, pharynx, oesophagus, intestinal bifurcation and the cirrus-sac. Fluorescence stereomicroscopy revealed for the first time the cubic crystal protein inclusions in the forebody, which were further detailed by confocal and SEMs. Confocal microscopy provided detailed information of the muscular architecture associated with the attachment structures (suckers), digestive system (pharynx and oesophagus), egg-forming complex (ovary, Mehlis' gland and Laurer's canal) and male reproductive system, which are similar to those found in other digenean flukes. SEM images of cryofractured parasites showed mucus and developing eggs within uterine loops. It was demonstrated that the combination of advanced tools generated complementary information, confirming the importance of experimental morphology in parasitology. Therefore, the knowledge of the adult structural organization of E. coelomaticum was improved and this work has contributed to propose new morphological criteria to evaluate the effects of antiparasitic drugs on flukes of medical and veterinary importance.

Phylogenetic relationships within Dicrocoeliidae (Platyhelminthes: Digenea) from birds from the Czech Republic using partial 28S rDNA sequences

Partial (D1-D3) 28S rRNA gene sequences from 16 isolates of digenean parasites of the family Dicrocoeliidae recovered from 16 bird species from the Czech Republic were used for phylogenetic reconstruction. Comparison with sequences available from GenBank suggests that the genus Brachylecithum is paraphyletic, requiring further validation and possible systematic revision. Although partial 28S rDNA is relatively conserved, analyses suggest that the following taxa are synonymous: Lutztrema attenuatum = L. monenteron = L. microstomum, Brachylecithum lobatum = B. glareoli. Zonorchis petiolatus is reassigned back to the genus Lyperosomum with L. collurionis as a junior synonym. The study revealed how complicated the systematics of the family Dicrocoeliidae is currently. The morphology of the group is variable, and the current distinguishing characters at species and even generic level are not sufficiently distinctive; it is difficult to identify the specimens correctly and identification of GenBank isolates is not reliable. Extensive sampling of isolates for both molecular and morphological studies is necessary to resolve the relationships within the family.

Molecular characteristics of representatives of the genus Brachylecithum Shtrom, 1940 (Digenea, Dicrocoeliidae) with comments on life cycle and host specificity

The genus Brachylecithum was for the first time subject to molecular taxonomic phylogenetic analysis in order to ascertain relationships among its component taxa. We used two markers—the nuclear ribosomal 28S ribosomal DNA (rDNA) gene and the mitochondrial cox1 gene, for six species of the genus; 11 sequences of partial 28S rDNA and partial cox1 were obtained from adult B. capilliformis, B. glareoli, B. kakea, B. laniicola, B. lobatum, and B. strigis, and from larval stages obtained from snails of the genus Cepaea. We propose to synonymize B. strigis with B. lobatum, while the genetic differences in the 28S rDNA gene and mitochondrial cox1 gene confirm the species status of B. capilliformis and indicate a distinct group within Brachylecithum, including B. kakea and B. laniicola. Cercarial and metacercarial isolates from the snails showed 100 % similarity to B. lobatum; thus, it is the first record of Cepaea snails as intermediate hosts of this species and the first report on life cycle abbreviation within the Dicrocoeliidae.