title: Molecular and karyological identification and morphological description of cystocercous cercariae of Phyllodistomum umblae and Phyllodistomum folium (Digenea, Gorgoderidae) developing in European sphaeriid bivalves.
abstract: Two cystocercous gorgoderid cercariae of the genus Phyllodistomum Braun, 1899, Phyllodistomum umblae (Fabricius, 1780) and Phyllodistomum folium (Olfers, 1816), developing in sphaeriid bivalves from Norway and Lithuania, were studied and compared. Our previous molecular studies revealed very close phylogenetic relation of these two species and proved that cystocercous cercariae of P. folium develop in sporocysts in the gills of sphaeriid bivalves. In the present study morphological descriptions are given for the two cercariae, together with karyological and molecular characteristics. Comparative karyological and sequence analysis using ITS2 and 28S rDNA revealed the conspecificity of cercariae emitted from Pisidium hibernicum and Sphaerium corneum with adult P. umblae from Thymallus thymallus and Coregonus albula. The cercariae of P. folium and P. umblae are very similar morphologically with main differences in the structure of the tail. The two species clearly differ in karyotype structure. The diploid set of P. folium is composed of 18 chromosomes, but 16 chromosomes with one pair of large metacentrics were found in mitotic cells of P. umblae. Interspecific karyotypic difference presumably arose from Robertsonian fusion of two uni-armed chromosomes.
authors.affiliation: Institute of Ecology of Nature Research Centre, Akademijos str. 2, LT-08412 Vilnius, Lithuania. Electronic address: romualda@ekoi.lt.
authors.forename: Romualda
authors.initials: R
authors.lastname: Petkevičiūtė
authors.affiliation: Institute of Ecology of Nature Research Centre, Akademijos str. 2, LT-08412 Vilnius, Lithuania; Department of Parasitology, Institute of Zoology, B. Khmelnytskogo 15, 01601 Kyiv, Ukraine. Electronic address: olena.kudlai@gmail.com.
authors.forename: Olena
authors.initials: O
authors.lastname: Kudlai
authors.affiliation: Institute of Ecology of Nature Research Centre, Akademijos str. 2, LT-08412 Vilnius, Lithuania. Electronic address: stunzenas@ekoi.lt.
authors.forename: Virmantas
authors.initials: V
authors.lastname: Stunžėnas
authors.affiliation: Institute of Ecology of Nature Research Centre, Akademijos str. 2, LT-08412 Vilnius, Lithuania. Electronic address: grasta@ekoi.lt.
authors.forename: Gražina
authors.initials: G
authors.lastname: Stanevičiūtė
mesh_terms: D000818:Animals; D049872:Bivalvia / Q000469:parasitology*; D058487:Cercaria / Q000033:anatomy & histology / Q000145:classification* / Q000235:genetics*; D004275:DNA, Ribosomal / Q000235:genetics; D006790:Host-Parasite Interactions; D007621:Karyotyping; D013045:Species Specificity; D014200:Trematoda / Q000033:anatomy & histology / Q000145:classification* / Q000235:genetics*
chemical_list: D004275:DNA, Ribosomal
keywords: 28S; Cystocercous cercariae; ITS2 rDNA; Karyotype; P. folium; Phyllodistomum umblae