Morphological and molecular evidence for the recognition of Allocreadium bursensis n. sp. (Trematoda: Allocreadiidae) from Angora loach Oxynoemacheilus angorae from Turkey.

This is the first study reporting parasites from the freshwater cyprinid Oxynoemacheilus angorae (Steindachner 1897) caught in Nilüfer Stream, Bursa, in the Northwest Anatolian Region of Turkey. Allocreadium bursensis n. sp. was described from the intesine of O.angorae based on morphological and genetic characteristics. Allocreadium bursensis n. sp. was differentiated from other Allocreadium spp. in having a combination of external (ventral and oral suckers ratio; body length and width and its ratio to forebody) and internal (cirrus pouch position; uterus extension in hindbody; egg size; disposition of anterior border of vitellarium; esophagus length) features. Phylogenetic hypotheses based on maximum parsimony, maximum likelihood, Bayesian inferrence, and neighbor joining analyses of sequence data strongly supported the hypothesis that A. bursensis is nested within the clade of Allocreadium species hosted by cypriniform fish, and it is more closely related to the Far Eastern species A. pseudoisoporum (Primorsky region, Russia) than to the African A. apokryfi. According to genetic p-distances, the taxonomic status of trematodes collected in Turkey was established as independent relative to nine of the valid Allocreadium spp.: 1.8-5.8% in 28S gene and 18.8-22.6% in cox1 gene. The present study increases the number of Allocreadium species and their definitive hosts recorded in Turkey and raises the number of Palearctic representatives of Allocreadium spp. to 26.

The SSU rRNA secondary structures of the Plagiorchiida species (Digenea), its applications in systematics and evolutionary inferences.

The small subunit ribosomal RNA (SSU rRNA) is widely used phylogenetic marker in broad groups of organisms and its secondary structure increasingly attracts the attention of researchers as supplementary tool in sequence alignment and advanced phylogenetic studies. Its comparative analysis provides a great contribution to evolutionary biology, allowing find out how the SSU rRNA secondary structure originated, developed and evolved. Herein, we provide the first data on the putative SSU rRNA secondary structures of the Plagiorchiida species. The structures were found to be quite conserved across broad range of species studied, well compatible with those of others eukaryotic SSU rRNA and possessed some peculiarities: cross-shaped structure of the ES6b, additional shortened ES6c2 helix, and elongated ES6a helix and h39 + ES9 region. The secondary structures of variable regions ES3 and ES7 appeared to be tissue-specific while ES6 and ES9 were specific at a family level allowing considering them as promising markers for digenean systematics. Their uniqueness more depends on the length than on the nucleotide diversity of primary sequences which evolutionary rates well differ. The findings have important implications for understanding rRNA evolution, developing molecular taxonomy and systematics of Plagiorchiida as well as for constructing new anthelmintic drugs.

Genetic divergence of human pathogens Nanophyetus spp. (Trematoda: Troglotrematidae) on the opposite sides of the Pacific Rim.

Human and animal nanophyetiasis is caused by intestinal flukes belonging to the genus Nanophyetus distributed on both North American and Eurasian coasts of Northern Pacific. In spite of the wide geographical distribution and medical and veterinary importance of these flukes, the intra-generic taxonomy of Nanophyetus spp. remains unresolved. The two most widely distributed nominal species, Nanophyetus salmincola and Nanophyetus schikhobalowi, both parasitizing humans and carnivorous mammals, were described from North America and eastern Eurasia, respectively. However, due to their high morphological similarity their interrelationships remained unclear and taxonomic status unstable. In this study, we explored genetic diversity of Nanophyetus spp. from the Southern Russian Far East in comparison with that of samples from North America based on the sequence variation of the nuclear ribosomal gene family (18S, internal transcribed spacers, ITS1-5·8S-ITS2 and 28S). High levels of genetic divergence in each rDNA region (nucleotide substitutions, indels, alterations in the secondary structures of the ITS1 and ITS2 transcripts) as well as results of phylogenetic analysis provided strong support for the status of N. salmincola and N. schikhobalowi as independent species.