The first mitochondrial genome of Codonobdella sp. (Hirudinea, piscicolidae), an endemic leech species from Lake Baikal, Russia and reassembly of the Piscicola geometra data from SRA.

In this study, we assembled a complete mitochondrial genome of Codonobdella sp. sample from Lake Baikal, Russia and reassembled third party raw data of Piscicola geometra. Mitogenomes of both freshwater piscine leeches consist of 37 genes, including 13 protein-coding genes (PCGs), two ribosomal genes (12S and 16S), 22 transport RNA genes, and one control region. The complete mitogenome of Codonobdella sp. is 14,486 bp long and A + T biased (75.51%). The complete mitogenome of Piscicola geometra is 14,788 bp long and A + T biased (78.27%).

Amazing Discoveries of Benthic Fauna from the Abyssal Zone of Lake Baikal.

Lake Baikal is a natural laboratory for the study of species diversity and evolution, as a unique freshwater ecosystem meeting the all of the main criteria of the World Heritage Convention. However, despite many years of research, the true biodiversity of the lake is clearly insufficiently studied, especially that of deep-water benthic sessile organisms. For the first time, plastic waste was raised from depths of 110 to 190 m of Lake Baikal. The aim of this study was to examine the biological community inhabiting the plastic substrate using morphological and molecular genetic analysis. Fragments of plastic packaging materials were densely populated: bryozoans, leeches and their cocoons, capsules of gastropod eggs, and turbellaria cocoons were found. All the data obtained as a result of an analysis of the nucleotide sequences of the standard bar-coding fragment of the mitochondrial genome turned out to be unique. Our results demonstrate the prospects for conducting comprehensive studies of artificial substrates to determine the true biodiversity of benthos in the abyssal zone of Lake Baikal.

New information on the distribution pattern of Acanthobdella peledina (Annelida, Acanthobdellida) in Eastern Siberia.

The Acanthobdellida is a group of annelid parasites of fish, which are restricted to subarctic parts of the Northern Hemisphere. These ancient worms arouse the interest of the scientific world due to their mosaic combination of (1) primitive oligochaetous characters (e.g. the presence of setae on the very anterior segments, a lateral nerve system and a metameric coelomic cavity around the intestinal canal) and (2) evolutionarily advanced hirudinean ecological and morphological features (e.g. suckers and parasitic lifestyle), attesting to their intermediate role between Oligochaeta and Euhirudinea (i.e. leeches with setae).

Genetic diversity of Diplomonadida in fish of the genus Coregonus from Southeastern Siberia.

Diplomonadida are primitive flagellate protozoa, among which both commensals and pathogens have been recorded. To date, members of the genera Hexamita and Spironucleus have been reported in the digestive system of fish in the Baikal region. We determined the genetic diversity of Diplomonadida in fish of the genus Coregonus from south-eastern Siberia using molecular-genetic methods. Fish for analysis were caught in Lake Baikal and in the Barguzin, Nepa, Chechuy, and Kirenga rivers from 2010 to 2013. Gall bladders, hindguts and foreguts of 120 specimens of Coregonus migratorius representing three morpho-ecological groups, 25 specimens of Coregonus lavaretus baicalensis, 25 specimens of Coregonus tugun and 30 specimens of Coregonus lavaretus pidschian were analysed via amplification with primers specifically designed for eukaryotes. Amplicons positive for Diplomonadida were sequenced. A phylogenetic analysis revealed that diplomonad flagellates of whitefish from Southeastern Siberia belong to Spironucleus barkhanus. Positive Diplomonadida DNA samples were analysed with primers designed in the present study for the amplification of small subunits of ribosomal DNA fragments of S. barkhanus (about 1,430 bp) and sequenced. Phylogenetic analysis revealed inside the clade of S. barkhanus besides the cosmopolitan genotype from European salmon that was detected earlier in Baikalian grayling, a new genotype unique to the fish of the genus Coregonus from Lake Baikal.

Leech-like parasites (Clitellata, Acanthobdellida) infecting native and endemic eastern Siberian salmon fishes.

Salmonoid fish bdellosis is caused by leech-like ectoparasites in the monogenetic order Acanthobdellida. Although Acanthobdella species have been known to infect several threatened species in Eurasia, little is known about their ecology and epidemiology. In this paper, we report on the mass affection (up to 70.7%) of fish in lower course of the Chechuj River, a right tributary of the Lena and provide information on finding Acanthobdella peledina on two of six salmonoid fish species inhabiting there: lenok and grayling. New and more specific data on morphological peculiarities and feeding strategy were obtained. The ratio of body length to width in studied acanthobdellid collection is significantly less than one provided for the A. livanowi and the rest A. peledina from other water systems of Eurasia. Biology and lifestyle of the parasite population are revealed for the first time.