Species delimitation through DNA barcoding of freshwater leeches of theGlossiphoniagenus (Hirudinea: Glossiphoniidae) from Eastern Siberia, Russia

Role of Antimicrobial Peptides in Immunity of Parasitic Leeches

The review summarizes the current state of knowledge about leech immunity, with emphasis on the special role of antimicrobial peptides (AMPs), and highlights the wide variety of primary AMP structures, which seem to correlate with a variety of life strategies and the ecology of ectoparasites. Antimicrobial proteins and AMPs are a diverse class of natural molecules that are produced in all living organisms in response to an attack by a pathogen and are essential components of the immune system. AMPs can have a wide range of antibiotic activities against foreign and opportunistic bacteria, fungi, and viruses. AMPs play an important role in selection of colonizing bacterial symbionts, thus helping multicellular organisms to cope with certain environmental problems. AMPs are especially important for invertebrates, which lack an adaptive immune system. Although many AMPs are similar in physicochemical properties (a total length from 10 to 100 amino acids, a positive total charge, or a high cysteine content), their immunomodulatory activities are specific for each AMP type.

Diversity of the Piscicola Species (Hirudinea, Piscicolidae) in the Eastern Palaearctic with a Description of Three New Species and Notes on Their Biogeography

Biodiversity is considered one of the most significant parameters for characterizing aquatic environments. The value of species diversity is taken into account when assessing the ecological state and quality of the ecosystem. However, erroneous taxonomic identification distorts biodiversity signification and, consequently, prevents a clear understanding of ecological signals and traits. In this study, we presented the first data on Piscicola leech species diversity in the vast area of the Eastern Palaearctic. To avoid misidentifications, an integrated approach was applied, combining modern DNA-based and classical morphological methods. Previously, only one species of the genus, Piscicola geometra, was recorded in the whole of Siberia. We discovered three new species: Piscicola sibirica sp. nov., Piscicola khubsugulensis sp. nov. (Eastern Siberia) and Piscicola nordica sp. nov. (European Northeast). The species Piscicola pojmanskae was reduced to synonymy with Piscicola geometra, whose description was updated. Taxonomic adjustments allowed us to ascertain the eastern edge of the Piscicola geometra distribution and to understand the biogeography of the group as a whole. The Piscicola geometra range is limited to Western Siberia, while the widespread Piscicola sibirica sp. nov. and the purely Khovsgolian Piscicola khubsugulensis sp. nov. inhabit Eastern Siberia.

Cryptic taxonomic diversity and high-latitude melanism in the glossiphoniid leech assemblage from the Eurasian Arctic

The family Glossiphoniidae is a diverse and widespread clade of freshwater leeches, playing a significant role in functioning of aquatic ecosystems. The taxonomy and biogeography of leeches from temperate, subtropical, and tropical regions attracted much attention of zoologists, while their taxonomic richness and distribution in the Arctic are poorly understood. Here, we present an overview of the Eurasian Arctic Glossiphoniidae based on the most comprehensive occurrence and DNA sequence datasets sampled to date. This fauna contains 14 species, belonging to five genera and three subfamilies. One genus and five species are new to science and described here. The world's northernmost occurrences of glossiphoniids are situated on the Taymyr Peninsula at 72° N, although further records at higher latitudes are expected. Most Arctic leeches are characterized by broad ranges crossing several climatic zones (e.g., Glossiphonia balcanica and G. nebulosa), although the distribution of two new species may be confined to the high-latitude areas. The Taymyr Peninsula with the nearby Putorana Plateau represents the most species-rich area (totally 9 species), while the European Arctic, Iceland, Kolyma Highland, and Chukotka Peninsula house depleted faunas (2-4 species per subregion). Finally, we show that the high-latitude melanism is a common phenomenon in glossiphoniid leeches.

Genome-Based Taxa Delimitation (GBTD): A New Approach

Proper taxonomic identification is essential for biological research. Unfortunately, there are no clear guidelines for taxonomic assignment above the species level. Here, we present a novel approach—GBTD—to the use of genetic divergence to evaluate the taxonomic position of certain samples with simultaneous estimation of the current systematics correctness. This approach includes measuring the raw and model-adjusted distances between DNA sequences and attributing them to the lowest taxonomic levels that are common in sample pairs to reveal distance distributions matching different taxonomic levels (species, genus, family etc.). GBTD facilitated the reassessment of the taxonomic position of the samples, whose genetic distances relative to other samples in the dataset did not match their taxonomic divergence. A data set of complete mitochondrial genome sequences of segmented worms was chosen to test this approach. As a result, numerous inconsistencies in the systematics of samples from GenBank were pointed out. These inconsistencies included both the oversplitting and overlumping of individuals into taxa of different levels and clear cases of misidentification. Our approach sparks re-evaluation of the current systematics where traditional methods fail to provide sufficient resolution.

First data on the Hirudinea fauna of lotic ecosystems of the Khanty-Mansi Autonomous Area (Russia)

Hirudinea, a small and ecologically important group of aquatic organisms, is poorly studied in northern Eurasia. In this study, we demyth the idea of the faunistic poverty of this region and present the first findings of rheophilic leeches from the Khanty-Mansi Autonomous Area, Russia. Investigation of 25 rivers (Severnaya Sosva, Ob, Konda-Irtysh, and Bolshoi Yugan river basins) resulted in finding 10 leech species with parasitic and non-parasitic life strategies. These species belong to two orders (Rhynchobdellida and Arhynchobdellida), three families (Glossiphoniidae, Piscicolidae, and Erpobdellidae) and six genera (Alboglossiphonia, Glossiphonia, Helobdella, Hemiclepsis, Piscicola, and Erpobdella). Five species, A.hyalina, G.verrucata, E.monostriata, E.vilnensis, and potentially new morphological species of piscine leeches Piscicola sp., have been discovered for the first time in Western Siberia. Data on species diversity of rheophilic leeches include the exact systematic position for all leech taxa. Each species from the list is supplemented with information about its geographical distribution.

DNA barcoding for species delimitation of the freshwater leech genus Glossiphonia from the Western Balkan (Hirudinea, Glossiphoniidae)

Glossiphoniid leeches are a diverse group and sometimes abundant elements of the aquatic fauna inhabiting various types of freshwater habitats. In this study, we sampled leeches of the genus Glossiphonia from the Western Balkan in order to test the suitability of the mitochondrial cytochrome c oxidase subunit 1 (COI) marker sequence for species delimitation. Morphological analysis revealed the presence of four taxa, G.complanata with two subspecies, G.c.complanata and G.c.maculosa, the latter an endemic of Ohrid Lake, G.nebulosa and endemic G.balcanica. In total, 29 new barcodes of Glossiphonia were sequenced in the course of this study and compared with the available molecular dataset of the latter genus from GenBank/BOLD databases. The applied ASAP distance-based species delimitation method for the analysed dataset revealed an interspecific threshold between 4-8% K2P distance as suitable for species identification purposes of the Western Balkan Glossiphonia species. Our study revealed that morphologically identified taxa as G.nebulosa and G.concolor each consists of more than one clearly different phylogenetic clade. This study contributes to a better knowledge of the taxonomy of glossiphoniid leeches and emphasises future work on the revision of this genus using a standard molecular COI marker in species identification.

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.