Dataset Paper An Illustrated Checklist of Leech Species from Lake Baikal ( Eastern Siberia , Russia )

Lake Baikal is situated in the northeast of Central Asia. It is one of the most ancient (25–30MY), the deepest (1637m), and the largest (volume of 23 000 km, length of 636 km, width up to 80 km, catchment area of 540 000 km, and coastline of 1800 km) repository of single volume of unfrozen fresh water of the planet (20% of the global supply) [1]. Transparency of the Baikal water reaches 40–50m with extremely poor mineralization and higher oxygen saturation. e oxygen content at the bottom even in the deepest areas is no lower than 70%–80% of saturation. e combination of these factors, together with numerous other ones, has resulted in the fact that the lake has a unique complex of living organisms (1550 animal species and over 1000 species of plants) [2]. Lake Baikal now holds the largest number of described metazoan species of all known lakes and can be considered as a centre of megadiversity. e organisms inhabiting the lake adapted to a variety of environmental conditions, having mastered and repopulating the diversity of habitats from interstitial zone to maximal depths. e pronounced endemism and speci�c wealth of its fauna (82% of known species) has attached a keen interest of biologists and biogeographers worldwide. A start of Lake Baikal studies occurred at the middle of the eighteenth century, but they have been carried out with the greatest intensity in the twentieth century. Despite a 200-year history of limnological studies, Lake Baikal is still full of white spots; one of them is the fauna of parasitic annelids. Baikal leeches demonstrate a high level of biological diversity and endemism, both at the genus level and at the species level. By 2001, there were 13 leech species stated in Lake Baikal [2]. ese species are adapted to living in cold, clean, oxygenated water and fed by Baikal endemic animals: bullheads, amphipods, and perhaps other groups. Unfortunately, there is still no clear idea on their preferences to a host. e aim of this paper is to update knowledge on leech species composition of Lake Baikal fauna.


Introduction
Lake Baikal is situated in the northeast of Central Asia.It is one of the most ancient (25-30 MY), the deepest (1637 m), and the largest (volume of 23 000 km 3 , length of 636 km, width up to 80 km, catchment area of 540 000 km 2 , and coastline of 1800 km) repository of single volume of unfrozen fresh water of the planet (20% of the global supply) [1].Transparency of the Baikal water reaches 40-50 m with extremely poor mineralization and higher oxygen saturation.e oxygen content at the bottom even in the deepest areas is no lower than 70%-80% of saturation.e combination of these factors, together with numerous other ones, has resulted in the fact that the lake has a unique complex of living organisms (1550 animal species and over 1000 species of plants) [2].Lake Baikal now holds the largest number of described metazoan species of all known lakes and can be considered as a centre of megadiversity.e organisms inhabiting the lake adapted to a variety of environmental conditions, having mastered and repopulating the diversity of habitats from interstitial zone to maximal depths.e pronounced endemism and speci�c wealth of its fauna (82% of known species) has attached a keen interest of biologists and biogeographers worldwide.A start of Lake Baikal studies occurred at the middle of the eighteenth century, but they have been carried out with the greatest intensity in the twentieth century.Despite a 200-year history of limnological studies, Lake Baikal is still full of white spots; one of them is the fauna of parasitic annelids.
Baikal leeches demonstrate a high level of biological diversity and endemism, both at the genus level and at the species level.By 2001, there were 13 leech species stated in Lake Baikal [2].ese species are adapted to living in cold, clean, oxygenated water and fed by Baikal endemic animals: bullheads, amphipods, and perhaps other groups.Unfortunately, there is still no clear idea on their preferences to a host.e aim of this paper is to update knowledge on leech species composition of Lake Baikal fauna.

Methodology
e previously published information and an extensive material collected by the author in the period from 2002 to 2012 were used in this paper.Species de�nition was done with identi�cation keys [3][4][5] and the original descriptions [6][7][8] according to the modern classi�cation of the group.Morphological analysis has been conducted using a stereomicroscope MSP-2 var. 2 (LOMO).All images were taken with a camera NIKON D700.Seventeen of 20 species are provided with color illustrations principally of living animals that can contribute to easier identi�cation of the taxon in the future.e three missing species of our collection are as follows.

Dataset Description
e dataset associated with this Dataset Paper consists of 18 items which are described as follows.
Dataset Item 1 (Table ).An updated list of species of leeches inhabiting Lake Baikal, composed of 20 species.e exact systematic position is stated for all leech species.Each involved species has a brief taxonomic characteristic.

Concluding Remarks
At present, the occurrence of 20 species in Lake Baikal is documented.is species diversity includes both widespread Holarctic and Palaearctic and also endemic species from 4 families and 12 genera.Five species of the following list were noted for the �rst time in Eastern Siberia, of them A. weberi, H. nuda, Baicalobdella sp., Codonobdella sp., and Erpobdella sp.At the same time, P. geometra (Linnaeus, 1761) and C. mammillatus (Malm, 1863) were excluded from the species list of Lake Baikal.We never found these two species in Baikal.We agree with that P. geometra has wide distribution throughout the entire territory of the former USSR except for waters of the Kamchatka Peninsula and Lake Baikal [4] and that distribution of C. mammillatus is con�ned to northern waters including large tributaries of Lake Baikal such as the Selenga River (found in 1.5 km from the con�uence of Lake Baikal) and the Upper Angara River, but never the Lake Baikal itself [12].Both piscicolid species have been wrongly listed previously for the lake [1,11].
[1]vyrkuy Bay (eastern side of North Basin of the lake) on stones at a depth of 0.3-0.7 m.Alive leeches were green with length of 14-16 mm and width of 3 mm.Alcohol-�xed specimens rapidly lost a beautiful intravital coloring.Dataset Item 4 (Image).Helobdella stagnalis (Linnaeus, 1758) takes care of numerous progeny.isspecies is considered one of the most common freshwater leeches in the world.isspecies is cosmopolite.Within Baikal, H. stagnalis inhabits shallow bays and salinas.Our collection has samples from the Maloe More, the Chivyrkuy Gulf, and the Gulf Posolsky Sor.It cannot swim; it crawls on aquatic plants and other objects, using its suckers as organs of attachment.Most suck the hemolymph of freshwater invertebrates like oligochaetes, larvae of insects, and freshwater snails[1].Freshwater jawless leeches are remarkable for their parental care.eyproduce a membranaceous bag to hold the eggs, which is carried on the underside.eyoungattachto the parent's belly aer hatching and are thus ferried to their �rst meal.for the genus location and papillae on dorsal part of body similar to G. complanata.Its length is 5-6 mm.It is endemic to Lake Baikal.B. echinulata inhabits the open waters of Lake Baikal at a depth of 14-300 m. is species is easily distinguished from other Baikal Toricinae by the presence of small papillae on the ventral side of the body.Feeding details are unknown.Baicalobdella cottidarum.B. torquata is endemic to Lake Baikal.It is a typical component of the littoral zone of open Baikal.We found this species only in the South basin of Lake Baikal and in the Maloye Morye Bay at depths of 7-10 m. e small leeches are 5-8 mm in length and 2-3 mm in width.Body color varies from light green to pale rusty retaining a characteristic mosaic pattern on the dorsal side of urosome.B. torquata sucks the blood of Baikal endemic amphipods.Dataset Item 14 (Image).Baicalobdella sp.: ethanol-�xed specimen ventrally (le) and dorsally (right).Endemic species to Lake Baikal was found in the north entrance of the Maloye Morye Strait, on depth of 10-11 m.In contrast to the B. torquata, this species is larger and lacks the characteristic white clitellum.Dataset Item 15 (Image).Codonobdella truncata (Grube, 1873): �ve ethanol-�xed specimens of Codonobdella truncata.It is endemic to Lake Baikal.is species inhabits abyssal of the South, Middle, and North Baikal basins.We found them in the range of depths from 180 to 1215 m. e worms are up to 27 mm, feeding on deep-water �shes and amphipods.It inhabits only in Palaearctic waters, where it is widespread and can be attributed even to trans-Palearctic group.It is a predator of small vertebrates and invertebrates.H. sanguisuga belongs to very voracious predators, which ingest their prey completely or tear to big pieces.Our specimens from the Gulf Kotovo (Chivyrkuy Bay of Lake Baikal) were up to 70 mm in length.It does not refuse dead animals and smaller specimens of own species.e big-size leeches are about 50 mm in length and 4-5 mm in width.
[3]10] 1: Species Column 2: Genus Column 3: Subfamily Column 4: Family Column 5: Suborder Column 6: Order Column 7: Subclass Column 8: Class Column 9: Phylum Dataset Item 2 (Image).Intravital colour of eromyzon tessulatum(Muller, 1774).Palaearctic species was found in the Gulf Posolsky Sor (eastern part of Middle Basin of the lake).Individuals were located at underside of the stones at a depth of 0.5-1 m. e species is known as bloodsucker of birds inhabiting warmed shallow bays of Lake Baikal[1].Specimens are 10-12 mm in length and about 2 mm in width and can stretch up to 15-17 mm, becoming 1 mm in width.Dataset Item 3 (Image).Hemiclepsis marginata (Muller, 1774): le is live leech and right are �xed specimens dorsally (upper) and ventrally (lower).It is widespread Palaearctic species and bloodsucker of �shes, tadpoles, and amphipods[1,10].especieswasfound in the Zmeinaya Gulf of the Dataset Item 5 (Image).Helobdella nuda (Moore, 1924): alive animal (le) and �xed sample (right).�ntilnow, the species was known from China and the Amur River basin.We found H. nuda in shallow part of Chivyrkuy Bay.Minor size leeches are 5-8 mm at a moderate tension.It has more than two eyes as opposed to H. stagnalis.Life style is similar to the sister species.As H. stagnalis, it cannot swim and feeds with the hemolymph of freshwater invertebrates.Dataset Item 6 (Image).Glossiphonia complanata (Linnaeus, 1758): leech attacks mollusc (right).Holarctic species is widespread in Siberia[3].Specimens of our collection were caught in littoral zone of the Chivyrkuy Bay.e leeches have a �attened body.Life cycle of G. complanata is typical for the majority of the genus.It prefers to sit on the rocks or slowly crawling.When resting, it looks like a small leaf but during the move it can be quite drawn out.isleechfeedsalmost exclusively on mollusks and sometimes worms or larvae of insects.With elastic proboscis, G. complanata pierces delicate covers of the victim and sucks its blood.esize is about 10-25 mm.On the dorsal side, there are three pairs of longitudinal rows of papillae.G. complanata like other glossiphoniids takes care of nurture.Dataset Item 8 (Image).Alboglossiphonia weberi (Blanshard, 1897).especiesbelongs to the usual components of the Indo-Malayan fauna but extended beyond the northern borders of the area[3].First A. weberi is indicated in Eastern Siberia and Lake Baikal in particular.A few specimens were found in the Gulf Posolsky Sor.is species has three pairs of eyes typical Dataset Item 11 (Image).Baicaloclepsis grubei Lukin et Epstein, 1959: ethanol-�xed specimen from dorsal (le) and ventral (right) projections.It is endemic to Lake Baikal.ey are sizeable leeches (length of 30-40 mm, width of 10-15 mm).B. grubei was found only in the Maloye Morye Bay at relatively shallow depths of 14-40 m.All specimens were collected from benthic samples.e question of a potential host of the bloodsucking leech remains open.Dataset Item 12 (Image).Two species of Baikal leeches: (A) Baicalobdella torquata (Grube, 1871) and (B)