Graylings of Baikal Lake basin (Thymallus, Thymallidae): Diversity of forms and their taxonomic status

The morphological characters, molecular-genetic features, and patterns of the dorsal fin in different subspecies and forms of Arctic grayling Thymallus arcticus populating Lake Baikal and its tributaries, Irkutsk Reservoir, and Lake Khubsugul have been studied. Three groups are discernable. The first includes the white and black Baikal graylings T. a. baicalensis, as well as the western Siberian T. a. arcticus; the second group is represented by the Kosogol grayling T. a. nigrescens, and the third is composed of T. arcticus ssp. from the Yakchii lakes (the Verkhnyaya Angara basin) with a phenotype close to graylings populating the upper reaches of the Lena River. All of them are distinguished by some morphological characters, elements of the dorsal fin pattern, and by body coloration. The populations of black Baikal graylings are genetically uniform, and their distinctions from white Baikal graylings are insignificant, which agrees with the absence of a considerable divergence of these forms by a complex of meristic characters. It is assumed that in the black and white Baikal graylings the exchange by genetic information has either ceased quite recently, or persists, although, insignificantly. Some genetic remoteness of the west Siberian grayling from Irkutsk Reservoir and Nizhnyaya Tunguska, closely related to the Baikal grayling, is recorded. The formation of the Khubsugul subspecies is possibly a result of the contact of grayling populations during the rearrangements of the river system in the last glaciation period in the upper reaches of Yenisei and Selenga in Mongolia. The habitation in the Baikal system of the Upper Lena graylings indicates a connection between the Lena and Baikal basins in the past. The results of a multivariate analysis of meristic characters and the sequences of mitochondrial DNA confirm the conclusion made by Svetovidov (1931, 1936), concerning the absence of grounds to assign a species status to the Baikal forms.     

On the diversity and taxonomic status of graylings (Thymallus Thymallidae) from the Lena River

Two forms of graylings were distinguished in the Lena River, which differ in body coloration, the shape and pattern of the dorsal fin, and biological characteristics. With respect to these traits, the forms are divided between the upper and lower Lena. The first inhabits most of the basin, from the upper courses to the lower reaches, whereas the second inhabits the Lena delta and the adjacent arctic rivers and their tributaries. Comparative analysis of meristic traits revealed their low appropriateness for diagnosing Lena lineages as well as grayling populations inhabiting other northern rivers of Siberia. The body and fin coloration in the upper Lena form significantly differ from that found in forms and subspecies of graylings from the basins of the other rivers in the ranges of Eastern Siberian, Kamchatka, and Alaska. The lower Lena form should be classified with the Eastern Siberian subspecies T. arcticus pallasii and is closer to the populations of graylings from the rivers Anabar and Yana, and the rivers of the Chukot Peninsula and Alaska, and the upper courses of the Missouri. These results are supported by analysis of the mitochondrial DNA of graylings throughout the Paleoarctic. Further studies of these lineages and phylogenetic relationships between Arctic lineages are necessary for the final determination of the taxonomic status of the upper Lena form.     

Secondary contact between two divergent lineages of grayling Thymallus in the lower Enisey basin and its taxonomic implications

A contact zone between two widespread divergent lineages of grayling Thymallus sp. has been identified in the lower Enisey basin (Khantaiskoye Lake) in north central Siberia (Russia). Sequences of the mitochondrial DNA control region revealed two lineages with 2·6% divergence. Haplotypes from these two lineages clearly fall within two previously described clades, one presumably corresponding to Arctic grayling Thymallus arcticus found throughout the Siberian coastal zone as well as North America, and the other corresponding to grayling found elsewhere in the Enisey basin, including Lake Baikal and its tributaries. Allelic variation at seven microsatellite loci strongly suggests reproductive isolation in sympatry between these two lineages in Khantaiskoye Lake. Integration of these new data with existing knowledge on Thymallus throughout its Siberian range supports a taxonomic revision. The currently recognized sub-specific lineages of Arctic grayling along the Siberian Arctic coast as well as grayling from North America should probably be regarded as T. arcticus . Arctic grayling, however, are limited to the coastal zone and lower reaches of the Enisey. Most of the Enisey basin, including Lake Baikal and its tributaries are occupied by another taxon, which should be recognized as Thymallus baicalensis . This perspective strictly follows evolutionary principles, eliminates the use of four sub-specific names and circumvents the illogical mosaic distribution of T. arcticus arcticus , which nevertheless does not represent a monophyletic lineage.     

Molecular-phylogenetic analysis of cyclopoids (Copepoda: Cyclopoida) from Lake Baikal and its water catchment basin

Baikalian cyclopoids represent one of the richest endemic faunas of freshwater cyclopoid copepods. The genus Diacyclops Kiefer, 1927 is the most numerous by species number in the lake. In this work, molecular-phylogenetic analysis of 14 species and 1 sub-species from Lake Baikal and its water catchment basin is performed. The regions of mitochondrial cytochrom-oxydase I (COI) and of nuclear small-subunit 18S rRNA were used as evolution markers. In the obtained set of COI gene sequences, an effect of synonymous substitution saturation is revealed. Baikalian representatives of the genus Diacyclops form at phylogenetic schemes by two markers a monophyletic group, it suggest their origin from a common ancestral form. Preliminary estimate of this group age is 20–25 My.     

Finding a new form of the grayling Thymallus arcticus (thymallidae) in the basin of lake baikal

A dwarf form of the Arctic grayling Thymallus arcticus, inhabiting a group of small lakes at the origin of the Yakchii stream, which flows into the Verkhnyaya Angara River (basin of Lake Baikal), has been found in the northeastern watershed of the Baikal and Lena basins. The form is similar to upper Lena populations in body coloration and the pattern of dorsal fin. Our comparison by meristic characters indicated that the grayling of the Yakchii Lakes is more similar to the fish from Kutima River (basin of the upper courses of the Lena River) than to the black Baikal grayling T. arcticus baicalensis. The presence in Lake Baikal of a population similar to upper Lena graylings may have three causes: (1) possible drainage from Baikal to the pra-Lena via ancient valleys of the Barguzin and the Upper Angara; (2) appearance of transit zones as a result of glacial or tectonic events during the periods of watershed development between the Baikal and Lena basins; (3) the upper Lena grayling could be an endemic of the Baikal basin which was replaced by graylings penetrating from the Yenisei basin and remained in the form of relic populations in the upper courses of certain tributaries of the northern and northeastern parts of Lake Baikal.     

A new subspecies of the amur grayling Thymallus grubii flavomaculatus ssp. nova (Thymallidae)

A new subspecies of the Amur grayling is described, the yellow-spotted grayling Thymallus grubii flavomaculatus ssp. n. populating the upper reaches of large tributaries of the Lower Amur basin and some rivers flowing to the Tatar Strait, the Sea of Okhotsk, and the Sea of Japan. From nominative subspecies T. g. grubii populating the basin in the upper reaches of the Amur and from other representatives of the genus Thymallus, this subspecies differs in the dorsal fin pattern whose principal trait is a yellow spot on the last two-five interray membranes, in the body coloration, and in some morphological characters. The yellow-spotted grayling in the upper reaches of tributaries sympatrically coexists with the Lower Amur grayling Thymallus sp. No specimens with intermediate characters are found. The sympatric forms spawn at different times, thus being isolated reproductively. Isolation of the yellow-spotted grayling as a subspecies of the Amur grayling T. grubii is confirmed by the results of molecular-genetic investigations.     

Biological and morphological characteristic of the Arctic grayling Thymallus arcticus (Thymallidae) from Alpine Lakes of the basin of the upper reaches of the Angara River

Specific morphological and biological features of the populations of the Arctic grayling Thymallus arcticus from lakes Urunge Nur, Mongosha, Sadaiskoe, and Gusinoe situated in the Upper Sayan Mountains in the sources of the Oka and Kitoi rivers (the basin of the upper reaches of Angara) that have been not studied previously are considered. The results of the multivariate analysis indicated the uniformity of all samples by 12 meristic characters. Graylings of the studied lakes are similar to graylings from the Angara and Nizhnyaya Tunguska rivers and the Irkutsk Reservoir, as well as to the Baikal grayling T. a. baicalensis in body coloration and pattern of the dorsal fin. The samples studied and T. a. baicalensis considerably differ in the above characters from populations inhabiting the basin of the upper reaches of the Ob that belong to the nominative subspecies T. a. arcticus. The differences established between the Angara-Yenisei and the Upper Ob graylings give grounds to doubt the justification of including them into one taxon, T. a. arcticus. The same is evidenced by the results of molecular-genetic studies of graylings from the Palearctic (Froufe et al., 2005). The data obtained indicate the necessity of ascertaining the boundaries of the ranges of different forms of graylings in the Angara-Yenisei and Ob basins and of the revision of their taxonomic status. Populations inhabiting the Angara and Yenisei rivers, except their sources and the section of the lower reaches, should be assigned to the Baikal subspecies, T. a. baicalensis. Graylings from different lakes in the upper reaches of Oka and Kitoi differ in their linear-weight indices. The indices of growth are highest where they occupy a dominant position. Their food in the summer consists mainly of the larval and imaginal stages of amphibiotic and aerial-terrestrial insects. Only in Lake Urunge Nur do graylings of elder age groups use fish of other species for food. The extreme conditions of habitation of the grayling in Lake Gol’tsovoe are the cause of food deficiency, which determines its dwarfism.     

Depth distribution of oligochaetes in Lake Baikal (Siberia - Russia)

In the course of a preliminary sampling program, oligochaetes were collected along two transects in soft sediments in Lake Baikal. The number of oligochaetes present in the samples was counted, without distinguishing between species. The results suggest an exponential decrease in number of individuals (N) relative to depth (11,165 N m^–2 at 21 m, 265 N m^–2 at 1200 m). Most oligochaetes were found in the top 7 cm of sediment. The orange colour of the sediments suggests a high oxygen availability, even at the greatest water depths.

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Résumé Au cours d'un programme d'échantillonnage préliminaire, les oligochètes du lac Baïkal ont été récoltés dans le sédiment mou prélevé le long de deux transects. Les oligochètes présents dans les échantillons ont simplement été dénombrés, sans identification déspèces. Les résultats suggèrent une diminution exponentielle du nombre d'individus en fonction de la profondeur du lac (11165 N m^–2 à 21 m, 265 N m^–2 à 1200 m). La plupart des oligochètes ont été trouvés dans les 7 premeirs cm de la couche supérieure du sédiment. La couleur orangée du sédiment suggère une grande disponibilité en oxygène, même aux profondeurs les plus grandes.

     

Comparative analysis of oocyte growth in two forms of Baikal grayling <Emphasis Type="Italic">Thymallus baicalensis</Emphasis> (Thymallidae)

Size characteristics of oocytes of the elder generation of the end of previtollogenesis, as well as of the beginning and middle of the phase of cytoplasm vacuolization in two forms of Baikal grayling Thymallus baicalensis were studied. In each form, the dependence of oocyte parameter on the age and size of females is traced. During the studied phases of development—at the termination of the period of previtellogenesis and at the proper beginning of the period of vitellogenesis—oocytes of the white and black graylings have similar sizes; cytoplasm vacuolization in white grayling proceeds less actively. It was established that differences in the diameter of mature ovicells in the black and white Baikal graylings result from dissimilar rate of accumulation of trophic substances in the oocytes of the given forms of this species and are determined by differences in the rate of growth of oocytes during the formation in them of yolk inclusions.     

The developmental cycle of Proteocephalus thymalli (Cestoda, Proteocephalidae)--a parasite of the Arctic grayling from Lake Baikal

The life cycle of Proteocephalus thymalli (Cestoda, Proteocephalidae), a parasite of Siberian glame (Thymallus arcticus), was repeated under experimental conditions. The first intermediate hosts, the copepods Epischura baicalensis, Cyclops kolensis and C. vicinus, were determined. The developmental time of P. thymalli in the first intermediate host was determined and the morphology of the larval and adult phases was described.     

New data on the distribution of the Upper Carboniferous (Pennsylvanian) flexible crinoid Cibolocrinus (Crinoidea,Flexibilia)

Two new species of flexible crinoids of the genus Cibolocrinus (Crinoidea, Flexibilia) from the Upper Carboniferous of the Moscow Region are described: C. kutasovi (Moscovian Stage, Podolskian Regional Substage) and C. gerassimovi (Gzhelian Stage, Dobryatinian Regional Substage). The first species, C. kutasovi, belongs to a group with low cone shaped cups that first appeared in the Moscow Basin and then spread to the Midcontinent of North America. In one specimen of C. gerassimovi the smallest infrabasal plate is situated in the A ray, which is not typical for flexible crinoids. A poorly preserved crown of Cibolocrinus sp. from the Upper Carboniferous (Gzhelian Stage) of the Darvaz Ridge (western Pamir, central Tajikistan) is also described. The described specimens of Cibolocrinus from the Moscow Region and the Darvaz Ridge are the first reliable specimens of this genus described from Europe and Asia.     

Finding of Arcrtic Charr Salvelinus alpinus (Salmonidae) and Sculpin Cottus cf. poecilopus (Cottidae) in the Verkhnyaya Angara basin Near the Divide with the Lena River System: New Data About the Invasion Routes of the Representatives of Lena Ichthyofauna Into Baikal Basin

Journal of Ichthyology - In Lake Amut (the Verkhnyaya Angara drainage basin) the third population of Arctic charr Salvelinus alpinus (L.) in Baikal basin was found, a presumed invader from the Lena...     

Biological specific features of the Lower Amur grayling Thymallus tugarinae (Salmoniformes: Thymallidae): 1. Age composition

We consider age composition of samples of the Lower Amur grayling Thymallus tugarinae inhabiting water bodies of the lower and middle course of the Amur and several rivers of the northwestern part of Sakhalin Island and the southern coast of the Sea of Okhotsk. Age composition of the Lower Amur grayling from the studied samples is not similar because of several reasons. In rivers of the Amur basin, the species has a maximal age of 6+.     

Morphological variation of oocytes of initial phases of vitellogenesis in two forms of Baikal grayling <Emphasis Type="Italic">Thymallus baicalensis</Emphasis> (Thymallidae)

The variation of oocytes of initial phases of vitellogenesis in two forms of Baikal grayling Thymallus baicalensis was studied. The dependence of their diameter on the size-age indices of females, as well as differences in the sizes of oocytes between the studied forms, was established. Comparison of oocytes of identical forms of development revealed that oocytes of the white grayling during termination of the phase of cytoplasm vacuolization and at the beginning of the phase of yolk accumulation have a smaller diameter of the cell, of the nucleus, respectively, and of yolk granules and a greater, with respect to cell diameter, size of vacuoli. The revealed differences of morphological characteristics of oocytes of initial phases of vitellogenesis in combination with the well-known, stably smaller (by a factor of 1.5) size of mature eggs of the white Baikal grayling that matures at a later age at larger sizes indicate a profound adaptive diversification in the course of development of the reproductive system of both forms.     

New data reinforcing the taxonomic status of Lepidion eques as synonym of Lepidion lepidion (Teleostei,Gadiformes)

The Mediterranean morid codling Lepidion lepidion is thought to be endemic, yet its taxonomic distinctiveness from the morphologically similar and more wide-ranging Atlantic Lepidion eques is unresolved, and has been controversial since the beginning of the twentieth century. Despite the abundant taxonomic literature questioning the interspecific relationship between these taxa, their current status remains unchanged. To elucidate the differentiation of the specimens identified as L. lepidion and L. eques collected across much of their geographic ranges, the sequence divergence of the cytochrome oxidase I “DNA barcode” gene of the mitochondrial genome was evaluated. A network analysis indicates that the most observed haplotypes are common to both species throughout their Mediterranean and North Atlantic distribution areas. This molecular evidence suggests the absence of biogeographical barriers and is insufficient to support the different species designations, giving L. eques the taxonomic status of junior synonym of L. lepidion.     

New data on the distribution of calcareous nannofossils in the Upper Jurassic Loino section (Kirov region,Russia)

The middle Volgian clayey deposits of the panderi Zone in the Loino section of the Kirov region have been found to contain an assemblage of calcareous nannofossils never studied in such high latitudes of the Boreal Realm. The species constituting this assemblage are characterized by wide geographic and stratigraphic distributions.     

The taxonomic status ofSedum telephium and its allied species (Crassulaceae)

The taxonomic status ofSedum Telephium and its allied species (Crassulaceae-Sedoideae) is discussed, and a new genus,Hylotelephium, is recognized. Under the genus, 27 new combinations are proposed and one new species,H. callichromum, from Central Asia is described. This study has been supported partly by Grants-in-Aid for Fundamental Scientific Research by the Ministry of Education of Japan, No. 034047 in 1975 and 1976.     

Vertical distribution of acanthocephalans of the order Echinorhynchida in Lake Baikal

Vertical distribution of acanthocephalans of the order Echinorhynchida is studied in Lake Baikal. Four species and subspecies from cottid fishes (Perciformes: Cottoidei) were examined, namely Pseudoechinorhynchus borealis (Linstow, 1901), Metechinorhynchus salmonis salmonis (Muller, 1780), M.s. baicalensis Bogolepova, 1957, M. truttae (Schrank, 1788). In the littoral (0-5 m) and sublittoral (5-100 m) areas all these species and subspecies were occurred, white in the profundal (100-300 m) and abyssal (900-1600 m) areas only Metechinorhynchus salmonis baisalensis has been found.     

On the taxonomic status and distribution of Funaria durieui

Funaria durieui, described from Algeria, is reported from the Iberian peninsula and the Canary islands. A new name, Entosthodon schimperi, is suggested.