ISSN 0206-0477. NEW CONTRIBUTIONS TO FRESHWATER FISH RESEARCH ST. PETERSBURG, 2001 (PROCEEDINGS OF THE ZOOLOGICAL INSTITUTE, VOL. 287)

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A REVISION OF ALTAI OSMANS OF THE GENUS OREOLEUCISCUS (CYPRINIDAE: LEUCISCINAE) WITH A DESCRIPTION OF A NEW SPECIES, O. ANGUSTICEPHALUS, FROM RIVER KOBDO (HOVD) SYSTEM, WEST MONGOLIA

N.G. Bogutskaya

Zoological Institute, Russian Academy of Sciences, Universitetskaya nab., 1, St. Petersburg, 199034, Russia

A comparative morphological study of Altai osmans, the genus Oreoleuciscus, from different parts of its distribution was performed. Besides non-type samples, material examined includes syntypes and holotypes of most species and varieties described earlier. An analysis of 33 morphometric and meristic characters, 14 craniological parameters as well as other features of skeletal structure including vertebrae counts and degree of ossification of the dorsal unbranched rays, and cephalic sensory canals confirmed a conclusion (Bogutskaya, 1990c) that the genus Oreoleuciscus contains three species. The Nogon Nuur narrow-headed osman is described here as a new species, O. angusticephalus. The main diagnostic characters are the number of branched rays in both dorsal and anal fins, structure of the last unbranched dorsal ray, the number of pores in the sensory canals, the relative width of the head in its different parts, the shape of the supraethmoid and the pterotic posterior process. Key for the identification of species of the genus and synonymies are given. Species of the genus Oreoleuciscus (Altai osmans, or mountain daces) are the most typical representatives of the ichthyofauna of Central Asian Internal Basin (North-West Mongolia), a comparatively small area, geomorphologically subdivided into the west Mongolian Great Lakes Valley and Gobi Valley Lakes (or Lake Valley). The basin consists predominantly of large lentic water masses without outlets beyond it. They are fed by relatively short upland streams or rivers that drain the southern slopes of Tanny-Ula, the Hangayin (Hangay) and northen slopes of the Mongolian Altai mountain ranges. Beyond this region Altai osmans occur only in the basin of the Upper Ob River. Altai osmans are nearly eurybiont inhabiting fresh and brackish water lakes, rivers, streams, situated at an altitude from 700 to 2000 m above sea level. Variability of environmental conditions and the poverty of

5 ichthyofauna determining a nearly complete absence of competition with fishes of other genera apparently favoured great morphological and ecological diversity of this genus. The initial phase of the systematic studies of Altai osmans is characterized by the tendency to describe morphologically distinct groups of specimens or single deviating specimens as species or varieties. Thus Warpachowski (1889) in his excellent monograph distinguished the following species and varieties: Oreoleuciscus potanini, O. potanini var. recurviceps, O. pewzowi, O. pewzowi var. altus, O. pewzowi var. longicaudus, O. humilis, O. humilis var. phoxinoides, O.similis, O. dsapchynensis, O. herzensteini, O. gracilis and (based on a head alone) O. choerocephalus. Later, O. ignatowi Nikolski, 1902 and O. ignatovi Dorogostaiski, 1908, were described. A part of these forms were reduced to synonyms by Berg (1912, 1949, and others) who distinguished three main species, O. humilis, O. potanini and O. pewzowi, and also O. recurviceps and O. similis. The next phase is characterized by a study of Altai osmans on a relatively larger material, mainly from water bodies of mountain Altai and Tuva in the USSR. Application of the characters used by Warpachowski (1889) and Berg (1912, 1949, and others) showed that they do not always permit an accurate identification of species of Altai osmans (Gladkov, 1938; Kafanova, 1961; and others). The great variation and age-and-size variability of morphometric characters (in particular relative length of the head and body depth, length of the lower jaw relative to minimum depth of the body, length of the operculum) determined doubts concerning species status of O. humilis (Krivoshchekov, 1959; Egorov, Zhamsaran, 1961) and O. pewzowi (Iohansen, 1940; Nichols, 1930) which were later synonymized with O. potanini (Svetovidova, 1965). Relatively extensive collections of Altai osmans from Mongolia (from both the Kobdo (Chovd Gol, Hovd) River basin and from the Lake Valley) were studied by Dashdorzh and co-authors (Dashdorzh et al., 1969). A detailed analysis of morphometric and some meristic characters confirmed existence of differences between O. potanini and O. humilis, that are particularly conspicuous in the number of branched rays in the dorsal and anal fins, and also showed distinctiveness of specimens, identified as O. pewzowi (without comparison with syntypes of this species), from O. humilis. It is important that geographic separation of the two groups of Altai osmans was revealed: O. potanini was recorded only in the basin of the Kobdo River, whereas O. humilis and O. pewzowi 6 were connected with water bodies of Hangayin and the Lake Valley (except one sample from Achit Nuur). One of the characters dividing the two groups mentioned above is the structure of simple rays in the dorsal fin. As a whole these data correlate well with the results of a comparative analysis of Altai osmans from basins of the Kobdo River on the one hand and forms inhabiting water bodies of the Ubs-Nur (Uvs Nuur) Valley on the other (Gundrizer, 1962, 1976). It should be noted that many authors (Svetovidova, 1965; Gundrizer, 1976; Dashdorzh et al., 1969) accepted the characters used by Warpachowski (1889) and Berg (1912, 1949) as the key characters without a re-examination of type specimens of the earlier described species and varieties. Without a comparison with the latters the systematic revisions were incomplete and even some nomenclature inaccuracies arose (see below). The third phase in the study of Altai osmans is associated with the work of joint Soviet-Mongolian biological expedition in 1975-1980. The data obtained by the expedition became the basis of a number of summarizing reviews on morphology and mode of life of species of the genus Oreoleuciscus within the limits of a larger part of its distribution area in Mongolia (Dgebuadze, 1982; Baasanzhav et al., 1983, 1985; Borisovets et al., 1984, 1985a, 1985b, 1985c, 1987, etc.). Without a special revision of taxonomic status of individual groups of Altai osmans and referring them all to species O. potanini these authors paid more attention to the analysis of diversity of these fishes. Based on the study of a large number of morphometric and meristic characters conclusions were made on the occurrence of five morpho-ecological forms, or types, in the studied water bodies. These forms are conventionally called herbivorous, sharp-snouted, piscivorous, dwarf and lake forms of Altai osman. The former three are associated with the basins of rivers Kobdo and Dzavhan Gol, the latter two occur in water bodies of the slopes of Hangayin, and Lake Valley. It is shown that the dwarf and lake form are relatively close and form a single group, the differences of which from all osmans of the Kobdo basin are approximately equal to the differences between the herbivorous and piscivorous forms (Borisovets et al., 1985c). Taxonomic status of the latter two forms was analyzed by Vasilieva (1982). The study of a number of craniological characters showed considerable differences between two forms of Altai osmans from Lake Nogon-Nuur and somewhat later (Vasilieva, 1985) differences between these both forms and Altai osmans from River Taytzyn-Gol (Tatsain Gol) and Lake Taytzyn-Tsagaan-Nuur (Tatsain Tsagaan Nuur). In the same publication, the author also analyzed the degree of thickening and 7 segmentation of the last simple dorsal ray and divided all Altai osmans into two large groups. The first group includes osmans with a relatively rigid ray (corresponds to O. potanini), the second group uniting soft- rayed Altai osmans is represented by two subgroups: one is characterized by a wider skull and a lower number of pores of the sensory canal on the dentary (corresponds to O. humilis), the other by a narrower skull with a large number of pores (Lake Nogon-Nuur). Two hypotheses have been proposed for the taxonomic status of O. humilis: it is either a distinct species capable of forming lake forms, or the dwarf osman is an eco- morphological form of the soft-rayed narrow-headed osman. The latter is given a name O. pewzowi though the author clearly showed that the syntypes of Leuciscus pewzowi belong to O. potanini (Vasilieva, 1985). According to this, Leuciscus pewzowi had to be considered as a junior synonym of Chondrostoma potanini, and the soft-rayed osman from Lake Nogon-Nuur had to be given a new name in case of the first hypothesis. Analysis of variation of a number of characters, osteological ones included, and topography of sensory canals on the head (Bogutskaya, 1990c) confirmed that, in spite of the comparatively large intraspecific variation of a number of characters, three groups of forms can be distinguished within the genus Oreoleuciscus, which are given the rank of species (O. humilis, O. potanini, Oreoleuciscus sp.). They differ in the structure of simple dorsal rays, the number of pores in sensory canals, general configuration of neurocranium and a number of other characters. These data in many respects conformed to the main conclusions of the previous authors (Gundrizer, 1976; Vasilieva, 1985; Borisovets et al., 1985a, 1985b, 1985c) concerning the taxonomy of the genus Oreoleuciscus if one discards the nomenclatural confusion related to usage (Gundrizer, 1976; Vasilieva, 1985) of the name “pewzowi”. The purpose of the present study is to straighten out the accumulated systematic data on Altai osmans on the basis of a comparative morphological study of specimens from different localities all over the area of distribution of the genus and their comparison with type specimens of species and varieties for defining validity of names and taxonomic status of individual “forms” of Altai osmans. The question of taxonomic composition of the genus Oreoleuciscus is closely related to the question of taxonomic status of the genus Acanthorutilus Berg, 1912. Initially only one species, O. dsapchynensis, based on a single specimen from River Dzavhan Gol (ZISP 6410), was placed into this genus. Later, four more species from Asia Minor were added to Acanthorutilus: A. anatolicus Hanko, A. handlirschi Pietschman, 8 A. maeandricus Ladiges and A. crassus Ladiges. An opinion became established in the literature that the genus Acanthorutilus is close to Mediterrranean Pseudophoxinus Heckel, 1843 and Phoxinellus Heckel, 1843 and possesses the disrupted distribution range (Sychevskaya, 1983; Bãnãrescu, 1960; and others). Karaman (1972) excluded Asia Minor species from Acanthorutilus and referred them to Phoxinellus. A more detailed revision of Asia Minor leuciscins shed more light on taxonomy of the genera Pseudophoxinus and Phoxinellus (Bogutskaya, 1991, 1997). The four species mentioned were included in Pseudophoxinus, a genus which is essentially different from Oreoleuciscus being a member of the tribe Leuciscini in contrast to the latter which is a member of the tribe Pseudaspinini. The holotype of O. dsapchynensis is similar to O. potanini by all diagnostic characters (see below) and, accordingly, Acanthorutilus should be regarded as a junior synonym of Oreoleuciscus Warpachowski, 1889, which confirms the point of view of the previous authors (Gundrizer, 1976; Dashdorzh et al., 1969).

Material and Methods

In total, 763 specimens of Altai osmans form water bodies of Altai, Tuva and North-West Mongolia including 120 osteological preparations have been examined. Material included specimens deposited in the collections of the Zoological Institute, Russian Academy of Sciences, St. Petersburg (ZISP), Natural History Museum of the National Academy of Sciences of Ukrain, Kiev (NMU), Zoological Museum of the Moscow University (ZM MGU) and also uncatalogued specimens collected during the Soviet-Mongolian expedition. Material for each species is given in respective places of descriptions. One hundred and fifteen specimens were radiographed. Most osteological preparations were made after clearing and staining with alizarin red “S“, some from salted specimens. The last two branched rays in both the dorsal and anal fins are counted as two, not one ray. Pore counts were made from both left and right sides of the head; the number of canal opening on an individual bone includes entry and exit ones. Fin rays were specifically examined in radiographs in parallel with traditional binocular observations to reveal accurate border of an articulated simple ray section and a point of dichotomy of a branched ray. Abbreviations used are: l. l. - number of lateral line scales on the left side of the body, SL - standard length, D - dorsal fin, A - anal fin, sp. br. - gill-rakers , vert. -

9 total vertebrae (including four Weberian vertebrae and the fused preural- ural centrum as the last one), abd. vert. - abdominal vertebrae (including intermediate ones; precaudal vertebrae auctorum), interm. vert. – intermediate vertebrae (transitional vertebrae auctorum; abdominal vertebrae with parapophyses fused to centra and non-articulated with ribs), preD vert. - predorsal abdominal vertebrae (vertebrae anterior to the first dorsal pterygiophore), caud. vert. - caudal vertebrae; cephalic sensory canals: CIO - infraorbital canal, CPM - preopercular-mandibular canal, CSO - supraorbital canal, CST - supratemporal canal; skull measurements: H eth - depth of ethmoid region, H soc - depth of occipital region, L bas. n. - length of neurocranial base (from anterior end of vomer to posterior end of basioccipital without pharyngeal process), L cr. r., length of cranial roof (from anterior margin of supraethmoid up to origin of supraoccipital crest), Lt eth - width of neurocranium between lateral margins of lateral ethmoids, Lt spho - width of neurocranium between lateral margins of sphenotic lateral processes, Lt pto - width of neurocranium between lateral margins of pterotics; bones and their elements: aart - anguloarticular, boc - basioccipital, dn - dentary; ectpt - ectopterygoid, entpt - entopterygoid, eoc - exoccipital, epo - epiotic, eth.l. - lateral ethmoid, f - frontal, f. car. - carotid foramen, f. dil. op. – dilatator fossa, f. st - subtemporal fossa, hm - hyomandibular, ic - intercalar, iop - interorperculum, keth - kinethmoid, meth - mesethmoid, mtpt - metapterygoid, mx - maxilla; op - operculum, orbs - orbitosphenoid, p - parietal, p. m. - masticatory plate of pharyngeal process, pal - palatine, peth - preethmoid, pmx - premaxilla, pr. cor. - coronoid process, pr. p.-lat. - postero-lateral process of pterosphenoid, pr. pto - posrerior pterotic process, pr. spho - lateral process of spherotic, pro - prootic, ps - parasphenoid, pto - pterotic, pts - pterosphenoid, qu - quadrate, rart – retroarticular, s - symplectic, seth - supraethmoid, soc - supraoccipital; sop - suboperculum, spho - sphenotic, v - vomer.

Oreoleuciscus Warpachowski, 1889

Oreoleuciscus Warpachowski, 1889: 27 (type-species: Chondrostoma potanini Kessler, 1878) Acanthorutilus Berg, 1912: 81 (type-species: Leuciscus dsapchynensis [Herzenstein, nom. mus.] Warpachowski). Body elongated, not laterally compressed; abdominal keel is lacking. Bases of dorsal and anal fins short. D III(IV)(7)8, 9; A III (7)8-10. Dorsal

10 fin posteriorly placed so that predorsal distance larger than postdorsal one. Dorsal fin origin above ventral fin base. Scales small, 80-120 in l. l. Lateral line scales larger than other scales; the number of scales of the lateral row above the lateral line can attain 138. Throat and abdomen often scaleless or covered with small, rounded, non-overlapping scales like those on back in front of dorsal fin and flanks below lateral line (except caudal peduncle). In most cases shape of scales changes from head to posterior end of the body, being more elongated on caudal peduncle. Lateral line usually complete, sometimes lacking from 1 to 4 last scales or slightly interrupted (absent from 1 to 6 scales) along body. Pharyngeal teeth in one row, 6-5 or 5-5, sometimes hooked. Gill-rakers relatively short or long particularly in central part of arch, 15-43 on outer side of first arch. Gill-rakers compressed and bear small but conspicuous denticles along medial margin. CSO shortened and commonly terminates at posterior margin of frontal. CST usually interrupted and medial ends of its lateral branches bent backwards. CPM not connected with CIO terminating at upper end of operculum. CPM always interrupted between lower jaw and preoperculum. Total vertebrae from (40)41 to 46, rarely 47 or 48. Abdominal region is relatively long, being commonly 6 to 9 vertebrae longer than caudal region. Intermediate vertebrae numerous, often 5. Second and third vertebrae fused. Anal fin origin markedly in front of first caudal vertebra: anteriormost 3 to 5 pterygophores of anal fin located under 2 or 3 posterior intermediate vertebrae. Neurocranium shallow, elongated. Supraethmoid with rounded anterior and narrowed posterior part; its anterolateral corners not pronounced and attachment of ligaments from palatines occurs not on anterior margin of supraethmoid, but on its lateral edges. Frontal elongated with shallow long orbital notch. Interorbital septum of orbitosphenoid not pronounced in specimens of middle and large size. Unlike the majority of leuciscins, contact of pterosphenoid through its postero-lateral process with ascending process of parasphenoid very long. Origin of adductor arcus palatini muscle spread forward expanding onto lateral surface of pterosphenoid. Levator arcus palatini muscle attached not only to lateral sphenotic process like in most leuciscins but also to ventral surface and lateral margin of frontal along dilatator fossa up to its very anterior end. Supraoccipital takes part in formation of subtemporal fossa on both sides of head, a character typical only of the tribe Pseudaspinini sensu Bogutskaya (1990c). This bone bears a pair of anterolateral cone-shaped extensions each located in notch of respective 11 epiotic and forming posterior apex of subtemporal fossa. Third and subsequent infraorbitals with narrow lamellate portions, often of irregular shape or reduced. Number of infraorbitals posterior third one varies from 1 to 4 due to fragmentation of bones according to segments of CIO. Suboperculum with narrow but high anterodorsal process. Hyomandibular shallow, relatively wide, with very short ventral branch (nearly not pronounced in large specimens). Cleithrum has deep notch on anterior margin. Males have longer abdominal fins, elongated cone-shaped urogenital papilla, and also epithelial tubercles during spawning season. Howes (1984) placed the genus Oreoleuciscus in the “aspinine-group” together with genera Luciobrama, Aspiolucius, Aspius, Pseudaspius, Elopichtys, Aspiopsis, Pogonichtys, Genghis, and Tribolodon. Our data (Bogutskaya, 1990b, Bogutskaya, 1994) indicate that this is a mixed group uniting large, mostly predatory leuciscins belonging to separate phylogenetic lineages. Oreoleuciscus is included into the tribe Pseudaspinini (Bogutskaya, 1990b) which contains also Pseudaspius, Tribolodon, Phoxinus. The distinguishing characters of this tribe are the presence of a notch on the cleithrum, the hyomandibular with a short ventral branch and discommunicated CPM and CIO, CPM on the operculum being always absent. Most similar to the genus Oreoleuciscus is the genus Phoxinus, possessing a similar type of arrangement and connection of cephalic canals as well as position of the anterior anal fin pteriogyphores. According to the paleontological data (Sychevskaya, 1983), and others) a representative of the Leuciscinae similar to Oreoleuciscus has been reported for the Late Pleiocene in Dzagso Khairkhan (Mongolia); at the same time, in the Neogene ichthyofauna of Siberia this genus is unknown. Apparently Oreoleuciscus is a primary endemic of the Western Mongolian Province having its origin in the Eurosiberian Neogene ichthyofauna of phoxinoid leuciscine cyprinids.

Key for the identification of species of the genus Oreoleuciscus

1(2). Eight branched rays in dorsal and anal fins. Eight to ten, rarely 11, pores in supraorbital sensory canal. Less than 22 pores in infraorbital canal ...... O. humilis 2(1). Commonly 9 or 10 branched rays in the dorsal and anal fins. More than 11 pores in the supraorbital canal. More than 22 pores in the infraorbital canal

12 3(4). Last simple dorsal fin ray thickened, segmented for less than 1/2 of its length. Head wide, its width between margins of pterotics 50 % of skull roof length, width between lateral margins of sphenotic lateral processes equal to or ecxeeds 40 % of skull roof length. Posterior pterotic process short, does not reach basioccipital articulatory surface level ...... O. potanini 4(3). Last simple dorsal fin ray soft, segmented for more than 1/2 of its length. Head narrow, its width between margins of pterotics does not exceed 50 % (up to 52% in small specimens only) ofskull roof length, width in the region of processes of sphenotica is not more than 40 % (in small specimens not more than 42%) of skull roof length. Posterior pterotic process long, reaches much behind basioccipital articulatory surface level . . . . O. angusticephalus

Oreoleuciscus humilis Warpachowski, 1889 dwarf Altai osman (Fig. 1)

Leuciscus potanini (part.; misidentification) - Herzenstein in Potanin, 1883: 244 (part.: ZISP 6381, 8079, 8080 River Chuya near Koschagatch [Kasch-Agatch, Kosh-Agach); Ulangom [Ulaangom] in the basin of Lake Ubs-Nur [Uvs Nuur]) Oreoleuciscus humilis Warpachowski, 1889: 50, Tabl. 2, Fig. 3 (Ulangom; River Chuya near Kosch-Agatsch [a settlement of Petropavlovskoje]) Oreoleuciscus humilis var. phoxinoides Warpachowski, 1889: 54, Tabl. 2, Fig. 4 (Ulangom; Kosch-Agatsch) Oreoleuciscus ignatovi (non Nikolskji) (nonem nudum) - Dorogostaiski, 1908: 238 (Lake Kandy-Nur [Handi Nuur] and Bust-Nur [Bust Nuur]) Oreoleuciscus humilis - Berg, 1912: 85 (Upper Ob River; basin of Lake Ubs-Nur). Oreoleuciscus pewzowi altus (misidentification) - Nichols, 1930: 16 (Lake Orog-Nuur [Orog Nuur] and Kolobolkhi-Nur). Oreoleuciscus potanini (misidentification) - Nichols, 1930:16 (Lakes Bon-Tsagaan- Nuur [Böön Tsagaan Nuur] and Kolobolkhi-Nur). Oreoleuciscus pewzowi pewzowi (misidentification) - Nichols, 1930: 16 (Lake Bon- Tsagaan-Nuur) Oreoleuciscus humilis - Iohansen, 1940: 164 (Upper Chuya River). Oreoleuciscus humilis - Berg, 1949: 541 (Chuya River; basin of Lake Ubs-Nur) Oreoleuciscuis pewzowi - Berg, 1949: 540 (part.: Lake Kandy-Nur and Bust-Nur) Oreoleuciscus pewzowi var. altus - Berg, 1949: 540 (part.: Lake Orog-Nuur) Oreoleuciscus potanini (misidentification) - Egorov, Zhamsaran, 1961: 42 (Lake Ubs- Nur) Oreoleuciscus potanini - Svetovidova, 1965: 24 (part.: Lake Terekhol) Oreoleuciscus humilis - Dashdorzh et al., 1969: 290 (Lake Telmen Nuur, rivers Tazarhain, Tuin Gol, Taytzyn Gol, Tess [Tesiyn Gol]) Oreoleuciscus pewzowi (misidentification) - Dashdorzh et al., 1969: 290 (part.: River Baydrag-Gol [Baidarik, Baydarag Gol], lakes Bon-Tsagan-Nur, Orog-Nuur, Sangijn-Dalai- Nur [Sangiyn Dalay Nuur]) Oreoleuciscus potanini pewzowi (misidentification) - Gundrizer, 1976: 162, Fig. 1 (lake and river ecotypes, basin of Lake Uvs Nuur, Lake Orog Nuur)

13 96.0 mm. Ulaangom (basin of Lake Ubv Nuur). Sl , ZISP 6378. O. humilis Fig. 1. Lectotype of

14 Oreoleuciscus potanini - Baasanzhav et al., 1983: 146, Fig. 22 (part.: dwarf form, water bodies of Lake Valley) “Altai osman” - Borisovets et al., 1985c: 1200, Fig. 2 (part.: dwarf and lake forms) Oreoleuciscus humilis – Vasilieva, 1985: 204 (River Tatsain Gol, Lakes Böön Tsagaan Nuur, Tatsain Tsagaan Nuur) Oreoleuciscus pewzowi – Vasilieva, 1985: 201 (part.: Lakes Tere Khol, Orog Nuur, Böön Tsagaan Nuur, Hari Nuur, basin of Lake Uvs Nuur) Oreoleuciscus potanini – Travers, 1989: 193, Fig. 12 (Lake Böön Tsagaan Nuur, River Tsagaan Gol, Lake Biger Nuur) Oreoleuciscus humilis - Bogutskaya, 1990c: 114, Fig. 1-4 (River Chuya; Lake Uvs Nuur system, water bodies in Lake Valley) Oreoleuciscus humilis – Dgebuadze, 1995: 239 (Lake Valley: Baydrag-Gol, Bon- Tsagaan-Nuur, Tuyn-Gol, Orog-Nuur, Taytzyn-Gol, Taytzyn-Tsagaan-Nuur, Ungijn-Gol [Ongiiyn Gol]) Oreoleuciscus humilis – Golubtsov et al., 1999: 890 (Lake Terekhol) Material: ZISP 6378 (1, lectotype of O. humilis, Ulaangom), ZISP 50026 (2, paralectotypes, of O. humilis, Ulaangom), ZISP 8079 (4, paralectotypes of O. humilis, Kosh-Agach), ZISP 6377 (11, syntypes of O. humilis var phoxinoides, Ulaangom), ZISP 6381 (10, syntypes of O. humilis var. phoxinoides, Kosh-Agach), ZISP 6382 (3, ? syntypes of O. humilis var phoxinoides, Kosh-Agach), ZISP 10554 (3, Ulaangom), ZISP 8080 (7, syntypes of O. humilis var phoxinoides, Kosh-Agach), ZISP 14787 (1, River Chuya), ZISP 15285 (2, Lake Handi Nuur), ZISP 15286 (1, Lake Bust Nuur), ZISP 16320 (1, Lake Handi Nuur), ZISP 21676 (5, Lake Orog Nuur), ZISP 21678. (1, Lake Orog Nuur), ZISP 22081 (1, River Tuyn Gol), ZISP 22096 (2, Lake Orog Nuur), NMU 2485 (13, River Tesiyn Gol), NMU 2568 (20, River Tesiyn Gol), NMU 2571 (14, River Tesiyn Gol), NMU 2715 (21, Lake Terekhol), ZM MGU P-15904 (9, Lake Orog Nuur), uncat. (39, Lake Böön Tsagaan Nuur); uncat. (30, River Tatsain Gol), uncat. (18, Lake Tatsain Tsagaan Nuur), uncat. (40, Lake Bayan Nuur), uncat. (50, Lake Terekhol), uncat. (35, Lake Uvs Nuur), uncat. (15, Lake Biger Nuur), uncat. (18, River Tesiyn Gol); 65 osteological preparations (rivers Baydrag Gol, Tatsain Gol, Lake Terekhol, Tatsain Tsagaan Nuur, Bayan Nuur, Uvs Nuur). Lectotype: Female with ripe eggs. SL 96.0 mm. Morphometric characters are given in Tabl. I. D III 8, the last simple ray is articulated along 52 % of its length; A IV 8; dent. 6-5; l.1. 90; sp. br. 25, vert. 41, abd. vert. 24, caud. vert. 17, preD vert. 14, interm. vert. 4; CSO 8/81 , CIO 17/14, CPM 7+82 /6+9, CST 3+2. Paralectotypes: four males and two females. SL 82.1-95.4 mm. Morphometric characters see Tabl. 1. D III 8, the last simple ray is

1 Number of pores on the left and right side. 2 Number of pores in two canal fragment (on the lower jaw and preoperculum) 15 Table 1 Morphometric characters of O. humilis

Character Lectotype Paralectotypes Lake Boon– Lake Orog Nuur ZISP 6378 ZISP 8079 Tsagaan Nuur n=12 n=4 n=20 SL, mm 96.0 82.2–95.4 161.8–174.2 179.5–210.5 Percents of SL Snout length (1) 6.6 5.8–6.5 7.9–9.1 7.1–9.0 Eye diameter (2) 5.6 5.2–5.9 3.7–4.9 3.8–4.5 Postorbital distance (3) 15.3 14.5–15.1 17.1–20.9 18.0–20.4 Head length (4) 25.0 25.8–27.5 28.5–34.4 30.0–34.2 Head depth at nape (5) 13.6 13.0–14.7 14.3–16.7 15.1–16.7 Head width at nape (6) 10.5 10.5–11.0 12.2–14.6 11.9–13.3 Interorbital distance (7) 5.8 5.9–6.2 6.5–7.8 6.4–7.3 Maximum body depth (8) 15.5 14.6–17.2 20.9–22.0 19.1–22.5 Minimum body depth (9) 8.0 7.7–8.7 9.4–10.5 8.0–10.2 Predorsal distance (10) 54.0 51.9–33.6 53.0–57.4 54.2–57.4 Postdorsal distance (11) 37.5 36.9–39.7 32.1–36.4 33.5–38.3 Caudal peduncle length (12) 19.5 20.0–22.9 18.2–21.2 18.4–21.8 Dorsal fin length (13) 10.4 10.8–12.2 9.8–11.1 9.5–10.8 Dorsal fin depth (14) 19.2 18.2–22.8 17.5–20.3 18.0–19.8 Anal fin length (15) 8.7 8.6–10.8 9.0–11.1 8.7–10.5 Anal fin depth (16) 13.9 14.2–17.3 14.4–17.7 14.7–16.5 Pectoral fin length (17) 15.4 14.9–17.7 16.3–17.8 15.4–17.5 Pelvic fin length (18) 13.0 13.2–14.7 12.0–15.5 12.0–14.1 P–V distance (19) 23.1 22.5–24.1 24.5–25.7 23.7–25.7 V–A distance (20) 20.1 18.7–20.9 18.6–20.4 17.1–19.8 Upper jaw length (21) 6.9 6.2–6.8 7.3–8.2 7.3–8.5 Lower jaw length (22) 9.7 8.8–9.6 10.3–12.2 10.4–11.8 Cranial roof length (23) 18.5 17.3–18.6 18.8–22.1 19.88–22.2 Percents of operculum length Operculum depth (24) 84.5 75.8–84.1 73.1–90.5 70.0–84.6 Percents of cranial roof length Lt pto (25) 55.6 55.4–57.7 52.9–60.6 52.1–58.8 Lt spho (26) 47.3 46.4–48.7 42.6–47.9 40.9–49.3 Lt eth (27) 34.3 33.1–36.9 35.8–39.5 31.7–35.1 Percents of Lt pto Lt spho (28) 84.3 83.7–87.0 76.1–88.5 77.7–89.3 Percents of Lt spho Lt eth (29) 71.3 70.0–76.4 74.7–84.7 67.2–78.6 articulated along 51-54 % of its length; A III, IV 8; dent. 6-5, 5-5; l.1. 83-94; sp. br. 23-25, vert. 41, 42, abd. vert. 24, 25, caud. vert. 17, 18, preD vert. 14, 15, interm. vert. 4, 5; CSO 8, 9, CIO 14-18, CPM [6(7)]+[6- 8(9)], CST [2, 3]+[2, 3]. Diagnosis. Usually 8 branched rays in both dorsal and anal fins. Vertebrae few, total number 40 to 43. Gill-rakers numerous, 22-43. Cephalic pores relatively few: 8-10, rarely 11 pores in CSO, 14-19, seldom to 21, pores in CIO. Simple dorsal rays not thickened, soft; last simple ray segmented for more than one half of its length. Supraethmoid

16 broad, particularly in large specimens. Neurocranium wide, Lt pto 52- 60% of L cr. r. Description. The throat and, to a certain extent, the abdomen are scaleless; in most specimens there are also areas on the back and on the sides that are covered by small not overlapping scales. Lateral line scales are notably larger that the others, 81-114. There are usually 8 branched rays in the dorsal fin. In our material (377 specimens examined) there was only one specimen with 9 rays. In the anal fin there are also 8 branched rays, 9 were found only in 1.3% of specimens. Dorsal fin rays are soft; the last (third or fourth) simple ray is not thickened, flexible for 51-60% (seldom up to 68%) of its length, rarely articulated part of the ray is slightly shorter (48-50%). The next to last simple ray is short. Its length is 33-52% of the length of the last simple ray. Gill-rakers are strongly compressed, as a rule long, dense, (22-24)25- 40(43). The most numerous gill-rakers were found in Altai osmans from Lake Böön Tsagaan Nuur and Orog Nuur. In CSO there are 8-10(11), most commonly 8 or 9 pores (there are 6-8(9) canal openings on the frontal, 2 or 3 on the nasal). In CIO (14)15- 19(20, 21), more frequently 16 or 17 pores (there are 4 or 5, rarely 6, canal openings on the 1-st infraorbital). In CPM pores are arranged in the following way: on the lower jaw there are (3,5)6,7(8,9) pores with 3 to 8, commonly 5 or 6, canal openings on the dentary and (6)7-9(10) pores on the preoperculum. In CST which is usually interrupted in the middle, there are 3 to 6, more frequently 4 or 5 pores. The total number of vertebrae (38 specimens examined) is 40 (2 specimens), 41 (12), 42 (17) or 43 (7). Number of abdominal vertebrae 24 (25), 25 (12) or 26 (1). Predorsal vertebrae 13 (1), 14 (23) or 15 (14). Intermediate vertebrae 4 (24) or 5 (14). Number of caudal vertebrae 16 (2), 17 (19) or 18 (17). Vertebral formulae 24+17 (12), 24+18 (11), 25+17 (6), 25+18 (6), 24+16 (2). The mouth is terminal; the tip of the mouth is on the level of the middle of the eye or slightly lower. The general appearence of fish changes with growth, especially the shape of the head. The most pronounced changes are an increase of the postorbital distance, the snout length, the head length, and length of the lower jaw (Tabl. 1), a flattenning of the dorsal surface of the head, a general increase of the mouth size, a reduction of the eye size. Shape and proportions of the head directly reflect the shape of the skull and correlation of its separate elements. An analysis of a number of osteological characters shows that many of them are 17 subject to relatively high age-and-size variability (Bogutskaya, 1990c). The neurocranium width Lt eth increases while its Lt pto and Lt spho decreases, the ratio of the latters remains relatively constant (Lt spho consititutes 76-80% of Lt pto). The supraethmoid width, length of the lower jaw, depth and length of the operculum, length of the hyomandibular are positively correlated with fish size, but the depth of the hyomandibular is negatively correlated (the length of the hyomandibular becomes nearly equal to its depth in large specimens, whereas in the small ones it constitutes slightly more than a half of it) (Tabl. 2). There are also changes in shape of the bones of the ethmoid region, of the orbitosphenoid, parasphenoid, jaw bones (Bogutskaya, 1990c). Although variability of many characters indicated is relatively high, some to a certain extent are typical of the species. Thus the neurocranium (see in Bogutskaya, 1990c, Fig.1, 3) is wide in general, in specimens of different sizes values of Lt pto and Lt spho are within the ranges of 52.1-60.6 and 40.9-49.3% of L cr. r. respectively. The supraethmoid is broad, in specimens of middle and large size it is markedly wider than the underlying bones of the ethmoid region and its width is up to 14% of L bas. n. The lateral spenotic process bears a relatively deep notch on the posterior margin, so that the postlateral end of the process bends backwards as a hook. The posterior pterotic process is narrow, directed backwards. Its length slightly increases with the increase of body size and the end of the process can reach the level of articulatory surface on the basioccipital. The pharyngeal process is low; the masticatory plate is concave, often quite strongly. Its shape varies from oval to nearly pentagonal, but lateral edges are always smoothed, angles are not pronounced. The preoperculum does not change its shape in connection with the increase of fish size, its horizontal branch is always equal in length to the ascending branch. Comparative remarks. Oreoleuciscus humilis differs from two other species of the genus by a low number of branched rays in the dorsal and anal fins (no one specimen was found among O. potanini or O. angusticephalus sp. n. with 8 branched rays in D and A at the same time), by a low number of pores in the cephalic sensory canals (particularly in CSO and CIO), a wide supraethmoid and also a low number of vertebrae and more numerous and longer gill-rakers. Oreoleuciscus humilis differs from O. potanini also by the following features: not thickened simple rays in the dorsal fin, the last one segmented along more than one half of its length, a hooklike posterior end of the sphenotic process directed backwards, a pointed posterior pterotic

18 Table 2 Data of skull measurements of Altai osmans

O. humilis O. potanini O. angusticephalus

Character n=35 n=30 n=25 n=20 n=2 n=4

SL, mm 108–176 200–442 159–220 over 250 218; 300 over 300

Percents of L bas. n.

Lt pto 42.5–48.1 40.8–47.5 43.6–46.9 40.2–47.8 39.3; 37.5 34.0–38.6

Lt spho 32.9–40.0 30.4–39.0 32.2–37.9 29.2–39.5 25.7; 29.6 21.7–26.6

Lt eth 24.9–30.1 27.0–33.6 25.4–31.6 26.2–32.6 23.5; 26.0 23.2–25.3

H soc 22.6–26.8 22.8–27.8 25.1–29.2 25.5–30.3 24.3; 24.7 24.0–26.0

H eth 6.1–8.1 6.5–8.3 7.5–13.1 6.9–13.8 6.3; 6.9 6.0–6.7

Supraethmoid width 8.9–11.7 10.3–13.9 7.8–10.2 8.4–10.5 7.5; 7.6 7.2–8.9

Lower jaw length 38.9–49.1 45.6–57.1 39.2–46.6 40.2–52.2 49.4; 54.9 53.5–57.6

Operculum length 39.1–47.4 40.0–49.3 35.5–44.3 36.1–42.3 45.4; 47.3 41.4–49.1

Percents of hyomandibular depth

Hyomandibulare length 54.0–72.5 67.4–94.5 54.2–64.2 51.4–81.8 76.1; 79.5 99.3– 103.1 process, and, in large specimens, an elongated operculum and a long lower jaw (Tabl. 2). Oreoleuciscus humilis is similar to O. angusticephalus sp. n. in having soft nonthickened highly segmented simple rays in the dorsal fin and an elongated head, but differs notably from this species, in addition to the above mentioned characters, also by a wider skull, particularly in the region of pterotics. The Ubs-Nur osman described by Gundrizer (1976) under the name O. potanini pewzowi corresponds to the species O. humilis. Unfortunately, this author, having made a conclusion that typical O. pewzowi described from the Kobdo River system is Potanin’s osman and in no way relates to the Ubs-Nur osman, continued using the name “pewzowi”. A wrong conclusion is made also concerning the status of O. humilis as a species described on the basis of a mixed group of specimens. However all syntypes of O. humilis, as can be seen also from descriptions given above, are similar in their diagnostic characters between themselves and with the Ubs-Nur osman. The latter according to the data of Gundrizer

19 (1976) is characterized by fewer dorsal and anal fin branched rays, fewer than in O. potanini number of vertebrae and scales in the lateral line. Morphological differences of O. humilis from other forms of Altai osmans were shown also by Borisovets and his co-authors (1985c, and others). Species status of O. humilis is confirmed also by electrophoretic analysis of muscle proteins (Timofeyev, Dgebuadze, 1985). Distribution. This species inhabits lakes and rivers of Lake Valley from Biger Nuur in the west to Ongiyn Gol in the east where this species is the only one from the genus Oreoleuciscus. For a detailed description of this region see Dgebuadze (1999). Oreoleuciscus humilis also occurs in the system of Lake Uvs Nuur with tributaries (the largest one is River Tess, or Tesiyn-Gol), in some water bodies probably historically connected with this drainage in Tuva and Mongolia, for example, Lake Terekhol, lakes Handi Nuur, Bust Nuur and Sangiyn Dalay Nuur in the east, and also in Telmen Nuur. The question if O. humilis is spread in the Upper Ob’ River needs a special remark. An opinion that O. humilis and O. potanini are sympatric at least in River Chuya is originally based upon a fact that some from syntypes of O. humilis and O. humilis var. phoxinoides are labelled “Kosch-Agatch” (the Chuya drainage) and this locality is respectively given as a type-locality for these names (together with Ulaangom in the Uvs Nuur basin) by Warpachowski (1889). However, no reliable recent data exist on occurrence of O. humilis in the Upper Ob’ system. A special investigation was undertaken by Golubtsov with co-authors (1999) who only found O. potanini in seven localities within the systems of rivers Argut, Chuya, Bashkaus and Chulyshman. These authors believe that “Warpachowski (1889) … identified some specimens of O. potanini from the headwaters of the Ob’ system as representatives of O. humilis.” (p. 893-894). However, the present study undoubtedly shows that all syntypes of O. humilis and O. humilis var. phoxinoides from both Ulaangom and Kosh Agach as well as non-type ZISP 14787 labelled “Tchuya” belong to one and the same species. Untill it is proved that the Kosh Agach syntypes are mislabelled, O. humilis still has the River Chuya system as one from its type-localities. Localities where this species is studied from are given on a map in Fig. 2. Mode of life. Two eco-morphological forms, conventionally termed a dwarf form and a lake form, can be distinguish within a species O. humilis (Baasanzhav et al., 1983, 1985; Borisovets et al., 1985a, 1985b, and others). According to the data of these authors, the dwarf form (length of individuals up to 214 mm) occurs in shallow waters of lakes and rivers falling into them. In rivers, it prefers sections with slow water (raceways 20 - 3 - 2 - 1 , O. potanini , 2 – O. humilis sp. n. angusticephalus 3 – Fig. 2. Localities for specimens examined: 1 –

21 191.4 mm. Dain-gol, Upper Dzavhan Gol. SL , ZISP 4210. O. potanini Fig. 3. Lectotype of

22 and pools). Its feeds on invertebrates (mainly insect latvae), plants and detritus. The lake form is much larger (length up to 550 mm), inhabits only lakes and when it length attains 180-200 mm it passes to piscivorous feeding. Individuals of the dwarf form matures at smaller sizes (at SL about 70 mm and four years of age) than the lake form. Spawning of both forms occurs in June-August, in the dwarf form slightly earlier than in the lake form. Spawning areas of these fishes inlude parts of delta coasts and river flood plains covered by water during floods. Spawning is portioned, eggs are laid on plants and sand. The dwarf and the lake forms of O. humilis from Lake Valley are investigated in conditions of periodic droughts accompanying the disappearance of lakes and some part of rivers in a paper by Dgebuadze (1995). It is shown that during the drought both forms disappear from the lakes and populations of the dwarf form remain in the rivers; after the lakes are filled again, the lake form originates anew from the river dwarf form.

Oreoleuciscus potanini (Kessler, 1879) Altai osman, or Potanin’s osman (Fig. 3)

Chondrostoma Potanini Kessler, 1879: 307 (“Quellzuflussen des Daingol” [Lake Dain- gul, or ? Dayan Nuur], upper reaches of River Kobdo) Chondrostoma Potanini – Kessler, 1880: 267 (“Quellzuflussen des Daingol”) Leuciscus Potanini – Herzenstein in Potanin, 1883: 244 (part.: River Chuya [ZISP 6382], River Tchonokhoraikh [Tchon-Hariha, a channel between Har Nuur and Durgen-Nur [Dörgö Nuur], River Tatche-teli [Tel, a channel between Har Nuur and Dzavhan Gol], River Kobdo) Leuciscus latifrons (nomen nudum) – Herzenstein, 1883: 244 (Ulaangom) Leuciscus Pewzowi (nomen nudum) – Herzenstein, 1883: 244 (Chonokhoraikh) Oreoleuciscus Potanini – Warpachowski, 1889: 30, Tabl. 3, Fig. 1 (basin of River Kobdo; River Chuya) Oreoleuciscus Potanini var. recurviceps Warpachowski, 1889: 38, Tabl. 3, Fig. 2 (locality unknown, probably River Naryn in Upper Kungui [Hüngüy] system) Oreoleuciscus Pewzowi Warpachowski, 1889: 41, Tabl. 1, Fig. 2 (Tchon-Charicha) Oreoleuciscus Pewzowi var. altus Warpachowski, 1889: 45, Tabl. 1, Fig. 3 (Tatche- Teli) ? Oreoleuciscus pewzowi var. longicaudus Warpachowski, 1889: 49, Tabl. 3, Fig. 3 (Tatche-teli) Oreoleuciscus similis (nom. mus. by Herzenstein) Warpachowski, 1889: 57, Tabl. 2, Fig. 1 (Dsapchyn [River Dzavhan Gol]) Oreoleuciscus dsapchynensis (nom. mus. by Herzenstein) Warpachowski, 1889: 61, Tabl. 2, Fig. 2 (Dsapchyn) Oreoleuciscus Herzensteini Warpachowski, 1889: 65, Tabl. 1, Fig. 1 (River Kungui) Oreoleuciscus gracilis Warpachowski, 1889: 68, Tabl. 1, Fig. 4 (Ulangom) ? Oreoleuciscus choerocephalus Warpachowski, 1889: 72, Tabl. 3, Fig. 4 (Airik-Nor [Ayrag Nuur])

23 Morphometric characters

Lectotype, Paralectotypes, Holotype, Syntype, Holotype, Character O. potanini O. potanini O. dsapchynensis O. gracilis O. similis ZISP 4210 ZISP 4211, ZISP 6410 ZISP 6376 ZISP 6411 50027 SL, mm 191.4 148.3–192.5 226.3 87.0 226.5 Percents of SL (1) 5.7 5.9–7.3 6.2 6.9 7.4 (2) 4.6 4.1–4.6 3.9 6.7 3.4 (3) 16.0 15.1–19.2 13.5 16.3 20.7 (4) 26.2 25.9–27.3 24.1 27.6 32.0 (5) 14.5 13.9–15.2 13.5 15.9 16.7 (6) 10.4 10.8–12.2 10.9 11.7 12.5 (7) 6.3 5.4–7.0 6.2 7.2 6.9 (8) 17.4 17.7–19.6 20.2 18.8 20.7 (9) 9.1 8.9–10.1 9.5 9.3 10.3 (10) 53.3 50.4–53.9 45.5 50.6 54.6 (11) 37.3 36.1–39.4 42.0 37.9 36.2 (12) 19.6 17.3–20.7 21.6 23.2 18.4 (13) 11.6 10.9–12.3 13.0 11.8 11.6 (14) 20.3 20.0–23.1 − 24.9 − (15) 10.7 10.4–12.6 11.8 12.1 11.1 (16) 15.2 16.0–17.9 − 18.6 − (17) 16.2 15.7–17.5 − 15.9 − (18) 15.3 14.7–16.1 − 16.1 − (19) 25.0 22.9–27.2 20.7 20.1 24.2 (20) 24.0 24.0–23.0 24.7 21.0 20.4 (21) 5.6 6.2–6.7 5.7 7.2 9.2 (22) 8.4 8.1–9.5 9.3 9.3 12.3 (23) 18.1 17.0–19.1 16.3 18.4 19.3 Percents of operculum length (24) 92.6 73.4–89.7 99.4 88.2 75.9 Percents of cranial roof length (25) 53.6 51.3–58.8 55.7 58.1 54.9 (26) 46.1 41.7–47.2 48.9 50.0 44.9 (27) 33.6 30.7–38.9 32.4 33.1 31.6 Percents of Lt pto (28) 86.8 78.3–91.3 87.9 86.0 81.7 Percents of Lt spho (29) 74.8 72.3–78.0 65.3 66.3 70.4

Oreoleuciscus ignatowi Nikolskji, 1902: 188 (“Tscheibok-kol in montibus Altai, in syst. fl. Baschkaus” [Choebak Khol]) Oreoleuciscus potanini - Berg, 1912: 86 (River Kobdo; basin of the Upper Ob River) Oreoleuciscus pewzowi - Berg, 1912: 88 (part.: basin of River Kobdo) Oreoleuciscus pewzowi var. altus - Berg, 1912: 88 (Lake Choebak Khol) Oreoleucsicus pewzowi - Gladkov, 1938: 296 (Lake Choebak Khol) Oreoleuciscus potanini - Iohansen, 1940: 164 (part.: basin of the Upper Ob River) Oreoleuciscus potanini - Berg, 1949: 539, Fig. 311 (part.: lake of the Lower Kobdo River) Oreoleuciscus pewzowi - Berg, 1949: 540 (basin of River Kobdo)

24 Table 3 of O. potanini

Holotype, Holotype, Holotype, Syntypes, Syntypes, Syntypes, O. herzensteini O. pewzowi O. potanini O. pewzowi O. pewzowi O. ignatowi var. var. var. ZISP 6412 longicaudus recurviceps altus ZISP 7761 ZISP 6413 ZISP 6386 ZISP 6380 ZISP 11193 193.1 116.4 147.2 217.0; 250.1 75.5–142.0 207.8–352.0 Percents of SL 7.2 8.2 6.2 7.2; 7.9 4.7–7.9 8.8–9.6 3.9 6.7 4.9 4.0; 4.8 4.5–6.6 3.6–5.0 17.0 18.4 17.3 18.1; 21.8 14.5–18.8 19.8–23.3 27.7 32.6 28.3 30.5; 34.1 24.1–31.1 32.7–37.7 16.1 16.0 16.1 15.4; 16.2 14.7–15.4 16.1–18.7 13.0 11.6 12.2 10.2; 12.6 10.2–11.8 11.6–14.4 6.8 6.5 6.3 5.6; 6.1 6.2–6.5 7.4–8.9 23.9 17.9 21.9 17.1; 18.6 17.0–20.3 19.6–21.7 10.8 8.0 9.5 8.8; 8.4 7.6–10.0 7.4–10.0 53.8 54.0 53.9 54.0; 54.7 50.7–54.8 54.5–59.2 35.2 37.2 36.7 37.1; 35.5 35.8–38.1 31.7–34.3 16.6 20.3 20.0 19.7; 17.5 18.8–21.9 17.3–19.5 12.5 10.7 9.5 10.4; 11.2 10.6–12.6 11.6–12.0 18.6 21.3 21.0 17.7;17.1 21.5–24.6 19–21.8 11.7 10.8 10.9 10.2; 10.4 9.7–11.8 11.0–11.6 11.4 16.8 15.6 15.3; 13.9 16.4–18.4 14.1–16.0 15.3 15.7 − 14.6; 15.9 17.9–18.8 15.9–17.2 − 14.5 − 13.4; 14.5 14.5–16.3 12.5–14.6 26.2 19.5 24.0 21.2; 22.2 19.1–22.5 19.8–25.3 23.0 18.9 23.6 21.8; 21.2 19.2–20.4 20.2–22.1 7.6 9.6 6.9 8.0; 9.7 7.5–8.8 8.4–10.1 9.6 12.6 9.4 10.9;12.9 10.2–11.6 12.0–14.1 18.4 21.6 18.6 19.0; 21.7 19.6–20.0 19.8–23.1 Percents of operculum length 82.3 78.0 82.1 72.7; 67.6 78.4–90.3 76.9–90.1 Percents of cranial roof length 56.9 48.8 53.3 49.8–51.4 51.6–55.4 50.8–52.2 47.3 39.6 42.0 38.7–41.6 42.5–46.9 40.8–43.2 33.8 28.8 31.0 32.8–34.5 28.2–34.8 29.2–30.1 Percents of Lt pto 83.2 82.0 79.0 73.7–81.9 80.3–90.0 78.2–85.1 Percents of Lt spho 71.4 70.0 73.9 80.0–86.6 73.2–80.7 69.4–71.6

Oreoleuciscus pewzowi var. altus - Berg, 1949: 540 (part.: basin of River Dzavhan Gol; Upper Ob River) Oreoleuciscus potanini - Svetovidova, 1965: 246 (part.: basin of River Kobdo; Lake Choebak Khol) Oreoleuciscus potanini - Dashdorzh et al., 1969: 290 (basin of River Kobdo) Oreoleuciscus potanini - Baasanzhav et al., 1983: 146, Fig. 23, 25 (part.: herbivorous and sharp-snouted forms, basin of River Kobdo) “Altai osman” - Borisovets et al., 1985c: 1200, Tabl. 1, Fig. 2 (part.: herbivorous and sharp-snouted forms, basin of rivers Kobdo and Dzavhan Gol)

25 Oreoleuciscus potanini – Vasilieva, 1985: 199 (upper Ob River; basin of River Kobdo) Oreoleuciscus potanini - Bogutskaya, 1990c: 126 (Upper Ob River; basin of rivers Kobdo and Dzavhan Gol) Oreoleuciscus potanini – Golubtsov et al., 1999: 894 (rivers Argut, Chuya, Bashkaus and Chulyshman) Material: ZISP 42101 (1, lectotype; Daingol), ZISP 50027 (separated from 4210) (2, paralectotypes; Daingol), ZISP 4211 (4, paralectotypes; Daingol), ZISP 6376 (2, bearers of a name Leuciscus latifrons nom. nud. by Herzenstein and syntypes of O. gracilis Warpachowski; Ulangom), ZISP 6379 (2, River Kobdo), ZISP 6380 (7, syntypes of O. pewzowi var. altus; Tatche-teli), ZISP 6383 (5, River Chuya near Kasch-Agatch), ZISP 6385 (3, Tschon-Charicha), ZISP 6386

pr. spho pr. spho

pr. pto pr. pto

ab

Fig. 4. Neurocranium: a - O. potanini, L bas. n. 105.1 mm, Lake Nogon Nuur, b - O. angusticephalus sp. n., L bas. n. 111.8 mm, Lake Nogon Nuur.

1 I have found only seven specimens in total deposited in ZISP under the numbers 4210 and 4211 (syntypes) though Kessler (1879) and Warpachowski (1889) gave a total number of ten. 26 p f.dil.op. pto f epo seth

boc

peth meth orbs pts ps pro a pr.p.-lat. pr.pto eth.l.

eoc p.m.

b v ic soc spho f.car. f.st epo

pal entpt mtpt eoc hm ectpt c d op qu s

keth pop pmx

mx pr.cor. sop dn aart iop e f rart

Fig. 5. Skull of O. potanini, L bas. n. 105.1 mm, Lake Nogon Nuur: a - neurocranium, lateral view, b - neurocranium, ventral view, c - neurocranium, posterior view, d - hyomandibular and palato-quadrate complex, e - bones of opercular cover, f - jaw bones

27 (2, syntypes of O. pewzowi; Tschon-Charicha), ZISP 6387 (1, syntype of O. pewzowi, deform.; Tschon-Charicha), ZISP 6408 (1, River Buyant Gol), ZISP 6409 (1, River Chuya), ZISP 6410 (1, holotype of O. dsapchynensis; Dzavhan Gol), ZISP 6411 (1, holotype of O. similis; Dzavhan Gol), ZISP 6412 (1, holotype of O. herzensteini; River Hüngüy), ZISP 6413 (1, holotype of O. potanini var. recurviceps, locality unknown), ZISP 7761 (1, holotype of O. pewzowi var. longicaudus; Tatche-teli), ZISP 8078 (1, 1; locality unknown), ZISP 10553 (1, River Chuya), ZISP 11193 (3, syntypes of O. igantowi; Lake Choebak Khol); ZISP 11194-11200 (65, Lake Choebak Khol), ZISP 12024 (12, Lake Tash-Obolon-Bashi), ZISP 12645 (2, River Kobdo), ZISP 14788 (3, Lake Choebak Khol), ZISP 15755 (3, Tzagan-Nur1 ), ZISP 15757 (3, River Hüngüy), ZISP 15762 (6, River Chuya), ZISP 20813 (9, Lake Ureg-Nur [Örög Nuur]), ZISP 10814 (8, Lake Ishtyk Khol, basin of River Chuya), ZISP 20815 (1, Lake Ishtyk Khol), ZISP 26699 (3, River Ob), ZISP 39052 (3, channel between lakes Khirgis-Nur [Hyargas Nuur] and Airik- Nur [Ayrag Nuur]), ZISP 39053 (6, Lake Örög Nuur), NMU 2715 (1, Lake Örög Nuur), ZM MGU P-15900 (1, Lake Nogon Nuur), ZM MGU P-15902 (3, Lake Hara-Nur [Har Nuur]), uncat. (26, Lake Dzhulukul [Dzulu Khol]), uncat. (27, Lake Khuh Nuur, Upper Dzavhan Gol) and also 49 osteological preparations (Dzavhan Gol, Lakes Khuh Nuur, Nogon Nuur, Dzulu Khol, channel between lakes Hyargas Nuur and Ayrag Nuur). Lectotype: Female with ripe eggs. SL 191.4 mm. Morphometric characters are given in Tabl. 3. D III 9, the last simple ray is articulated along 35 % of its length; A III 10; 5th ceratobranchials absent; l.1. 87, sq. l. 91; sp. br. 18, vert. 44, abd. vert. 25, caud. vert. 19, preD vert. 15, interm. vert. 5; CSO 6+7/13, CIO 30/27, CPM 6+9/6+2+12, CST 5+5. Paralectotypes: four males and two females. SL 148.3-192.5 mm. Morphometric characters see Tabl. 3. D III 9, the last simple ray is articulated along 37-48% of its length; A III 9, 10; dent. 6-5, 5-5; l.1. 84- 99; sp. br. 18, 19; vert. 44, 45, abd. vert. 25, 26, caud. vert. 18, 19, preD vert. 14, 15, interm. vert. 4, 5; CSO (11)12-14, CIO 24-30, CPM [(7)8- 10]+[10-13], CST [3-5]+[3-5]. Diagnosis. Usually 9 branched rays in dorsal and 9 or 10 in anal fins. Vertebrae numerous, total number 43 to 46. Gill-rakers not very

1 There are several lakes called “Tzagan (Tsagaan) Nuur” in West Mongolia. These specimens are collected by K.V. Yurganova, 14.07.1911; judging on description of her trip (Kerzhner, 1972), at this date she was in the surroundings of Uliastay which is located on Bogdyn Gol, a tributary of Surgyn Gol (Upper Dzavhan Gol). 28 dense, 15 to 25. Cephalic pores relatively numerous: 12-18, very rarely 11 pores in CSO, 22-33, commonly 25-30, pores in CIO. Simple dorsal rays thickened, slightly or notably rigid; the segmented part of the last ray usually constitutes less than 1/2 of its length. Supraethmoid narrow in specimens of all sizes. Neurocranium wide, Lt pto and Lt spho respectively 52-60% and 40-52% of L cr. r. Posterior pterotic process short, does not reach the level of articulatory surface of basioccipital. Description. The body including the throat up to the isthmus is often covered by the overlapping scales or scales on the ventral side is reduced to a certain extent. There are 82 to 116 lateral line scales. There are commonly 9, seldom 8 (8%) or 10 (1%) branched rays in the dorsal fin and 9, sometimes 10 (10%), in the anal one. The last (most commonly the third) simple ray in the dorsal fin is thickened to a certain extent, often quite rigid. Articulated part of this ray constitutes as a rule less than 1/2 (more frequently 38-48 %) of length of this ray and striation of the ray (traces of fusion of the segments) is seen along a relatively short portion below. A relatively small number of specimens (from both Large Lakes Hollow and form the upper Kobdo and Dzabkhan rivers) was found with the third simple dorsal ray relatively soft and .articulated along 48- 52% of its length. The most thickened and to the least degree articulated ray has been noted in specimens form Lake Choebak Khol, Lake Nogon Nuur, Dzavhan Gol River, in which segments are not fused for only 25- 40% of the ray which frequently has the appearance of a spine, flexible only on the very apex (for example, in the holotype of O. dsapchynensis, specimens of the sharp-snouted form from Lake Nogon-Nuur). The indicated structural features of the last simple dorsal ray are found in specimens from 65-70 mm SL. In individuals of smaller sizes (SL 30.4- 32.5 mm: Lake Tash-Obolon-Bashi) this ray is segmented over 50-55% of its length. Anterior part of the dorsal fin is more rigid also because of the frequently thickened, comparatively long next to last simple ray (its length is 50-78% of the length of the last simple ray). Gill-rakers are relatively short, (15)16-24 (25) on the outer side of the first gill arch. In CSO there are 11 to 18, most commonly 12 to 15 pores (there are (7)8-11(12) canal openings on the frontal, 3 to 5 on the nasal). In CIO 22 to 33, more frequently 25 to 30 pores (there are 5 to 12, commonly 6 or 7, canal openings on the first infraorbital). In CPM pores are arranged in the following way: on the lower jaw there are (7)8-11(12) pores with 3 to 9, commonly 5 to 8, canal openings on the dentary and 8 to 14,

29 usually 9 to 12, pores on the preoperculum. In CST which is usually interrupted in the middle, there are 6 to 10 pores. The total number of vertebrae (46 specimens examined) is 43 (4 specimens), 44 (21), 45 (16) or 46 (5). Number of abdominal vertebrae 24 (2), 25 (13), 26 (21), 27 (9) or 28 (1). Predorsal vertebrae 12 (2), 13 (4), 14 (23), 15 (13) or 16 (3). Intermediate vertebrae 4 (2), 5 (25) or 6 (18). Number of caudal vertebrae 17 (3), 18 (20), 19 (16), 20 (6) or 21 (1). Most frequent vertebral formulae 26+18 (11), 26+19 (7), 25+19 (7), 27+18 (6), 25+20 (3). The mouth is terminal, subinferior or seldom almost superior, so that the tip of the mouth is on the level of the upper margin of the eye. The snout is usually stout. The jaws are not long: length of the upper and lower jaw constitutes up to 9 and 11% of SL respectively. Dorsal surface of the head is weakly convex. Length of the head normally does not exceed 30% of SL. The neurocranium (Fig. 5, 6) is relatively short (L cr. r. is 16-20% of SL), wide (Tabl. 2), slightly narrowing in the central part (in the region of sphenotics). According to the data of measurements of 90 undissected specimens (SL more than 70 mm) from lakes Khuh Nuur, Dzulu Khol, Choebak Khol, Tash-Obolon-Bashi, Nogon Nuur, Hüngüy River and Chonokhoraikh, Lt pto is 52.2-62.4 (on the average 55.8), Lt spho is 41.4-51.6 (44.9), Lt eth is 31.8-38.5 (36.1) % of L cr. r.; Lt spho is 76.7-92.8 (85.2) % of Lt pto and Lt eth is 64.3-80.0 (75.3) % of Lt spho. The operculum is relatively deep, its depth is 76.8-102.4 (on the average 86.6) % of the bone length. Comparison of specimens of different sizes shows that width of the skull within the regions indicated does not change or changes insignificantly with the increase of fish body size (Tabl. 3). Thus specimens (ZISP 12024) with SL 30.4-32.5 mm have the same wide head as specimens with the length of 70.5-109.0 mm: Lt pto is 52.1-58.3 and 54.4-58.0% of L cr. r. respectively. These data are confirmed by results of the measurement of skulls in dissected specimens of O. potanini (Tabl. 2). The shape of neurocranium and also of other elements of the skull shows a relatively low variability. Some differences have been revealed between specimens from River Chuya and upper Dzavhan Gol on one hand and specimens from Lake Nogon Nuur on the other hand. The latter differs in having a slightly more elongated neurocranium, a small hyomandibulare, a more elongated and small operculum (Bogutskaya, 1990c). Characters of the neurocranium structure (Fig. 4a, 5) distinguishing O. potanini show comparatively low variability. The supraethmoid is narrow, its width does not exceed 10.5% of L bas. n. The lateral sphenotic 30 process has an obliquely cut or weakly concave posterior margin which never has the shape of a pronounced hook. The dilatator fossa even in large specimens is narrow and short (Fig. 4a), does not exceed 35% of L. bas. n.; the fossa is medially deepened and possesses a well developed roof formed from the frontal and pterotic. The posterior pterotic process is relatively blunt at the end, relatively short even in the largest specimens, it does not reach the level of the articulatory surface of the basioccipital. The pharyngeal process, its masticatory plate and preoperculum are similar in shape with those of O. humilis. Specimens of the sharp-snouted form having a narrow elongated snout differ from typical O. potanini described above only in the shape of the snout. The neurocranium of the sharp-snouted forms differs only by a shallower and more elongated ethmoid region – H eth is about 6%, length of the ethmoid region 20-21% of L bas. n. (vs. 7-14 and 16-17% respectively in the typical form).

ab

Fig. 6. Head, dorsal view: a - O. potanini, SL 220.5 mm, ZISP 39052, b - O. angusticephalus sp. n., SL 216.4 mm, ZISP 50164, both from the channel between lakes Hyargas Nuur and Ayrag Nuur. 31 In a number of examined samples of O. potanini there are specimens, which to a certain extent differ in some characters from the typical form being closer to O. angusticephalus sp. n.. Thus among specimens from Lake Choebak Khol (collected by Igantov, 1901) there are three specimens (syntypes of O. ignatowi Nikolski; SL 207.8-352.0 mm) possessing a relatively large head (length of the head 32.7-37.7% SL) and a long lower jaw (12.0-14.1% SL). However, in the structure of the dorsal simple rays and other morphometric characters they do not differ from typical O. potanini (Tabl. 3). A similar “large-headed” specimen (SL 335.0 mm) was found also in the upper reaches of River Dzavhan Gol (ZISP 15755) (length of the head and length of the lower jaw 36.0 and 14. 5% SL respectively). The holotype of O. similis (SL 226.5 mm) differs by a long head (32.0 % SL), a long lower jaw (12.3% SL) and an elongated operculum (depth is 75.9% of length of the bone), but it possesses a rigid last simple dorsal fin ray and a broad skull (Tabl. 3), which are typical of O. potanini. Different from typical specimens of O. potanini caught in Chonokhoraikh (a channel between lakes Har Nuur and Dörgö Nuur) (ZISP 6380) are three specimens (syntypes of O. pewzowi) caught in the same water body. They are characterized by a slightly narrower and longer head, a longer lower jaw and an elongated operculum (Tabl. 3). Because the last simple ray of the dorsal fin is thickened, articulated for only 35- 42% of its length, syntypes of O. pewzowi were referred to O. potanini (Vasilieva, 1985; Bogutskaya, 1988, 1990c). A comparison of the head width in these specimens with that in typical O. potanini and specimens of O. angusticephalus sp. n. of the same size (SL 216-238 mm) also shows that the syntypes of O. pewzowi (Lt pto is 49.8-51.4, Lt spho is 38.7-41.6% of L cr. r.) is closer to O. potanini than to O. angusticephalus sp. n. (44.4-47.6 and 34.2-37.0% of L cr. r. respectively). Comparative remarks. O. potanini is clearly distinguishable from O. humilis by the number of branched rays in the dorsal and anal fins, number of vertebrae, number of cephalic pores as well as in having a thickened rigid last simple ray in the dorsal fin accompanied by a relatively long next to last ray and a narrow supraethmoideum. Besides the structure of the dorsal simple rays, differences between O. potanini and O. angusticephalus sp. n. are related basically to the cranial width and some other features of skull structure. Thus in O. potanini the neurocranium is relatively wider in all regions, which is particularly pronounced when specimens of middle and large size are compared (Fig. 6, Tabl. 2). In undissected specimens of O. potanini 32 Lt pto is more than 50%, and Lt spho more than 39 % of L cr. r., whereas in O. angusticephalus sp. n. only a few of the smallest specimens had Lt pto up to 52% and Lt spho up to 42% of L. cr. r. Considerable differences are also observed in the shape of the lateral sphenotic process, posterior pterotic process, dilatator fossa, masticatory plate, preoperculum, operculum and hyomandibular. Using characters of cranial structure is not always possible, so, the structure of the last simple ray in the dorsal fin and the relative width of the skull are key characters of external morphology for distinguishing between O. potanini and O. angusticephalus sp. n. However, two specimens were found among all studied of Altai osmans (Tatche-teli; one of syntypes of O. pewzowi var. altus, ZISP 6380, SL 94.5 mm and the holotype of O. pewzowi var. longicaudus ZISP 7761, SL 116.4 mm), possessing characters of both species. Like all other specimens from Tatche-teli they have the hard last simple dorsal ray segmented for only 35-47% of its length, but differ by a narrow, long head: L cr. r. constitutes 21.2 and 24.3% of SL, Lt pto is 49.0 and 48.8% of L cr. r. respectively, which coincides with values of these parameters in one-size specimens of O. angusticephalus sp. n. I have identified them as O. potanini on the basis of the presence of hard thickened ray in the dorsal fin. It is possible that they can be hybrids of O. potanini and O. angusticephalus. Distribution. Lakes and rivers of the Upper Ob drainage; basin of rivers Kobdo and Dzavhan Gol including water bodies of the west Mongolian Great Lakes Valley and Lake Örög Nuur (without outlet, south from the Tsagaan Shibetu mountain). Localities where this species is studied from are presented on a map in Fig. 2. with one exception for ZISP 6376 (syntypes of O. gracilis Warpachowski) with a locality “Ulangom” given on the label. An analysis of literature and my own data gives no reliable recent evidence for occurrence of O. potanini in the basin of Lake Uvs Nuur. Mode of life. According to data of a number of authors (Baasanzhav et al., 1985; Borisovets et al., 1985c) Potaninin’s osman inhabits lakes and parts of rivers with slow current. It does not migrate at long distances, avoiding areas with rapid current. It feeds mostly on aquatic vegetation, and also invertebrates; larger specimens consume fish. Maximum sizes in water bodies of Mongolia are 40-50 cm; for the Upper Ob River there are indications of catching larger fishes (Krivoshchekov, 1959). Length of the sharp-snouted form do not exceed 30 cm. Life duration is 31 to 34 years. This fish attains maturity at an age of 7-8 years at a length of 170- 190 cm, but individuals are met that mature earlier (at a length of 80-100 cm 33 237.8 mm. Lake Nogon Nuur. SL sp. n. ZM MGU P-15901. O. angusticephalus Fig. 7. Paratype of

34 and an age of 4-5 years) and die having smaller sizes (140-150 mm). Spawns in channels and coastal areas of lakes. Spawning lasts from early May until August.

Oreoleuciscus angusticephalus, sp.n. narrow-headed Altai osman (Fig. 7)

Oreoleuciscus pewzowi (non Warpachowski) – Vasilieva, 1985: 202 (part.: Lake Nogon- Nuur) ? “Altai osman” – Borisovets et al., 1985c: 1203 (part.: piscivorous form, Lake Nogon Nuur and Dörgö Nuur) Oreoleuciscus sp. – Bogutskaya, 1990c: 128 (Lake Nogon Nuur). Etymology. Latin translation of the name “narrow-headed”, which reflects the most typical character of this new species. Material: ZISP 50163 (1, holotype; channel between lakes Khirgis- Nur and Airik-Nur), ZISP 50164 (7, paratypes, the same locality), ZM MGU P-15901 (3, paratypes, SL 136.2, 159.2, 237.8 mm; Lake Nogon Nuur), 6 osteological preparations (Lake Nogon Nuur; channels between Hyargas Nuur and Ayrag Nuur). Holotype: immature female. SL 175.5 mm. Morphometric characters are given in Tabl. 4. D III 9, the third simple ray is soft, articulated along 55 % of its length; A III 10; dent. 5-5; l.1. 91; sp. br. 20, vert. 44, abd. vert. 26, caud. vert. 18, preD vert. 15, interm. vert. 5; CSO 15/16, CIO 29/27, CPM 12+10/11+10, CST 4+4. Paratypes: SL 115.2-237.8 mm. Morphometric characters see Tabl. 4. D III (IV)9 (8 in one specimen), the last simple ray is articulated along 52-56% of its length; A III 9, 10; dent. 6-5, 5-5; l.1. 89-105; sp. br. 16-20; vert. 44, 45, abd. vert. 25, 26, caud. vert. 18, 19, preD vert. 14, interm. vert. 5; CSO 13-17, CIO 26-33, CPM [10-12]+[10-14], CST [3- 5]+[3-5]. Diagnosis. Usually 9 branched rays in dorsal and anal fins. Vertebrae numerous, total number 43 to 47. Gill-rakers not very dense, 15 to 22. Cephalic pores numerous: 13-18 in CSO, 26-35, commonly 27-33, pores in CIO. Simple dorsal rays soft; the segmented part of the last ray usually constitutes more than 1/2 of its length. Supraethmoid narrow in specimens of all sizes. Neurocranium narrow, Lt pto and Lt spho respectively 44-52% and 33-44% of L cr. r. Posterior pterotic process long, its end reaches much behind the level of articulatory surface of basioccipital. Description. The troat and anterior part of the abdomen (less frequently the entire abdomen) are scaleless, adjoining parts of the body are covered by non-overlapping scales. There are 89 to 108 lateral line

35 Table 4 Morphometric characters of O. angusticephalus sp. n.

Character Holotype, Paratypes, Paratypes Non–type, ZISP 50163 ZISP 50164 ZM MGU Nogon–Nur P–15901 SL, mm 175.5 115.2–216.4 136.2–237.8 79.4–149.1 Percents of standard length (1) 8.3 6.9–8.4 8.3–8.7 6.6–8.7 (2) 4.7 4.6–5.8 4.2–5.5 4.2–6.4 (3) 22.2 18.7–22.6 28.8–21.8 17.4–21.8 (4) 35.3 31.7–35.4 32.7–34.7 30.0–35.0 (5) 16.2 15.1–16.6 15.2–16.0 14.4–17.2 (6) 11.4 10.4–11.6 10.8–11.4 10.9–12.8 (7) 6.3 5.6–6.4 6.5–7.2 5.9–7.8 (8) 19.0 17.9–19.7 16.0–19.1 16.0–21.9 (9) 7.6 7.8–8.3 8.0–8.9 7.6–9.3 (10) 53.3 51.0–54.2 53.5–57.1 52.0–58.0 (11) 36.4 34.3–39.9 35.2–39.3 35.2–42.5 (12) 18.7 17.9–21.4 19.7–22.5 19.7–24.0 (13) 11.6 10.8–12.0 10.4–11.9 10.4–13.1 (14) 22.1 19.8–26.0 21.4–24.5 20.1–26.0 (15) 11.4 10.7–12.1 9.2–11.2 9.2–12.5 (16) 17.5 16.9–19.2 16.5–18.0 15.9–19.6 (17) 15.6 14.2–20.2 14.8–15.5 13.9–17.1 (18) 14.5 13.7–15.6 13.4–15.2 13.4–16.7 (19) 20.7 20.2–23.9 19.3–20.7 17.4–22.7 (20) 19.9 16.7–21.1 15.7–17.6 15.2–22.1 (21) 9.1 7.7–9.6 7.9–9.6 7.8–9.6 (22) 13.1 11.8–13.7 11.7–13.2 10.7–13.4 (23) 22.2 20.6–21.8 21.0–21.4 19.9–22.8 Percents of operculum length (24) 71.6 69.1–74.1 71.1–76.9 70.5–83.5 Percentsof cranial roof length (25) 46.9 44.2–48.2 44.4–47.6 46.8–52.0 (26) 33.8 34.2–38.7 35.4–37.0 35.5–42.2 (27) 28.7 28.6–31.3 30.7–33.3 30.4–35.4 Percent of Lt pto (28) 72.1 72.5–80.7 75.8–77.5 75.2–83.2 Percents of Lt spho (29) 86.8 77.8–89.6 88.4–97.1 75.8–92.5 scales. There are three, rarely four, simple and 9, rarely 8 or 10, branched rays in both the dorsal and anal fins; not a single specimen with 8 branched rays simultaneously in both fins A have been found. The last simple rays are never thickened and rigid, but segmentation of the last one is developed slightly less than that in O. humilis - in the majority of specimens an articulated part of the ray consitutes only a little bit more than 1/2 (seldom up to 56-65%) of the ray length; sometimes the ray is segmented for 50-46% of its length. The next to last simple ray is longer

36 than in O. humilis and constitutes 58-72% of the length of the last simple ray. Gill-rakers are relatively short and few, 15-22 on the outer side of the first gill arch. Range of variation of the number of pores in certain canals on the head and those of O. potanini overlap; but on the whole O. angusticephalus sp. n. have a somewhat larger number of pores: in CSO there are 13-17(18), more frequently 14 to 16 pores (in the nasal there are 4-6 canal openings and (9)10-13(14) on the frontal). In CIO there are (26)27-33(34, 35), commonly 28 to 31, pores (on the first infraorbitale there are 7-11(12), more frequently 9 to 11 canal openings). In CPM pores are arranged in the following way: on the lower jaw there are 8 to 13, more frequently 10 to12 pores (7 to 13 canal openings on the dentary) and on the preoperculum there are 10 to 15, usually 11 to 14, pores. In CST which is interrupted for rare exceptions there are (6, 7)8- 10 pores. The total number of vertebrae (31 specimens examined) is 43 (4 specimens), 44 (17), 45 (7), 46 (2) or 47 (1). Number of abdominal vertebrae 25 (7), 26 (19), 27 (4) or 28 (1). Predorsal vertebrae 13 (6), 14 (22) or 15 (3). Intermediate vertebrae 4 (4), 5 (22) or 6 (5). Number of caudal vertebrae 17 (4), 18 (13), 19 (13) or 20 (1). Most frequent vertebral formulae 26+18 (10), 26+19 (6), 25+19 (5), 27+17 (2), 25+18 (2). The mouth is terminal; the lower jaw is protruding forward, particularly in larger specimens. The snout is pointed. The head is long, 30-35% SL. The lower jaw is long, constitutes more than 11% SL even in the smallest specimens. The neurocranium (Fig. 4b, 8) is relatively long (length of the cranial roof is 20-23% of SL), narrow (Tabl. 2), notably narrowing in the region of sphenotics. According to data for all 44 specimens Lt pto constitutes 44.2-52.0 (on the average 47.8), Lt spho 33.4-42.2 (36.3), Lt eth 28.6- 35.4 (33.5) % of L cr. r.; Lt spho is 72.5-83.4 (79.1) % of Lt pto; Lt eth is 75-97.1 (86.2) % of Lt spho. The operculum is elongated, particularly in larger specimens; its depth is 69.1-85.5 (on the average 76.4) % of its length. Comparison of specimens having different sizes showed that with fish growth width of the neurocranium on the level of sphenotics and pterotics decreases, Lt spho can attain or be even less than Lt eth (the latter constitutes up to 90-107% of Lt spho); length of the lower jaw encreases, the hyomandibular becomes more elongate (in large specimens its length can be nearly equal or higher than the depth) (Tabl. 2).

37 f.dil.op.

spho pr.pto a

ic

b v p.m.

c d

op

e f

Fig. 8. Skull of O. angusticephalus sp. n., L bas. n. 111.8 mm, Lake Nogon Nuur: a - neurocranium, lateral view, b - neurocranium, ventral view, c - neurocranium, posterior view, d - hyomandibular and palato-quadrate complex, e - bones of opercular cover, f - jaw bones. 38 The supraethmoid is narrow, its width does not exceed 9% of L bas. n. The lateral sphenotic process with a concave posterior margin, so that the posterior end of the process is turned into a small sharp hook. The dilatator fossa is wide, long, its length is 37-42% of L bas. n. (Fig. 4b). The frontal does not form the roof of the fossa and its medial edge is smoothed. The posterior pterotic process is directed backwards, narrow, pointed at the end, long, particularly in large specimens. Its end (in lateral view) is notably behind the articulatory surface on the basioccipital. The masticatory plate on the pharyngeal process is weakly concave or flat of elongated pentagonal shape with pronounced postlateral angles. The preoperculum with an elongated horizontal branch exceeding the ascending branch in length (Fig. 8). Comparative remarks. Oreoleuciscus angusticephalus sp. n. is similar with O. humilis by the presence of a soft last simple dorsal ray, segmented for more than one half of its length, elongated head and operculum, an elongated lower jaw, especially in specimens of larger size. However these species are clearly distinct in particular in the number of vertebrae, in the number of pores in all canals on the head, general width of the neurocranium, width of the supraethmoid, number of branched rays in the dorsal and anal fins. Oreoleuciscus angusticephalus sp. n. shares with to O. potanini a certain number of characters such as the number of rays is the dorsal and anal fins, the number of vertebrae and gill-rakers . Ranges of the number of pores in individual cephalic canal in both species are quite wide and overlapping but if modal ranges are concerned the species can be well distinguished. Thus, in CSO on the frontal the modal ranges of pores are 10 to 13 in O. angusticephalus and 8 to 11 in O. potanini, in CIO 28 to 31 and 25 to 30 with respectively 9 to 11 and 6 or 7 canal openings on the first infraorbital. In CPM on the lower jaw the modal ranges of the number of pores are 10 to 12 and 8 to 11 respectively with 8 to 10 and 5 to 8 canal openings on the dentary. Differences between O. angusticephalus sp. n. and O. potanini concern mainly the structure of the simple rays in the dorsal fin, shape of the skull and its different regions and bones. Differences in shape of the neurocranium (Fig. 3), hyomandibular, operculum and preoperculum are better pronouned in fish of larger size. By the diagnostic external characters O. angusticephalus differs distinctly from O. potanini (including the specimens of the sharp- snouted form from Lake Nogon Nuur examined in this study). The most differentiating external character is the relative width of the skull since some specimens of O. potanini possess relatively soft simple dorsal rays and a long head. Comparison of groups of one-size specimens of O. potanini from 39 different water bodies (SL more than 100 mm) with one size O. angusticephalus sp. n. has shown that values of width of the neurocranium between the lateral margins of pterotics and sphenotics in them do not overlap, in the majority of cases a chiatus is comparatively wide. Thus, Lt pto and Lt spho in O. angusticephalus from the channel between lakes Hyargas Nuur and Ayrag Nuur (paratypes, SL 115-216 mm) constitutes 44.2-48.2 and 34.2- 38.3 as compared to 53.2-58.0 and 44.5-51.2% of L cr. r. in specimens from Lake Choebak Khol (SL 104-220 mm). In same degree the indicated specimens of O. angusticephalus sp. n. differ form specimens of O. potanini (ZISP 39052, SL 119-334 mm) (Fig. 5) caught simultaneously with them in the same channel (in the latter Lt pto and Lt spho are respectively 51.5-53.9 and 40.3-48.0% of L cr. r.). The relative length of the upper and lower jaws as well as the degree of operculum elongation are also differentiating in the majority of cases (Tabl. 3, 4). For the first time O. angusticephalus sp. n. was considered as a distinct species in our concept by Vasilieva (1982, 1985), but unfortunately this was not supported by a pertinent taxonomic procedure. Data of this author and also results of the present work confirm occurrence in the lakes of the lower reaches of River Kobdo of two groups of Altai osmans, which can receive the rank of species because of certain morphological differences described above. A further study of diversity of Altai osmans using additional characters, will possibly provide new data for understanding taxonomic relations of O. potanini and O. angusticephalus sp. n.. Distribution. Lakes of the lower reaches of Kobdo and Dzavhan Gol. Sympatric with O. potanini. Mode of life. Oreoleuciscus angusticephalus sp.n. apparently correlates with the piscivorous form of Altai osman of a number of authors (Borisovets et al., 1985c, and others). Individuals of this form differ by large sizes (length up to 100 cm) and long life duration — more than 40 years. They reach maturity at an age of 8-9 years at body length of 200-240 mm. The young feed on plankton, fish is predominant in the diet of adult fishes. Spawning occurs in May and June. Eggs are laid on the sand, pebble, vegetation. Time and places of spawning partly coincide with those of O. potanini.

Acknowledgements

I am very thankful to Drs. E. D. Vasilieva, Yu.Yu. Dgebuadze and O.N. Pugachev for specimens given at my disposal from their collections. The study was sponsored by grants from the Russian Foundation for

40 Basic Research (98-04-48524, 00–15–97794, 01-04-49552) the “Biodiversity” Program (1998-2001), and a grant “Scientific collection”, USC ZIRAS, 03-16.

Literature

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41 Borisovets, E.E., Yu. Yu. Dgebuadze, V.Ya. Ermokhin. [Morphometric analysis of Altai osmans (genus Oreleuciscus, Cyprinidae, Pisces) in water bodies of Mongolian People’s Republic: Multivariate approach] // Zool. Zhurn., 1985c. Vol. 64, N 8. P. 1199-1212 (in Russian). Borisovets, E.E., Yu. Yu. Dgebuadze, V.Ya. Ermokhin. [Using of mathematical methods for the identification of forms of Altai osmans Oreoleusciscus (Pisces, Cyprinidae)] // Zool. Zhurn., 1987. Vol. 66, N 12. P. 1850-1863 (in Russian). Dashdorzh, A., A. Dulmaa, K. Pivinicka. Contribution to the systematics of the genus Oreoleuciscus Warpachowski, 1889 (Cyprinidae) // Vestn. Èeskoslov. spol. zool., 1969. Vol. 33, N 4. P. 289-299. Dgebuadze, Yu. Yu. [Mecahnisms of form formation and systematics of fishes of the genus Oreoleusciscus (Pisces, Cyprinidae)] // Zoologicheskiye issledovaniya v MNR [Zoological research in Mongolian People’s Republic]. - Moscow: Nauka, 1982. P. 81-92 (in Russian). Dgebuadze, Yu. Yu. The land/inland-water ecotones and fish population of Lake Valley (West Mongolia) // Hydrobiologia, 1995. Vol. 30, N 3. P. 235-245. Dorogostaiskii, V.C. [A trip to North-West Mongolia: a brief report on the travel conducted in the summer 1907 on mission of the Russian Geographic Society] // Izvestiya Imperatorskogo Russkogo Geograficheskogo Obshchestva, 1908. Vol. 44, N 5. P. 223-246 (in Russian). Egorov, A.G., M. Zhamsaran. [Dwarf Altai osman Oreoleuciscus potanini (Kessler) from Lake Ubsa-Nur // Scientific reports of the higher school. Biol. Sciences, 1961. Vol. 2. P. 42-43 (in Russian). Gladkov, N.A. [Note on fishes of Altai] Trudy Altaiskogo gos. zapovednika, 1961. Vol. 1. P. 295-300 (in Russian). Golubtsov A.S., Berendzent P. B. & C.A. Annett. Morphological variation and taxonomic status of Altai osmans, Oreoleuciscus, from the upper reaches of the Ob’ River system // J. Fish Biol., 1999. Vol. 54. P. 878-899. Gundrizer, A.N. [New forms of fishes from water bodies of Ubsanur Hollow] // Ucheny’ye zapiski. Tomskogo Universiteta, 1962. Vol. 44. P. 250-253 (in Russian). Gundrizer, A.N. [The study of Altai osmans of the genus Oreoleuciscus Warp.] // Problemy ekologii. Vol. 4. - Tomsk: Izd-vo Tomsk. Univ., 1976. P. 157-166 (in Russian). Herzenstein, S.M. [A list of fishes collected in north-western Mongolia during expeditions of 1876, 1877, 1879, and 1880] // Ocherki severo-zapadnoi Mongolii. [Essays of North-Western Mongolia]. Vol. 3. - St. Petersburg, 1883. 244 pp (in Russian). Howes, G.J. Phyletics and biogeography of the aspinine cyprinid fishes // Bull. Brit. Mus. Nat. Hist. (Zool.), 1984. Vol. 47, N 5. P. 283-303. Johansen, B.G. [New data on Altai osmans Oreoleuciscus Warp. (Cyprinidae, Pisces)] / / Trudy Biol. Inst., Tomsk Univ., 1940. Vol. 7. P. 132-177 (in Russian). Kafanova, V.V. [Materials on systematics of Altai osmans of the genus Oreoleuciscus Warpachowski] // Voprosy ikhtiologii, 1961. Vol. 1, N 1. P. 9-18 (in Russian). Karaman, M. Susswasserfishe der Turkei. 9 Teil. Revision einiger kleinwuchsiger Cypriniderngattungen Phoxinellus, Leucaspius, Acanthobrama usw. aus Dudeuropa, Klenasiaen, Vorderasien und Nordafrica // Mitt. Hamburg. Zool. Mus. Inst., 1972. Bd. 69. S. 115-155. Kerzhner, I.M. [Historical survey of studies of the insect fauna of the Mongolian People’s Republic] // Nasekomye Mongolii [Insects of Mongolia], vyp. 1. Leningrad: Nauka, 1972. P. 57-112 (in Russian). Kessler, K. Beitrage zur Ichthyologie von Central-Asien // Bull. Acad. Imp. Science St. Petersburg, 1879. Vol. 25. P. 282-310. Kessler, K. Beitrage zur Ichthyologie von Central-Asien // Melanges biol., 1880. Vol. 10. P. 233-272.

42 Krivoshchekov, G.M. [Materials on life history and fishery of Altai osmans] // Biologicheskiye osnovy rybnogo khozyaistva [Biological bases of fisheries]. - Tomsk: Izd-vo Tomsk. Univ., 1959. P. 173-178 (in Russian). Nichols, J.T. Fish of the genus Oreoleuciscus in Gobi Desert Lakes // Copeia, 1930. Vol. 1. P. 16. Nikolskji, A.M. [New species of fish Oreoleuciscus ignatowi n. sp. from Altai] // Ezhegodnik Muz. Imp. Akad. Nauk, 1902. Vol. 7. P. 188-190 (in Russian). Svetovidova, A.A. [Revision of the genus of Altai osmans Oreoleuciscus Warp. (Pisces, Cyprinidae)] // Voprosy Ikhtiologlogii, 1965. Vol. 5, N 3. P. 245-261 (in Russian). Sychevskaya, E.K. [History of formation of ikhtiofauna of Mongolia and the problem of faunal complexes] // Ryby Mongolskoi Narodnoi Respubliki [Fishes of Mongolian People’s Republic]. - Moscow: Nauka, 1983. P. 225-249 (in Russian). Timofeyev, A.V. Yu.Yu. Dgebuadze. [Polymorphism of miogens of Altai osmans (genus Oreoleuciscus, Cyprinidae) from water bodies of Mongolian People’s Republic] // Abstracrts of communications of the VI All-Union Conference on ecological physiology and biochemistry of fishes. – Vilnius, 1985. P. 250-251 (in Russian). Travers R.A. Systematic account of a collection of fishes from the Mongolian People’s Rupublic: with a review of the hydrobiology of the major Mongolian drainage basins // Bull. Br. Mus. nat. Hist. (Zool.), 1989. Vol. 55, N 2. P. 173-207. Vasilieva, E.D. [Osteological analysis of osmans of the genus Oreoleuciscus (Cyprinidae)] // Voprosy Ikhtiologii, 1982. Vol. 22, N 3. P. 374-382 (in Russian). Vasilieva, E.D. [On the taxonomic status of some forms of the genus Oreoleuciscus (Cyprinidae)] // Voprosy ikhtiologii, 1985. Vol. 25, N 2. P. 196-211 (in Russian). Warpachhowski, N.A. [Monograph of the new genus of cyprinid fishes (Oreoleuciscus)]. - St. Petersburg: Izd. Imper. Akad. Nauk, 1889. 79 pp.

ÀÍÍÎÒÀÖÈß ÓÄÊ. 597.5.Cyprinidae Í.Ã. Áîãóöêàÿ Çîîëîãè÷åñêèé èíñòèòóò ÐÀÍ

ÐÅÂÈÇÈß ÀËÒÀÉÑÊÈÕ ÎÑÌÀÍÎÂ ÐÎÄÀ OREOLEUCISCUS (CYPRINIDAE: LEUCISCINAE) Ñ ÎÏÈÑÀÍÈÅÌ ÍÎÂÎÃÎ ÂÈÄÀ, O. ANGUSTICEPHALUS, ÈÇ ÁÀÑÑÅÉÍÀ Ð. ÊÎÁÄÎ, ÇÀÏÀÄÍÀß ÌÎÍÃÎËÈß

Ïðîâåäåíî ñðàâíèòåëüíî-ìîðôîëîãè÷åñêîå èçó÷åíèå àëòàéñêèõ îñìàíîâ ðîäà Oreoleuciscus (Leuciscinae, Cyprinidae) èç ðàçíûõ ìåñò àðåàëà, â òîì ÷èñëå ñèíòèïîâ è ãîëîòèïîâ îïèñàííûõ ðàíåå âèäîâ è âàðèåòåòîâ. Íà îñíîâàíèè àíàëèçà 33 ïëàñòè÷åñêèõ è ìåðèñòè÷åñêèõ ïðèçíàêîâ, 14 êðàíèîëîãè÷åñêèõ ïàðàìåòðîâ, à òàêæå äðóãèõ îñîáåííîñòåé ñòðîåíèÿ ñêåëåòà, (â òîì ÷èñëå ïîçâîíî÷íèêà è ñòåïåíè îêîñòåíåíèÿ íåâåòâèñòûõ ëó÷åé), è êàíàëîâ ñåéñìîñåíñîðíîé ñèñòåìû íà ãîëîâå ïîäòâåðæäåí âûâîä (Áîãóöêàÿ, 1990c) î òîì, ÷òî ðîä Oreoleuciscus ïðåäñòàâëåí 3 âèäàìè. Óçêîãîëîâûé îñìàí èç îç. Íîãîí-Íóð, íå èìåâøèé âàëèäíîãî íàçâàíèÿ, îïèñûâàåòñÿ êàê O. angusticephalus sp. n. Îñíîâíûìè äèàãíîñòè÷åñêèìè ïðèçíàêàìè ÿâëÿþòñÿ ÷èñëî âåòâèñòûõ ëó÷åé â ñïèííîì è àíàëüíîì ïëàâíèêàõ, ñòðîåíèå ïîñëåäíåãî íåâåòâèñòîãî ëó÷à â ñïèííîì ïëàâíèêå, ÷èñëî ïîð ñåéñìîñåíñîðíûõ êàíàëîâ íà ãîëîâå, îòíîñèòåëüíàÿ øèðèíà ãîëîâû â ðàçíûõ îòäåëàõ, ôîðìà supraethmoideum è çàäíåãî îòðîñòêà pteroticum. Ïðèâîäÿòñÿ îïðåäåëèòåëüíàÿ òàáëèöà âèäîâ ðîäà è ïîäðîáíàÿ ñèíîíèìèÿ.

43