© RUSSIAN JOURNAL OF THERIOLOGY, 2006 Russian J. Theriol. 5 (2): 7983 Introduction The Ust-Kan cave is situated in the Belyi Kamen mountain massive built with specifically light-colored Silurian (LlandoveryWenlock) limestones. The cave is located on the right bank of the Charysh River in 3.5 km E from the district center, the Ust-Kan settlement, 50º 54' 40" N, 84º 48' 50" E. The cave has a southwest- ern orientation. The entrance is at 45 m above the river level and at 1037 m above sea level. The cave was discovered and thoroughly studied by Rudenko in the middle of the last century (Rudenko, 1960, 1961). In late 1990s new excavations of the site were started by the Institute of archaeology and ethnography of the Siberian Division of the Russian Academy of Sciences. The Pleistocene sequence of the Ust-Kan Cave have been divided into 12 levels, some of them with minor morphological subdivisions. Most levels produced ar- chaeological materials of the Mousterian (Derevyanko et al., 2001; Agadjanian et al., 2003). Small mammal remains are common in every level. They are represent- ed by isolated teeth, fragmentary long bones, and verte- brae. The overall faunal composition of beds 1 through 8 indicates Late Pleistocene age. The lower levels (12 through 9), which are distinctly red-colored, yielded a mixed assemblage combining Late Pleistocene forms and species typical for earlier intervals of Pleistocene (Tab. 1). Three associations of late Middle Pleistocene, and two Early Pleistocene age are defined analytically. Early and Middle Pleistocene faunas were previ- ously unknown in Central Altai. This is why the discov- ery of archaic voles in the lower levels of the Ust-Kan Cave has a great scientific value. The most archaic association of the locality is dated to the earliest stage of Early Pleistocene, early Biharian by the presence of the primitive lagurine Prolagurus ternopolitanus To- pachevsky, 1973. New form of rhizodont voles (Rodentia, Arvicolinae, Clethrionomyini) from Pleistocene of Central Altai (Russia) Natalia V. Serdyuk & Alexey S. Tesakov ABSTRACT. Lower beds of multi-layered Paleolithic site of the Ust-Kan Cave yielded a heterogeneous material of small mammals containing a characteristic Early Pleistocene association. Along with molars of typical early Biharian forms, few remains of a very hypsodont clethrionomyine vole have been encountered. This form shows weakly differentiated enamel, high dentine tracts, lacks mimomyian characters, and has sparse cement. The combination of characters permits its interpretation as a late rhizodont stage of one of phyletic lineages of modern high mountain voles of the genus Alticola. It shows some similarities with the flat-sculled vole, A. strelzowi. The new form is described as a new genus and species, Altaiomys ustkanicus gen. & sp. nov. KEY WORDS: Arvicolinae, Alticola, evolution, Early Pleistocene, Altai, Russia. Natalia V. Serdyuk [nataly@paleo.ru], Paleontological Institute of the Russian Academy of Sciences, Profsoyuznaya 123, Moscow 117997, Russia; Alexey S. Tesakov [tesak@ginras.ru], Geological Institute of the Russian Academy of Sciences, Pyzhevsky per. 7, Moscow 119017, Russia. Íîâàÿ ôîðìà êîðíåçóáûõ ïîëåâîê (Rodentia, Arvicolinae, Clethrionomyini) èç ïëåéñòîöåíà öåíòðàëüíîãî Àëòàÿ (Ðîññèÿ) Í.Â. Ñåðäþê, À.Ñ. Òåñàêîâ ÐÅÇÞÌÅ.  íèæíåé ÷àñòè ðàçðåçà ìíîãîñëîéíîãî ïàëåîëèòè÷åñêîãî ïàìÿòíèêà Óñòü-Êàíñêàÿ ïåùåðà îáíàðóæåíû ñëîè ñ ãåòåðîãåííûì êîìïëåêñîì ìåëêèõ ìëåêîïèòàþùèõ, âêëþ÷àþùèì õàðàêòåðíóþ àññîöèàöèþ ðàííåãî ïëåéñòîöåíà (ýîïëåéñòîöåíà). Ñðåäè ìîëÿðîâ îáû÷íûõ ôîðì ðàííåãî áèõàðèÿ îòìå÷åíû íåñêîëüêî êîðåííûõ çóáîâ î÷åíü ãèïñîäîíòíîé ïîëåâêè òðèáû Cleth- rionomyini ñî ñëàáî äèôôåðåíöèðîâàííîé ýìàëüþ, âûñîêèìè òðàêòàìè, îòñóòñòâèåì ìèìîìèñíûõ ïðèçíàêîâ è ìàëûì êîëè÷åñòâîì öåìåíòà. Ïî êîìïëåêñó ïðèçíàêîâ ýòà ôîðìà èíòåðïðåòèðóåòñÿ êàê ïîçäíÿÿ êîðíåçóáàÿ ñòàäèÿ îäíîé èç ôèëåòè÷åñêèõ ëèíèé, âåäóùåé ê ñîâðåìåííûì ñêàëüíûì ïîëåâêàì Alticola. Íàèáîëåå áëèçêèì ñõîäñòâîì îíà îáëàäàåò ñ ïëîñêî÷åðåïíûìè ïîëåâêàìè A. strelzowi. Ýòà ôîðìà îïèñûâàåòñÿ êàê íîâûé ðîä è íîâûé âèä, Altaiomys ustkanicus gen. & sp. nov. ÊËÞ×ÅÂÛÅ ÑËÎÂÀ: Arvicolinae, Alticola, ýâîëþöèÿ, ðàííèé ïëåéñòîöåí, Àëòàé, Ðîññèÿ.