Mimomys occitanus Thaler, 1955: 1255-1257 Chaline 1974: 343-353 Terzea 1981: 119-124 Chaline et al. 1981: 821-826 Mimomys hassiacus atavus Fejfar, 1961b: 57-60 Mimomys stehlini Chaline & Michaux 1975: 749- 757 Dolomys odessanus Topachevsky & Nesin 1989: 49 Propliomys cf. hungaricus Kormos,1934 Dolomys occitanus ( Thaler, 1955 ) Promimomys konstantinovae Topachevsky & Nesin 1989: 82-86 Dolomys occitanus Maul 1996: 348 Dahlmann 2001: 73 Pliocene small mammals (Mammalia, Lipotyphla, Chiroptera, Lagomorpha, Rodentia) from Muselievo (North Bulgaria) Popov, Vasil V. Geodiversitas 2004 26 3 403 491 (Thaler, 1955) Thaler 1955 [765,1131,1326,1354] Mammalia Muridae Dolomys GBIF Animalia Rodentia 60 463 Chordata species occitanus      Mimomys occitanus Thaler, 1955: 1255-1257. —  Chaline 1974: 343-353, figs 3-8, 9 5,6. —  Terzea 1981: 119-124, figs 2, 3, 4A-D, 5A, B. —  Chaline et al.1981: 821-826.     Mimomys hassiacus atavus Fejfar, 1961b: 57-60, taf. 18, figs 5, 6; abb. 5a, c, 6d.    Mimomys stehlini–  Chaline & Michaux 1975: 749- 757, pl. I, text-fig. 1.    Dolomys odessanus–  Topachevsky & Nesin 1989: 49, fig. 18.  FIG. 32. —  Propliomyscf. hungaricusKormos,1934, first lower molars; A, right, Ms43, occlusal view; B, left fragment, Ms47, occlusal view; C, left fragment, Ms45, occlusal view; D, left fragment, Ms46, occlusal view; E, left fragment, Ms48, occlusal view; F, right, Ms44, occlusal view; G, right, Ms43, buccal view; H, right, Ms44, buccal view; I, left, Ms46, buccal view; J, left, Ms47, buccal view; K, left, Ms45, buccal view; L, left, Ms48, buccal view. Scale bar: 1 mm.  FIG. 33. —  Dolomys occitanus( Thaler, 1955), first lower molars in occlusal view; A, right, Ms42; B, left, Ms1; C, left, Ms2; D, right, Ms3; E, right fragment, Ms5; F, left fragment, Ms6; G, right fragment, Ms4; H, right fragment, Ms7; I, left, Ms8; J, right, Ms9; K, right, Ms10; L, right, Ms11; M, left, Ms12; N, right, Ms13; O, left, Ms14. Scale bar: 1 mm.    Promimomys konstantinovae–  Topachevsky & Nesin 1989: 82-86, fig. 31.    Dolomys occitanus–  Maul 1996: 348. — Fejfar & Reppening 1998: 163, abb. 3, 5. —  Dahlmann 2001: 73, abb. 20: 37-52    MATERIAL EXAMINED. —  23 m1: morphotype “  Mimomys”:  17 m1 (9 fragments, 8 intact [Ms7-14]; morphotype “  Dolomys”:  6 m1 [Ms1-6, 42], 19 M3 [Ms23-40]).  MEASUREMENTS (Min-M-Max, SD, N). — Lm1 = 2.67-2.91-3.20, 0.169, 8; am1 = 1.00-1.26-1.37, 0.163, 7; Wm1 = 1.07-1.23-1.65, 0.191, 8; LM3 = 1.50-1.76-2.00, 0.127, 17. DESCRIPTION There is no crown-cementum in the side folds of the molars. In most specimens, the enamel is not differentiated, but in some teeth it is slightly thinner on the tips of the salient angles. The crown is moderately high but the dentine tracks of the linaea sinuosaare low. m1: the variable shape of occlusal surface can be classified into two morphotypes, called “  Dolomys”- and “  Mimomys”-morphotypes. The “  Dolomys”-morphotype ( Fig. 33A-G) is characterized by an open isle fold. The Sb3-wall is in a low position. The “  Mimomys”-morphotype bears  Mimomys-ridge, prism-fold and isle-fold or enamel islet ( Fig. 33H-O). M3: in unworn or slightly worn specimens, the BRA1 and LSA3 are deep, but after some wear they become reduced by insulation. The anterior islet vanishes quickly with further wear, while the posterior one is a long persistent structure, presented even in some worn teeth (Ms40). The clear relationship between the stage of wear and the number of islets indicates that all teeth belong to one species. Most teeth bear two roots. The anterior root is a compound structure, formed by the fusion of two roots. In some specimens the anterior fangs, although partially fused, are still clearly visible (Ms23, 25, 26, 35, 37-39). One tooth shows a very small third root (Ms23).  REMARKS There is a great controversy regarding the taxonomic status of the “  Dolomys” and “  Mimomys” morphotypes of m1s referred to this species. Sulimski (1964)described them as two separate species –  Dolomyscf. hungaricusand  Mimomyscf. stehliniKormos, 1931. Chaline (1974)found in the large assemblage from Sète that these typesare connected by intermediate forms, depending mainly on the stage of wear (see also  Vande Weerd 1979: table 9), and he therefore regarded the whole material as one highly variable species,  Mimomys occitanus. It is a primitive, more or less mesodont form with a relatively high share of specimens in which the isle-fold remains open even in the advanced stages of crown wear – the so called “  Dolomys”-morphotype. According to Chaline (1974)and Chaline & Michaux (1975)two evolutionary lineages derived from this variable species: one leading through Mimomis  stehliniKormos, 1931,  M. polonicus Kowalski, 1960,  M. pliocaenicus(Forsyth Major, 1889), and  M. saviniHinton, 1910to  Arvicola mosbachensis(Schmidtgen, 1911), the other one through  Propliomys hungaricusand  Pliomys episcopalis Méhely, 1914to  P. lenki(Heller, 1930)[=  P. coronensis( Méhely, 1914)]. The former phyletic sequence is referred to the “  Mimomys”-lineage, the later one to the “  Dolomys”-lineage. In fact, the second lineage represents the evolution of  Propliomys-  Pliomys Méhely, 1914( Kretzoi 1955, 1962; De Bruijn & Vander Meulen 1975; Chaline 1975). This disagreement in the nomenclature within the second lineage reflects the similarity in teeth morphology of the earliest forms of these related genera (  Dolomysand Propliomys-Pliomys) ( Nehring 1898; Méhely 1914; Hinton 1926; Kormos 1934b). On the other hand the co-occurrence of the “ancestral” (“  Dolomys”-morphotype of  M. occitanus) and the derived forms (typical  Propliomyswith relatively high enamel free areas on m1) in Muselievo does not confirm that they belong to the same phyletic lineage. The lineage Propliomys- Pliomysapparently constitutes an early specialized branch of the evolution of voles and cannot be regarded to derive from  Mimomys occitanusas though by Chaline & Michaux (1975). According to  Vande Weerd (1979),  M. occitanusis an intermediate stage of evolution from  Promimomys Kretzoi, 1955to the advanced forms of  MimomysForsyth Major, 1902. During this evolution, morphological changes of m1 with a variable direction have been proposed: from forms with an isolated islet (  Promimomysand  Mimomys davakosi Van de Weerd, 1979) through an open islet (most specimens in  M. occitanus) to an isolated islet again (  M. stehlini) (  Vande Weerd 1979). This variable trend however seems unlikely, having in mind that the direction of an evolutionary change is usually irreversible.  FIG. 34. —  Dolomys occitanus( Thaler, 1955), first lower molars in buccal view; A, right, Ms42; B, left fragment, Ms1; C, right fragment, Ms7; D, left fragment, Ms2; E, left fragment, Ms8; F, right fragment, Ms11; G, right fragment, Ms13. Scale bar: 1 mm. The analysis of the detailed morphology of the enamel islet in the anteroconid of the m1 of  Dolomys,  Promimomysand  Mimomyspresented by Maul (1996)provides a new perspective for the solution of this evolutionary and taxonomic problem. Maul (1996)found that  M. occitanusdiffers from the earliest members of the genera  Promimomysand  Mimomysin having a low positioned wall of the  Mimomys-isle (Sb3-wall). This feature is considered a derived one, leading to an evolutionary trend toward lowering of the wall. With the decrease in the height of the wall more  Dolomys-morphotypes appear in a population which have greater functional advantage because of their longer cutting edges. In this context, it seems likely that  M. occitanusis an ancestral species to forms with a lower Sb3-wall like  Dolomys nehringiand does not belong to the Promimomys-Mimomysevolutionary lineage comprising voles with a higher Sb3-wall ( Maul 1996). For the time being, this hypothesis is the best solution of the problem and the attribution of the species “  occitanus” to the genus  Dolomysis followed here. According to Fejfar (2001), in contrast to the previous views ( Chaline 1974; Chaline & Michaux 1975;  Vande Weerd 1979), the evolutionary chain leading to  M. stehliniis as follows:  M. davakosi Van de Weerd, 1979 -  M. gracilis( Kretzoi, 1959) - M. stehlini. According to the structure of M3, the genus  Dolomysis rather specific and comprises such large species as  D. milleri Nehring, 1898and  D. nehringi Kretzoi, 1959(Chaline 1975). The occlusal pattern of m1 of these species (see for example Kretzoi 1962: abb. 4; Rabeder 1981: abb. 182) is quite different from the “  Dolomys”- morphotypes of  Dolomys occitanus. In this context the opinion of Maul (1996)that  D. occitanusis an ancestor of  D. nehringiseems unlikely. The occurrence of M 3 inthe locality very similar to  D. nehringiconfirms this opinion. The same line of reasoning can be developed against the Chaline’s hypothesis that  Dolomys- morphotypes of  D. occitanusrepresent an ancestral form for  Propliomys hungaricus. The “  Dolomys”-morphotype is quite different from the m1s of the true  Propliomys hungaricusfrom Csarnóta-1 ( Kormos 1934b: fig. 46; Terzea 1981: fig. 5s, d) and their co-occurrence in Muselievo (see above) indicates that this genus cannot be considered as a derivate of  D. occitanus. For the time being, it can be said only that the ondatrine taxa, occurring in the European Pliocene [  Dolomys occitanus( Thaler, 1955),  Dolomys milleri( Nehring, 1898),  Dolomys nehringi Kretzoi, 1962,  Dolomys adroveri( Fejfar, Mein & Moissenet, 1990), and  Propliomys hungaricus(Kormos, 1934)], represent a mosaic of species related to  D. occitanus, which radiated quickly during the Ruscinian and early Villanyian (MN14-16-zones) ( Fejfar & Repenning 1998). As a whole, the population from Muselievo corresponds to the variability of  Dolomys occitanusfrom the typelocality (Grotte 1 de Sète) ( Chaline 1974). In the scatter diagram composed for Lm1 and Em1 ( Chaline 1974: fig. 2) the specimens from Muselievo would occupy the upper half of the cluster of the population from Sète. Hence, the material under study represents a slightly more advanced form. The m1s from Muselievo resemble also  D. occitanusfrom Ciuperceni- 2 inboth size and morphology ( Terzea 1981, 1997; and pers. comm.) and differ only in having somewhat higher dentine tracks. Most probably the material from the nearby Romanian locality Dranic, determined as  Mimomys moldavicus(Radulescu & Samson 1996)belongs to  D. occitanustoo, having in mind that  M. moldavicus(Kormos, 1932)is a rather primitive form with extremely low dentine tracks, referable to  Promimomys(Fejfar et al. 1990). In general, the material from Muselievo is very similar to m1 and M3 sample of  Dolomys occitanusfrom Wölfersheim ( Germany) ( Fejfar & Repenning 1998; Dahlmann 2001). The difference concerns only the somewhat longer m1 and the hyposinusids slightly lower in the sample from Muselievo.  FIG. 35. —  Dolomys occitanus( Thaler, 1955), third upper molars; A, left, Ms23, occlusal view; B, right, Ms24, occlusal view; C, right, Ms25, occlusal view; D, right, Ms26, occlusal view; E, left, Ms27, occlusal view; F, right, Ms28, occlusal view; G, left, Ms29, occlusal view; H, left, Ms30, occlusal view; I, right, Ms31, occlusal view; J, left, Ms32, occlusal view; K, right, Ms33, occlusal view; L, left, Ms34, occlusal view; M, right, Ms35, occlusal view; N, left, Ms36, occlusal view; O, left, Ms37, occlusal view; P, left, Ms38, occlusal view; Q, left, Ms39, occlusal view; R, right, Ms40, occlusal view; S, left, Ms23, lingual view; T, the same, buccal view; U, right, Ms24, lingual view; V, the same buccal view. Scale bar: 1 mm. The “  Mimomys” morphotypes of  D. occitanusare superficially similar to  M. davakosibut differ in having higher dentine tracks (  Vande Weerd 1979). This difference is clearly visible in relation to the material from Ptolemais 3, the typelocality of  M. davakosi, especially in respect to the anterosinuid. Moreover,  M. davakosi, being a typical member of the  Mimomyslineage, shows a higher position of the Sb3-wall (cf. Maul 1996: fig. 3). MATERIAL, EXAMINED 23 63 466 1