Urocricetus Satunin 1902

Lebedev, V. S., Bannikova, A. A., Neumann, K., Ushakova, M. V., Ivanova, N. V. & Surov, A. V., 2018, Molecular phylogenetics and taxonomy of dwarf hamsters Cricetulus Milne-Edwards, 1867 (Cricetidae, Rodentia): description of a new genus and reinstatement of another, Zootaxa 4387 (2), pp. 331-349 : 342-343

Urocricetus Satunin 1902 , new rank

Type species: Cricetulus kamensis Satunin, 1902

Diagnosis. Small hamsters with long to moderately sized tail, naked elongated feet and wavy margin of dorsal coloration. Rostrum slender and long, zygomatic plate straight. Hamular process of squamosum narrow and straight. Molars relatively narrow and high-crowned, main cusps elongated, labial and lingual anterocones (-conids) positioned close to each other, mesolophids (posterior ridges of metaconid) in m1 and m2 usually present. Auditory bullae small to medium-sized with extended tubular anterior part, stapedial foramen of normal size and position.

Differential diagnosis. Urocricetus can be distinguished from all recent cricetines other than Phodopus by the shape of bullae tympani, which has a long tube-like protrusion on its anterior part ( Fig. 6 ). It differs from Phodopus by position and size of the stapedial foramen, lack of fur on palms and soles, and length of tail.

Content. Includes at least two species– U. kamensis and U. alticola , the status of thibetanus and lama requires additional examination. Does not include kozlovi .

The monophyly of Cricetulus sensu lato is also violated by the phylogenetic position of C. migratorius , which proves to be more closely related to Cricetus and Allocricetulus than to C. barabensis and C. longicaudatus . This result, which was first obtained by Neumann et al. (2006), is fully supported here based on a more extensive sampling. There is no evidence that this phylogenetic arrangement is an artifact of some secondary signal such as base composition bias.

It should be indicated that the genus Cricetulus in its traditional sense (i.e. including C. migratorius ) appears to be an artificial grouping of small-sized hamsters. No morphological or chromosomal synapomorphies are known to support its monophyly despite the fact that Palearctic hamsters are relatively well studied from both perspectives (e.g. Vorontsov 1982; Romanenko et al. 2007).Thus, the grey hamster can not be retained within Cricetulus sensu stricto, which should include only C. barabensis (type species), C. sokolovi and C. longicaudatus . From a morphological viewpoint, there are no reasons to lump C. migratorius and its sister taxa— Cricetus and Allocricetulus— into a single genus taking into account the substantial level of morphological and genetic divergence among the three branches. Therefore, the only possible decision is to assign C. migratorius to a new genus, the description of which is given below.

Figures

FIGURE 6. Ventro-lateral view of the auditory bulla; (a) Cricetulus longicaudatus (ZMMU S-63115), (b) Urocricetus aff.alticola (ZMMU S-155360).