Alexandromys baicalensis, Fetisov, 1941 (Fetisov, 1941)

Lissovsky, Andrey A., Petrova, Tatyana V., Yatsentyuk, Svetlana P., Golenishchev, Fedor N., Putincev, Nikolay I., Kartavtseva, Irina V., Sheremetyeva, Irina N. & Abramson, Natalia I., 2017, Multilocus phylogeny and taxonomy of East Asian voles Alexandromys (Rodentia, Arvicolinae), Zoologica Scripta 47 (1), pp. 1-12 : 8

4.4 | Taxonomic status of A. baicalensis

The nominal taxon Microtus arvalis baicalensis Fetisov, 1941 was described as a subspecies of the common vole M. arvalis . The holotype (ID 231, collected on 22.7.1936 on “Ordak Golets”) was kept in the collection of the East-Siberian University, now State Irkutsk University (IGU). Fetisov (1941) mentioned 26 specimens of M. arvalis collected by him in 1936. An earlier publication ( Fetisov, 1937) contains a list of exact places where the series was collected: Tsagan-Chelutay (51.505 N; 106.172 E), Ortsak (51.292 N; 103.785 E; this is the correct name for “Ordak”: “d” and “ts” are similar letters in Russian), Khan-Ula (51.182 N; 103.982 E) and Khatyn-Ula (undefined). The holotype is absent in both the collection of IGU and the inventory documents. It is known that A. Fetisov moved some specimens he collected to larger museums. However, we did not find the specimens in the ZMMU or ZIN collections. The only two specimens related to the topic were found in the ZIN collection. These are voles initially identified as M. arvalis collected by Fetisov on 9.7.1936 (ZIN 25840) and 14.7.1936 (ZIN 25841) at Snezhnaya River. Taking into account that the difference in collection date is a few days, they should be collected at Khan-Ula Golets (distance between Ortsak and Khan-Ula is about 18 km), the only site situated at this river. As Fetisov (1937, 1941) mentioned voles collected in 1936 in the region of Snezhnaya River in the original description of Microtus arvalis baicalensis , the latter two specimens (25,840 and 25,841) should be designated as paratypes (ICZN, 1999 Art. 72.4.1.1, 72.4.5).

Voles of M. arvalis do not inhabit high altitudes of East Siberia, thus Ognev (1950) referred to M. a. baicalensis as a junior synonym of A. mongolicus . If this species identification was correct, this name could be a senior synonym to Mongolian voles of western or central Mongolia. It should be noted that Ognev did not list any exact museum specimen of M. a. baicalensis in the publication.

Our analysis found that two paratypes of M. a. baicalensis belong to different species: one is A. middendorffii and another is young specimen of A. oeconomus . Such identification is concordant with teeth morphology of these two specimens. The second case could be considered as accidental collector’s identification mistake—the tail length of the adult root vole is notably larger than values provided by Fetisov (1941), so probably adult root voles were absent in the type series of M. a. baicalensis . However, our identification of A. middendorffii explains this confusion. Specimens of A. middendorffii are very similar to M. arvalis in terms of dental morphology ( Gromov & Erbajeva, 1995; Gromov & Polyakov, 1977). Distribution of A. middendorffii and A. mongolicus is allopatric, and thus, it is less probable that the type series included both species. Consequently, we can hypothesise that the holotype of M. a. baicalensis also belonged to A. middendorffii .