Checklist of rodents and insectivores of the Mordovia, Russia

Abstract A list of 40 species is presented of the rodents and insectivores collected during a 15-year period from the Republic of Mordovia. The dataset contains more than 24,000 records of rodent and insectivore species from 23 districts, including Saransk. A major part of the data set was obtained during expedition research and at the biological station. The work is based on the materials of our surveys of rodents and insectivorous mammals conducted in Mordovia using both trap lines and pitfall arrays using traditional methods.


Introduction
There is a need to review the species composition of rodents and insectivores in all regions of Russia, and the work by Tovpinets et al. (2020) on the Crimean Peninsula serves as an example of such research. Studies of rodent and insectivore diversity and distribution have a long history, but there are no lists for many regions of Russia of rodent and insectivorous species. Lists of species have been updated for a few regions, with some species excluded and others added. The Republic of Mordovia is one of these regions, where eminent theriologists (S.I. Ognev, S.S. Turov, L.G. Morozova-Turova, I.I. Barabash-Nikiforov, L.P. Borodin, M.N. Borodina, P.L. Borodin) once worked. The inventory of the mammalian fauna of Mordovia resumed at the beginning of the 21 st century as part of dissertation research and continues to this day. Over this period, not only has the species composition of the region changed but also the status of many species.
The Mordovian fauna is heterogeneous and consists of four different ecological and faunal complexes of species-taiga, coniferous and broad-leaved forests, and steppewhich are widely distributed in several natural areas (Andreychev 2020).
Here, we publish a checklist of rodent and insectivore records across the Republic of Mordovia. This checklist was based on comprehensive surveys of small mammals carried out from 2006 to 2020.
Insectivores are represented in Mordovia by 12 species belonging to three families.

Family Castoridae Hemprich, 1820
Genetic studies of two similar species, Microtus arvalis and M. rossiaemeridionalis, have not been conducted in the region. Approaches and criteria for differentiation of two similar species, Erinaceus roumanicus and E. europaeus, have been applied for a number of specific morphological and craniometric characteristics (Zaitsev 1984;Frost et al. 1991). First, E. roumanicus has a patch of white hair on its belly. And E. europaeus has no white hair on its belly. Differences in the skull are also apparent; in E. roumanicus, the premaxillary-maxillary suture has one or two inflections (in E. europaeus it is smooth), the length of the premaxillary-nasal suture does not exceed 9.0 mm (in E. europaeus >9.0 mm), and the maximum length of the nasal bones in their back part is greater than or equal to 3.0 mm (E. europaeus <3.0 mm) (Zaitsev 1984;Frost et al. 1991;Zaitsev et al. 2014). The color of the needles of these two species can serve as a criteria for their differences. Six species (Eliomys quercinus, Cricetulus migratorius, Lagurus lagurus, Myodes rutilus, Microtus subterraneus, and Neomys anomalus) reported from the Republic of Mordovia were not detected during our surveys. However, these species were captured by our colleagues, either long ago or even in the last year, and most of them (E. quercinus, C. migratorius, L. lagurus, and M. rutilus) were recorded in the Mordovian state nature reserve, Temnikovsky district (Borodina et al. 1970). Microtus subterraneus has recently been found in Mordovia (Kirillova et al. 2019). This record represents the easternmost occurrence of of this species. Previously, this underground vole was recorded in neighboring regions of Mordovia, namely near the village of Zhelannoe in Ryazan region and from Zametchinsky district in Penza region. This species is rare and included in Red Data Books of several Russian regions, including the Leningrad, Tver, Penza, Moscow, Pskov reion, and Novgorod regions. The appearance of a new species for Mordovia can be explained by its expansion into new territories. This is confirmed by the new record of this species from the Smolensk region (Belyaev 2020). In addition, a species atypical of the Mordovian fauna, Neomys anomalus, is now known (Borodin 2013).
The rodent and insectivore fauna of Mordovia is in general large, as it includes both steppe and taiga species. The largest rodent of Mordovia is C. fiber, which is widely distributed in the region's water bodies (Andreychev 2017). The rodent and insectivore fauna of Mordovia is larger than in adjacent regions. However, the fauna lacks some species that exist in adjacent regions: Ulyanovsk region -Allocricetulus eversmanni Brandt, 1859 (Red Book 2008); Penza region -Spermophilus major Pallas, 1778, Sicista strandi (Formozov, 1931) (Il'in et al. 2006

Temporal coverage
The data were collected from 2006 to 2020.

Method
Most of the dataset was obtained in the Republic of Mordovia during expedition research and at the biological station. The work is based on the materials of our surveys of rodents and insectivorous mammals conducted in the Republic of Mordovia, using trap lines and pitfall arrays using traditional methods. Small rodents were captured using small spring snap-traps (120 × 55 mm) left over night in lines of from 50 to 100 traps with a distance of 5 m between them and baited with bread and sunflower oil. We also used live traps baited with salami and apple to catch dormice. Voucher specimens are stored in the personal collection A. Andreychev, Saransk (teriomordovia@bk.ru