Lemmus lemmus

Spitsyn, Vitaly M., Bolotov, Ivan N., Kondakov, Alexander V., Klass, Anna L., Mizin, Ivan A., Tomilova, Alena A., Zubrii, Natalia A. & Gofarov, Mikhail Y., 2021, A new Norwegian Lemming subspecies from Novaya Zemlya, Arctic Russia, Ecologica Montenegrina 40, pp. 93-117 : 115

Lemmus lemmus species complex

Distribution: Northern Eurasia.

Comments: This informal group contains four biological species, i.e. Norwegian L. lemmus (Linnaeus, 1758) , Siberian L. sibiricus (Kerr, 1792) , East Siberian L. aff. sibiricus ‘Eastern Clade’, and Amur L. amurensis Vinogradov, 1924 lemmings. Phylogenetically, L. lemmus and L. sibiricus are most closely related species ( Table 4). These two species were not supported as separate MOTUs by the species delimitation modeling ( Fig. 2 ). However, we consider them as young allopatric species that originated in distant Pleistocene refugia (Western Europe + Novaya Zemlya vs Siberia). The level of DNA divergences between L. lemmus and L. sibiricus corresponds well to interspecific differences (i.e. the mean cytb and COI p-distance>2%; several diagnostic nucleotide substitutions in the nuclear GHR and RAG1 gene fragments) ( Tables 4 -5). Conversely, the level of cytb divergence of these species from other taxa (4.4-4.9%) is at least twice their distance, as is the divergence between L. aff. sibiricus ‘Eastern Clade’ and L. amurensis (4.5%). The two latter taxa were fully supported as separate species-level units by our species delimitation modeling ( Fig. 2 ).

Figures

Figure 2. Maximum likelihood (IQ-TREE) phylogeny of Lemmus taxa based on the cytb gene haplotypes. The Novaya Zemlya Lemming (Lemmus lemmus chernovi ssp. nov.) is colored red. The numbers near nodes are ultrafast bootstrap support values/Bayesian posterior probabilities. The red asterisks indicate the putative species-level clades supported by bPTP and sPTP species-delimitation models. The scale bar indicates the branch length. Outgroup taxa (Dicrostonyx torquatus, D. hudsonius, Synaptomys cooperi, and Myopus schisticolor) are not shown.