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| Lemmus lemmus chernovi Spitsyn, Bolotov & Kondakov in Spitsyn, Bolotov, Kondakov, ... et Gofarov, 2021. |
Abstract
Norwegian Lemming Lemmus lemmus is a remarkable population cycling species having a number of aposematic traits in coloration and behavior. This species was thought to be the only mammal endemic to Fennoscandia. Here, we report on the discovery of a distinct lineage of this species from Novaya Zemlya. This lineage is described here as the new subspecies Lemmus lemmus chernovi ssp. nov. that morphologically differs from the nominate subspecies by having a cryptic coloration. Our time-calibrated phylogeny revealed that this insular subspecies was isolated there since the Eemian interglacial (mean age 93 Ka). Hence, bright coloration and antipredator behavior of the nominate subspecies are novel aposematic traits that evolved since its isolation in a European refugium. This new discovery indicates that Novaya Zemlya supported a cryptic polar refugium for cold-adapted terrestrial fauna during the Pleistocene. Finally, our findings highlight that allopatric ranges of the true lemmings (Lemmus) reflect stepwise range expansions in cold climatic episodes with subsequent isolation in refugia during interglacial events.
Key words: Arctic Ocean islands, cryptic polar refugium, Eemian interglacial, integrative taxonomy, Lemmus lemmus, Lemmini, phylogeography, Pleistocene glaciations
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| Dorsal view of lemming specimens: (A) Novaya Zemlya Lemming (Lemmus lemmus chernovi ssp. nov.) [holotype RMBH Lem005], and (B) Norwegian Lemming (L. lemmus lemmus) [RMBH Lem040, Kola Peninsula]. Scale bar = 10 mm. (Photos: Vitaly M. Spitsyn). |
Lemmus lemmus chernovi Spitsyn, Bolotov & Kondakov ssp. nov.
Common name: Novaya Zemlya Lemming
Differential diagnosis: The Novaya Zemlya Lemming differs from the nominate subspecies by having a cryptic coloration of dorsal surface that is dark gray with yellow and reddish hairs in adults (Fig. 6A) to reddish in juveniles, with an unclear longitudinal black stripe in anterior part from neck to nose (vs bright yellow coloration with black anterior part of the trunk and large black spots on head). The new subspecies is morphologically similar to Lemmus sibiricus but adult specimens from Novaya Zemlya could be distinguished from it by dorsal coloration with yellow and reddish hairs (vs brown and reddish hairs).
Etymology: This subspecies is named in memory of the late Academician of the Russian Academy of Sciences Yury I. Chernov (1934-2012), a prominent Russian zoologist, biogeographer, and Arctic explorer.
Distribution and habitat: This subspecies is endemic to the Southern Island of Novaya Zemlya, while its reliable records from the Northern Island of this archipelago are unknown (Fig. 1A). It inhabits a broad range of meadow-like (Fig. 1B) and tundra habitats
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| Figure 5. Ancestral coloration reconstruction (Bayesian Binary MCMC analysis) of Lemmus taxa based on our fossilcalibrated BEAST v. 1.10.4 phylogeny. Black numbers near nodes are BEAST’s BPP. The Lemmus trimucronatus + L. nigripes clade (cryptic coloration) is omitted. (Photos: Vitaly M. Spitsyn). |
Vitaly M. Spitsyn, Ivan N. Bolotov, Alexander V. Kondakov, Anna L. Klass, Ivan A. Mizin, Alena A. Tomilova, Natalia A. Zubrii and Mikhail Y. Gofarov. 2021. A New Norwegian Lemming Subspecies from Novaya Zemlya, Arctic Russia. Ecologica Montenegrina. 40; In Progress. 93-117. DOI: 10.37828/em.2021.40.8
