Marmotini

Belongs within: Xerinae.
Contains: Tamias, Spermophilus.

The Marmotini are a clade of either terrestrial or terrestrially nesting squirrels, including the chipmunks, marmots and prairie dogs. Many Marmotini nest socially, and all undergo at least some period of hibernation over winter. The most sociable are the prairie dogs of the North American genus Cynomys, which form large ‘towns’ containing numerous family groups.

Marmots, ground squirrels and prairie dogs

Published 10 July 2007

The Marmotini are one of the few clades of squirrels to make it to North America, along with the flying squirrel genus Glaucomys and the genera Tamiasciurus and Sciurus*. There are five genera—the more arboreal Tamias (chipmunks) and the terrestrial Ammospermophilus, Spermophilus, Marmota (marmots) and Cynomys (prairie dogs)—though some authors divide up some of these genera, notably Tamias and Spermophilus (which is probably paraphyletic). Tamias, Spermophilus and Marmota include Eurasian members, while Ammospermophilus and Cynomys are solely North American. I haven’t been able to find what are the specific morphological characters uniting this clade (reading between the lines in Callahan & Davis, 1982, I suspect they’re genitalic characters), but it is also recovered with molecular phylogenies (Mercer & Roth 2003). All Marmotini hibernate during winter to some extent (A. Watts).

*There is another genus present in North America, Microsciurus, but Mercer & Roth (2003) find it to be nested within Sciurus.

Perhaps the most interesting features I’ve come across in a quick scan of the Marmotini are their reproductive patterns and their sociality. Marmotini produce large litters of relatively small cubs or pups or whatever a baby squirrel is called, and apparently have the smallest size at weaning relative to adult size (see here).

Marmota and Cynomys both contain species that live socially. All species of Cynomys are social and form form large ‘towns’ containing numerous family groups. These colonies are larger than those of Marmota, of which there are some non-social species (in line with the common name of ‘prairie dog’, the name Cynomys translates as ‘dog-mouse’). These two genera form a clade relative to the other Marmotini, but it is debatable whether sociality has appeared multiple times within the clade or whether it has appeared once and then been lost in the non-social marmots—the nested position of the solitary Marmota monax within marmots suggests to me that the latter may be more likely (Cardini et al. 2005).

Groundhogs, woodchucks and other big squirrels

Published 11 October 2011

The section above was one of the earliest articles I wrote at this site, before I really knew what I was doing*. So I’ll have a go at improving it now.

*Not, of course, that I know what I’m doing now.

Marmotini is the clade of squirrels that includes ground squirrels (Spermophilus), antelope ground squirrels (Ammospermophilus), marmots (Marmota) and prairie dogs (Cynomys). Authors seem to differ on whether to also include the chipmunks (Tamias), but the question is somewhat semantic: agreement seems to be universal that the chipmunks represent the sister group to the remaining marmotins (Herron et al. 2004), so the only real question is how inclusive one wishes to make the term. The Chinese rock squirrels Sciurotamias may also belong to the Marmotini (Steppan et al. 2004). Except for the semi-arboreal chipmunks, marmotins are largely terrestrial in habits. They nest in underground burrows (including chipmunks), and some species form quite complex societies.

Ground squirrels previously assigned to the genus Spermophilus* have a wide range through Eurasia and North America. However, both morphological and molecular data indicate that Cynomys is derived from within ‘Spermophilus’, and molecular data indicate that Ammospermophilus and Marmota are as well (Herron et al. 2004). Helgen et al. (2009) divided the former Spermophilus between eight genera. Six of these genera are found in North America, one (Spermophilus proper) is found in Eurasia, and only one (Urocitellus) spans the divide between northeast Asia and North America. Whether the Marmotini as a whole are Eurasian or North American in origin is equivocal: of the three basalmost branches, Sciurotamias is definitely Eurasian, Tamias could be either (the Siberian chipmunk Tamias sibiricus is the sister to the remaining North American species) and the Spermophilus clade is probably North American in origin, with dispersals back to Eurasia in Marmota, Urocitellus and Spermophilus (Herron et al. 2004).

*Particularly in the European literature, it was not uncommon in the past to find the name Citellus being used in place of Spermophilus. Citellus Oken 1816 is indeed an older name than Spermophilus Cuvier 1825; however, the publication that the former derives from was not one that used the binomial system, and hence it has been declared invalid as a source of names (International Commission on Zoological Nomenclature 1956).

Marmotins were the dominant squirrel group in North America during the Neogene; tree squirrels, though present, were exceedingly rare (Emry et al. 2005). The Pliocene Paenemarmota was the largest of all marmotins, reaching the size of a large beaver (Repenning 1962).

Systematics of Marmotini

Characters (from Moore 1959): Two transbullar septa per auditory bulla; orbital length at least 1.15× interorbital breadth; no temporal foramen in squamosoparietal suture; sphenopalatine foramen usually with less than half area of sphenoidal fissure; supraorbital notches generally open and trenchant.

Marmotini [Marmotinae]SSH04
    |--SciurotamiasFS15
    |    |--S. davidianusMR03
    |    `--S. forrestiIT07
    `--+--TamiasFS15
       `--+--AmmospermophilusFS15
          |    |  i. s.: A. insularisIT07
          |    |--+--A. harisiiFS15
          |    |  `--A. interpres (Merriam 1890)FS15, MB86
          |    `--+--A. leucurusFS15
          |       `--A. nelsoniFS15
          `--+--+--SpermophilusFS15
             |  `--CynomysFS15
             |       |  i. s.: C. hibbardiMH03
             |       |         C. sappaensis (Goodwin 1995)MH03
             |       |--C. (Cynomys)AF86
             |       |    |--C. (C.) ludovicianus (Ord in Guthrie 1815)AF86, B75 [=Arctomys ludovicianaB75]
             |       |    `--C. (C.) mexicanus Merriam 1892AF86, MB86
             |       `--C. (Leucocrossuromys)AF86
             |            |--C. (L.) parvidensAF86, FS15
             |            `--+--C. (L.) gunnisoniAF86, FS15
             |               `--C. (L.) leucurusAF86, FS15
             `--+--+--+--Callospermophilus lateralisHGP74 [=Spermophilus (Callospermophilus) lateralisHGP74, FS15]
                |  |  `--+--‘Spermophilus’ madrensisFS15
                |  |     `--‘Spermophilus’ saturatusFS15
                |  `--+--Otospermophilus variegatus (Erxleben 1777)GB68, MB86 (see below for synonymy)
                |     |    |--O. v. variegatusMB86
                |     |    |--‘Spermophilus’ v. couchii Baird 1855MB86
                |     |    `--‘Spermophilus’ v. rupestris (Allen 1903)MB86
                |     `--+--‘Spermophilus’ atricapillusFS15
                |        `--‘Spermophilus’ beecheyiFS15
                `--MarmotaFS15
                     |--+--M. flaviventrisFS15
                     |  |    |--M. f. flaviventrisG56
                     |  |    `--M. f. nosophoraG56
                     |  `--+--M. olympusFS15
                     |     `--+--M. caligataFS15
                     |        `--M. vancouverensisFS15
                     `--+--M. monax (Linnaeus 1758)FS15, B75 [=Mus monaxB75]
                        |    |--M. m. monaxB75
                        |    |--M. m. bunkeri Black 1938B75
                        |    `--M. m. rufescensB75
                        `--+--+--+--M. broweriFS15
                           |  |  `--M. marmotaFS15
                           |  `--+--M. caudataFS15
                           |     `--M. menzbieriFS15
                           `--+--+--M. baibacinaFS15
                              |  `--M. bobakFS15
                              `--+--M. camtschaticaFS15
                                 `--+--M. himalayanaFS15
                                    `--M. sibiricaFS15
Marmotini incertae sedis:
  CitellusB74
    |--C. beecheyiB49
    |--C. beldingiG56
    |--C. citellusRJ11
    |--C. lateralisJ68
    |    |--C. l. lateralisJ68
    |    |--C. l. chrysodeirusJ68
    |    |--C. l. cinerascensJ68
    |    `--C. l. tescorumJ68
    |--C. mexicanusGM71
    |--C. saturatusJ68
    `--C. tridecemlineatusGD61
  EutamiasB74
    |--E. alpinusM68
    |--E. amoenusJ68
    |--E. asiaticusD56
    |--E. canipesS85
    |--E. cinereicollisS85
    |--E. dorsalisGM71
    |--E. ruficaudusJ68
    |--E. minimusS85
    |    |--E. m. minimusS85
    |    |--E. m. atristriatusS85
    |    |--E. m. consobrinusS85
    |    |--E. s. operariusS85
    |    `--E. m. scrutatorS85
    |--E. quadrivittatusS85
    |--E. sibericusB74
    |--E. sonomaeJ68
    |--E. townsendiS00
    |    |--E. t. townsendiS00
    |    `--E. t. senexS00
    `--E. umbrinusS85
  ProtospermophilusSSH04
  MiospermophilusSSH04

Otospermophilus variegatus (Erxleben 1777)^{GB68, MB86} [=Spermophilus (Otospermophilus) variegatus^{GB68, FS15}]

*Type species of generic name indicated

References

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[B49] Baker, E. W. 1949. A review of the mites of the family Cheyletidae in the United States National Museum. Proceedings of the United States National Museum 99 (3238): 267–320.

[B75] Bowles, J. B. 1975. Distribution and biogeography of mammals of Iowa. Special Publications, The Museum, Texas Tech University 9: 1–184.

[B74] Bugge, J. 1974. The cephalic arterial system in insectivores, primates, rodents and lagomorphs, with special reference to the systematic classification. Acta Anatomica 87 (Suppl. 62): 1–160.

Callahan, J. R., & R. Davis. 1982. Reproductive tract and evolutionary relationships of the Chinese rock squirrel, Sciurotamias davidianus. Journal of Mammalogy 63 (1): 42–47.

Cardini, A., R. S. Hoffmann & R. W. Thorington Jr. 2005. Morphological evolution in marmots (Rodentia, Sciuridae): size and shape of the dorsal and lateral surfaces of the cranium. Journal of Zoological Systematics and Evolutionary Research 43 (3): 258–268.

[D56] Dawes, B. 1956. The Trematoda with special reference to British and other European forms. University Press: Cambridge.

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[FS15] Faurby, S., & J.-C. Svenning. 2015. A species-level phylogeny of all extant and late Quaternary extinct mammals using a novel heuristic-hierarchical Bayesian approach. Molecular Phylogenetics and Evolution 84: 14–26.

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[GD61] Guilday, J. E., & J. K. Doutt. 1961. The collared lemming (Dicrostonyx) from the Pennsylvania Pleistocene. Proceedings of the Biological Society of Washington 74: 249–250.

Helgen, K. M., F. R. Cole, L. E. Helgen & D. E. Wilson. 2009. Generic revision in the Holarctic ground squirrel genus Spermophilus. Journal of Mammalogy 90 (2): 270–305.

Herron, M. D., T. A. Castoe & C. L. Parkinson. 2004. Sciurid phylogeny and the paraphyly of Holarctic ground squirrels (Spermophilus). Molecular Phylogenetics and Evolution 31: 1015–1030.

International Commission on Zoological Nomenclature. 1956. Opinion 417. Rejection for nomenclatorial purposes of volume 3 (Zoologie) of the work by Lorenz Oken entitled Okens Lehrbuch der Naturgeschichte published in 1815–1816. Opinions and Declarations Rendered by the International Commission on Zoological Nomenclature 14: 1–42.

[IT07] Isaac, N. J. B., S. T. Turvey, B. Collen, C. Waterman & J. E. M. Baillie. 2007. Mammals on the EDGE: conservation priorities based on threat and phylogeny. PloS One 2 (3): e296.

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[MH03] Martin, R. A., R. T. Hurt, J. G. Honey & P. Peláez-Campomanes. 2003. Late Pliocene and Early Pleistocene rodents fom the northern Borchers Badlands (Meade County, Kansas), with comments on the Blancan-Irvingtonian boundary in the Meade Basin. Journal of Paleontology 77 (5): 985–1001.

[MB86] Matson, J. O., & R. H. Baker. 1986. Mammals of Zacatecas. Special Publications, Museum of Texas Tech University 24: 1–88.

[MR03] Mercer, J. M., & V. L. Roth. 2003. The effects of Cenozoic global change on squirrel phylogeny. Science 299: 1568–1572.

Moore, J. C. 1959. Relationships among the living squirrels of the Sciurinae. Bulletin of the American Museum of Natural History 118 (4): 153–206.

[M68] Murray, K. F. 1968. Distribution of North American mammals. Systematic Zoology 17 (1): 99–102.

Repenning, C. A. 1962. The giant ground squirrel Paenemarmota. Journal of Paleontology 36 (3): 540–556.

[RJ11] Rising, J. D., A. Jaramillo, J. L. Copete, P. G. Ryan & S. C. Madge. 2011. Family Emberizidae (buntings and New World sparrows). In: Hoyo, J. del, A. Elliott & D. A. Christie (eds) Handbook of the Birds of the World vol. 16. Tanagers to New World Blackbirds pp. 428–683. Lynx Edicions: Barcelona.

[S00] Siddiqi, M. R. 2000. Tylenchida: Parasites of plants and insects 2^nd ed. CABI Publishing: Wallingford (UK).

[SSH04] Steppan, S. J., B. L. Storz & R. S. Hoffmann. 2004. Nuclear DNA phylogeny of the squirrels (Mammalia: Rodentia) and the evolution of arboreality from c-myc and RAG1. Molecular Phylogenetics and Evolution 30: 703–719.

[S85] Sullivan, R. M. 1985. Phyletic, biogeographic, and ecologic relationships among montane populations of least chipmunks (Eutamias minimus) in the Southwest. Systematic Zoology 34 (4): 419–448.