The least known with the smallest ranges: analyzing the patterns of occurrence and conservation of South American rodents known only from their type localities

Pablo Teta, Guillermo D’Elía


The identification of taxa with small range sizes is important both from an ecological and conservational perspective. As other small mammals, several species of rodents have restricted geographical distributions, a situation that could increase their immediate risk of extinction. Species having restricted ranges and/or low population sizes have usually lower genetic variation than wide-ranging relatives, being highly susceptive to disruptive treats, such as new or introduced competitors, pathogens, and predators, severe climatic events, cataclysms, and/or population-level phenomena. We reviewed the most recent compilations on South American rodents to identify those only known from their type locality (i. e., an area with a maximum latitudinal and longitudinal range of < 10 km). This restriction is in accordance with an extent of occurrence < 100 km2, which fits partially with the criterion B1 of the IUCN for an extent of occurrence of a critically endangered species. For each species, we recorded the year of description, country of origin, main habitat use, use of substrate, and conservation status. We identified 58 species of South American rodents that are known only from their type localities or their vicinities. These species belong to two suborders, seven families, and 29 genera. The family with more species in this list is Cricetidae, which accounted for a half of the included species. Most species in our list were described during the decades of 1890-1930 and 1990 to recent. The habitat type with more species in the list was tropical forest. Almost a third of the species are considered under the highest categories of threat, such as CR, EN o VU. Two species within the list are considered to become extinct in historical times, including the akodont Juscelinomys candango and the vizcacha Lagostomus crassus. Almost half of the species in our list are referred as DD. Fifty eigth rodent species from South American are only known from their type localities and their surroundings; i. e., ca. 9 % of the currently approximately 650 recorded species of the subcontinent. The species list provided here need to be depurated trough additional field and collection based work. Even when some species could be removed from this list (due taxonomical changes or additional records from other localities), it is also possible than others could be included. Most species in our list are found at or close to highland areas, such as the Andes or the Serra do Mar, suggesting that at least partially the rarity of some of them could be related to the relative inaccessibility of these places. As in previous contributions focused on geographically restricted taxa, most species in our list are considered as DD in the IUCN Red List. This is unfortunate, since species listed as DD usually do not gain much attention (i. e., conservation programs, founds) as those considered as CR, EN or VU. Previous authors discussed this point, suggesting the need to designate as CR all species geographically restricted to their type localities, at least when no recent records (i. e., in the last 25 years) exists.

Palabras clave

distribution; endemism; extinction; rare species; Rodentia; small mammals

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Abreu-Júnior, E. F., A. R. Percequilloa, L. Geise, Y. L. R. Leite, and A. C. Loss. 2018. Unveiling the identity of Kerr’s Atlantic tree rat, Phyllomys kerri (Rodentia, Echimyidae). Mammalian Biology 91:57-70.

Amori, G., and M.N. Clout. 2003. Rodents on islands: a conservation challenge. Pp. 63-68 in Rats, Mice and People: Rodent Biology and Management (Singleton, G. R., C. A. Hinds, C. J. Krebs, and D. M. Spratt, eds.). ACIAR Monographs 96. Sidney, Australia.

Amori, G., G. A. Esposito, and L. Luiselli. 2016. Known from a handful of specimens: analyzing the worldwide patterns of occurrence and conservation of rodents and shrews recorded only from the type locality. Journal of Threatened Taxa 8:8556-8563.

Bidau, C. J. 2015. Familia Ctenomyidae. Pp. 818-877 in Mammals of South America (Patton, J. L., U. F. J. Pardiñas, and G. D’Elía, eds.). The University of Chicago Press. Chicago & London.

Caughley, G. 1994. Directions in conservation biology. Journal of Animal Ecology 63:215–244.

Cherem, J. J., J. Olimpio, and A. Ximenez. 1999. Descrição de uma nova espécie do gênero Cavia Pallas, 1766 (Mammalia- Caviidae) das Ilhas dos Moleques do Sul, Santa Catarina, Sul do Brasil. Biotemas 12:95-117.

Chiquito, E. A., and A. R. Percequillo. 2019. The taxonomic status of Nectomys saturatus Thomas, 1897 (Cricetidae: Sigmodontinae). Zootaxa 4550:321-339.

D’Elía, G., P-H. Fabre, and E. P. Lessa. 2019a. Rodent systematics in an age of discovery: recent advances and prospects. Journal of Mammalogy 100:852-871.

D’Elía, G., F. Jaksic, L. D. Bacigalupe, F. Bozinovic, J. L. Canto, C. Correa, F. E. Fontúrbel, F. Lisón, M. A. Méndez, R. Nespolo, J. C. Opazo, E. Palma, J. R. Rau, S. M. Rodríguez, E. Rodríguez-Serrano, P. Sabat, R. A. Vásquez, and P. Victoriano. 2019b. Sugerencias para mejorar la regulación chilena de manipulación de vertebrados terrestres en poblaciones naturales en el contexto de investigaciones científicas. Gayana 83.

Emmons, L. H. 1999. A new genus and species of Abrocomid rodent from Peru (Rodentia: Abrocomidae). American Museum Novitates 3279: 1-14.

Emmons, L. H., Y. L. R. Leite, D. Kock, and L. P. Costa. 2002. A review of the named forms of Phyllomys (Rodentia: Echimyidae) with the description of a new species from coastal Brazil. American Museum Novitates 3380:1-40.

Fernandes, F. A., R. Fornel, and T. R. O. Freitas. 2012. Ctenomys brasiliensis Blainville (Rodentia: Ctenomyidae): clarifying the geographic placement of the type species of the genus Ctenomys. Zootaxa 3272:57-6 8.

Fleming, P. A., and P. W. Bateman. 2016. The good, the bad, and the ugly: which Australian terrestrial mammal species attract most research? Mammal Review 46:241-254.

Gaston, K. J. 1994. Rarity. Population and community biology series, vol. 13. Springer, Dordrecht.

Hutterer, R. 1994. Island rodents: a new species of Octodon from Isla Mocha, Chile (Mammalia: Octodontidae). Zeitschrift für Säugetierkunde 59:27-41.

IUCN (2017). The IUCN Red List of Threatened Species. Version 2017-1. Retrieved from

Lacher, T. E., W. J. Murphy, J. Rogan, A. T. Smith, and N. S. Upham. 2017. Evolution, phylogeny, ecology, and conservation of the Clade Glires: Lagomorpha and Rodentia. Pp. 15–26 in Handbook of mammals of the world, Volume 6: lagomorphs and rodents (Wilson, D. E., J. T. E. Lacher, and R. A. Mittermeier, eds.). Lynx Ediciones. Barcelona, Spain.

Lanzone, C., C. A. Labaroni, A. Formoso, L. M. Buschiazzo, F. Da Rosa, and P. Teta. 2018. Diversidad, sistemática y conservación de roedores en el extremo sudoccidental del Bosque Atlántico Interior. Revista del Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” 20:151-164.

MacArthur, R. H., and E. O. Wilson. 1967. The theory of island biogeography. Princeton University Press. Princeton, U.S.A.

Maestri, R., and B.D. Patterson. 2016. Patterns of species richness and turnover for the South American rodent fauna. PLoS ONE 11(3): e0151895.

Meiri, S., A. M. Bauer, A. Allison, F. Castro-Herrera, L. Chirio, G. Colli, I. Das, T. M. Doan, F. Glaw, L. L. Grismer, M. Hoogmoed, F. Kraus, M. LeBreton, D. Meirte, Z. T. Nagy, C. de C. Nogueira, P. Oliver, O. S. G. Pauwels, D. Pincheira-Donoso, G. Shea, R. Sindaco, O. J. S. Tallowin, O. Torres-Carvajal, J-F. Trape, P. Uetz, P. Wagner, Y. Wang, T. Ziegler, and U. Roll. 2017. Extinct, obscure or imaginary: The lizard species with the smallest ranges. Diversity and Distributions. DOI: 10.1111/ddi.12678.

Pacheco, V. 2015. Genus Thomasomys Coues, 1884. Pp. 617–682 in Mammals of South America (Patton, J. L., U. F. J. Pardiñas, and G. D’Elía, eds.). The University of Chicago Press. Chicago & London.

Patterson, B. D. 2002. On the continuing need for scientific collecting of mammals. Mastozoología Neotropical 9:253-262.

Patton, J. L., U. F. J. Pardiñas, and G. D’Elía (eds.). 2015. Mammals of South America, Volume 2: Rodents. The University of Chicago Press. Chicago and London.

Rodríguez-Posadas, M.E. 2014. Primer registro del ratón de agua del táchira, Neusticomys mussoi (Rodentia, Cricetidae) en Colombia. Mastozoología Neotropical 21: 367-372.

Spotorno, A. E., and J. L. Patton. 2015. Superfamily Chinchilloidea Bennett, 1833. Pp. 762-783 in Mammals of South America (Patton, J. L., U. F. J. Pardiñas, and G. D’Elía, eds.). The University of Chicago Press. Chicago & London.

Steppan, S. J. and O. Ramírez. 2015. Genus Phyllotis Water house, 1837. Pp. 481-507 in Mammals of South America (Patton, J. L., U. F. J. Pardiñas, and G. D’Elía, eds.). The University of Chicago Press. Chicago & London.

Teta, P., and G. D’Elía. 2017. Taxonomic notes on the long-clawed mole mice of the genus Geoxus (Cricetidae), with the description of a new species from an oceanic island of southern Chile. Hystrix, The Italian Journal of Mammalogy, 26. DOI:

Teta, P., J. P. Jayat, C. Lanzone, A. Ojeda, A. Novillo, and R. A. Ojeda. 2018. Geographic variation in quantitative skull traits and systematic of southern populations of the leaf-eared mice of the Phyllotis xanthopygus complex (Cricetidae, Phyllotini) in southern South America. Zootaxa 4446:68-80.

Thomson, S. A., R. L. Pyle, S. Ahyong et al. 2018. Taxonomy based on science is necessary for global conservation. PLoS Biology 16(3):e2005075.

Turvey, S. T. 2009. Holocene extinctions. Oxford University Press, Oxford.

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