ARTÍCULOS Y NOTAS

On the type locality of Ctenomys bicolor Miranda Ribeiro, 1914 (Rodentia: Ctenomyidae)

Claudio J. Bidau¹ and Fernando Dias de Avila-Pires²

¹ Laboratório de Biologia e Parasitologia de Mamíferos Silvestres Reservatórios, Instituto Oswaldo Cruz, FIOCRUZ, Av. Brasil 4365, Manguinhos, 21045-900 Rio de Janeiro, RJ, Brazil [Correspondence: <bidau50@gmail.com>].
² Rua Bico de Lacre, 79 88050-150 Cacupé, Florianópolis, SC, Brazil.

ABSTRACT: We restrict the type locality of Ctenomys bicolor Miranda Ribeiro, 1914, to Rôndonia state (Brazil) within these coordinates: 11º 50' 10'' S and 12º 00' 00'' S, and 60º 51' 35'' W and 61º 19' 29'' W.

RESUMEN: Sobre la localidad típica de Ctenomys bicolor Miranda Ribeiro, 1914 (Rodentia: Ctenomyidae). Restringimos la localidad típica de Ctenomys bicolor Miranda Ribeiro, 1914, al estado de Rondônia (Brasil) entre las siguientes coordenadas: 11º 50' 10'' S and 12º 00' 00'' S, and 60º 51' 35'' W and 61º 19' 29'' W.

Key words. Commisão Rondon; Mato Grosso; Rondônia; Two-colored tuco-tuco; Type locality.

Palabras clave. Comisión Rondon; Localidad típica; Mato Grosso; Rondônia; Tuco-tuco bicolor.

The South American genus Ctenomys (tucotucos) includes 62 Linnean species of subterranean rodents plus a number of forms of uncertain taxonomic position (Bidau, 2006, 2009). Other authors however, report different numbers of species (i.e. Woods and Kilpatrick, 2005) although in this case include names that have later been synonymyzed (Bidau, 2009). Despite the high number of species within the genus, most type localities are well defined mainly thanks to the work of the eminent taxonomist Oldfield Thomas who described 27 species and 8 subspecies of tucotucos today accepted as valid (Hill, 1990; Bidau, 2006, 2009). However, several problematic or imprecise type localities exist and include: C. bicolor Miranda Ribeiro, 1914, C. brasiliensis Blainville 1826, C. colburni Allen, 1903, C. dorsalis Thomas, 1900, C. fodax Thomas, 1910, C. frater barbarus Thomas, 1921, C. knighti Thomas, 1919, C. magellanicus fueguinus Philippi, 1880, C. magellanicus osgoodi Allen, 1905, C. minutus Nehring, 1887, C. nattereri Wagner, 1848, C. opimus Wagner, 1848, C. pontifex Thomas, 1918, C. porteousi Thomas, 1916, C. rondoni Miranda Ribeiro, 1914, C. saltarius Thomas, 1912, C. sericeus Allen, 1903, C. steinbachi Thomas, 1907, and C. torquatus Lichtenstein, 1830. Some of these uncertain localities have been identified (e.g. C. knighti; see Bidau, 2006) or restricted (e.g. C. steinbachi; Anderson et al., 1987). Other localities remain enigmatic (C. brasiliensis, C. torquatus, C. dorsalis; Bidau, 2006, 2009).
Correct identification of type localities is of foremost relevance especially in cases where doubts on the taxonomic status of described biological entities arise. Two tuco-tuco taxa from Brazil described by Miranda Ribeiro (1914) have been the subject of taxonomic speculation and unjustified synonymization, in part because of the lack of precision of their type localities: Ctenomys bicolor and C. rondoni. In this paper, we produce evidence enough to restrict the type locality of C. bicolor (Mato Grosso, Brazil) to a relatively small territory of present-day Rondônia state.
The type specimen of C. bicolor (MN 2025) was collected on October 9, 1912 by the Comissão Rondon (probably by Alípio de Miranda Ribeiro, the expedition's zoologist) (Avila-Pires, 1968: 182). The description of the new species based on this single individual of unknown sex, appeared two years later (Miranda Ribeiro, 1914: 41) without mention of the type locality which was latter indicated by Moojen (in Miranda Ribeiro, 1955: 415) and Avila-Pires (1968: 182) as Mato Grosso. This was interpreted as the type locality of C. bicolor being somewhere in the present-day state of Mato Grosso, Brazil (Cabrera, 1961: 514).
The former is erroneous. The lack of precision probably derives, in part, from the fact that in 1912, Rondônia state did not exist. In 1943, the Território Federal de Guaporé was created by the fusion of lands excised from Amazonas and Mato Grosso states, reaching the status of state of Rondônia, only in 1981. In fact it is possible to localize the original type locality with much more precision using the dates of localities traversed and camps established, by the expedition of the "Commisão de Linhas Telegráphicas Estratégicas de Matto-Grosso ao Amazonas" led by Col. Cándido Rondon, which are found in Viveiros (1958). On October 11, 1912, two days after the collection date of the type specimen, the expedition discovered the Pimenta Bueno river and according to Rondon, on that date they were at 18º 7' W of Rio de Janeiro and 11º 49' 15" S latitude and at 354 km from Juruena (Viveiros, 1958: 302) where the expedition had officially started. The former coordinates (61º 19' 27" W and 11º 49' 15" S) correspond to present-day Rondônia state where the small locality of Primavera de Rondônia, on the left margin of Pimenta Bueno river, today exists. The previous registered date corresponds to September 5, 1912 where, from the camp named by Rondon as "Campos dos Palmares de Maria de Molina" (coordinates established by the expedition: 12º 07' 12" S and 60º 28' 56" [17º 16' 29" W of Rio de Janeiro], km 329 538 from Juruena) discovered by Lt. Lira, they moved nearby to the Cabeçeira dos Sete Indios where they established the José Bonifácio camp (Viveiros, 1958: 299), very near the present-day population of José Bonifácio in Rondônia. They stayed up to Independence Day (September 7) and then started West reaching the margins of Commemoração de Floriano river, on September 17 (Viveiros, 1958: 301). On September 21 Rondon found and named the "Cabeçeira Cacimba de Pedra", and on September 28 the expedition discovered the Barão de Melgaço river (Viveiros, 1958: 302). The next registered date is October 11, 1912 as previously mentioned.
Thus, two facts emerge from this simple analysis; first, it is erroneous to attribute the type locality of C. bicolor to Mato Grosso state: the type specimen was undoubtly collected in present day Rondônia state. Second, the geographic extension of the area within which the type locality must be seeked, is enormously reduced to a territory between the Barão de Melgaço river and the coordinates for the October 11 camp on the Pimenta Bueno. Furthermore, since the type specimen was collected on October 9 and considering the slow rate of progress of the expeditioneers as narrated by Rondon (Viveiros, 1958), the actual locality should be placed very near the Pimenta Bueno river camp. A conservative estimation localizes C. bicolor type locality within a 1000 square km rectangle limited by the following coordinates: 11º 50' 10" S and 12º 00' 00" S, and 60º 51' 35" W and 61º 19' 29" W. This territory includes parts of the "municípios" Primavera de Rondônia and Pimenta Bueno but, as stated above, the actual area is possibly much smaller.
Considering the fact that tuco-tucos do not usually inhabit forests preferring sandy, loose and friable soils (Reig et al., 1990; Bidau, 2009), tuco-tuco colonies of C. bicolor should be looked for within this area, in sandy strips and river banks. Circumstantial evidence supports the former hypothesis: during the "Roosevelt-Rondon Expedition" of 1913-1914 (Roosevelt, 1914), Leo E. Miller, mammalogist of the expedition from the American Museum of Natural History, collected a single tuco-tuco specimen at José Bonifácio (12º 10' S 60º 15' W) (Miller, 1918: 238) which J.A. Allen later assigned, without explanation, to C. nattereri Wagner (Allen, 1916: 569) (AMNH 37121). According to Miller's own account (in Allen, 1916: 595), the expedition found sporadic tuco-tuco colonies along a 500 mile (800 km) traject from Tapirapoana (present-day Mato Grosso state, at 14º 51' 01" S/57º 46' 04" W) to José Bonifácio (Rondônia state, see above) at a "…strip of sandy country in which the animal seemed to be comparatively numerous… The country was treeless, with a growth of grass and patches of wild pineapples". Since the taxonomic status of C. bicolor is in need of revision (Bidau, 2009), especially its relationship to C. rondoni and C. nattereri, we hope this contribution will further new collecting trips to the area delimited in this paper.

Acknowledgements. The authors are extremely grateful to Dr. Sérgio Vaz at the Museu Nacional (Rio de Janeiro, Brazil) for providing invaluable bibliography. João Alves de Oliveira and Stella Maris Franco allowed access to the holotype of Ctenomys bicolor. Rocío Hassan kindly reviewed the manuscript. Financial support from CNPq (grant 480596/2007-7), FAPERJ (grant APQ1 3225/ 2007), and FIOCRUZ is greatly acnowledged.

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Recibido 03 octubre 2007.
Aceptado 30 septiembre 2008.

Editor asociado: D Verzi