Introduction

The Maués marmoset, Mico mauesi (Mittermeier et al., 1992), was described in the last decade of the 20th century and originally placed in the genus Callithrix. The species was described from a specimen at the Museu Paraense Emílio Goeldi (holotype: MPEG -22177) and observations of captive and wild animals. At the time of its description the species was only known to occur at the type locality, on the left bank of the Rio Maués-Açu (03°23'S, 57°46'W), just across from the city of Maués in the state of Amazonas, Brazil. Based on distribution patterns of other species of Amazonian marmoset, Mittermeier et al. (1992) predicted that the new species would occur throughout the entire medium to lower Maués-Urariá-Abacaxis interfluve and that its range would be limited by these three rivers.

During primate surveys conducted in and around the Canumã-Urariá-Abacaxis interfluve, Suva Jr. and Noronha (1995, 2000) registered the presence of M. mauesi at two localities on the right bank of the lower Rio Abacaxis: Abacaxis (03°55'S, 58°45'W) and Santa Maria (03°54'S, 58°46'W). Three specimens were collected at Santa Maria and deposited in the zoological collection of the Museu Paraense Emílio Goeldi (MPEG — 23962, 23963, 23964). These findings (Silva Jr. and Noronha, 1995, 2000) and data from the literature (Hershkovitz, 1977; Vivo, 1988, 1991), confirm the northern and western limits of the species' range as proposed by Mittermeier et al. (1992). According to the range map produced by these authors, the distribution of M. mauesi should be limited to the east by the Rio Maués-Açu and extend as far south as 05° S. The objective of this study is to update knowledge of the geographic distribution of M. mauesi through the collection and analysis of new field data.

Methods

Data on the occurrence and habitat of the maués marmoset were collected during a field trip to the lower Rios Madeira and Tapajós interfluve (Noronha, 2004). The area surveyed during the study spanned the headwaters of the Rios Maués, Abacaxis and Sucundurí. Data were collected using two methods: direct sightings and interviews with local informants. Mico mauesi was identified based on the diagnostic characters described by Mittermeier et al. (1992) and comparisons with material from the zoological collections of the Museu Paraense Emílio Goeldi and the National Institute of Amazonian Research (MPEG-23962, 23963, 23964; INPA-4082, 4109, 4105, 4106).

Results and discussion

During the study, eight new occurrence records were obtained for M. mauesi, seven via direct sightings and one in an interview. Marmosets with the traits described by Mittermeier et al. (1992) were seen at sites 4, 5, 6, 7, 8, 9 and 10 (Fig. 1). All records were obtained in terra firme primary forest, secondary growth and igapó, suggesting that the habitat requirements of this species are similar to other members of the genus (Digby et al., 2005; Mittermeier et al., 1992; Silva Jr. and Noronha, 1995, 2000). These new records demonstrate that the geographic distribution delineated by Mittermeier et al. (1992) underestimated the true range of the species. Although northern and western limits were predicted correctly, authors were over cautious with respect to the eastern and southern limits. Data from this study extend the range east to the Rio Maués-Açu; south almost as far as the Igarapé do Surubim (06°53'S, 59°03'W) along the corridor formed by the Rios Tapajós and Sucundurí; west to the Rio Sucundurí, reaching the mid and upper Sucundurí-Abacaxis interfluve (the northernmost record was the Cantagalo site: 06°33'S, 59°05'W). Interviews with local residents suggest that the species may extend as far south as the region of Igarapé do Urucú (07°09'S, 58°56'W), on the right bank of the Rio Sucundurí.

Figure 1.

Geographic range of Mico mauesi, based on Mittermeier et al. (1992), Silva Jr. and Noronha (1995, 2000) and this study: (1) left bank of the Rio Maués-Açu (03°23'S, 57°46'W), across from Maués (type locality), municipality of Maués; (2) Abacaxis (03°55'S, 58°45'W), right bank of the Rio Abacaxis, municipality of Nova Olinda do None; (3) Santa Maria (03°54'S, 58°46'W), right bank of the Rio Abacaxis, municipality of Nova Olinda do None; (4) right bank of the Rio Sucundurí (06°48'S, 59°04'W), municipality of Apuí; (5) right bank of the Rio Abacaxis (06°4l'S, 58°50'W) municipality of Maués; (6) left bank of the Rio Tapajós (06°34'S, 58°35'W), municipality of Maués; (7) Cantagalo, right bank of the Rio Sucundurí (06°33'S, 59°05'W), municipality of Borba; (8) left bank of the Rio Tapajós (06°34'S, 58°24'W), municipality of Maués; (9) mouth of the Igarapé do Surubim, right bank of the Rio Sucunduri (06°53'S, 59°03'W), municipality of Apuí; (10) Floresta Nacional do Pau Rosa, right bank of the Rio Abacaxis (04°40'S, 58°15'W), municipality of Maués; (11) mouth of the Igarapé do Urucú (07°09'S, 58°56'W), left bank of the Rio Sucunduri, municipality of Apuí.

According to Hershkovitz (1977), Mico humeralifer is expected to occur in the Sucundurí-Tapajós-Juruena interfluve. Rylands (1994) suggested that this species' range could extend as far south as 8° S. This study however, does not support these expectations. It is possible that Mico mauesi's range extends between the Rios Sucundurí and Juruena, reaching as far south as the transition between dense tropical forest, open tropical forest and savanna (BRASIL, 1975) at around 7°40'S, or even as far as the Serra do Sucunduri at 8°10'S. These predictions coincide with the southern limit for M. humeralifer proposed by Rylands (1994). According to Rylands (1981), south of this latitude the species M. melanurus should occur between the Rios Aripuanã and Juruena. This hypothesis is partially supported by the occurrence of M. melanurus in the Serra do Sucundurí (08°34'S, 59°08'W) and on the right bank of the Rio Bararati (08°21'S, 58°37'W). Mico melanurus was the only member of the genus occurring at these localities (M. A. Noronha, unpubl. data). Our results show that the geographic distribution of M. mauesi is large relative to that of other species of the genus in the Madeira-Tapajós interfluve. We did not find any area of contact between M. mauesi and any other species of Mtco, suggesting that the species is parapatric with respect to its congeneric neighbors M. humeralifer, M. melanurus, M. acariensis and M. saterei.

This study quadrupled the number of recorded localities for M. mauesi, and revealed a range over twice that proposed by Mittermeier et al. (1992). The improved knowledge of this taxon's geographic distribution also provides information about its occurrence within protected areas. The maués marmoset is probably present in the Floresta National do Pau Rosa (994,800 ha), Parque Nacional do Juruena (2,002,565 ha) and the Floresta Nacional de Maués (438,440 ha), and if we assume that the southern limit of its range is close to the Serra do Sucundurí, it also occurs in the Reserva de Desenvolvimento Sustentável do Bararati (113,606 ha), Parque Estadual do Sucundurí (808,312 ha) and the Floresta Nacional do Apuí (185,946 ha).