The fish fauna of streams from the upper rio Tocantins basin , Goiás State , Brazil

Study area The present study was made in the tributaries of rio das Almas and rio Maranhão basins, in the upper rio Tocantins basin (considered from its source in the Planalto of Goiás to the confluence with the rio Paranã) (Figure 1). The rio Maranhão rises in the ecological station of the Águas Emendadas in the Planalto Central, between the Goiás State and Distrito Federal; and rio das Almas rises in the Serra dos Pirineus State Park, in the municipality of Pirenópolis, Goiás State (Oliveira and Bispo 2001; Lima et al. 2007). The climate in this region is humid subtropical characterized by dry winter and hot summer (cwa). The average annual temperature is 21-25°C and the average annual rainfall is 1.500 mm, with 80% occurring between October and April (Ferreira and Tokarski 2007). The study was performed in July 2010, twenty one sites were sampled in rio das Almas basins (municipality of Pirenópolis) and rio Maranhão basins (municipalities of Barro Alto and Goianésia) (Table 1). The collections were made using standard ichthyological gear, including sieves, seine nets and throw nets, aiming to capture a representative number of individuals in each sample unit. The sampling effort was of 60 minutes at each site. The collected fish were fixed in formalin solution 10% and after 48 h transferred to ethanol 70% solution. Species were identified using available literature, keys and help of specialists. The taxonomic classification follows Reis et al. (2003). Voucher specimens were deposited in the fish collection of the Museu de Zoologia da Universidade Estadual de Londrina, Londrina, (MZUEL), Paraná State, Brazil. Collects were authorized by IBAMA (collecting permit number 12120-1).


Study area
The present study was made in the tributaries of rio das Almas and rio Maranhão basins, in the upper rio Tocantins basin (considered from its source in the Planalto of Goiás to the confluence with the rio Paranã) (Figure 1).The rio Maranhão rises in the ecological station of the Águas Emendadas in the Planalto Central, between the Goiás State and Distrito Federal; and rio das Almas rises in the Serra dos Pirineus State Park, in the municipality of Pirenópolis, Goiás State (Oliveira and Bispo 2001;Lima et al. 2007).The climate in this region is humid subtropical characterized by dry winter and hot summer (cwa).The average annual temperature is 21-25°C and the average annual rainfall is 1.500 mm, with 80% occurring between October and April (Ferreira and Tokarski 2007).
The study was performed in July 2010, twenty one sites were sampled in rio das Almas basins (municipality of Pirenópolis) and rio Maranhão basins (municipalities of Barro Alto and Goianésia) (Table 1).The collections were made using standard ichthyological gear, including sieves, seine nets and throw nets, aiming to capture a representative number of individuals in each sample unit.The sampling effort was of 60 minutes at each site.The collected fish were fixed in formalin solution 10% and after 48 h transferred to ethanol 70% solution.Species were identified using available literature, keys and help of specialists.The taxonomic classification follows Reis et al. (2003).Voucher specimens were deposited in the fish collection of the Museu de Zoologia da Universidade Estadual de Londrina, Londrina, (MZUEL), Paraná State, Brazil.Collects were authorized by IBAMA (collecting permit number 12120-1).

Data Analysis
To assess the inventory efficiency the richness extrapolation estimators Chao 1 (Chao 1987) and ACE (Abundance-based Coverage Estimator, Lee and Chao

Introduction
Brazil has the highest diversity of freshwater species of fishes in the world, with high species richness and endemism in many groups.This great biodiversity is related to large river systems, composed of basins and regions with very different ecosystem characteristics (Buckup et al. 2003;Abell et al. 2008;Lévêque et al. 2008).
The rio Tocantins-Araguaia basin is one of the most important hydrographic region of Brazil, with a drainage area of approximately 767.000 km 2 (Mérona et al. 2010).The rio Tocantins drains an approximated area of 343,000 km 2 ; it rises in the central region of Brazil in the Goiás State, and flows from South to North for about 2.750 km.The rio Tocantins ends in the Amazon delta in the Bay of Marajó, near the city of Belém, Pará State (Santos et al. 2004).The altitude varies from 100 m above the sea level in the lower course of the river to 1.000 m in the high region of the basin (Santos et al. 2004).The ichthyofauna of the rio Tocantins basin is closely related to the Amazon basin, especially in the lower course (Goulding et al. 2003), but the rio Tocantins basin is remarkable by containing both a high degree of endemism and high diversity (Santos et al. 2004;Hubert and Renno 2006;Lucinda et al. 2007;Abell et al. 2008;Bertaco and Carvalho 2010;Carvalho et al. 2010;Bertaco et al. 2011).
As a result of human actions the ichthyofauna of streams in this basin is suffering strong pressure, mainly by the expansion of agricultural frontiers, construction of dams, mining and introduction of exotic species (Ferreira and Tokarski 2007).These environmental problems resulting from uncontrolled human occupation make necessary urgent studies of local ichthyofauna.Thus, this work is aimed to provide a list of fish species of the rio das Almas and rio Maranhão basins, in the upper rio Tocantins basin, Goiás State, Brazil.

Materials and Methods
Abstract: This study aimed to provide a list of fish species from tributaries of rio das Almas and rio Maranhão basins, in the upper rio Tocantins basin, Goiás State, Brazil.For this study 21 stream stretches were sampled during the dry season in July 2010.A total of 2,279 individuals of 67 species, 19 families and five orders were collected.The most representative families in number of species were Characidae, Loricariidae, and Crenuchidae respectively.The genus Knodus, Hypostomus and Characidium showed the greatest abundance and distribution among the samplings.Poecilia reticulata was considered the only non-native species.The presence of a large number of endemic and undescribed species or with undefined taxonomic situation, in addition to the rapid habitat loss in this region, juts the need for the development of further studies in this basin.The fish fauna of streams from the upper rio Tocantins basin, Goiás State, Brazil  1994) were used; and a species accumulation curve was generated (Figure 2), expressed by the number of individuals sampled to assess the efficiency of fish sampling methodology (Chao 2005).The program EstimateS 8.2 (Cowell 2009) was used for the calculations.

Results and Discussion
A total of 2.279 individuals representing 67 species belonging to 19 families and five orders were collected (Table 2).About of total number of species registered in this study, 46 were collected in the rio Maranhão sub basin, and 51 species in the rio das Almas sub basin.30 species were common for the two sub basins.On the other hand, 15 exclusive species were present in the rio maranhão sub basin, and 21 in the rio das Almas sub basin.
The genus Knodus (Knodus cf.chapadae, Knodus sp.1 and Knodus sp.2) showed the greatest abundance and distribution in the collections, and can be an example of success in these environments.Some authors as Ortaz (2001), studying the feeding habit of Knodus deuterodonoides and Knodus sp., and Ceneviva-Bastos and Casatti (2007) to Knodus moenkhausii, considered these species as generalists and opportunists in the use of food resources; and according to Ceneviva-Bastos and Casatti (2007) these abilities may be reflected in the abundance and distribution of species once they can allocate energy to reproduction, becoming dominant in those environments.
Other important genera were Characidium and Hypostomus, by both the number of species (five and four species respectively) and a larger distribution and abundance.This result may be related to the preference of these species for habitats with strong rapids and rocks substrate where they can feed on insects, larvae and algae that are associated with these environments.Morphological adaptations as fusiform body, pectoral and pelvic fins enlarged and ventrally positioned in the body, beside adaptations in the mouth and lips in the case of Hypostomus, can help these species to adhere to the substrate and resist the flow of the current (Watson and Balon 1984;Matthews 1998;Aranha et al. 2000).
Two species considered as threatened of extinction were registered, Mylesinus paucisquamatus and Brycon nattereri.Mylesinus paucisquamatus is an endemic specie of the rio Tocantins basin, already B. nattereri is also found in the rio Paraná and rio São Francisco basins.The damming that alters the hydrologic cycle, destruction of riparian forests, and water pollution are among the main threats to these species (Lima et al. 2008;Machado et al. 2008).
The non-native species P. reticulata was recorded; this species is native from northwestern South America and Central America (Reis et al. 2003).The presence of P. reticulata can be an indicator of environmental degradation (Casatti et al. 2006), because it is an opportunistic species with high adaptive capacity and tolerance to variations in different habitat types (Kennard et al. 2005;Vieira and Shibatta 2007).In the localities where it was collected, this species may compete directly with native species for food or space.However, we believe that this species may have been assimilated as an additional component of the local diversity.In the stretches where it was sampled a high diversity of other species was also found, in contrast with the conjecture that P. reticulata can only be found in environments with low water quality where other species are unable to endure (Araújo et al. 2003).This species was found in five of the 21 sampled stretches, where the corrégo Lajes (T10) reached the highest abundance, which can be indicative of its establishment.
The information presented in this study can be important for the understanding, management and conservation of fish species in the upper rio Tocantins basin.The large number of endemic (23.8% of species) and undescribed species or with undefined taxonomic situation (43% of species), in addition to the rapid habitat loss in this region by agriculture, mining, livestick, dams and deforestation; make necessary the development of further studies for a better knowledge of the ichthyofauna of the upper rio Tocantins basin.

Figure 2 .
Figure 2. Species accumulation curve (Sobs) and the richness extrapolation estimators Chao 1 and ACE, for collections made in the upper rio Tocantins basin.