Fish , tributaries of middle Rio Mogi Guaçu , upper rio Paraná basin , São Paulo state , Southeastern Brazil

In this paper we compiled a fish list obtained from field collections performed between 1999 and 2005 in four tributaries of the Rio Mogi Guaçu, upper Rio Paraná basin, São Paulo State, Brazil. The collected fishes belong to six orders, 21 families, 60 genera and 82 species. The number of species represents 20 to 30% of the fish richness for the entire upper Rio Paraná basin according to recent estimates. A comparison to earlier published fish lists of the Rio Mogi Guaçu basin, chiefly from its main river channel, is also presented. Introduction The fish fauna of the state of São Paulo is one of the more exhaustively studied in the Neotropics (Langeani et al. 2007). A great number of these studies were focused on the species inhabiting the Rio Mogi Guaçu basin, a major tributary of the Rio Grande, which confluences into the Rio Paranaíba and forms the Rio Paraná. From early 19 century to nowadays, several papers dealing with species description, fish biology and community ecology of the Rio Mogi Guaçu basin have been published (e.g. Ihering 1929; Schubart 1962; Godoy 1975; Oliveira and Garavello 2003; Apone et al. 2008). In this paper we present an updated check list of fish species compiled from six years of collecting efforts carried out in four small tributaries that flow to the floodplain area of the middle Rio Mogi Guaçu. Species composition is compared to earlier published studies (Schubart 1962; Galetti et al. 1990; Gonçalves and Braga 2008) dealing with the ichthyofauna of other environments of the Rio Mogi Guaçu basin, such as its mainstream, floodplain oxbow lakes and reservoirs. Material and methods Fish specimens were collected from 1999 to 2005 during previous studies dealing with longitudinal and seasonal distribution of species in four affluent rivers of the Rio Mogi Guaçu. Oliveira and Garavello (2003) studied the fish fauna from Ribeirão Cabaceiras, Birindelli and Garavello (2005) from Ribeirão Araras, Perez Jr. and Garavello (2007) from Rio do Pântano and Apone et al. (2008) from Rio Quilombo (Figure 1). Three sample sites were visited in Ribeirão Cabaceiras: Cab 1 (21°49'11" S, 47°57'55" W), Cab 2 (21°47'53" S, 47°58’29" W) and Cab 3 (21°42'20" S, 47°57'44" W); three sites were sampled in Ribeirão Araras: Ara 1 (2152'18" S, 47°53'24" W), Ara 2 (21°48'48" S, 47°51’28" W) and Ara 3 (21°43'09" S, 47°50'05" W); four sites sampled in Rio Quilombo drainage: Neg (21°59'53" S, 47°47’50" W), Qui 1 (21°54'54" S, 47°45'48" W), Qui 2 (21°50'36" S, 47°47’36" W) and Qui 3 (21°46'23" S, 47°46'44" W); and three sites were sampled in Rio Pântano: Pan 1 (21°57'28" S, 47°40'15" W), Pan 2 (21°51'26" S, 47°41'43" W) and Pan 3 (21°44'31" S, 47°40'13" W). Check List 5(3): 488–494, 2009.


Introduction
The fish fauna of the state of São Paulo is one of the more exhaustively studied in the Neotropics (Langeani et al. 2007).A great number of these studies were focused on the species inhabiting the Rio Mogi Guaçu basin, a major tributary of the Rio Grande, which confluences into the Rio Paranaíba and forms the Rio Paraná.From early 19 th century to nowadays, several papers dealing with species description, fish biology and community ecology of the Rio Mogi Guaçu basin have been published (e.g.Ihering 1929;Schubart 1962;Godoy 1975;Oliveira and Garavello 2003;Apone et al. 2008).
In this paper we present an updated check list of fish species compiled from six years of collecting efforts carried out in four small tributaries that flow to the floodplain area of the middle Rio Mogi Guaçu.Species composition is compared to earlier published studies (Schubart 1962;Galetti et al. 1990;Gonçalves and Braga 2008) dealing with the ichthyofauna of other environments of the Rio Mogi Guaçu basin, such as its mainstream, floodplain oxbow lakes and reservoirs.

Results and discussion
The 13,168 specimens collected belong to six orders, 21 families, 60 genera and 82 species (Table 1).As observed in almost all studies dealing with Neotropical fish diversity, Characiformes and Siluriformes were the species richest orders registered, comprising more than 85% of the total.The other four orders registered Gymnotiformes, Cyprinodontiformes, Perciformes and Synbranchiformes are also widely distributed in Brazilian river basins and usually present less diversity relative to Characiformes and Siluriformes.The total number of species observed in the four tributaries studied represents 20% to 30% of entire upper Rio Paraná ichthyofauna, according to recent literature (Langeani et al. 2007).
Among drainages, fish richness ranged from 48 species in Ribeirão Cabaceiras to 68 species in Rio Quilombo.Total richness registered for all study area may be interpreted as consequence of each tributary fish composition, but most species were shared between two or more rivers.Thirtyseven species were registered in all four rivers, eleven in three rivers and eighteen in two rivers.The sixteen species found in only one of the studied basins occurred in Quilombo or Pântano rivers, the two richest basins studied.
An important factor that explains total richness found is the diversity of fish habitats explored.Sample sites in each of four small river drainages were longitudinally distributed, including creek habitats near the source and main channel with associated flooded habitats near the mouth of each river.Different kind of environment explored allowed the inventory of distinct fish species and the sample sites near the mouth invariably showed more species than creeks habitats.
Previous fish inventories in Rio Mogi Guaçu were mainly focused on the main river channel and oxbow lakes.Comparisons between the fish list presented here and the lists provided by some of these studies (e.g., Schubart 1962;Galetti et al. 1990) show that the lower stretches of the tributaries of Rio Mogi Guaçu present an ichthyofaunistic composition very similar to that found in environments with greater water volume in the basin.Schubart (1962) presented a list of 94 fish species resulted of many years of research in the main channel of the Rio Mogi Guaçu, at Cachoeira de Emas, in the Estação Experimental de Biologia e Piscicultura located in Pirassununga.Taxonomical problems apart, the majority of fishes listed by Schubart were found in the rivers studied herein, especially for those of the families Anostomidae, Curimatidae, Parodontidae, Prochilodontidae, Heptapteridae, and many species of the families Characidae and Loricariidae.The species that were recorded by Schubart (1962) but were not represented herein comprises those of the groups Bryconinae, Trichomycterinae, Auchenipteridae and Apteronotidae, and the introduced species of the family Cyprinidae.Galetti et al. (1990) studied two oxbow lakes in an area of environmental protection and listed 36 fish species, from which only two species were not found in the tributaries of Mogi Guaçu herein sampled, the characid Salminus brasiliensis (Cuvier, 1816) and an auchenipterid species referred by the authors as Trachycorystes sp.
Most of these species registered only in previous studies, are medium to large sized species frequently found in the main channel of Rio Mogi Guaçu and their absence in our list is probably due to the kind of environment here sampled.Nevertheless, these and other medium to large sized species may occur in the stretches near the mouth of the tributaries herein studied, as other transient species that colonize the tributaries of the main channel during the wet season, as showed in earlier publications (Oliveira and Garavello 2003;Birindelli and Garavello 2005;Perez Jr. and Garavello 2007;Apone et al. 2008).
In a recent review about fish studies in Rio Mogi Guaçu Meschiatti and Arcifa (2009) compiled a list of 150 species.The review reported a hundred years of ichthyological studies in the Rio Mogi Guaçu, as stated: "The first study (Boulenger, 1900) described Loricaria latirostris from specimens caught in this river".However, the studies date back 150 years ago, since Rudolf Kner's descriptions of fish species from Irisanga (= Orissanga), locality in Mogi Guaçu basin, São Paulo State, according to Britski and Garavello (1978).
The number of species reported in the review is doubtful because the taxonomical criteria presented is vague, with clear mistakes derived from species names compiled from literature and without any mention about fish specimens examined or deposited in fish collections.So, approximately 10 % of the species listed by Meschiatti and Arcifa (2009) are put in doubt herein, chiefly because some of the species names presented in their review were compiled from a list of material examined presented in A. K. Oliveira's unpublished thesis, which also includes doubts on some fish specimens identity.The remaining approximately 135 species cited in the review may occur in the Rio Mogi Guaçu and, if so, the species richness found in the four tributaries studied by us represents about 60% of the fish assemblage in the basin.
The list presented herein shows that small to medium tributaries shelter a high diversity of fish species that are, in most cases, not well studied in terms of their ecological and biological traits.Those environments are also important because their species contribute to the total fish richness in Rio Mogi Guaçu.In fact, there is little information about how local richness influences regional diversity and contrariwise in Rio Mogi Guaçu basin.