Checklist of chelonians from the upper Madeira River and the lower Madeira-Purus interfluvium ( Brazilian Amazon ) , including a range expansion for Podocnemis sextuberculata Cornalia , 1849

We present data on occurrence of chelonians for the Madeira River (southwestern Amazon, Brazil). Sampling was undertaken along the BR-319 Highway in the Madeira-Purus interfluvium and along a 125-km stretch of the upper Madeira River. Findings were contrasted with a checklist of species expected to occur in the region according to current distribution maps, and with literature data for the Madeira subbasin. Out of 12 expected species, we recorded five in the MadeiraPurus interfluvium (three other species were registered by other recent voucher-based studies in the region), and eight species in the upper Madeira region. Podocnemis expansa (Schweigger, 1812) and P. unifilis Troschel, 1848 occurred below and inbetween the upper Madeira rapids. Podocnemis sextuberculata Cornalia, 1849 had its range extended by over 700 km, but may be limited upriver by the rapids. Mesoclemmys gibba (Schweigger, 1812) and M. raniceps Gray, 1855 occurred sympatrically along the river. Chelonian diversity along the lower and upper Madeira appears to be complementary.


INTRODUCTION
The distribution areas of chelonian species in the Brazilian Amazon frequently are based on scarce locality records spread over huge areas, with the notable exception of the most conspicuous podocnemidids and the terrestrial Chelonoidis denticulata (Linnaeus, 1766) (see Iverson 1992 and his updated digital distribution maps in Iverson et al. 2000).A number of factors contribute to this state of affairs, such as the huge extension and logistical difficulty of surveying Amazonian aquatic habitats, the secretive habits of many species, and the fact that many chelonian records stay only in the logbooks of scientific expeditions and lack collected specimens or even photographs of the turtles or tortoises.Also important is the accelerated habitat destruction and alteration in the southeastern Amazon, and increasingly so in its southwestern region (Vieira et al. 2008), which may compromise the environmental integrity of entire watersheds in the region over the next decades (Soares-Filho et al. 2006).Even in this scenario, the Madeira River, the largest tributary of the right margin of the Amazonas River, stands out as surprisingly devoid of chelonian records.The Madeira basin is included, partially or as a whole, in the inferred distribution area of several chelonian species (Rueda-Almonacid et al. 2007).Five of these have no published geographically referenced locations for the Madeira River, while others, including the ubiquitous Podocnemis unifilis Troschel, 1848 and Podocnemis expansa (Schweigger, 1812), have one or two locations, most of them in the lower portion of the river (Iverson et al. 2000;Berry and Iverson 2001;Schneider et al. 2012).Podocnemis expansa is the only species recorded from the upper Madeira (Iverson 1992;Iverson et al. 2000).Only three species (Platemys platycephala (Schneider, 1792), Podocnemis unifilis and Podocnemis erythrocephala [Spix, 1824]) have one record in the region between the Madeira and Purus rivers (Madeira-Purus interfluvium) (Iverson et al. 2000;Schneider et al. 2012).
The upper Madeira River featured one of the most impressive sets of whitewater rapids in the Amazon basin (Cella-Ribeiro et al. 2013), which have been evaluated as a potential historical barrier for fishes (see review in

Upper Madeira region
The upper Madeira River is embeded in a deep valley punctuated by crystalline rock outcrops that form 18 sections of rapids between the cities of Porto Velho and Guajará-Mirim, the latter on the upstream tributary Mamoré River (Cella-Ribeiro et al. 2013).The water current was generally strong and fast flowing, along steep river banks, with only a few small tributary rivers.A Queiroz et al. 2013), river dolphins (Gravena et al. 2014), and crocodilians (Hrbek et al. 2008).A biogeographical transition also has been detected in one anuran species inhabiting the left margin of the upper Madeira (Simões et al. 2012).Due to the absence of distribution data, it is unknown whether the rapids act as a barrier and affect chelonian diversity up-and downstream on the Madeira.The sole record of P. expansa from the Madeira River (Iverson et al. 2000) is immediately downstream from the rapids, although the species is known to reproduce in the Guaporé River, an upstream tributary (Soares 2000;Cantarelli 2006).Seven other species have been recorded from the headwaters of the Madeira in Bolivia, but none or only one or two records are from the lower Madeira (Ernst 1987;Ernst and Leuteritz 1999;Iverson et al. 2000;Berry and Iverson 2001;Schneider et al. 2012).
In recent years there have been several biodiversity surveys along the Madeira River and the Madeira-Purus interfluvium, such as the PROBIO Project, sponsored by the Brazilian Ministry of Environment (Rapp-Py-Daniel et al. 2007), the environmental impact assessment of the repavement of the Manaus to Porto Velho BR-319 Highway (UFAM/DNIT 2009) as well as other projects associated with the PPBio Program along the highway (http://ppbio.inpa.gov.br), the environmental surveys for management plans of conservation units (NUSEC/UFAM 2014a, 2014b), and the environmental impact assessment and monitoring projects for two hydroelectric powerplants in the upper Madeira River (Santo Antônio http://www.santoantonioenergia.com.br and Jirau http://www.energiasustentaveldobrasil.com.br).These studies produced a considerable amount of information about the occurrence and distribution of the fauna in the Madeira River basin, including chelonians.
Here we report on chelonian species recorded during two field-intensive projects carried out in the Madeira River subbasin: a 2-year chelonian survey for the environmental monitoring program of the Santo Antônio hydropower plant, in the upper Madeira (state of Rondônia, Brazil), and a 4-year research project on foodwebs of small forest streams along the BR-319 Highway in the state of Amazonas (Brazil).We report a qualitative subsample of the total number of chelonians sampled during both studies, namely those specimens that are individually verifyable through physical and/ or photographic vouchers with exact geographic coordinates.Quantitative survey data of both studies will be reported elsewhere.The records are contrasted with the scarce information available on the occurrence of chelonians in the lower part of the Madeira River subbasin, as well as the list of expected species in the area, based on the available distribution data from literature.Our objectives were: (a) to assess the distribution of number of islands with sandbanks formed large beaches during the low water season, from July to October, and adjacent pools of lentic water.Near Porto Velho the margins of the Madeira are covered mostly by pasture and small-scale agriculture land, while upstream there are patches of terra-firme forest, seasonally flooded forests and more open, white-sand forests.The flooded forests are restricted to lowland areas near the riverbank.Permanent to semi-permanent lakes also are found along the larger rivers in the area.The climate is tropical humid with average monthly temperatures between 20-30°C, and minimum and maximum temperatures between 18 and 33°C.The dry season extends from June to September, the rainy season from October to May.Monthly rainfall is less than 30 mm in June to July and up to 330 mm in December to January (Horbe et al. 2013).Small streams and pools are present in the forest, and many of these may dry out completely in the dry season.
Surveys were carried out in 2010 and 2011 along a 125 km stretch of the river between the Santo Antônio rapids (08°48'11" S, 063°57'00" W), 10 km upstream from the city of Porto Velho, and the Jirau rapids (09°19′46″ S, 064°43′54″ W) (Figure 2), as part of the environmental monitoring program for the construction of the hydropower plant of Santo Antônio.This part of the river featured three other rapids: Teotônio, Morrinhos and Caldeirão do Inferno (Figure 2).Teotônio and Jirau used to be the most formidable of the upper Madeira rapids, the only ones that precluded navigation yearround (Cella-Ribeiro et al. 2013).All fieldwork was undertaken prior to the formation of the hydroelectric dam reservoir, which permanently obliterated the rapids up to Caldeirão and flooded lowland areas on the riverbanks in November 2011.
Aquatic surveys were carried out from mid-July to the end of September along a 110 km river stretch between the Santo Antônio and the Caldeirão do Inferno rapids (09°16′05″ S, 064°39′45″ W).Choice of trapping sites was arbitrary, at suitable points for chelonians in the Madeira river and its main tributaries in the area: until 50 km upstream the Jaci-paraná River (09°12′08″ S, 064°23′14″ W), 23 km upstream   1. List of chelonian specimens collected and/or recorded photgraphically along the BR-319 Highway (state of Amazonas, Brazil), in the Madeira-Purus interfluvium along the lower and middle Madeira River (east of Humaitá), and in and along the upper Madeira River (state of Rondônia, Brazil), between the city of Porto Velho and the locality of Cachoeira do Jirau.na=not available or not applicable; Column "Sex": M=male, F=female, J=juvenile; "SCL"= straight carapace length (decimal positions are indicated according to measurement resolution); "Region": UM=upper Madeira River, MPI=Madeira-Purus interfluvium; "Margin": R=right, L=left; "Voucher nr"=registration code of the physical voucher in the herpetological collection of INPA; "Photo voucher nr"=code that relates the specimen to its photographs in Appendix 2; "Tissue sample code"=registration code of the tissue sample of this individual in the tissue collection of INPA. to the rapids of the large blackwater Karipunas Stream (09°11′30″ S, 064°37′27″ W), 3 km upstream the whitewater Jatuarana Stream (08°49′54″ S, 064°02′56″ W) and 1 km upstream the black/clearwater Latumia Stream (08°50′00.7″S, 063°59′48.1″W) (Figure 2).Lakes near the river margins also were surveyed.We used fyke nets, trammel nets and seine nets (Vogt 1980(Vogt , 2012) ) for trapping turtles, choosing the most suitable method in each case according to water depth and current velocity.Fyke nets were exposed for three days at each location and checked every 24 hours.Trammel nets were usually exposed for 9 hours at each location and checked every 3-4 hours.Net seining was used exclusively in the Madeira River to capture Podocnemis spp. in deep-water pool aggregations, usually in the proximity of nesting beaches.More details about the trapping devices and effort can be found in Keller et al. (2013).
Records from terrestrial and small-scale aquatic habitats (forest streams and pools) were obtained from third-party surveys along 125 km of the river margin from the Santo Antônio to the Jirau rapids (Figure 2).Sampling was carried out in standardized RAPELD modules (see Fraga et al. [2014] for a description of the terrestrial sampling infrastructure in the area) or during faunal rescue operations in areas to be flooded by the Santo Antônio dam reservoir and therefore subjected to deforestation.We had access to rescue animals brought to the wild animal screening center of the Santo Antonio hydroelectric power plant.
Species identification and scientific nomenclature follows Rueda-Almonacid et al. (2007), who provide identification keys, diagnoses, descriptions, and biological and distributional data for all species in this study.The identification of Mesoclemmys specimens was confirmed by Richard Vogt (INPA).Both projects were planned to base their records of chelonian species on a photographic registry and to limit physical vouchers to a representative minimum.Physical vouchers were produced via sedation and subsequent lethal overdosis of a lidocaine chlorhydrate/epinephrine anesthetic for veterinary use (Anestésico L, Eurofarma ® ).Animals that died accidentally during trapping or handling were preserved as physical vouchers whenever possible.All whole bodied specimens were fixated in 10% formalin and permanently preserved in 70% ethanol.Tissue samples (interdigital membrane skin preserved in 70% ethanol) have been obtained as indicated in Table 1 and are deposited in the tissue collection of INPA (Instituto Nacional de Pesquisas da Amazônia).Physical vouchers were deposited in the Zoological Collection of INPA.

Literature review
We reviewed available records and general inferred distribution areas of Amazonian chelonians in Rueda-Almonacid et al. (2007), the updated digital distribution maps of Iverson (1992) in the World Turtle Database on EmySystem http://emys.geo.orst.edu/(Iverson et al. 2000) and the species accounts from the on-line version of the Catalogue of American Amphibians and Reptiles (https://www.zenscientist.com/index.php/pdflibrary2/Open-Access-Journals/caar/; available species accounts by Ernst 1981aErnst , 1981b;;Ernst 1987;Ernst andLeuteritz 1999a, 1999b;Berry and Iverson 2001;Iverson and Vogt 2002;Schneider et al. 2012).We also considered comments on habitat and distribution of species in Vogt (2008) and Vogt et al. (2007).From the evaluation of all data sources, we determined the list of chelonian species expected to occurr in or along the Madeira River.

RESULTS
Overall we were able to produce 66 new voucher-based and georeferenced records of nine chelonian species for the Madeira River basin (Appendix 1; Table 1).Forty-two are exclusively photo vouchers (Appendix 2) recorded by the authors or as occasional encounters by other field crews.Twenty-four are physical vouchers, of which nine were sacrificed to obtain collection vouchers of Chelus fimbriatus (Schneider, 1783), Mesoclemmys raniceps (Gray, 1855) and Platemys platycephala.All other physical vouchers (including all Podocnemis spp) either (a) died accidentally by drowning when entangled in trammel nets or fyke nets or due to stress during handling of unhealthy individuals, (b) were found dead in abandoned fishing nets by local fishermen, or (c) were found as dried out carapaces in the field.No physical vouchers were obtained for Mesoclemmys gibba (Schweigger, 1812), Peltocephalus dumerilianus (Schweigger, 1812), and Podocnemis sextuberculata Cornalia, 1849 due to logistical circumstances or because they were only recorded by third parties.A brief diagnostic description of each species recorded is given in Appendix 1.

Madeira-Purus interfluvium
Sampling effort was of 39,400 effort-hours (1 effort hour = one trap of any kind exposed in the environment for 1 hour).Five chelonian species were recorded along the Madeira-Purus interfluvium (Chelus fimbriatus, Mesoclemmys gibba, Mesoclemmys raniceps, Platemys platycephala and Peltocephalus dumerilianus), resulting in 21 vouchers (Figure 1 1) was captured opportunistically on land while it was possibly searching for a suitable nesting site.Egg-bearing status was established through inguinal palpation.

Upper Madeira region
The aquatic survey consisted of 751 sampling points over the two years, distributed over the whole study area, resulting in 12,887 effort-hours.Further details on sampling effort and capture yield can be found in Keller et al. (2013).Including third-party records, we recorded the occurrence of eight chelonian species (Chelonoidis denticulata, Chelus fimbriatus, Mesoclemmys gibba, Mesoclemmys raniceps, Platemys platycephala, Podocnemis expansa, Podocnemis sextuberculata and Podocnemis unifilis), resulting in 45 new voucher-based and geographically referenced location points for the upper Madeira region (Table 1; Figure 2; Appendix 2).Podocnemis expansa and P. unifilis occurred both downstream and upstream of the largest Teotônio rapids.Four individuals of P. sextuberculata were captured immediately downstream from the first rapids (Santo Antônio).One of the C. denticulata individuals (Appendix 2, photo voucher CD-02; Table 1) was found swimming across the main channel of the Madeira River, at a point were it was approximately 700 m wide.One M. gibba had an unusually brown colloration and dorsal vermiculations on the head (Appendix 2, photo-voucher MG-05).

Checklist and up/downstream complementarity of chelonian fauna
Based on the literature review, 12 species were expected to occur in the Madeira River basin (Table 2), of which three (Podocnemis erythrocephala, Podocnemis sextuberculata and Peltocephalus dumerilianus) were expected to occur only in the lower and middle Madeira and/or its smaller tributaries, and one (Phrynops geoffroanus [Schweigger, 1812]) was expected to occur only in the upper Madeira.All four Podocnemis species are expected to occur in the lower to middle Madeira, but the small water bodies sampled were not suitable for any of them because they inhabit larger rivers.
Of the 12 expected species, we confirmed the presence of five in the Madeira-Purus interfluvium, and eight in the upper Madeira region (Table 2), including an unexpected record of Podocnemis sextuberculata in the upper Madeira.Mesoclemmys raniceps was found in both study areas and had no previous voucher-based record for the Madeira River, apart from one record at the confluence of the Madeira with the Amazonas River (Iverson et al. 2000).We did not find Phrynops geoffroanus, Kinosternon scorpioides (Linnaeus, 1766), nor Podocnemis erythrocephala in either survey areas.Apart from Chelonoidis denticulata and the already mentioned non-verifiable Podocnemis spp, all species found in the upper Madeira also were present in the Madeira-Purus interfluvium along the lower flow of the Madeira.

DISCUSSION
Our surveys confirmed the current occurrence of Podocnemis expansa and P. unifilis in the upper Madeira River, both immediately downstream from the first rapids and in between rapids.Quantitative surveys in the same study area confirmed the presence of both species (Keller et al. 2013), as well as the genetic homogeneity of P. expansa (Vieira 2015) between all rapids in the Keller et al. | Check list of chelonians in the Madeira River 110 km river stretch.This indicates that the rapids do not act as an impermeable barrier for the species.The presence of both species was also confirmed among the rapids upstream of the Jirau hydropower dam (ESBR 2012;Vieira 2015).Both species were known to occur in huge numbers in the Madeira River and the Guaporé River, an upstream tributary, but stocks crashed due to large-scale overexploitation, especially in the late 19 th to early 20 th centuries, fueled by the Amazon rubber boom, the Madeira-Mamoré railway construction, and the growing demand of consumer markets in Manaus and Belém, specially for P. expansa (Vianna 1973;Smith 1979).Podocnemis expansa nesting has been recorded since 2001 in the lower flow of the Madeira (Manicoré municipality), although in very few numbers (Andrade et al. 2011).Likewise, RAP surveys near Manicoré failed to observe individuals and/or nesting signs of P. expansa, which was attributed to the historic overexploitation of chelonians in the region (Vogt et al. 2007).Podocnemis unifilis has been recorded on nesting beaches in the lower Madeira and its tributaries (Andrade et al. 2011), and as a preferred consumption item in local communities (Vogt et al. 2007; NUSEC/UFAM 2014a, 2014b).
No locality records exist for P. sextuberculata in the reviewed databases, but the species has been cited as nesting in large numbers on beaches in the lower Madeira (Andrade et al. 2011).One single individual was captured in the Aripuanã River, a tributary of the middle Madeira (Vogt et al. 2007), coinciding with the southern limit of this species' distribution as inferred by Rueda-Almonacid et al. (2007).Thus, our record of P. sextuberculata in the Madeira River at Porto Velho extends the known distribution of the species by approximately 730 km to the boundaries of the upper Madeira.Despite our considerable sampling effort, and having captured both P. expansa and P. unifilis in the inter-rapids sections of the river, we only recorded four individuals of P. sextuberculata below the rapids.Chelonian surveys in 2012 and 2013, after the flooding of the reservoir, also failed to capture P. sextuberculata upstream from the Santo Antônio dam (the former location of the first rapids) (Felix-Silva and Sábato 2014).It is possible that the Madeira rapids acted as a dispersion barrier for this species, although Felix-Silva and Sábato (2014) claim to have detected a single oviposition of atretic eggs of P. sextuberculata on a beach above the former Morrinhos rapids in 2013 (see Figure 2).
Podocnemis erythrocephala has two records from the lower Madeira region (Iverson 1992;Iverson et al. 2000) and was cited for this region as nesting in significant numbers along small blackwater tributaries of the Matupiri River in the municipality of Borba (Andrade et al. 2011).Suitable habitats for P. erythrocephala (small rivers and streams of black/clear water) were surveyed in the upper Madeira, but the species was not captured.Provided that the species occurs upstream of the lower Madeira, its dispersion may have been hindered by the rapids, as may be the case for P. sextuberculata.
In this study, Peltocephalus dumerilianus has been recorded in the Madeira-Purus interfluvium in the municipality of Manicoré (middle Madeira).Three previous voucher-based records exist for this region, but their georeferenced location has not been published so far.One carapace was found along the Mariepauá River, on the right margin of the Madeira (Vogt et al. 2007), and two individuals were captured between km 300 and km 450 of the BR-319 Highway (UFAM/DNIT 2009).The species also frequently was mentioned as a preferred consumption item by local inhabitants in the same region (NUSEC/UFAM 2014a, 2014b).Although we failed to capture P. dumerilianus in the upper Madeira, the species was described very accurately by fishermen as occurring in lakes and streams further inland from our survey area.Thus its occurrence remains possible, but still to be confirmed, in the upper Madeira region.
The occurrence of Chelus fimbriatus was confirmed both in the lower Madeira-Purus interfluvium and in the upper Madeira River, indicating that the species is likely to be present in tributaries and lentic aquatic habitats along the whole Madeira River.This is further confirmed by the record of a C. fimbriatus carapace near the Aripuanã River, on the right margin of the middle Madeira (Vogt et al. 2007).Interestingly, one individual of C. fimbriatus (CF-02, Table 1) was captured by fyke net on the main channel of the upper Madeira River, in a section where the bank is steep-sloped, the channel is around 30m deep (Tizuka 2013), and there is no nearby tributary.The species is usually associated with lentic and shallow water bodies (Rueda-Almonacid et al. 2007;Vogt 2008).One individual (Table 1, INPA-H 35460) was found estivating alongside other conspecific individuals that were buried in a dried floodplain lake.
Both Mesoclemmys gibba and M. raniceps had no published voucher-based records for the Madeira River, apart from one location each at the Madeira-Amazonas confluence (Ernst 1981a;Iverson et al. 2000).Mesoclemmys raniceps appeared in almost all sampling sites along the Madeira-Purus interfluvium and was captured more frequently than M. gibba (13 overall records of M. raniceps, including the nine listed in Table 1, and one M. gibba).Other voucher-based records of M. gibba exist for the same area, but their georeferenced location has not been published so far.Two individuals were captured along the BR-319 Highway between km 250 and km 535 (UFAM/DNIT 2009) and some individuals were found along the Aripuanã River (Vogt et al. 2007).The faunal rescue in areas to be flooded by the Santo Antônio dam, which lies entirely within our study area in the upper Madeira, listed 116 individuals of Mesoclemmys on both margins of the Madeira (Keller et al. 2013), including five of the ten Mesoclemmys in Table 1 (photo vouchers MG-03, MR-09,10,11 and 12 in Appendix 2).All rescued Mesoclemmys were identified as M. gibba by the rescue team (Marçal et al. 2011).However, four of five rescued individuals we were able to examine in the screening center were M. raniceps, not M. gibba.Both species may be easily mistaken for each other (see Appendix 1) by non-specialized researchers, as is often the case with rescue crews.Therefore, it is likely that an unknown proportion of the Mesoclemmys identified as M. gibba during rescue operations actually were M. raniceps.The available data indicate that both M. raniceps and M. gibba occur in sympatry along the Madeira River and in the Madeira-Purus interfluvium.In the upper Madeira basin, only records of M. raniceps exist along the Mamoré-Guaporé River (Iverson et al. 2000).It is still not clear whether both species occur syntopically.In the lower Madeira region, M. gibba has been found in ponds and temporary pools, while M. raniceps were captured in small streams.However, in the upper Madeira, two M. gibba were found in a forest stream (Appendix 2, photo vouchers MG-04 and 05), while all other Mesoclemmys were found in igapó (flooded forest) areas.
No georeferenced record of Phrynops geoffroanus has been published so far for the Madeira River, including our surveys.The species is listed for the upper Madeira in the initial environmental impact assessment report for the Santo Antônio and Jirau dams (Lima et al. 2005), and also for the upstream area of Costa Marques, on the Guaporé River, in the ecological zoning report for the state of Rondônia (Tecnoslo/DHV/EPTISA 1998).Lima et al. (2005) claim to have recorded two basking individuals of P. geoffroanus during visual surveys along a 297-km transect (380 km travel distance) in an area corresponding to the future reservoirs of both the Santo Antônio and Jirau powerplants (no voucher exists to support these records).We performed visual surveys along a 346-km transect (2,837 km travel distance) (Keller et al. 2013), but only in the area of the Santo Antonio reservoir, where we failed to record P. geoffroanus.Thus, its presence in the upper Madeira remains probable but in need of confirmation.
Platemys platycephala generally is expected to be found in rainforest ponds and pools throughout the Amazon, although georeferenced records are few in contrast with its perceived ubiquitous presence (Ernst 1987;Iverson et al. 2000).Some old records for this species exist in the Bolivian part of the Madeira basin, but only one in the lower Madeira region and two in the Madeira-Purus interfluvium (Ernst 1987;Iverson et al. 2000).Platemys platycephala was the most frequently found species in the Madeira-Purus interfluvium survey (19 records overall, including the seven voucher-based specimens in Table 1).It was also the second most common chelonian species found during fauna rescue in the area of the Santo Antônio dam reservoir (100 records listed for both margins of the Madeira) (Keller et al. 2013) and the Jirau dam reservoir (12 individuals, NATURAE 2012).The available data indicate that P. platycephala likely occurs continually on both margins along the middle and upper Madeira River.
Two records of Kinosternon scorpioides for the Madeira basin in Iverson (1992) have been withdrawn in the updated digital version of its distribution map (Iverson et al. 2000), but one older record remains in the lower Madeira-Purus interfluvium (Berry and Iverson 2001).Egg-laying sites of the species were recorded in mangrove areas along the blackwater Matupiri River, a tributary of the lower Madeira River (Andrade et al. 2011) and scattered records were mentioned from the interior of Rondônia state (Vogt 2008).All recent voucher-based surveys along the Madeira and the Madeira-Purus interfluvium (Vogt et al. 2007; UFAM/DNIT 2009; this study) have failed to record the species.Likewise, it was not found during faunal rescue for the Santo Antônio and Jirau dam reservoirs (Marçal et al. 2011;NATURAE 2012).
The absence of Chelonoidis denticulata in the Madeira-Purus interfluvium was surprising, especially considering that 80% of the sampling modules were located in well preserved and sparcely inhabited forested areas.Informal surveys with local inhabitants confirmed the absence of this species in forests along the BR-319 Highway.Likewise, during RAP surveys along the middle flow of the Madeira between Borba and Manicoré, no tortoises were found in the wild; they were recorded only as captive individuals in one local community (Vogt et al. 2007), or mentioned as collected, kept as pets and consumed in questionaires to local inhabitants (NUSEC/UFAM 2014a, 2014b).This scarcity might be due to habitat unsuitability, as well as overexploitation.As expected, the species occurred in forested areas along the upper Madeira.Faunal rescue yielded 115 Chelonoidis individuals on both margins of the Madeira in the area now under the Santo Antônio reservoir (Keller et al. 2013), and six individuals in the area of the Jirau dam reservoir (NATURAE 2012); these were all identified as C. denticulata (Marçal et al. 2011;NATURAE 2012).
Of the 16 or 17 species of chelonians listed for the Amazon region by Vogt (2008) and Rueda-Almonacid et al. (2007), respectively, 12 have been found to occur or expected to occur in or along the Madeira River.Records in the Madeira-Purus interfluvium were in accordance with the findings of other voucher-based surveys in the area (Vogt et al. 2007; UFAM/DNIT 2009).Podocnemis expansa and P. unifilis occur in the inter-rapids sections of the upper Madeira.Podocnemis sextuberculata, which had previously been recorded only in the lower Madeira (downstream of the confluence with the Aripuanã River), is now known to occur as far as the lower limit of the rapids sections of the upper Madeira.Chelus fimbriatus, Mesoclemmys raniceps, Mesoclemmys gibba, Platemys platycephala and Chelonoidis denticulata likely occur along the whole river and the adjacent Madeira-Purus interfluvium.Peltocephalus dumerilianus is confirmed to occur in the middle Madeira region, with its possible presence in the upper Madeira requiring confirmation.To our knowledge, there is still no voucher-based and georeferenced published record for Phrynops geoffroanus or Kinosternon scorpioides for the Madeira River, although anecdotal information suggests these species occur at least in part of the river basin.Podocnemis erythrocephala was not confirmed either, although previous records exist for the species in the lower Madeira region (Iverson et al. 2000), including important breeding sites (Andrade et al. 2011).
Despite the scarcity of publicly available records of chelonians from the Madeira River, the diversity of species in and along the Madeira is high by Amazonian standards.Vogt et al. (2007) concluded that there is a generally low abundance of chelonians in the middle Madeira region.While this seems to be true for historically overexploited mass-breeders like Podocnemis expansa and P. unifilis, and also for the highly appreciated and easily collected Chelonoidis denticulata, it may have been a misleading impression for other, more secretive species.The available data indicate that Mesoclemmys raniceps and M. gibba, as well as Platemys platycephala, may actually be frequent and relatively abundant along the Madeira.The phylogeographic relation and possible niche segregation of M. raniceps and M. gibba are among the interesting questions that follow from their distribution pattern along the Madeira.
With the possible but unconfirmed exception of Phrynops geoffroanus, the available data indicate that the chelonian species found in the areas affected by the Santo Antônio and Jirau reservoirs in the upper Madeira also are found downstream from the dams.Moreover, chelonian diversity seems to be higher in the lower Madeira region, with the additional presence of Podocnemis sextuberculata, P. erythrocephala and Kinosternon scorpioides.Therefore, the impact of the hydropower plants probably will not be on overall chelonian diversity in the Madeira subbasin but more importantly, will affect the connectivity of populations up-and downstream from the dams of the species that depend on main river channels for dispersal and migration, mainly Podocnemis expansa and P. unifilis.

ACKNOWLEDGEMENTS
Chelonian surveys in the upper Madeira River were carried out as part of the Wildlife Conservation Program from Santo Antonio Energia S.A., the concessionaire responsible for building and operating the Santo Antonio Hydroelectric Plant, in the Madeira River in southwestern Brazilian Amazonia (Rondônia state).Surveys in the Madeira-Purus interfluvium were financed by PRONEX/FAPEAM/CNPQ (edital 003/2009, project "Fatores ecológicos e históricos na evolução da biota amazônica: variação molecular e fenotípica de espécies e comunidades biológicas na Amazônia Ocidental", co-ordinated by Albertina P.Lima; and edital 16/2006, project "Planejamento de levantamentos da biodiversidade e monitoramento de processos ecossistémicos para inclusão científica de comunidades rurais ao longo da BR-319 no estado do Amazonas", co-ordinated by William E. Magnusson).We thank Richard C. Vogt for help with the identification of Mesoclemmys individuals; Albertina Lima, Pedro Ivo Simões, Rafael de Fraga, Zilca Campos, Raquel Moura, Priscila Pereira, Jussara Dayrell and the CPRM survey group for the capture and/or photographic record of turtles and tortoises during their fieldwork, and the staff of the Wild Animal Screening Center (CETAS) of Santo Antonio Energia for access to turtles from the

APPENDICES APPENDIx 1
Species diagnosis of the chelonians recorded along the BR-319 Highway (state of Amazonas, Brazil), in the Madeira-Purus interfluvium along the lower and middle Madeira River (east of Humaitá), and in and along the upper Madeira River (state of Rondônia, Brazil), between Porto Velho and Cachoeira do Jirau.Unless otherwise stated, diagnostic characteristics are based on the species descriptions in Rueda-Almonacid et al. (2007) and Vogt (2008), highlighting those aspects that were more useful in field identification.Some attributes are referred to photo vouchers in Appendix 2. SCL = straight carapace length (maximum straight-line measurement).Common names in English [E] and Portuguese [P] are provided.

Suborder Pleurodira Family Chelidae
Chelus fimbriatus (Schneider, 1738) The species is easily identified by its large, flattened and triangular head (due to supra-tympanical dermal outgrowths and a long and fine cylindrical snout); the neck is long and thick, as broad as the head, and covered with tubercules; the carapace is marginally serrated with conspicuous dorsal and costal protuberances (see Appendix 2, photo-vouchers CF-01,02 and 03).It reaches about 50 mm SCL.

Mesoclemmys raniceps (Gray, 1855) (Black-lined Toadhead Turtle [E], lalá [P])
Adults of this species are up to 330 mm SCL.The most striking attribute is its massive head (about 25% of SCL), with conspicuously large masseter muscles, dark on the dorsal side, and yellowishrimmed jaws on the lateral and ventral side.The plastron is dark or interspersed with yellowish areas (Appendix 2, photo-vouchers MR-01 to 07, 09 to 11 and 13).Juveniles have dark vermiculations or spots on the head and/or neck (MR-08 and 12).

(Twistneck Turtle [E], jabuti-machado [P])
This small chelid (adults < 180 mm SCL) is found only in shallow forest pools and swamps.The narrow head is streamlined with the neck and is variably bright orange-yellow on the dorsal side; this pigment extends along the neck.Two conspicuous dorsal parallel keels run along the carapace, which also has broad black stripes on brown background (Appendix 2, photo-vouchers PP-01 to 08).

Family Podocnemididae
Podocnemis spp.have a characteristic interorbital groove, well developed interdigital membranes, and inhabit large to mediumsized rivers.
Podocnemis expansa (Schweigger, 1812) (South American Giant River Turtle [E], tartaruga-da-Amazônia [P]) This species has the most hydrodynamic morphology among Podocnemis, with a flat, posteriorly broadened carapce (Appendix 2, photo vouchers PE-01 to 04), strong limbs with stoutly developed interdigital membranes (see PE-01, bottom left) and eyes in dorsal position (best seen in PE-01 and 04).Adults can be distinguished by size alone (up to 900 mm SCL).In our samples, SCL were > 400 mm for males and > 500 mm for females (Keller et al. 2013).Carapace and limbs tend to be uniformly gray; the plastron is cream-colored or intermingled with black.Juveniles have large whitish spots on the head, which survive in adults as two post-orbital whitish spots with two black ocelae (best seen in PE-01 and 04).

Podocnemis unifilis Troschel, 1848 (Yellow-spotted River Turtle [E], tracajá [P])
This species has a more oval, domed gray-brown-olive carapace in comparison with P. expansa.Adult males vary from 200-370 mm and females from 300-470 mm SCL.Juveniles have bright yellow spots on the head (Appendix 2, photo-voucher PU-01) that persist in adult males, while adult females have a brownish head.The interorbital groove is rather subtle.

Podocnemis sextuberculata Cornalia, 1849 (Six-tubercled Amazon River Turtle [E], iaça, pitiú [P])
This is the smallest of the three Podocnemis recorded, with adults less than 350 mm SCL.The six plastral tubercules, on which the English name is based, are present only in juveniles.The interorbital groove is well marked and black colored; the head is brownish-gray with diffuse black pigmentation, and the general coloration is grayish-white, similar to P. expansa (Appendix 2, photo-vouchers PS-01 to 04).

Peltocephalus dumerilianus (Schweigger, 1812) (Big-headed Amazon River Turtle [E], cabeçudo [P])
This species is predominantly known from blackwater mediumsized lakes and rivers.It is stout and large-bodied (adults up to 400-500 mm SCL) with a highly domed carapace.No interorbital groove is present and the head is massive and barrel-shaped, with a pronounced snout and hooked jaws (Appendix 2, photo-voucher PD-01).The carapace is uniformly olive-brown to black or gray, and the plastron yellow to cream.

Suborder Criptodira Family Testudinidae
Chelonoidis denticulata (Linnaeus, 1766) (Yellow-footed Tortoise [E], jabuti amarelo [P]) This terrestrial species inhabits forested landscapes.Adults may reach 800 mm SCL, but nowadays are seldom found larger than 400 mm.The carapace is medium brown with large diffuse yellowcream spots that radiate from the center of the vertebral, coastal and marginal scutes; head and forelimb scales are covered with yellow to light orange spots on brown background (Appendix 2, photovouchers CD-01 to 04).The frontal and prefrontal scales are divided (best seen on CD-02).
Keller et al. | Check list of chelonians in the Madeira River Keller et al. | Check list of chelonians in the Madeira River

Table 1 .
Keller et al. | Check list of chelonians in the Madeira River Continued.Keller et al. | Check list of chelonians in the Madeira River ; Table 1; Appendix 2).One juvenile M. raniceps (INPA-H 33226, Table 1) was collected by a third party.Three species occurred mainly in small forest streams (M.raniceps, P. platycephala and C. fimbriatus).Mesoclemmys gibba were found in ponds in areas of open vegetation.One gravid female of P. dumerilianus (Appendix 2, photo voucher PD-01; Table

Table 2 .
Vogt et al. 2007lonian species expected to occur in one or both areas surveyed: Madeira-Purus interfluvium along the low and middle Madeira River (east of Humaitá) and in and along the upper Madeira River (between Porto Velho and Cachoeira do Jirau).Species marked with a hyphen were expected to occur in the region, but not in the type of aquatic habitats surveyed."otherstudies"refers to species records by other recent surveys that produced voucher based material in the lower Madeira region and corresponding area of the Madeira-Purus interfluvium ( 1Vogt et al. 2007; 2 UFAM/DNIT 2009).
Keller et al. | Check list of chelonians in the Madeira River