The Amazon Basin occupies a vast portion of northern South America and contains some of the highest species richness in the world. The northern Brazilian state of Amapá is delimited by the Amazonas River to the south, the Oyapock River to the northern boundary with French Guyana, and the Atlantic northeastern coast to Amazon estuary. Despite several expeditions to the Amazon in recent decades, little is known about the freshwater ichthyofauna from Amapá, with records limited to local inventories and species descriptions. This paper presents a compilation of the freshwater fish diversity sampled in fifteen sites covering two major Amapá ecoregions during the dry season of 2015. 120 species representing eight orders and 40 families are reported upon in this work. Eight species appear for the first time in the Brazilian territory providing new information for future conservation status evaluations.

Amazon, French Guyana, Neotropical, South America, Teleostei

At the northern limit of Brazil, the state of Amapá occupies the lower portion of the Amazon River basin at the border between Brazil, French Guyana, and Suriname. With more than 14 million hectares, ca. 90% of its native surface is still intact and ca. 73% is legally protected as either federal/state conservation units or indigenous territories (Bernard 2008). As example, the Tumucumaque National Park is the largest Brazilian protected unit and the largest continuous tropical forest national park in the world (Bernard 2008). Consequently, Amapá harbors a striking portion of the Neotropical fauna and flora in the Guiana Shield. That region along with the adjacent coastal ecosystems certainly needs further biological research.

Amapá includes three major Neotropical freshwater ecoregions (sensu Abell et al. 2008). The first is the Guianas containing the Oyapock River that has its headwaters in the Tumucumaque National Park. The second is the Amazonas Guiana Shield containing the Rio Jari and Rio Iratapuru, and the upper portions of the Rio Araguari basin including the large Rio Amapari. Third ecoregion is the Amazonas Estuary and Coastal Drainages that contains small rivers reaching the lower Amazonas such as Rio Cajari and Rio Preto as well as several independent coastal rivers reaching the east coast, including the middle/lower Rio Araguari, Rio Flexal, Rio Amapá Grande and its associated lakes, Rio Calçoene, Rio Cunani, Rio Cassiporé and Rio Uaçá (Fig. 1) (Jégu and Keith 1999).

Figure 1. 

Map of Amapá in northern Brazil, lower Amazon basin showing each collecting site (black circles). Numbers match those in Table 1.

Checklists of freshwater fishes have been continually published for French Guyana (Planquette et al. 1996; Keith et al. 2000; Le Bail et al. 2000, 2012), Suriname (Mol et al. 2012) and the Guiana Shield in general (Vari et al. 2009; Sidlauskas and Vari 2012). Likewise, biogeographic questions have been addressed to that region (Jégu and Keith 1999; Lujan and Armbruster 2011) as well as species descriptions (e.g. Jégu and Santos 1990; Vari 1992; Zarske and Géry 1998; Lucena and Gama 2007; Ottoni et. al. 2012). However, the diversity and composition of freshwater fishes from the Amapá and consequently the eastern limit of the Guiana Shield are limited to a concise and well-sampled inventory of fishes from the Tumucumaque National Park (Gama 2008) that is situated in the Amazonas Guiana Shield ecoregion (upper Oyapock River). Our aim is to present a survey of the ichthyofauna from Amapá sampled in the other two ecoregions: the Guianas (lower Oyapock River) and the Amazonas Estuary and Coastal Drainages. New records of freshwater fishes for Brazil should contribute to our understanding of the Neotropical ichthyofauna as well as to future evaluations of their conservation status.

Fifteen sites were sampled including small streams, river channels and large/lentic lagoons covering two ecoregions from Abell et al. (2008): Guianas (lower Oyapock River) and Amazonas Estuary and Coastal Drainages (Table 1; Fig. 1). Collection sites (Fig. 2) cover variable environments including small streams, rivers and lagoons and are near the main state road BR-156, which connects Laranjal do Jari to Oiapoque municipalities. Mazagão, Ferreira Gomes, Tartarugalzinho, Amapá and Calçoene are the intervening cities. Sampling efforts occurred during dry season in September and late November/early December 2015, mostly during daylight. Specimen collection involved tows of dipnets along the vegetated margins, a 5-meter bottom trawl and cast-netting in large streams or lagoons. Collection in the Lago Pracuúba comprised gillnets blocking fish passage overnight.

Figure 2. 

Sampled localities in the Amapá, northern Brazil. Numbers follow Table 1 and Fig. 1. Photographs by B.F. Melo and C. Oliveira. Photo 2 credits: Alan Kardec available at Google Earth.

Specimens were anesthetized in a solution of clove oil, preserved in 96% ethanol (for molecular studies) or fixed in 10% formalin solution (for morphological studies) and then preserved in 70% ethanol. Muscle tissues were collected and preserved in 96% ethanol. Vouchers are deposited in the Laboratório de Biologia e Genética de Peixes at the Universidade Estadual Paulista, Botucatu, São Paulo, Brazil (LBP). Expeditions had permission to collect wild species in Brazil under ICMBio license number 13.843-1 to Claudio Oliveira. Species identifications to the lowest taxonomic level were conducted consulting the taxonomic literature and identification keys (Géry 1977; Planquette et al. 1996; Keith et al. 2000; Le Bail et al. 2000; Lucena and Malabarba 2010; Sidlauskas and Vari 2012; Peixoto et al. 2015) and updated with Eschmeyer et al. (2016). Classification follows the current phylogenetic arrangement of bony fishes (Betancur-R et al. 2014). We used checklists (Reis et al. 2003; Le Bail et al. 2012), SpeciesLink (http://www.splink.org.br/) and FishNet2 (http://www.fishnet2.net/) to search previous records of the species listed herein.

The fish survey in the freshwater rivers of Amapá resulted in 120 species representing eight orders and 40 fish families that range from obligate freshwater to marine organisms (Table 2). Orders comprising the highest percentage of species richness were Characiformes (55%), Cichliformes (16.6%), Siluriformes (14.1%) and Gymnotiformes (7.5%) as expected in Neotropical freshwaters (e.g. Langeani et al. 2007; Vari et al. 2009; Polaz et al. 2014). These four orders represent 93.3% of the total species richness. Clupeiformes (Anchovia), Cyprinodontiformes (Fluviphylax and Melanorivulus), Gobiiformes(Dormitator), Beloniformes (Potamorrhaphis), Sciaenidae (Micropogonias) and Polycentridae (Monocirrhus and Polycentrus) complete the list with one or two species each. The most highly represented family was Characidae (25% of total species), followed by Cichlidae (16.6%) and Loricariidae (6.6%). Previous fish survey from Tumucumaque National Park listed 207 species from five expeditions (Gama 2008) and found a new species record in the Brazilian territory, the cichlid Cleithracara maronii. It is noteworthy, however, that some species are common in both lists despite sampling distinct ecoregions (e.g. Ageneiosus inermis, Apistogramma gossei, Bryconops caudomaculatus, Leporinus gossei, Microsternarchus bilineatus).

Eight species were identified from Brazilian territory previously thought to inhabit only the Guianas region. Herein, these species are formally recorded for Brazil and are Leporinus gossei, Chilodus zunevei, Melanocharacidium cf. blennioides, Jupiaba keithi, Phenacogaster wayana, Odontostilbe gracilis, Acnodon oligacanthus and Nannacara aureocephalus (Fig. 3). Among them, L. gossei, C. zunevei and N. aureocephalus were recently reported to Oyapock River in the Brazil-French Guyana boundary (Le Bail et al. 2012). Leporinus gossei was described from Marowijne river (Géry et al. 1991) and subsequently reported to many rivers of French Guyana (Planquette et al. 1996; Sidlauskas and Vari 2012) including the Brazilian section of the Oyapock River reported herein. Chilodus zunevei is recorded for the northeastern Suriname along the coastal rivers of French Guyana to Oyapock (Sidlauskas and Vari 2012) and now in the Rio Amapá. Melanocharacidium blenioides was described from the Potaro River in Guyana and ranges from Guyana to French Guyana (Buckup 2003). Herein, we report the species to the Rio Amapá. Jupiaba keithi is recorded from the Marowijne and Mana rivers of French Guyana (Zanata 1997); we found J. keithi in the Oyapock River. The recently described Phenacogaster wayana from Corantijn to Approuague rivers (Lucena and Malabarba 2010) is formally reported to Rio Amapá in Brazil. Odontostilbe gracilis occurs in a few places of the French Guyana (Planquette et al. 1996); we collected only a single specimen in the Rio Amapá. Acnodon oligacanthus is known only from the Guianas (Jégu 2003) and we found several specimens in the Rio Calçoene. Finally, Nannacara aureocephalus occurs in the Approuague river in French Guyana (Kullander 2003) and we found nine specimens in the Oyapock River. These new records should be incorporated in future evaluations of Brazilian threatened species conducted by the Ministério do Meio Ambiente/IUCN.

Figure 3. 

Species reported for the first time in Brazil. a Leporinus gossei, LBP 21114, Oyapock River b Chilodus zunevei, LBP 21129, Oyapock River cMelanocharacidium cf. blennioides, LBP 21185, Rio Amapá d Jupiaba keithi, LBP 21122, Oyapock River e Phenacogaster wayana, LBP 21218, Rio Amapá f Odontostilbe gracilis, LBP 21228, Rio Amapá g Acnodon oligacanthus, LBP 21012, Rio Calçoene h Nannacara aureocephalus, LBP 21065, Oyapock River. Scale bars: 1 cm.

The following species are known to occur in Brazil but are now first reported for coastal rivers of Amapá. Leporinus parae occurs in the lower Amazon basin, state of Pará, Brazil as well as in the Orinoco basin in Venezuela (Britski and Birindelli 2008). We collected L. parae in the Lago Pracuúba, an oxbow lake adjacent to the Rio Amapá Grande, leading to the first formal record of the species to Amapá. Jupiaba abramoides was previously known from the Rio Negro and we have now extended its range to the Oyapock River. Specimens of Curculionichthys, small armored catfishes distributed mostly throughout La Plata, São Francisco, Tapajós and Xingu basins (Roxo et al. 2015) were found in the Rio Cassiporé and Rio Jari and represent an undescribed species.

Besides Curculionichthys, three other taxa represent putative undescribed species: Curimatopsis sp., a member of the cryptic lineage Curimatopsis aff. crypticus (Melo et al. 2016), Lithoxus sp. from Rio Amapá and Apistogramma sp. ‘Amapá’ from the Oyapock River, commonly misidentified as A. gossei. These specimens are subject of ongoing taxonomic investigation in our laboratory. Furthermore, some taxa could only be identified at genus level, such as Astyanax sp., Bryconops sp., Bryconamericus sp., Bunocephalus sp., Hemigrammus sp., Hyphessobrycon sp., Pimelodus sp., among others (Table 2), and additional studies will be necessary to further classify these specimens. Overall, our survey increases our knowledge on the freshwater ichthyofauna of Amapá and of northern Brazil and provides new information for future conservation status evaluation. However, as other regions of the state remain unexplored, future inventories will likely reveal additional fish species in that part of the Guiana Shield.

We thank the Instituto de Pesquisas Científicas e Tecnológicas do Estado do Amapá (IEPA) for local assistance in the field expeditions. Thanks to Brandon T. Waltz, Francisco Langeani, Gabriel S.C. Silva, José L.O. Birindelli, Marina V. Loeb, Maxwell J. Bernt, Nadayca T.B. Mateussi, and Victor A. Tagliacollo for helping on the identifications, and to Benjamin W. Frable for English review and valuable suggestions on the manuscript. We also thank Javier Maldonado, Francisco Langeani and an anonymous reviewer for improving the manuscript. Authors received support from FAPESP grants 2014/26508-3 (BFM and CO), 2011/00269-4 (RB) and CNPq PDJ 40258/2014-7 (BFM).