An inventory of coastal freshwater fishes from Amapá highlighting the occurrence of eight new records for Brazil

Abstract 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.


Introduction
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).
Checklists of freshwater fishes have been continually published for French Guyana (Planquette et al. 1996;Keith et al. 2000;Le Bail et al. 2000, 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.

Material and methods
Fifteen sites were sampled including small streams, river channels and large/lentic lagoons covering two ecoregions from Abell et al. (2008) 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).
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 iden- tified 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. 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).