The freshwater fishes from the Costa Verde Fluminense region of southeastern Brazil

Abstract The region between the Brazilian Shield and the Atlantic Ocean is characterized by the presence of numerous hydrographic basins isolated by mountainous terrain that flow directly into the ocean without forming wide coastal plains. However, knowledge about the diversity and distribution of freshwater fish in several coastal areas is still incipient. One of these areas is the Costa Verde Fluminense region, situated between the municipalities of Mangaratiba and Paraty in the Brazilian State of Rio de Janeiro. In order to eliminate the gap of knowledge about the freshwater fish fauna of this region, we prepared a list of the species, and dichotomous identification keys and illustrations of all species. We examined material from expeditions carried out between 1942 and 2019, deposited in the Ichthyological Collection of the Museu Nacional, Universidade Federal do Rio de Janeiro, Brazil. The material comes from 29 continental coastal rivers and four drainages on Ilha Grande island. We recognized 54 fish species belonging to 16 families and 9 orders. The order Siluriformes was the most diverse with 18 species, followed by Characiformes with 14 species, Cyprinodontiformes with 10 species, Cichliformes with four species, Gobiiformes with three species, Syngnathiformes with two species, and Gymnotiformes, Salmoniformes and Synbranchiformes with one species each. These records include two putative undescribed species and four introduced species. Phalloceros anisophallos was the most widely distributed species, recorded in 24 drainages. More than a half (52 %) of the native species occur exclusively in coastal streams, demonstrating the importance of the area for biogeographic and conservation studies.


Introduction
The region between the Brazilian Shield and the Atlantic Ocean is characterized by the presence of numerous hydrographic basins isolated by mountainous terrain.These drainages flow directly into the ocean without forming wide coastal plains and harbor endemic fish populations (Buckup 2011).Most eastern Brazilian coastal basins are small and isolated drainages, characterized by relatively low fish diversity (when compared to the Paraná basin), and high level of endemism (Thomaz & Knowles 2018).One of these areas is the Costa Verde Fluminense region, situated between the municipalities of Mangaratiba and Paraty, which is home to one of the largest remnants of native Atlantic Forest in the Brazilian State of Rio de Janeiro.As for most eastern Brazilian coastal basins, the knowledge about the diversity and distribution of its freshwater fish fauna is still incipient.
The basins of the Costa Verde Fluminense are included in the Fluminense Ecoregion (FEOW352), limited to the north by the Paraíba do Sul (FEOW329) and to the south by Ribeira de Iguape (FEOW330) ecoregions (Abell et al. 2008).This ecoregion is occupied by one of the highest densities of urban occupation in the Atlantic Forest.Despite of the long history of human occupation of the Atlantic coast of Rio de Janeiro, the distribution of freshwater fishes is still poorly known.The first description of a fish species, Characidium japuhybense, from a locality situated in the Costa Verde region was published only in the middle of the 20 th Century (Travassos 1949) based on material collected in the Japuíba basin, at Angra dos Reis, a few years earlier by George Myers, Paulo Miranda-Ribeiro and Haroldo Travassos.Additional species have been described in recent decades, totaling 11 species described from specimens collected in the Costa Verde region (Table 1), but no comprehensive study of fish composition is currently available (Guimarães et al. 2021).Bizerril & Primo (2001) provided three lists of fish species from river drainages of Ilha Grande Bay, the largest area in the Costa Verde Fluminense region.Those lists are the most comprehensive ever published for Costa Verde Fluminense, but they are not associated with voucher specimens from museum collection.One of the lists was extracted from an unpublished master's thesis by H. São-Thiago, and included 22 marine and freshwater species from the Parati-Mirim River.The second list (based on "field data" and three unpublished contributions by C. Coutinho, E. Caramaschi, and H. São-Thiago compiled fish diversity from 22 coastal basins, including again the Parati-Mirim.The third list, based on personal communication by R. Mazzoni, presented 18 species of fish that occur in the drainages of the Ilha Grande island.
Here we present a compilation of fish species from the Costa Verde Fluminense region based on voucher specimens deposited in a permanent ichthyological collection.In addition to the list of voucher specimens collected from 33 river basins, we provide identification keys for all species.

Study area
The study area comprises the Costa Verde Fluminense region (Figure 1), in the municipalities of Mangaratiba, Angra dos Reis and Paraty, in the Brazilian State of Rio de Janeiro, and São José do Barreiro and Bananal in the Brazilian State of São Paulo.This region includes both continental and insular drainages of the Ilha Grande and Sepetiba Bays, between the rio Itinguçu (22°54'44.16"S,43°52'47.97"W) in the east and the western border of the State of Rio de Janeiro where it meets the ocean (23°22'06"S, 44°43'27"W).Additionally, we included the small drainages of the Ilha Grande, the largest island inside the Ilha Grande Bay.The continental rivers drain the coastal lowlands and the slopes of the Serra do Mar, locally known as Serra da Bocaina (Francisco & Oliveira 2009), while the headwaters of some of these rivers drain the main plateau of the Bocaina highlands.The sampled coastal rivers were numbered from east to west following the shoreline (Table 2).

Specimens
For the purpose of inclusion in our list, species were considered as freshwater according to Reis et al. (2003).The list is based on examination of specimens collected between 1942 and 2019 (Supplementary file 1), and deposited at the Ichthyological Collection of the Museu Nacional (MNRJ), Universidade Federal do Rio de Janeiro, Brazil, which harbors the largest collection of freshwater fishes from the Costa Verde Fluminense region.Literature records of species from the region are included in the list and discussed as deemed appropriate, but only when associated with material deposited in a museum collection.

Species
Specimens were identified to the lowest taxonomic level possible using available literature (e.g., Buckup et al. 2014;Costa 2009;Menezes    We first present a dichotomous key to identify fish orders.Orders that include a single family or single species, have their respective names given in parentheses.Separate keys are presented for families and genera which have more than one species present in the area. The extinction risk of each species of fish was obtained from the Brazilian Red List and IUCN Red List of Threatened species (MMA 2014;MMA 2018;ICMBIO 2018;IUCN 2021).The distribution map of the examined material (Supplementary file 1) was generated with QGIS software (http://qgis.org)following Calegari et al. (2016), and using river traces obtained manually from Google Earth satellite images.

Results
The 13.692 examined fish specimens (857 lots) belong to 54 species, 16 families, 9 orders of freshwater fishes (Table 3).Siluriformes (Figure 2) was the most diverse order (18 species), followed by Characiformes Table 3. Freshwater fishes found in the Costa Verde Fluminense region.Drainages are numbered from east to west according to the position of their outlet into the sea (see Figure 1 and Table 2).One asterisk (*) indicates non-native species.Two asterisks (**) indicate record based solely on Medeiros et al. (2022).

Family Characidae
Identification Key to Species

Family Crenuchidae
Identification Key to Species

Family Eleotridae
Identification Key to Species

Discussion
Although the Costa Verde Fluminense region is located between the two largest metropolitan areas (Rio de Janeiro and São Paulo) in Brazil, this study is the first comprehensive inventory of freshwater fishes of this region based on material deposited in a permanent collection.A previous broad ichthyological inventory of the region did not provide catalog numbers nor pictures of the material examined (Bizerril & Primo 2001), which limits identification and distribution discussions.Other publications provide reliable records, but focused on restricted taxa (Costa 2004;Medeiros et al. 2022;Souto-Santos et al. 2019) or restricted drainages (Guimarães et al. 2021).
Notable differences in species richness (number of species) were found among the drainages.Continental drainages of Ilha Grande Bay (drainages 6-28) are more diverse than those of Sepetiba Bay (drainages 1-5) and Ilha Grande island (drainages 30-33).The highest species richness was registered at Bracuí, Perequê-Açu, Parati-Mirim e Mambucaba, which are the basins with the largest area.
As expected for the Serra do Mar mountain range, several endemic coastal species were found.Eleven species have their type-locality within the study area (Table 1).Species of exclusively coastal distribution (52 %, excluding non native species from Eleven species are listed in the Brazilian red list as "Critically Endangered" (Characidium grajahuense, Listrura costai, Atlantirivulus lazzarotoi, and Kryptolebias brasiliensis), as "Endangered" (Atlantirivulus simplicis), as "Near Threatened" (Trichogenes longipinnis, Hemipsilichthys nimius, Pareiorhina rudolphi, Dormitator maculatus, and Kryptolebias ocellatus), and as "Vulnerable" (Taunayia bifasciata) (ICMBIO, 2018).Unlike most species recorded in Costa Verde Fluminense streams, T. bifasciata does not occur in lowland streams.A call for conservation of highland areas of the Costa Verde region was made by Medeiros et al. (2022), but our results highlight the strong need for conservation actions in lowland areas where these species are found.
Specific identifications of characids in faunal surveys of Atlantic Forest fishes are often inaccurate (Oyakawa et al. 2006).Identifying these species became an even more challenging task after the understanding that there are no clear morphological characters that diagnose some genera (Terán et al. 2020).
Previous ecological studies listed Bryconamericus microcephalus in rivers of the Ilha Grande (e.g.Mazzoni & Silva 2006).More recently the species of Bryconamericus from the Perequê-Açu drainage was identified as B. ornaticeps (Guimarães et al. 2021).However, based on our evaluation of morphological and molecular data from drainages associated with type localities we identify the species of Bryconamericus from Costa Verde Fluminense as B. ornaticeps Bizerril & Perez-Neto (1995).DNA sequences of the COI mitochondrial gene of Bryconamericus from Costa Verde Fluminense clusters with topotypes of B. ornaticeps, and are not related to topotypes of B. microcephalus (Buckup et al., in prep).Guimarães et al. (2021) provided a list of 23 species of freshwater fishes from the Perequê-Açu drainage.Our sampling from the Perequê-Açu revealed an additional species, Characidium japuhybense.Additionally, according to our reexamination of voucher specimens, their identifications of "Deuterodon intermedius" and "D.hastatus" correspond, respectively, to Psalidodon scabripinnis and an undescribed species of Deuterodon morphologically similar to Astyanax keronolepis.Based on DNA barcode sequences of samples MNRJ 50603 and MNRJ 50607, the former species is a member of Barcode Index Number (BIN) BOLD:AAC5910.According to data available in the Bold Systems database (https://www.boldsystems.org/index.php/Public_BINSearch),BIN BOLD:AAC5910 this BIN includes 456 specimens from an extensive area in southeastern South America.These specimens have been identified by over two dozen taxonomic names.Among those names, Psalidodon bockmanni (83 occurrences), Psalidodon paranae (62 occurrences), Psalidodon rivularis (42 occurrences); and Psalidodon scabripinnis (32 occurrences) are the most frequent ones.The majority of these identifications suggest that BOLD:AAC5910 corresponds to the so-called P. scabripinnis species complex.Here we use the name P. scabripinnis for this widespread species, following Limeira et al. (2022).The extensive geographic distribution of this species and future reexamination of type specimens may eventually require synonymizing several nominal species that are currently regarded as valid (e.g., P. paranae, P. rivularis).

Table 1 .
Freshwater fishes with type-locality located in river drainages of the Costa Verde Fluminense, southeastern Brazil.Sampled localities in the Costa Verde Fluminense (Rio de Janeiro) region.River drainages are numbered according to Table2.Circles may represent more than one sample locality.

Table 2 .
River drainages sampled in the Costa Verde Fluminense region, numbered from east to west according to the position of their mouth (Figure1) and coordinates of sampled localities.Drainages 30 to 33 are located on Ilha Grande island.Original geographic coordinates obtained with GPS at collection localities are provided, except for those indicated by an asterisk (*), which are estimated from topographic maps.