First record of Stichopathes occidentalis ( Gray , 1860 ) and range extensions of Antipathes atlantica Gray , 1857 ( Cnidaria : Anthozoa : Antipatharia ) in the southwestern Atlantic Ocean

Brazil has the highest known diversity of cnidarian anthozoans of the southwestern Atlantic Ocean. Although over 80 octocoral species and more than 80 scleractinians are known for the Brazilian Exclusive Economic Zone (EEZ), studies about the black coral fauna are still scarce in the region. The main studies available are those by Echeverría and Castro (1995), Loiola and Castro (2001), Echeverría (2002), Pérez et al. (2005), Loiola and Castro (2005), Castro et al. (2006), Loiola (2007) and Opresko and Loiola (2008). All together, these studies report for twenty one species in the Brazilian waters. According to Castro et al. (2006), the greatest black coral richness off Brazil occurs in the area near Cape of São Tomé (about 22°S), between 100 and 500 m depth, with six species cooccurring there. Ecological data about this group are also rare around the globe (Tazioli et al. 2007). Aim of this work is to report the new records of two antipatharians species for the N-NE Brazilian waters. Samples were manually removed from the colonies or trawled, taken to the laboratory for identification and then deposited in the Cnidarian Collection of the Oceanographic Museum of the Federal University of Pernambuco (MOUFPE). Identification was carried out following Opresko and Sánchez (2005) on the base of spine morphology. Some taxonomic features (such as colony height, polyps arrangement and color) were only observed in the field. The genus Stichopathes Brook, 1889 is cosmopolitan and comprises about 35 species, found from shallow-water reef environments to extremely deep areas. Two species of this genus have been recorded for the northwestern Atlantic Ocean in mesophotic reef ecosystems, namely Stichopathes occidentalis (Gray, 1860) and Stichopathes lutkeni Brook, 1889 (Opresko and Sanchez 2005). Here Abstract: Twenty one species of black corals have been recorded in the Brazilian Exclusive Economic Zone (EEZ) to date, distributed mainly at depths greater than 20 m. The diversity of these environments along the northern and northeastern coasts of Brazil has been poorly investigated, in particular few information are available for the cnidarian fauna. This note represents the first record of the genus Stichopathes for the southwestern Atlantic Ocean, and also fills in the gaps in the distribution of Antipathes atlantica between the northern and southern coasts of Brazil. 1 Universidade Federal de Pernambuco, Pós-Graduação em Biologia Animal, Centro de Ciências Biológicas, Departamento de Zoologia, Av. Professor Moraes Rego, 1235. CEP 50670-420. Recife, PE, Brazil. 2 Universidade Federal de Pernambuco, Pós-Graduação em Oceanografia, Centro de Tecnologia e Geociências, Departamento de Oceanografia, Av. Professor Moraes Rego, 1235. CEP 50670-420. Recife, PE, Brazil. 3 Universidade Federal de Pernambuco, Centro Acadêmico de Vitória. Rua Alto do Reservatório, s/n, Bela Vista. CEP 55608-680. Vitória de Santo Antão, PE, Brazil. * Corresponding author. E-mail: ralfts@gmail.com Ralf Tarciso Silva Cordeiro 1*, Henrique Albuquerque Maranhão 2, Suellen Tarcyla da Silva Lima 3 and Carlos Daniel Pérez 3 First record of Stichopathes occidentalis (Gray, 1860) and range extensions of Antipathes atlantica Gray, 1857 (Cnidaria: Anthozoa: Antipatharia) in the southwestern Atlantic Ocean


Introduction
The Neotropical region harbors a high diversity of freshwater fish, which includes almost 4500 already described species and nearly 1550 species still waiting for a scientific description (Reis et al. 2003).The Amazon basin is considered to shelter most of this diversity; however knowledge about the ichthyofaunal composition of this region is concentrated in the most accessible areas near large urban centers (Lowe-McConnell 1999).Furthermore, information about fish has been obtained mostly from the main tributaries of the Amazon River, and primarily targeting medium-to large-sized species of commercial value (Böhlke et al. 1978;Rapp Py-Daniel and Leão 1991).
Small streams, of the 1 st (no tributaries), 2 nd (two first order streams join) and 3 rd order (two second order streams join), have a unique species pool, and contribute significantly to regional diversity (e.g.Espírito-Santo et al. 2009).Furthermore, because of the isolated condition of the streams, they are considered important for evolutionary processes, such as speciation (Barthem 2004).However, studies in these environments are limited because of their remoteness (and hence difficult access) and because they shelter small bodied species that are of no commercial interest for use as human food (Lowe-McConnell 1999).
The interfluvial plain between the Madeira and Purus Rivers is one of the most pristine parts of the Amazonian region, but is also one of the least studied with a small amount of protected area coverage.In addition, the Brazilian Federal Government development policies for this region include paving an existing road and the opening of hydroways, dam construction and gas transportation The fish fauna of streams in the Madeira-Purus interfluvial region, Brazilian Amazon to site #1 and belong to the Purus river basin, and in the second expedition three streams were sampled near site #2, four near site #3, and four near site #4, all draining into the Madeira river (Figure 1).The duration of each expedition was approximatedly 20 days.Both expeditions were conducted at the beggining of the dry season with the southern part being visited first due to the rain stopping earlier than at the northern part.
The geology of the region is primarily comprised by Cenozoic deposits, with sediments from the Tertiary and early Quaternary periods, which make up the Solimões Formation.The relief is classified as one of the morphostructural units of the "lowered Amazonian tableland" (Radambrasil 1978).Soils are mostly red-yellow podzols, but there are also patches of red-yellow latosols, yellow latosols and hydromorphic laterites (Radambrasil 1978).
The climate is equatorial, warm and humid, including the categories of 'tropical monsoon' (Am), 'tropical rainforest' (Af), and 'tropical wet and dry' (Aw) based on the Köppen climate classification system (Radambrasil 1978).The mean annual temperatures ranges between 24 °C and 26°C.The wet season usually starts in October, with the highest volume of rain falling from January to March.Vegetation cover is dominated by dense and open tropical forests (Radambrasil 1978).

Fish sampling
The fish sampling protocol used in this study follows Mendonça et al. (2005), for the purposes of comparative analysis with similar studies (e.g.Dias et al. 2009;Espírito-Santo et al. 2009).In each stream that was surveyed, a 50 m long section was delimited for the collection of fish.The two extremities of the section were blocked using a fine-mesh net (5 mm between opposite knots) with the aim to prevent the escape of fishes during capture.Fish were captured using a purse seine of 2 m length (mesh size= 2 mm) and hand nets.Capture was conducted during daylight hours only and always in in the same direction; from downstream to upstream.Sampling effort was standardized as much as possible with three collectors working for a 2 h period in each 50 m section.

Results and Discussion
A total of 5508 fishes were collected belonging to 78 species, 22 families and six orders.The distribution of most species was related to drainage basins.Of the total species collected, 25 were found in both basins, 19 were collected only in the Purus basin, and 34 only in the Madeira basin (Table 1).Of the 78 species, 12 were identified to the genus level only, with an additional three requiring confirmation of identification to the species level.In other words, the taxonomic status of 19.2% of the collected species was undefined and may possibly be revealed as new species following review by taxonomists.
Existing research has indicated a large diversity in South American freshwater fish fauna, with Characiformes and Siluriformes usually being most dominant (Castro 1999;Lowe-McConnell 1999;Reis et al. 2003;Buckup et al. 2007).These observations have been further supported by studies in a number of Brazilian Amazon streams (Sabino and Zuanon 1998;Araújo-Lima et al. 1999;Bührnheim and Cox-Fernandes 2001;Dias et al. 2009;Espírito-Santo et al. 2009;Oliveira et al. 2009).In this study, Characiformes was also the most diverse order.However, the second order in species richness was Gymnotiformes, rather than Siluriformes as was found in the the above mentioned studies.In this study, Gymnotiformes represented both a relatively high proportion of species (19.2%), and a relatively high abundance (6.3%).The reason for this may have been due to the high proportion of litter banks in sampled streams, a substrate on which individuals of this order were collected.The species of this order usually inhabit slow moving or lentic (i.e.lake, pond or swamp like) environments (Fink and Fink 1978), which explain our results.On the other hand, the Perciformes, Cyprinodontiformes and Synbranchiformes all represented small proportions of the overall species abundance and richness, which was similar to that found in previous studies (Silva 1995;Mendonça et al. 2005;Espírito-Santo et al. 2009;Oliveira et al. 2009) and other freshwater environments of South America (Lowe-McConnell 1999).
The present study found very high fish species richness (78 spp.) when compared to existing studies of streams in the Brazilian Amazon (e.g.Araújo- Lima et al. 1999;Bührnheim and Cox-Fernandes 2001).For example, in the studies by Mendonça et al. (2005) and Espírito-Santo et al. (2009), in which 38 sections and 31 sections of creeks of 1 st to 3 rd order were sampled respectively, both following the same methodology used in this study, a total of 49 and 53 fish species were detected respectively.In addition to the relatively high species richness recorded in this study, there is other evidence of high species diversity in the Madeira-Purus interfluvial region, and hence its conservation importance.Field studies in the Amazonian region have uncovered about 4-5% of previously unnamed species (Peres 2005), which is much smaller than the 19.2% of species with undefined taxonomic status found in this study.Further analysis of the fish collected in this study, that do not match species found in biological collections and/or the specialised literature, may result in the classification of new species.Such species are likely to be of restricted distribution, enlarging the list of endemic fish proposed by Nogueira et al (2010).In conclusion, the results of this study reinforce the requirement for more targeted surveys on the distribution of Amazonian freshwater fish fauna in remote areas.The acquisition of such scientific information is essential to improve knowledge on distribution patterns of fish species; to monitor the impacts of anthropogenic activities, which can possibly threat species survivorship (Peres et al. 2010); and for implementation of effective conservation strategies for ecosystems supporting the fish fauna of Neotropical streams.

Figure 1 .
Figure 1.Study area at the interfluvial region of Madeira and Purus Rivers (dark gray) in the Brazilian Amazon biome (light gray).The numbers indicate the sampling sites at the southern (site #1, 11 streams sampled; Purus basin, near to Porto Velho, Rondônia state) and northern (sites #2, three streams; #3, four streams; and #4, four streams; Madeira basin, near to Manaus, Amazonas state) portions of the interfluvial plain.

Table 1 .
Composition of the fish fauna sampled in 22 streams of the Madeira-Purus interfluvial plain (Rondônia and Amazonas states, Brazilian Amazon).Purus/Madeira= number of individuals captured in each drainage basin; N = total abundance; FR%= relative frequency of the species in relation to the total number of collected specimens; FO%= frequency of occurrence in the sampled streams.

Table 1 .
Continued.We thank the GEOMA Project for financial and logistical support of the field and laboratory work at INPA.We thank Mario Cohn-Haft for coordinating the project and the Petrobras for providing a helicopter that greatly eased the accesss to the study area.The first author acknowledges the Instituto Internacional de Educação do Brasil (IIEB) -BECA Program for the Masters scholarship, and the Environmental Sciences Postgraduate Program of the UFPA-MPEG-EMBRAPA.JZ receives a productivity grant from CNPq (process # 307464/2009-1).IBAMA provided the license to collect biological material.Two anonymous reviewers made valuable contributions to improve the manuscript. Acknowledgments: