First record of basket stars Astrocyclus caecilia ( Lütken , 1856 ) and Astrophyton muricatum ( Lamarck , 1816 ) ( Echinodermata , Ophiuroidea , Euryalida ) for the state of Rio Grande do Norte , northeastern Brazil

This paper reports the first record of Astrocyclus caecilia for northeastern Brazil and Astrophyton muricatum for the state of Rio Grande do Norte. The studied specimens were captured accidentally by a fisherman using a fishing rod at a depth below 100 m over the continental shelf of the state of Rio Grande do Norte. Such accidental captures stress our meager knowledge on our fauna from the outer margin of the continental shelf in northeastern Brazil. With these records we fill a gap in the known distribution of those species.

Along the coast of the North and Northeast regions of Brazil our knowledge of the fauna below 20 m is still limited.Particularly the outer margin of the continental shelf (below the depth contour of 50 m) and the continental slope are poorly known in this respect (Migotto and Tiago 1999).Notwithstanding, some incipient initiatives have been taken along the last decades focusing on the characterization of the deep-water fauna in northeastern Brazil.We highlight the program REVIZEE Score N/NE (Programa de Avaliação do Potencial Sustentável de Recursos Vivos na Zona Econômica Exclusiva -REVIZEE) and the Programa de Caracterização e Monitoramento Ambiental da Bacia Potiguar, conducted by PETROBRAS in the Potiguar Basin (State of Rio Grande do Norte).
Ophiuran basket stars are common animals from deeper waters, being commonly found in association with biological substrates, mainly octocorals (Baker 1980).The order Euryalida (commonly known as basket stars or snake stars) is composed by three families (Euryalidae Gray, 1840, Gorgonocephalidae Ljungman, 1867 andAsteronychidae Verrill, 1899) and 181 species (Stöhr et al. 2012).Gorgonocephalidae is monophyletic (Okanishi et al. 2011), being characterized morpho logically by a usually tuberculate skin, as well as by simple or branching arms having rows of hooks on their dorsal surface (Ljungman 1867;Verrill 1899aVerrill , 1899b)), spiniform teeth, and gonads restricted to the disk (Okanishi et al. 2011).The family is known worldwide, being distributed from shallow waters down to more than 1000 m.It may be found associated with biological substrates (gorgonians, stony corals, fire corals, and sponges) and on rocky substrates (Hendler et al. 1995).
Species identifications were based on the descriptions of Tommasi (1970), Hendler et al. (1995), andLaguarda-Figueras et al. (2009).The disk diameter (dd) was measured using a digital EDC 6″ caliper, and the specimens were photographed using a Canon G9 10MP and a Canon A640 10MP digital camera coupled to a Nikon SMZ800 stereomicroscope and to an Olympus BX41 microscope.
The specimens examined were fixed in 70% ethanol and deposited in the echinoderm collection of the Paulo Young Invertebrate Collection (UFPB/ECH), Department of Systematics and Ecology, Federal University of Paraíba, Brazil.

NOTES ON GEOGRAPHIC DISTRIBUTION
(approximately ½ of the diameter of the disk), bar-like (Figure 1a and 1c), covered by granules that form rows of clear rings intercalated with darker areas (Figure 1c).These clear rings correspond to bigger granules, which have two rows of hooks (Figure 1c).Sometimes the clear rings of the distal portion of the radial shields are extended, contacting in the area among the radial shields.The dark bands are formed by contiguous granules of different sizes and forms, but smaller than those of the light bands (Figure 1c).There are five madreporites, Astrocyclus caecilia (Lütken, 1856) (Figure 1) This specimen has a pentagonal disk, 30.04 mm in diameter (Figure 1a), covered by a thick skin, with white spots in the interradial areas and among the radial shields (Figure 1a  and 1c).These spots correlate with groups of plate-shaped dermal ossicles.On the distal margin of dorsal interradial region of the disk, the plate-shaped dermal ossicles form three groups of spots, one central and rectangular or semicircular, and two lateral (Figure 1c).The radial shields are large slightly rectangular and located near the jaw.The genital slits are short and broad, located laterally to the first bifurcation of the arm.The ventral interradial region is covered by a thick skin and sparse granules (Figure 1d).The disk is thickened by a hump at the juncture of the disk and the base of each arm.This hump-like appearance is due to bar-like radial shields.
There are five branched arms (Figure 1a and 1b).The dorsal and lateral surfaces of the arms are annulated (Figure 1a and 1e), with inflated, white and transverse rows of hookletbearing plates.The areas between the rows of hooklet-bearing plates are depressed and brown in color.Each hooklet-bearing plate has two rows of numerous microscopic hooklets (Figure 1e) that have one longer terminal tooth (Figure 1f).The ventral region of the arms and the jaw is covered by skin and granules.Spines are absent from the first two arm segments.One small and conical arm spine is observed on the third arm segment.From the fourth arm segment onwards, there are three small, conical arm spines, which decrease in size from the ventral to the dorsal spine.There is a crown of up to four hyaline denticles at the end of each arm spine.
Astrocyclus caecilia is recorded from the Bahamas Islands, Florida, Mexico, and the Caribbean Sea (Cuba and Barbados) (Hernández-Herrejón et al. 2008;Alvarado and Solís-Marín 2013).In Brazil, this species was only known from the states of São Paulo and Rio Grande do Sul (Tommasi 1970).The record in this study is the first for northeastern Brazil.This species occurs from 5 to 677 m in depth (Tommasi 1970;Laguarda-Figueras et al. 2009).The present material was collected at a depth of 130 m, associated to the gorgonian Scleracis guadalupensis (Duchassaing & Michelotti, 1860).
The examined specimen was brownish.However, color in this species varies from reddish brown to cream-colored.Hernández-Herrejón et al. (2008) and Laguarda-Figueras et al. (2009) reported 9 arm bifurcations in specimens of A. caecilia with a disk diameter of 13 mm.Tommasi (1970) reported 15 bifurcations in a specimen with a disk diameter of 26.5 mm.Unfortunately, it was not possible to record the total number of arm ramifications in this study.Astrocyclus caecilia may be distinguished from the remaining species of Gorgonocephalidae that occur along the Brazilian littoral by the presence of five madreporites.
There are five branched arms (Figure 2c and 2d), uniformly covered by granules similar to those on disk (Figure 2f).First arm branch beginning on margin of disk (Figure 2a and 2c).First arm segments (before second branch) without spines or tentacle pores.Two arm spines occur, beginning on third arm branch.Towards the extremity of the arm, the number of arm spines increases to three and then four.Arm spines small, in the shape of cat claws (Figure 2g and 2i).Tentacle pores small and placed laterally.Distalmost arm branch with rings of hooks on dorsal surface.
According to Hendler et al. (1995), juvenile specimens (with less than 1.5 mm in disk diameter) with relative few arm branches are pink, while the color of large individuals are homogeneously black, brown, light chocolate brown, yellowish brown, bright orange-yellow, gray, or dirty-white.Specimens studied herein were brownish.Tommasi (1970) reported from 1 to 4 spines per radial shield in specimens from Lixa Reef (Abrolhos, Bahia, Brazil).According to Tommasi (1970), these spines had an irregular distribution, being found either on distal or on proximal regions.Specimens examined in this study had only 2 spines, always located on distal extremity of radial shield (Figure 2e).The juvenile specimen (dd = 20.38 mm) had arms with 11 ramifications.Unfortunately it was not possible to verify the number of bifurcations in the larger specimen (dd = 50.18mm), because it was damaged and the arms were broken (Figure 2a and 2b).Astrophyton muricatum differs from the remaining Brazilian species of Gorgonocephalidae by the presence of 1 to 4 spines on each radial shield.
During the 10 years, new records of 20 ophiuroids were recorded from Brazilian waters (Ventura et al. 2006;Borges and Amaral 2007;Barboza et al. 2010;Campos et al. 2010;Gondim et al. 2010Gondim et al. , 2011Gondim et al. , 2012;;Manso et al. 2011Manso et al. , 2014)).Two of these records were from relatively shallow waters down to 35 m, six records were below 50 m, and twelve from depths greater than 200 m.
The species recorded in this study were previously known from Brazil, but from very scattered locations.Astrocyclus caecilia was previously recorded in southeastern and southern Brazil.The present record in the northeastern fills a gap on species distribution, and suggests that it occurs along the entire Brazilian coast, nevertheless not yet recorded in locations where deeper depths were little explored by previous researches.The same may be suggested for Astrophyton muricatum, which was previously recorded for Pará, Ceará, and Bahia.The present record of this species for Rio Grande do Norte fills a gap in our knowledge of the distribution of this species in northeastern Brazil.
Recently, the species Asteroporpa (A.) annulata and the family Hemieuryalidae Verrill, 1899 were recorded for Brazil on the basis of specimens collected accidentally by a fisherman using a fishing-line and hook (Gondim et al. 2011(Gondim et al. , 2012)).The new accidental collections reported herein point to interesting interactions between researchers (taxonomists) and the population that directly explores natural resources (e.g., fishermen).This type of interaction contributes to the discovery of new species and to the obtainment of new locality records, helping us to increase our knowledge of the marine fauna from the outer continental shelf.
The species of Gorgonocephalidae recorded in the present study are distributed from Bahamas to the southern Brazil, showing that both species are capable of transposing the Amazon River barrier or that their patterns of distribution pattern may result from an older biogeographical barrier.Stampar et al. (2012) proposed two possible scenarios for the speciation of the genus Isarachnanthus Carlgren, 1924 (I.maderensis, I. nocturnus and I. bandanensis) (Ceriantharia) in the Atlantic Ocean, one of which suggest the possible existence of an internal sea connection in the middle of the South American continent during the Late Miocene.For several other animal groups, the Amazon River has been shown to do not hinder the interchange of species between the Brazilian coast and Caribbean Sea (e.g.Lazoski et al. 2001;Garcia et al. 2007;Floeter et al. 2008;Stampar et al. 2012;Petuch 2013).
At least 60% of the species of Ophiuroidea recorded for the Brazilian littoral also occur in the Caribbean.According to Collette and Rützler (1977), below depths of 50 m, sponges and gorgonians can function as "stepping stones", providing habitat for reef fish species, linking the Caribbean and Brazilian faunas.Considering that A. muricatum and A. caecilia inhabit biological substrata, the presence of these "stepping stones" may favor the dispersion of these species.Unfortunately their modes of larval development are unknown.Thus, more biogeographical and studies in population genetics are necessary to understand the connectivity existing between these populations.

ACKNOWLEDGMENTS
This paper is dedicated to the fisherman Luis Ferreira Damasceno (Belo), who during his profession collected littleknown marine specimens from the Brazilian coast and kindly donated these rare specimens for research.AIG was supported by CAPES (Coordenação de Pessoal de Nível Superior, Brazilian Ministry of Education) through a Ph.D. scholarship.MLC was supported by a CNPq productivity research grant (Process number: 300198/2010-8).We wish to express our sincere gratitude to two reviewers for their critical reading of the manuscript and constructive comments.

Figure 1 .
Figure 1.Main taxonomic characters of Astrocyclus caecilia.(a) Dorsal view of disk; (b) ventral view of disk; (c) detail of radial shield; (d) detail of jaw; (e) dorsal view of arm; (f) microscopic hooks (optical microscopic image); (g) ventral view of arm.

Figure 2 .
Figure 2. Main taxonomic characters of Astrophyton muricatum.(a) Dorsal view of disk in adult specimen; (b) ventral view of disk in adult specimen, madreporite in detail; (c) dorsal view of young specimen; (d) oral view of young specimen; (e) detail of radial shield; (f) dorsal view of arm; (g) ventral view of arm; (h) detail of jaw; (i) detail of arm spines; (j) microscopic hooks (optical microscopic image).