A new species of the Elasmopus rapax complex (Crustacea: Amphipoda: Maeridae) from Brazilian waters

Introduction

As proposed by Barnard (1972), four closely relatedgenera, Elasmopus Costa, 1853, Ifalukia Barnard, 1972,Mallacoota Barnard, 1972 and Parelasmopus Stebbing,1888, are grouped into an Elasmopus complex, until then

all members of the family Gammaridae Leach, 1814(Lowry & Hughes, 2009). Those genera were relocated tothe widely diverse family Melitidae Bousfield, 1973, andremaining under this status during thirty-five years.Afterwards three genera were also included in theElasmopus group, Hoho Lowry & Fenwick, 1983,Spathiopus Thomas & Barnard, 1985 and Beaudettia J.L.Barnard, 1965 (Lowry & Hughes, 2009). Currently, theyare assigned to the family Maeridae, recently established byKrapp-Schickel (2008).

Reçu le 15 mars 2010 ; accepté après révision le 21 octobre 2010.Received 15 March 2010; accepted in revised form 21 October 2010.

Cah. Biol. Mar. (2011) 52 : 57-70

A new species of the Elasmopus rapax complex (Crustacea:Amphipoda: Maeridae) from Brazilian waters

André R. SENNA and Jesser F. SOUZA-FILHOUniversidade Federal do Rio de Janeiro, Museu Nacional, Departamento de Invertebrados, Setor de Carcinologia.

Quinta da Boa Vista, s/n, São Cristóvão, Rio de Janeiro, RJ, CEP 20940-040, Brazil

Tel.: +55-21-2562-6985, E-mail: [email protected]

Abstract: A new amphipod species of the family Maeridae Krapp-Schickel, 2008 is described from Brazil. Elasmopus

longipropodus sp. nov. is very similar to E. rapax Costa, 1853, the type species of the genus, and has been cited as thisspecies to Brazilian coast during the last years. The new Brazilian maerid species differs from all the other species of theE. rapax complex by: male gnathopod 2 elongated with subparallel margins; epimeral plate 3 broadly rounded, withposterior margin slightly serrate; uropod 3, outer ramus with two sets of long robust setae on the outer margin; and maletelson with three subapical robust setae, the longer seta overreaching about 3 times the rounded tips of the telson.

Résumé : Une nouvelle espèce du complexe Elasmopus rapax (Crustacea : Amphipoda : Maeridae) des eaux brésiliennes.

Une nouvelle espèce d’amphipode de la famille Maeridae Krapp-Schickel, 2008 du Brésil est ici décrite. Elasmopus

longipropodus sp. nov. est très semblable à E. rapax Costa, 1853, l’espèce-type du genre, et elle a été appelée par ce nomdans les eaux brésiliennes au cours des dernières années. L’espèce nouvelle de Maeridae diffère de toutes les autres espècesdu complex E. rapax par le gnathopode 2 du mâle allongé avec des bords presque parallèles; plaque épimerale 3 largementarrondie avec le bord postérieur un peu dentelé, et le telson du mâle avec trois soies robustes sous-apicales, dont la pluslongue atteint plus de trois fois la longueur des pointes arrondies du telson.

Keywords: Crustacea l Melitoidea l Taxonomy l Elasmopus longipropodus sp. nov. l Continental shelf l Brazil

58 NEW SPECIES OF ELASMOPUS FROM BRAZIL

Very little is known about Maeridae from Brazilian coastand few studies have been reported species of this family inrecent times from Brazil. Among them, we can cite Serejo(1998), Krapp-Schickel & Ruffo (2000), Valério-Berardo etal. (2000), Senna & Serejo (2007), and Souza-Filho &Senna (2009).

Hitherto, there are 96 species of the genus Elasmopus

described worldwide, which seven of them are recorded toBrazilian waters: E. rapax Costa, 1853; E. brasiliensis

(Dana, 1853); E. pectenicrus Bate, 1862; E. spinidactylus

Chevreux, 1907; E. fusimanus Oliveira, 1951; E. karamani

Souza-Filho & Senna, 2009; and E. lejeunei Souza-Filho &Senna, 2009. Among those species, E. rapax was recordedto Brazilian waters by Wakabara (1972) in her PhD Thesis.During the last four decades, this identification has beenfollowed by some authors in ecological, faunistic, andcompilation studies in Brazil, such as Soares et al.(1987/89), Wakabara et al. (1991), and Wakabara & Serejo(1998).

The taxonomy within the genus Elasmopus is confused,especially in relation to the complex of species closelyrelated to E. rapax, with male gnathopod 2 palm with 3processes, and epimeral plate 3 with posterior marginsmooth or minutely serrate (Barnard, 1979). Several sub-species and phenotypes of E. rapax described by Barnard(1962 & 1969) from California and Mexico were posterior-ly recognized as valid species, with full specific names(Barnard, 1979). The latest author considers as E. rapax

only the specimens that present male gnathopod 2 verysimilar to those European E. rapax, described from the typelocality, Mediterranean Sea. According to him, the typicalE. rapax is represented in Chevreux & Fage (1925: 244)because the type-locality resides in Taranto, Italy, nearMediterranean France.

The new species described in this paper is the ninety-seventh known species of Elasmopus, the most diversemaerid genus around the world.

Materials and Methods

The material examined was collected from subtidal algaeand sponges at the Biological Reserve of Atol das Rocas(03°52’S-033°48’W), Rio Grande do Norte State, off thenortheastern Brazilian coast, during the project Diversidade

das Ilhas Oceânicas - Atol das Rocas. The atoll is set on aflat seamount peak about 150 km western from Fernandode Noronha Archipelago and 267 km northeastern from thecoast of Rio Grande do Norte State. The samples of algaewere collected by scuba diving inside the pools and off thering of the atoll with support of a small boat from October2000 to November 2001. The algae were anesthetized andsamples were washed and filtered through a 0.5 mm sieve.Additional type material was collected from subtidal algae,

calcareous algae, and sand, along the coastline of theBrazilian States of Pernambuco, Bahia, and Rio de Janeiro,during the years 1966, 1968, 1969, and 2003, by diversesample methods.

All material is preserved in 70% ethanol and it is housedin the Crustacea collections of the Museu Nacional,Universidade Federal do Rio de Janeiro (MNRJ) andDepartamento de Oceanografia, Universidade Federal de

Pernambuco (DOUFPE). Appendages and mouthpartswere mounted in glass slides with gelatin-glycerol. Theholotype male and one paratype female were dissected anddrawn. Illustrations were made under optic microscopewith camera lucida and represent the holotype, exceptwhen the male and female are indicated in the figure. Onemale and one female paratype specimens were dehydratedusing gradual ethanol series and dried to the critical pointwith carbon dioxide for scanning electron microscopy(SEM). Dry specimens were mounted on metal specimenstubs, coated with a gold-palladium mixture, and examinedwith a SEM JEOL 6390 series.

Setal classification adopted in this paper follows Watling(1989), while the nomenclature of gnathopod palm is basedon Poore & Lowry (1997).

List of abbreviations used on figures

Hb: Habitus; Hd: Head; Mxp: Maxilliped; MX1-2:Maxillae 1-2; Md: Mandibule; LL: Lower lip; UL: Upperlip; G1-2: Gnathopods 1-2; P3-7: Pereopods 3-7; Ep1-3:Epimeral plates 1-3; Ur1-3: Uropods 1-3; T: Telson; af:accessory flagellum; m: male; f: female.

Systematics

Order AMPHIPODA Latreille, 1816

Suborder Gammaridea Latreille, 1802Family Meridae Krapp-Schickel, 2008

Genus Elasmopus Costa, 1853Type species: Elasmopus rapax Costa, 1853

Genus diagnosis, modified from Karaman (1982) and

Krapp-Schickel & Jarrett (2000)

Lateral cephalic lobe short, anteroventral cephalic notchpresent. Antenna 1 longer than antenna 2, accessoryflagellum at least 2-articulate. Lower lip with inner lobespresent. Mandible, palp 3-articulate, article 1 withoutventro distal spine, article 3 strongly falciform, with D andE setae. Maxilla 1, inner plate suboval to subrectangular,inner margin not or weakly setose, apical margin with 1-2plumose setae; outer plate with multi-cuspidate setal-teethapically; palp 2-articulate. Maxilla 2, inner plate facial setalrow absent. Gnathopods 1-2 subchelate, different in shapeand size (male gnathopod 1 much smaller than gnathopod

A. R. SENNA, J. F. SOUZA-FILHO 59

2), palms acute to extremely acute. Coxae slightly elongate,coxa 4 with posterodistal lobe rounded to subquatrate.Pereopods 5-7 usually short and stout, basis with postero -ventral lobe present. Uropod 1, peduncle basofacial setapresent, rami subequal in size. Uropod 3, rami short,magniramous to parviramous, apically truncate; outerramus broad and strongly setose, 1-articulate or withvestigial article 2. Telson usually deeply cleft.

Composition of the genus

The genus Elasmopus groups 97 species: E. aduncus

Myers, 1995; E. affinis Della Valle, 1893; E. alalo Myers,1986; E. antennatus (Stout, 1913); E. arrawarra Hughes &Lowry, 2006; E. atolgidus J.L. Barnard, 1965; E.

balkomanus Thomas & Barnard, 1989; E. bampo J.L.Barnard, 1979; E. barbatus Schellenberg, 1939; E. bastidai

García-Madrigal, 2010; E. bollonsi Chilton, 1915; E.

brasiliensis (Dana, 1853); E. buchneri Spandl, 1924; E.

calliactis Edmondson, 1951; E. canarius Krapp-Schickel &Ruffo, 1990; E. caprai Maccagno, 1936; E. chilensis

Walker, 1913; E. congoensis Shoemaker, 1920; E.

crassimanus (Miers, 1884); E. crenulatus Berents, 1983; E.

delaplatus Stebbing, 1888; E. dentiferus Schellenberg,1938; E. diplonyx Schellenberg, 1938; E. dubius Walker,1904; E. ecuadorensis Schellenberg, 1938; E. erythraeus

(Kossmann, 1880); E. excavatus Schellenberg, 1938; E.

fusimanus Oliveira, 1951; E. gracilis Schellenberg, 1938;E. hawaiensis Schellenberg, 1938; E. holgurus J.L.Barnard, 1962; E. hooheno J.L. Barnard, 1970; E. integer

Myers, 1989; E. japonicus Stephensen, 1932; E. karamani

Souza-Filho & Senna, 2009; E. karlae García-Madrigal,2010; E. kontot Rahim, 2007; E. koreanus Kim & Kim,1991; E. lapu Myers, 1985; E. latibrachium Walker, 1904;E. laufolii Myers, 1986; E. lecroyae García-Madrigal,2010; E. lejeunei Souza-Filho & Senna, 2009; E. lemaitrei

Ortiz & Lalana, 1994; E. levis (Smith, 1873); E.

longipropodus sp. nov.; E. magnispinatus Kunkel, 1910; E.

marcelae García-Madrigal, 2010; E. marplatensis Alonsode Pina, 1997; E. mayo J.L. Barnard, 1979; E. menurte J.L.Barnard, 1974; E. minimus Chevreux, 1908; E. molokai J.L.Barnard, 1970; E. mutatus J.L. Barnard, 1962; E.

nanshaensis Ren, 1998; E. neglectus Chilton, 1915; E. oax-

aquensis García-Madrigal, 2010; E. ocoroni J.L. Barnard,1979; E. palu Appadoo & Myers, 2003; E. pectenicrus

(Bate, 1862); E. perditus Reid, 1951; E. piikoi J.L. Barnard,1970; E. pilosus Ledoyer, 1978; E. pocillimanus (Bate,1862); E. pseudaffinis Schellenberg, 1938; E. pseudinteger

Appadoo & Myers, 2003; E. pubescens (Dana, 1852); E.

puteus Appadoo & Myers, 2003; E. rapax Costa, 1853; E.

rishikondiensis Kanakadurga, Rao & Shyamasundari,1981; E. serricatus J.L. Barnard, 1969; E. seticarpus

Myers, 1985; E. slatyeri Lowry & Hughes, 2009; E.

sokotrae Walker & Scott, 1903; E. souillacensis Appadoo

& Myers, 2003; E. spinibasus Sivaprakasam, 1970; E.

spinicarpus Berents, 1983; E. spinidactylus Chevreux,1907; E. spinimanus Walker, 1904; E. spinipalpus Ledoyer,1982; E. spinipes Mateus & Mateus, 1986; E. steelei

Appadoo & Myers, 2003; E. steinitzi Ruffo, 1938; E.

takamotus Myers, 1986; E. temori J.L. Barnard, 1979; E.

thomasi Ortiz & Lalana, 1994; E. tiburoni J.L. Barnard,1979; E. tubar J.L. Barnard, 1979; E. vachoni Mateus &Mateus, 1986; E. vagans K.H. Barnard, 1940; E. vara-

nocephalensis Lowry & Hughes, 2009; E. visakhapatna-

mensis Kanakadurga, Rao & Shyamasundari, 1981; E.

waltersi Ledoyer, 1982; E. wahine J.L. Barnard, 1972; E.

warra Kelaher & Lowry, 2002; E. yunde J.L. Barnard, l974;and E. zoanthidea J.L. Barnard, 1979.

Elasmopus longipropodus sp. nov.(Figs 1-6)

Elasmopus rapax (not Elamospus rapax Costa, 1851):Soares et al., 1987/89: 244, pl. 3, figs. 1-12; Wakabara etal., 1991: 73. Elasmopus aff. rapax: Souza-Filho & Senna,2009: 67.

Material examined

Holotype: 1 male, 5.8 mm, dissected and drawn, in glyceringel slides, Atol das Rocas, Rio Grande do Norte State,

Figure 1. Elasmopus longipropodus sp. nov. Male, paratype,Atol das Rocas, 03°52’S-033°48’W, 05 October 2000, fromalgae, MNRJ 21764. Scale bar: 1.0 mm.

Figure 1. Elasmopus longipropodus sp. nov. Mâle, paratype,Atol das Rocas, 03°52’S-033°48’W, 05 octobre 2000, prélevé surdes algues, MNRJ 21764. Échelle : 1,0 mm.

Brazil, 03°52’S-033°48’W, 05 October 2000, from algae, P.S. Young, P. C. Paiva, A. A. Aguiar, col., MNRJ 21762.

Paratypes: 1 male, coated with gold-palladium, Atol dasRocas, Rio Grande do Norte State, Brazil, 03°52’S-033°48’W, 05 October 2000, from algae, P.S. Young, P.C.Paiva, A.A. Aguiar, col., MNRJ 21764; 1 female, coatedwith gold-palladium, Atol das Rocas, Rio Grande do NorteState, Brazil, 03°52’S-033°48’W, 29 June 2001, fromalgae, S.N. Brandão, C. Tavares, N. Magalhães, col., MNRJ21765; 3 males and 8 females, in ethanol, Atol das Rocas,Rio Grande do Norte State, Brazil, 03°52’S-033°48’W, 27October 2000, from algae, P.S. Young, P.C. Paiva, A.A.Aguiar, col., MNRJ 21766; 1 female, 4.0 mm, dissected anddrawn, in ethanol, Atol das Rocas, Rio Grande do NorteState, Brazil, 03°52’S-033°48’W, 10 October 2000, fromalgae, P.S. Young, P.C. Paiva, A.A. Aguiar, col., MNRJ21767; 7 males and 6 females, in ethanol, Atol das Rocas,Rio Grande do Norte State, Brazil, 03°52’S-033°48’W, 30December 2000, from algae, F.B. Pitombo, R. Barroso, col.,MNRJ 21768; 1 male, in ethanol, Atol das Rocas, RioGrande do Norte State, Brazil, 03°52’S-033°48’W, 13October 2000, from algae and sponges, P.S. Young, P.C.Paiva, A.A. Aguiar, col., MNRJ 21769; 24 males, 47females, and 2 juveniles, in ethanol, Atol das Rocas, Rio

Grande do Norte State, Brazil, 03°52’S-033°48’W, 05October 2000, from algae, P.S. Young, P.C. Paiva, A.A.Aguiar, col., MNRJ 21770; 2 males, in ethanol, Atol dasRocas, Rio Grande do Norte State, Brazil, 03°52’S-033°48’W, 08 November 2001, from algae, C.S. Serejo,M.C. Rayol, col., MNRJ 21771; 1 male and 1 female, inethanol, Atol das Rocas, Rio Grande do Norte State, Brazil,03°52’S-033°48’W, 07 October 2000, from calcareousalgae, P.S. Young, P.C. Paiva, A.A. Aguiar, col., MNRJ21772; 1 male, in ethanol, Japaris Beach, Ilha Grande,Angra dos Reis, Rio de Janeiro State, Brazil, 23º06’S-44º16’W, 27 July 1966, from algae, without collectorinformation, MNRJ 21773; 8 females, in ethanol, Baía deTodos os Santos, Bahia State, Brazil, 12º58’S-38º36’W, 20October 1968, from algae, without collector information,MNRJ 21774; 1 male and 1 female, in ethanol, northerncoast of Pernambuco State, Brazil, 07º36’S-34º49’W, 04February 1969, from algae, without collector information,MNRJ 21775; 6 males and 4 females, in ethanol, Arraial doCabo, Rio de Janeiro State, Brazil, 22º59’S-42º02’W,without date information, from algae, without collectorinformation, MNRJ 21541; 11 males, 10 females, and 13juveniles, in ethanol, Praia de Suape, Cabo de SantoAgostinho, Pernambuco State, Brazil, 08°21’26”S-34°57’22”W, 10 October 2003, intertidal, associated with


Figure 2. Elasmopus longipropodus sp. nov. Female, paratype, Atol das Rocas, 03°52’S-033°48’W, 29 June 2001, from algae, MNRJ21765. Scale bar: 1.0 mm.

Figure 2. Elasmopus longipropodus sp. nov. Femelle, paratype, Atol das Rocas, 03°52’S-033°48’W, 29 juin 2001 prélevé sur desalgues, MNRJ 21765. Échelle : 1,0 mm.


Figure 3. Elasmopus longipropodus sp. nov. Male, paratype, Atol das Rocas, 03°52’S-033°48’W, 05 October 2000, from algae,MNRJ 21764; female, paratype, Atol das Rocas, 03°52’S-033°48’W, 29 June 2001, from algae, MNRJ 21765. Scale bars: 0.1 mm formG1; 0.5 mm for mG2; 0.2 mm for mEp3 and fEp3.

Figure 3. Elasmopus longipropodus sp. nov. Mâle, paratype, Atol das Rocas, 03°52’S-033°48’W, 05 octobre 2000, prélevé sur desalgues, MNRJ 21764; femelle, paratype, Atol das Rocas, 03°52’S-033°48’W, 29 juin 2001 prélevé sur des algues, MNRJ 21765.Échelles : 0,1 mm pour mG1 ; 0,5 mm pour mG2 ; 0,2 mm pour mEp3 et fEp3.


Figure 4. Elasmopus longipropodus sp. nov. Male, 5.8 mm, holotype, Atol das Rocas, 03°52’S-033°48’W, 05 October 2000, fromalgae, MNRJ 21762; female, 4.0 mm, paratype, Atol das Rocas, 03°52’S-033°48’W, 10 October 2000, from algae, MNRJ 21767. Scalebars: 0.1 mm.

Figure 4. Elasmopus longipropodus sp. nov. Mâle, 5,8 mm, holotype, Atol das Rocas, 03°52’S-033°48’W, 05 octobre 2000, prélevésur des algues, MNRJ 21762; femelle, 4,0 mm, paratype, Atol das Rocas, 03°52’S-033°48’W, 10 octobre 2000, prélevé sur des algues,MNRJ 21767. Échelles : 0,1 mm.


Figure 5. Elasmopus longipropodus sp. nov. Male, 5.8 mm, holotype, Atol das Rocas, 03°52’S-033°48’W, 05 October 2000, fromalgae, MNRJ 21762; female, 4.0 mm, paratype, Atol das Rocas, 03°52’S-033°48’W, 10 October 2000, from algae, MNRJ 21767. Scalebars: 0.1 mm.

Figure 5. Elasmopus longipropodus sp. nov. Mâle, 5,8 mm, holotype, Atol das Rocas, 03°52’S-033°48’W, 05 octobre 2000, prélevésur des algues, MNRJ 21762; femelle, 4,0 mm, paratype, Atol das Rocas, 03°52’S-033°48’W, 10 octobre 2000, prélevé sur des algues,MNRJ 21767. Échelles : 0,1 mm.


Figure 6. Elasmopus longipropodus sp. nov. Male, 5.8 mm, holotype, Atol das Rocas, 03°52’S-033°48’W, 05 October 2000, fromalgae, MNRJ 21762; female, 4.0 mm, paratype, Atol das Rocas, 03°52’S-033°48’W, 10 October 2000, from algae, MNRJ 21767. Scalebars: 0.5 mm for Hd ; 0.1 mm for the remainder.

Figure 6. Elasmopus longipropodus sp. nov. Mâle, 5.8 mm, holotype, Atol das Rocas, 03°52’S-033°48’W, 05 octobre 2000, prélevésur des algues, MNRJ 21762; femelle, 4,0 mm, paratype, Atol das Rocas, 03°52’S-033°48’W, 10 octobre 2000, prélevé sur des algues,MNRJ 21767. Échelles : 0,5 mm pour Hd ; 0,1 mm pour le reste.

Sargassum sp., J.F. Souza-Filho, col., MNRJ 21763; 2males, in ethanol, Itamaracá Island, Pernambuco State,Brazil, 07º49’S-34º49.3W, 0.8 m, in sand, 17 January 1969,M. Kempf, col., DOUFPE 11655; 1 male and 2 females, inethanol, Itamaracá Island, Pernambuco State, Brazil,07º50’S-34º49W, 3.6 m, in blocks of calcareous algae, 06January 1969, M. Kempf, col., DOUFPE 11633.

Etymology

The species name, longipropodus, refers to the elongatepropodus of the male gnathopod 2, which distinguishes itfrom all the other species of the genus.

Diagnosis

Male gnathopod 2, propodus elongate, about 2.5 timeslonger than wide with subparallel margins, palm shorterthan posterior margin, with three processes, the first onerounded and distally truncated near hinge of dactylusbearing six robust setae on each side, the second midway,subacute and slightly curved anteriorly, the third strong andsubacute defining palmar corner. Pereopods 5-7, merus andcarpus poorly expanded, and poorly setose. Epimeral plate3, posteroventral corner broadly rounded, posterior marginslightly serrate, with five small notches. Uropod 3, innerramus slightly shorter than outer ramus, the latter 1-articulated, with two sets of long robust setae on the outermargin. Male telson with apicolateral cusps well developedbut not reaching the inner distal rounded, and three sub -apical robust setae, the longer seta overreaching about 3times the rounded tips.

Description

Based on the holotype male, 5.8 mm. Head with mediumlength eyes, rounded, with distinct ommatidia; lateralcephalic lobes broad, truncated, with anteroventral notchand slit, anteroventral corner rounded. Antenna 1 longerthan antenna 2, about 0.5 times body length; pedunculararticle 1 subequal in length to article 2, with a robust setadistally on the posterior margin, peduncular article 2 about1.7 times length of article 3; flagellum shorter thanpeduncle with 22 articles; accessory flagellum with 3articles. Antenna 2 densely setose, reaching the end ofpeduncle of antennae 1; peduncular article 4 subequal toarticle 5; flagellum with 11 articles. Mandible palp secondarticle about 4 times longer than wide, slightly shorter thanarticle 3; article 3 falcate, setose along concave margin,slightly longer than article 2, with four apical setae. Maxilla1 inner plate with 2 apical plumose setae; outer plate withseven robust setae variably cuspidate; palp 2-articulated,article 2 distally setose, facial setae present. Upper andlower lip, maxilla 2 and maxilliped with basic charactersfor the genus.

Gnathopod 1, subchelate, coxa anteroventral cornerproduced and rounded, ventral margin with some longsetae; basis, posterior margin with ten long setae; merusdensely setose distally; carpus densely setose, about 1.6times longer than broad; propodus with long facial andmarginal setae, palm oblique, minutely serrate and slightlyconvex, with seven facial robust setae, defined by a combof three robust setae, about 0.5 times posterior marginlength; dactylus reaching the palmar corner. Gnathopod 2subchelate; basis with five long setae on posterior margin,and two well defined anterior margins, on medial andlateral faces, separated by a strong excavation; ischiumproduced into a rounded lobe anteriorly; merus withpostero ventral corner produced and acute; carpus 1.5 timeswider than long, about 0.25 as long as propodus, postero -ventral corner slightly produced and setose; propoduselongate, about 2.5 times longer than wide, with subparallelmargins, without medial excavation, setose along posteriormargin, with seven sets of long simple setae transverse tothe anterior margin, palm extremely oblique, about 0.7times posterior margin length, bearing a rounded andapically truncated process near hinge of dactylus with threerobust setae on each side, a subacute process slightlycurved anteriorly, and palmar corner defined by a strongacute triangular process; dactyl slightly shortened, almostreaching the palmar corner, strongly curved, posteriormargin sinuous, minutely setose, apically blunt. Pereopod3, coxa longer than wide (1.5 times); basis with long setaeon posterior margin; merus 1.4 times propodus length withanterodistal angle slightly produced; carpus with fourrobust setae on posterior margin; propodus with a row ofrobust setae on posterior margin; dactyl short, about 0.4times propodus length, nail present. Pereopod 4 similar topereopod 3, but coxa 1.1 times as long as wide withposterior margin slightly excavate. Pereopod 5, coxa widerthan long, excavate ventrally, forming two lobes; basisposterior margin slightly convex, smooth, with sparse longsetae, posteroventral lobe slightly produced, rounded;merus and carpus longer than wide and poorly expanded.Pereopod 6, coxa wider than long, excavate ventrally; basisposterior margin slightly convex, smooth, with sparse longsetae, posteroventral lobe slightly produced, rounded;merus and carpus longer than wide and poorly expanded.Pereopod 7 coxa small, subquadrate, with posterior lobeslightly produced ventrally; basis posteriorly convex,posterior margin smooth with sparse long setae, postero -ventral lobe slightly produced, rounded; merus and carpuslonger than wide and poorly expanded; propodus 1.4 timescarpus length, posterior margin with five tufts of slendersetae.

Epimeral plate 1 posterior margin slightly serrate withtwo notches, posteroventral corner defined by a short spine.Epimeral plate 2 posterior margin slightly serrate with three


notches, posteroventral corner defined by a short spine.Epimeral plate 3, posteroventral margin smooth, posteriormargin slightly serrate with five small notches, postero -ventral corner broadly rounded. Uropod 1 peduncle withbasofacial robust seta, two robust setae distally, withoutdistoventral spur, nine robust setae dorsally; inner ramusabout 0.7 times as long as peduncle, with four marginalsetae and three distal robust setae. Uropod 2 peduncle,dorsally with three robust setae on inner margin and threeon outer margin; inner ramus about 1.3 times longer thanpeduncle, with five marginal robust setae and five apicalrobust setae; outer ramus about 1.3 times longer than innerramus. Uropod 3 peduncle with four distal robust setae;outer ramus apically truncated and slightly longer thanpeduncle, with six apical setae, with two sets of long robustsetae on the outer margin, slightly longer than peduncle;inner ramus slightly shorter than outer ramus, apicallytruncated, with five apical setae, inner margin with a singleseta. Telson slightly wider than long, deeply cleft (about75%), with apicolateral cusps well developed but notreaching the inner distal rounded, and a distolateralconcavity bearing three subapical robust setae, the longerseta overreaching about 3 times the rounded tips.

Female (sexually dimorphic characters)

Based on paratype female, 4.0 mm. Gnathopod 2 basisslender, posterior margin with four long setae, anteriormargin with three slender setae and five setules; ischiumnot produced in a rounded lobe anteriorly; carpus about 1.3longer than wide and 0.6 times as long as propodus;propodus 2 times longer than wide; palm oblique, slightlyconvex, smooth, with eight submarginal robust setae, about0.5 times as long as posterior margin; palmar corner withone robust seta; dactylus reaching end of palm. Telson 1.2xwider than long, deeply cleft (about 65%), each lobe withtwo apicolateral robust setae (one small and curved, theother 0.5 times telson length), one small apicolateralplumose slender seta, and one small lateral simple slenderseta; tip of telson slightly produced, truncated, and withsmall subacute cusps.

Remarks

Elasmopus longipropodus sp. nov. is clearly closely relatedto the Mediterranean species E. rapax and therefore amember of the E. rapax complex. Like the North Americanspecies, E. longipropodus sp. nov. is not easily recognizedfrom E. rapax or the other species of the complex, since themorphological differences among those taxa are restrictedto few characters on the male specimens, such as gnathopod2, epimeral plate 3, uropod 3, and telson (Table 1). TheBrazilian new species is similar to E. rapax by the malegnathopod 2 without excavation on the medial face of

propodus, and palm with three processes, the process neardactyl with base simple, dactyl slightly shortened, and basisof pereopod 7 smooth, with sparse long setae. On the otherhand, E. longipropodus sp. nov. differs from all the otherspecies of the complex by the elongated propodus of malegnathopod 2 with subparallel margins and palm extremelyoblique, about 0.7 times posterior margin length; epimeralplate 3 broadly rounded, and posterior margin slightlyserrate; uropod 3, outer ramus with two sets of robust setaeon the outer margin; and male telson with three subapicalrobust setae, the longer seta overreaching about 3 times therounded tips of each lobe. Elasmopus rapax presentspropodus of male gnathopod 2 suboval, with palm slightlylonger than posterior margin; epimeral plate 3 produced,with posteroventral corner acute and the posterior marginslightly serrate; uropod 3, outer ramus with three sets ofsetae on the outer margin; and male telson one set of smallrobust setae, not overreaching the rounded tip of each lobe.Elasmopus rapax and E. bampo Barnard, 1979 share longrobust setae in the female telson. Elasmopus longipropodus

sp. nov. also presents a female telson with long setae,however, the rounded and well developed tips in each lobe,common in this genus, are not present in the femalespecimens of this species, being slightly produced,truncated, and with small subacute cusps.

Distribution

Elasmopus longipropodus sp. nov. is widely spread alongthe Brazilian coastline and continental shelf (Fig. 7),including oceanic islands. Type locality: Atol das Rocas,03°52’S-33°48’W.

Key to species of Elasmopus from Brazilian

waters (only males)

1. Epimeron 3 produced in an acute spine; basis ofpereopod 5 with posterior margin concave ......................2

- Epimeron 3 not produced, sometimes with shortdenticles; basis of pereopod 5 with posterior margin notconcave ............................................................................32. Gnathopod 2, propodous without a row of tubercles andperpendicular rows of long setae on inner face, palm acute,shorter than posterior margin of propodus, palmar cornerdefined by 2 spines ............................................................

........Elasmopus karamani Souza-Filho & Senna, 2009- Gnathopod 2, propodous with a row of tubercles and

perpendicular rows of long setae on inner face, palmextremely acute, longer than posterior margin of propodus,not defined by spines or stout setae ..................................

..........Elasmopus lejeunei Souza-Filho & Senna, 20093. Gnathopod 2 with a rounded process bearing two smallstout setae near hinge of dactylus, palm not defined;


pereopod 7, posterior margin of basis castelloserrate ..................................Elasmopus fusimanus Oliveira, 1951

- Gnathopod 2 with or without process near hinge ofdactylus, but never rounded; pereopod 7, posterior marginof basis not castelloserrate .............................................. 44. Dactyli of pereopod 5-7, anterior margin with 3-4denticles............Elasmopus spinidactylus Chevreux, 1908

- Dactyli of pereopod 5-7, anterior margin smooth .. 5 5. Gnathopod 2, palm with 3 spines (one defining palmarcorner) and not densely setose ..........................................

................................Elasmopus longipropodus sp. nov.- Gnathopod 2, palm without spines and densely setose .................................................................................... 6

6. Gnathopod 2 with a well developed process near hingeof dactylus with 6-8 robust setae; pereopod 6, posteriormargin of basis not castelloserrate ....................................

............................Elasmopus brasiliensis (Dana, 1853)- Gnathopod 2 without processes near hinge of dactylus;pereopod 6 with posterior margin of basis castelloserrate

............................ Elasmopus pectenicrus (Bate, 1862)

Additional comments

Oliveira (1951) described two new species, Elasmopus

besnardi and E. fusimanus, and recorded E. brasiliensis, allof them from Brazilian waters. Elasmopus fusimanus isconsidered a valid species known only to the type locality,Ilha Grande Bay, Southeastern Brazilian coast. However,its type material is currently lost. On the other hand, E.

besnardi was described based only in a single female, fromTrindade Island, off the central coast of Brazil. This specieswas considered as species dubiae by Ruffo (1959) and“perhaps a synonym of E. brasiliensis” by Barnard (1965).The female specimen studied by Oliveira is also consideredlost at this time. Before finding more material of bothElasmopus species, it is not possible for us to make anyconsideration about their taxonomic identities. In relationto the Oliveira’s description of E. brasiliensis, Ruffo (1959)and Barnard (1965) cite that it refers in fact to E.

pectenicrus, based on the castelloserrate posterior marginof the basis of pereopod 6, a diagnostic character of thisspecies. However, the illustration of the male gnathopod 2,with seven robust setae on the protrusion near the dactylarhinge is clearly of E. brasiliensis. So, we believe that morethan one species were illustrated as E. brasiliensis byOliveira. Also, in fact, the original description of E.

brasiliensis by Dana (1853), with material from Rio deJaneiro, is not so clear about those characters. Moreover,the castelloserrate posterior margin of the basis ofpereopods 6 and 7 is not an exclusive character of E.

pectenicrus. Besides this species, a diverse group of almostentirely Indo-Pacific species with intertropical distributionshares the castelloserrate pereopods 6 and 7 (Krapp-Schickel & Ruffo, 1990).

Acknowledgements

The authors are grateful to Maurizélia Brito (chief of theBiological Reserve of Atol das Rocas - IBAMA/RioGrande do Norte) for sampling authorization and logisticalsupport on the project Diversidade das Ilhas Oceânicas -

Atol das Rocas; Dr. Maria Teresa Valério Berardo (Instituto

Oceanográfico - Universidade de São Paulo), for providingthe amphipod material originally studied by Dr. YokoWakabara in her PhD Thesis; Elivaldo Lima (Museu

Nacional - Universidade Federal do Rio de Janeiro) forSEM micrographs; and Dr. Guilherme R.S. Muricy (Museu

Nacional - Universidade Federal do Rio de Janeiro) for theFrench version of the abstract. Special thanks to Paulo S.Young (in memorian), Paulo C. Paiva, A.A. Aguiar, SimoneN. Brandão, Carolina Tavares, Noa Magalhães, Fábio B.Pitombo, Rômulo Barroso, Cristiana S. Serejo, and MariaC. Rayol, for their valuable contribution to the collectioneffort at Atol das Rocas. The distribution map was made by


Figure 7. Distribution of Elasmopus longipropodus sp. nov.▲: type-locality, Atol das Rocas, 03°52’S-033°48’W; ■:occurrence of the remainder paratypes (Distribution map byDanielle P. Cintra).

Figure 7. Distribution de Elasmopus longipropodus sp. nov.▲ : localité-type, Atol das Rocas, 03°52’S-033°48’W ; ■ : autreslocalisations des paratypes (Carte de distribution par Danielle P.Cintra).


Table 1. Diagnostic characters of the species in the Elasmopus rapax complex.Tableau 1. Caractères diagnostiques de l’espèces dans le complexe Elasmopus rapax.

Gnathopod2 Epimeral plate 3 Uropod 3 Telson Distribution

E. antennatus Weak rounded humpnear dactylus, withoutmedial spine, withoutspine defining palm ;palm and posteriormargin densely setose

Subacute, ventral marginwithout long setae,posterior margin straightand smooth

Inner ramus shorterthan outer, outerramus with 3 setsof stout setae

Slightly wider thanlong, about 65%deeply cleft, lobesapically truncatewith small cusps

California and BajaCalifornia

E. bampo Truncate hump neardactylus + 1 sharpenlarged spine + 1blunt spine + 1 medialspine defining palm

Subacute, ventral marginwith long setae, posteriormargin straight andminutely serrate

Rami subequal inlength, outer ramuswith 3 sets of stoutsetae

Slightly longer thanwide, about 80%deeply cleft, lobeswith rounded apicesmedially

California to Gulf ofCalifornia

E. ecuadorensis Rounded hump neardactylus, withoutmedial spine, withoutspine defining palm;palm, posterior marginand inner face denselysetose

Subquadrate, ventralmargin without longsetae, posterior marginslightly convex andminutely serrate


1.4X wider thanlong, about 40%deeply cleft, lobesapically truncate

Galapagos Islands

E. hawaiensis Rounded hump neardactylus, withoutmedial spine, withoutspine defining palm

Subquadrate, ventralmargin without longsetae, posterior marginslightly convex andminutely serrate


1.2X wider thanlong, about 55%deeply cleft, lobeswith rounded apicesmedially

Hawaiian Islands

E. longipropodus Truncate hump neardactylus + 1 bluntspine slightly curvedforward + 1 strongconical spine definingpalm

Rounded, ventral marginwithout long setae,posterior margin slightlyconvex and minutelyserrate


Slightly wider thanlong, about 65-75%deeply cleft, lobeswith rounded apicesmedially (female tel-son apically trun-cate)

Brazil

E. mayo Truncate hump neardactylus + 1 bluntspine slightly curvedforward + 1 conicalspine defining palm

Subquadrate, ventralmargin without longsetae, posterior marginstraight with 1-2 notches

Rami subequal inlength, outer ramuswith unknown setsof stout setae

1.2X longer thanwide, about 80%deeply cleft, lobeswith rounded apicesmedially (female tel-son as long as wide)

California, Mexico,Galapagos Islands,and Ecuador

E. ocoroni Sharp falcate humpnear dactylus + 1 bluntspine + 1 broad coni-cal spine definingpalm

Rounded, ventral marginwithout long setae,posterior margin slightlyconvex and minutelyserrate


Slightly wider thanlong, about 85%deeply cleft, lobeswith rounded apicesmedially

Galapagos Islands

E. rapax Sharp falcate humpnear dactylus + 1 acutespine + 1 small conicalspine defining palm

Subacute, ventral marginwithout long setae,posterior margin slightlysinuous and minutelyserrate


1.3X longer thanwide, about 85%deeply cleft, lobeswith rounded apicesmedially

Mediterranean Sea

Danielle P. Cintra (Pontifícia Universidade Católica do Rio

de Janeiro). We also thank the anonymous referees for theircritical comments on this manuscript. This study wassupported by Coordenação de Aperfeiçoamento de Pessoal

de Nível Superior (CAPES) and Centro de Pesquisas

Petróleo Brasileiro S/A (CENPES-PETROBRAS).

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A new species of the Elasmopus rapax complex (Crustacea: Amphipoda: Maeridae) from Brazilian waters

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