Abstract A new species of LeptophoxoidesBarnard, 1962 is described with material from the continental slope of Rio Grande do Norte state, northeastern Brazil at three different depths: 150, 400 and 2,500 meters. Leptophoxoides longisetae sp. nov. can be diagnosed and distinguished from the other two species of the genus, L. molarisBarnard, 1962 and L. marinaSenna, 2010, by the following characters: antenna 1 peduncular article 1 ventral apex weakly ensiform; maxilla 1 inner plate longer than outer; maxilliped palp article 3 with blunt and extremely protuberant apex; gnathopods 1-2 carpus almost cryptic; gnathopod 2 palm defined by a large and sharply produced palmar hump; pereopod 6 basis posterodistal corner produced as a blunt lobe; and telson with two dorsal long plumose setae on each side. This is the first record of the genus for northeastern Brazilian waters, uncovering a higher biodiversity in deep waters.

Abstract A new species of Foxiphalus Barnard, 1979 is described. The material examined was collected as part of the project “Avaliação da biota bentônica e planctônica da Bacia Potiguar e Ceará” (BPOT), off northeastern Brazilian continental slope on the state of Rio Grande do Norte at depths ranging from 135 to 283 meters. Foxiphalus potiguara sp. nov. is recognized among its congeners by: rostrum slightly exceeding the article 2 of antenna 1; lower lip outer lobes with strong shoulder cusps; maxilliped inner plate with two apical robust setae; gnathopod 2 carpus shortened; pereopod 5 basis tapering distally; and epimeral plate 3 posterior margin weakly crenulated. This is the first record of Foxiphalus for the Atlantic Ocean and we provide an amended diagnosis of the genus and an identification key to its world species. In addition, two new records of Phoxocephalidae are reported from northeastern Brazil: Heterophoxus shoemakeri Andrade & Senna, 2020 and Metharpinia dentiurosomaAlonso de Pina, 2003.

Abstract Amphipods of the family Phoxocephalidae G.O. Sars, 1891 collected by the R/V Almirante Saldanha off the coast of Uruguay and Argentina in 1972 were examined. New records from the northern Argentine Sea and Uruguayan Sea include two species of the subfamily Harpiniinae Barnard and Drummond, 1978: Pseudharpinia jonesyi Andrade and Senna, 2020a, previously known from southeast/southern Brazil; and Pseudharpinia tupinamba Senna and Souza-Filho, 2011, recorded hitherto only from southeastern Brazil. Six species of the subfamily Phoxocephalinae G.O. Sars, 1891 were also recorded: Fuegiphoxus abjectus Barnard and Barnard, 1980, Fuegiphoxus fuegiensis (Schellenberg, 1931), Metharpinia dentiurosoma Alonso de Pina, 2003b, Metharpinia grandirama Alonso de Pina, 2003b, Metharpinia protuberantis Alonso de Pina, 2001, and Parafoxiphalus longicarpus Alonso de Pina, 2001. Redescriptions and discussion on distribution and morphological variations are presented.

RESUMO Synopia ultramarina Dana, 1853 é considerada uma espécie circumtropical e foi originalmente descrita com material coletado em duas localidades, a meio caminho entre o sudoeste da África e o nordeste do Brasil. A espécie é redescrita aqui com amostras do Arquipélago de Fernando de Noronha, estado de Pernambuco, nordeste do Brasil. O material estudado foi coletado por mergulho autônomo, em camas de rodolitos, no canal Ressureta, entre as ilhas do Meio e Rata. Material adicional foi coletado ao largo da costa do estado do Ceará, durante consultorias ambientais coordenadas pela Petrobras S. A., e ao largo da costa do estado de Pernambuco, durante o Projeto REVIZEE NE IV. É apresentada discussão sobre as variações morfológicas da espécie, baseada no material estudado e em descrições prévias na literatura.

ABSTRACT Synopia ultramarina Dana, 1853 is considered a circumtropical species and was originally described based on material collected from two localities near halfway between the southwestern Africa and northeastern Brazil. The species is redescribed here with samples from Fernando de Noronha Archipelago, Pernambuco state, northeastern Brazil. The material examined was collected by SCUBA diving, from rhodolith beds, in Ressureta Channel, between Meio and Rata Islands. Additional material was collected from off Ceará state coast, during environmental consultancies, by Petrobras S. A., and off Pernambuco state coast, during the Project REVIZEE NE IV. Discussion on morphological variations of the species is presented, based on the studied material and previous descriptions in the literature.

Abstract New records of the species Metharpinia dentiurosomaAlonso de Pina, 2003, M. grandiramaAlonso de Pina, 2003, M. iadoAlonso de Pina, 2003, Microphoxus cornutus (Schellenberg, 1931) and Mi. uroserratusBustamante, 2002 are reported for Brazilian waters. A discussion about the Metharpinia-Microphoxus complex is presented based on literature review and new observations of sampled species. Emended diagnoses are presented for the recorded species of Metharpinia and identification keys to world species of Metharpinia and Microphoxus are provided.

A new amphipod species of Metharpinia Schellenberg, 1931 is described from Campos Basin, southeastern Brazilian coast. The material was collected with van Veen grab from unconsolidated substratum, off the mouth of the Paraíba do Sul River. The new species can be distinguished from its congeners by presenting a strongly constricted rostrum and a slender palp of maxilla 1. There are four species in Metharpinia from the South Atlantic: M. dentiurosoma Alonso de Pina, 2003, M. grandirama Alonso de Pina, 2003 and M. iado Alonso de Pina, 2003, and Metharpinia taylorae sp. nov. This is the first record of a species of the genus from Brazilian waters.

The lysianassoid species Eurythenes thurstoni Stoddart & Lowry, 2004 is recorded for the first time to the Southern Atlantic Ocean, with material collected from the South Mid-Atlantic Ridge during the MAR-ECO Project expeditions. The examined material presents some important variations when compared with the original description discussed in the text.

La especie lisianásida Eurythenes thurstoni Stoddart & Lowry, 2004 se registra por primera vez en el océano Atlántico sur, con el material colectado en la Cordillera Mesoatlántica Sur durante las expediciones del Proyecto MAR-ECO. El material examinado presenta algunas variaciones importantes en comparación con la descripción original, que se discute en el texto.

A new amphipod species of Bogidiellidae Hertzog, 1936 is described and illustrated based on specimens collected from bore wells in the state of Andhra Pradesh, Southern India. The new species is closely related to those belonging to a group of Bogidiella species with inner rami of pleopods reduced or absent. Bogidiella totakura sp. nov. differs from all the other species in the group mainly by the shape, size and ornamentation on gnathopods and telson. This is the second Indian species of Bogidiella.

A new species of the amphipod family Ampithoidae Stebbing, 1899 is described from the northeastern Brazilian waters. The new described taxon is grouped in the genus Cymadusa Savigny, 1816, since it presents all the diagnostic characteristics of the genus. The examined material was collected by scuba diving in the Rocas Atoll, off Rio Grande do Norte state coast, Camamu Bay and Todos os Santos Bay, Bahia state. The new species described here is close to C. filosa Savigny, 1816, type species of the genus, by presenting anterior margin of gnathopod 1 poorly setose, male gnathopod 2 densely setose, with palmar corner not defined by a spine and dactylus subequal in length to palm, being considered part of the C. filosa complex. Among the species of this complex, the one which most resembles to the new taxon is C. imbroglio Rabindranath, 1972, which is distinguished by the absence of both the trapezoid process in the palm and spine at the palmar corner in the gnathopod 2. This is the second species of the genus Cymadusa recorded from Brazilian waters.

A new species of the family Melitidae Bousfield, 1973, Melita petronioi sp. nov., is described with material collected from Patos Lagoon, coast of the Brazilian state of Rio Grande do Sul, southern Brazil. The new species is the unique species of Melita Leach, 1814 in Brazilian waters with urosomites 1 and 2 lacking spines, but urosomite 2 bearing two sets of dorsal stout setae, and the uropod 3 with the outer ramus 2-articulate. It is the first Melita species recorded to the southern region of the country.

Uma nova espécie Amphipoda do gênero Elasmopus Costa, 1853 é descrita com base em material coletado da zona entre marés de um costão rochoso, próximo ao Porto de Suape, costado estado brasileiro de Pernambuco. A nova espécie pode ser reconhecida pelo própodo do gnatópo de 2 suboval, estreitando-se de forma suave distalmente, margem palmar não definida por uma cerda grossa, espinho, ou ângulo palmar, comum tubérculo subdistal não agudo, margem posterior coberta por uma franja densa de cerdas plumosas, e margem posterior da base do pereópodo 7 castelosserrado. Esta é a nonagésima quinta espécie do gênero Elasmopus descrita ao redor do mundo, o mais diverso gênero na família Maeridae Krapp-Schickel, 2008, e a oitava espécie registrada para as águas brasileiras. É fornecida também uma chave de identificação para as espécies brasileiras de Elasmopus.

A new amphipod species of the genus Elasmopus Costa, 1853 is described based on material collected from intertidal rocky shore, near the Suape Harbor, coast of the Brazilian state of Pernambuco. The new species may be recognized by the propodus of gnathopod 2 suboval, slightly tapering distally, palmar margin not defined by a stout seta, spine, or palmar corner, with a subdistal blunt tubercle, posterior margin covered by a dense fringe of plumose setae, and posterior margin of basis of pereopod 7 castelloserrate. This is the ninety-fifth species of the genus Elasmopus described worldwide, the most diverse genus in the family Maeridae Krapp-Schickel, 2008, and the eighth species recorded from Brazilian waters. An identification key to Brazilian species of Elasmopusis also provided.

A new species of the amphipod family Phoxocephalidae Sars, 1895, Pseudharpinia tupinamba sp. nov., is described from southeastern Brazilian continental shelf. The new species is closely related to the type-species of the genus, P. dentata Schellenberg, 1931 described from Magellan Province, and was misidentified as the latter species by some authors in the past. Pseudharpinia tupinamba sp. nov. differs from P. dentata by the number of articles in the accessory flagellum of antenna 1, ratio of length and width of the propodus of pereopod 6, size of the posteroventral lobe of the basis of pereopod 7, presence of slender setae in posterior margin of epimeral plate 3, presence of a corona of cuticular spines in dorsodistal margin of peduncle of uropod 2, ratio of length of the inner ramus and the first article of outer ramus of uropod 3, ratio of length and width of the telson, and presence of slender setae on the lateral margins of telson. The new described species is the unique of this genus known from the Brazilian continental shelf.