Abstract Two species of bopyrid isopods from the subfamily Athelginae are recorded from new localities in northeastern Brazil. Parathelges foliatus Markham, 1972 was recorded for the first time from Brazil, in the state of Ceará, parasitising the hermit crab Clibanarius symmetricus (Randall, 1840). Pseudostegias atlantica Lemos de Castro, 1965 is recorded from the state of Ceará, parasitising Clibanarius antillensis Stimpson, 1859. Illustrations, species diagnosis and an updated distribution map are given for each species.

Resumo Neste presente trabalho, são apresentadas as flutuações espacial e sazonal da abundância e diversidade do mesozooplâncton, com especial atenção para assembleia de copépodes da área costeira do Arquipélago de Fernando de Noronha (AFN) (3°50'24''S and 32°24'48''W). A amostragem foi realizada durante as estações seca e chuvosa de dois anos consecutivos (julho e dezembro de 2013) e (junho e novembro de 2014). Um total de 37 taxa do mesozooplâncton foram registrados, sendo os copépodes o grupo mais diversificado (15 taxa). A Subclasse Copepoda dominou em ambos os períodos amostrados, com valores de abundância relativa equivalentes a 53% e 86%, respectivamente, nas estações seca e chuvosa. As espécies consideradas abundantes foram: Calanopia americana, Undinula vulgaris, Oithona plumifera e Corycaeus speciosus. A estação chuvosa favoreceu um aumento significativo na abundância do mesozooplâncton e copépodes. No entanto, um baixo valor do índice de diversidade de Shannon-Wiener foi observado para este mesmo período sazonal. Isso foi explicado pelo domínio das espécies C. americana e U. vulgaris na área estudada. Diferença espacial não foi verificada. A assembleia de copépodes apresentou um maior número de espécies consideradas carnívoro-predador de grande importância na teia trófica pelágica, indicadoras de condições oligotróficas e componente de grande porção dos itens alimentares dos peixes. Assim, sugerimos que a área costeira do Arquipélago de Fernando de Noronha é caracterizada por uma comunidade do mesozooplâncton espacialmente homogênea, onde as mudanças observadas estão principalmente relacionadas ao fator sazonal.

Abstract In the present work, spatial and seasonal fluctuations of the abundance and diversity of mesozooplankton are presented, with special attention being given to copepod assemblages from coastal area of the Fernando de Noronha Archipelago (FNA) (3°50'24''S and 32°24'48''W). Sampling was carried out during the dry and rainy seasons of two consecutive years (July and December 2013) and (June and November 2014). A total of 37 mesozooplankton taxa were recorded, being the copepods the most diversified group (15 taxa). The Subclass Copepoda dominated in both periods sampled, comprising 53% and 86% of the total abundance in the dry and rainy season respectively. The species considered abundant were: Calanopia americana, Undinula vulgaris, Oithona plumifera and Corycaeus speciosus. The rainy season favored a significant increase in the abundance of mesozooplankton and copepods. However, a low value of the Shannon-Wiener diversity index was observed in this same seasonal period. This was explained by the dominance of the species C. americana and U. vulgaris in the studied area. Spatial differences have not been verified. The copepod assemblages was composed mostly by species considered as predator-carnivours of greater importance on the pelagic trophic web, indicators of oligotrophic conditions and components of a major portion of fish food items. Thus, we suggest that a spatially homogeneous mesozooplankton community characterizes the coastal area of Fernando de Noronha Archipelago with variations related mainly to the seasonal factor.

Abstract Paguroids are usually detritivorous organisms and the occurrence of predation on mollusks is very unusual. This contribution reports the occurrence of a predatory behavior of the paguroid Dardanus venosus (H. Milne Edwards, 1848) on the snail Aurantilaria aurantiaca (Lamarck, 1816). Single specimen of paguroid was found attacking the snail in a sea grass meadow dominated by Halodule wrightii Ascherson on the coast of Ceará, northeastern Brazil. The paguroid and gastropod specimens were brought to the laboratory and placed in an aquarium and the behavior was recorded by photos. Paguroid behavior was characterized by sequencial movements of chelipeds in the attack to the snail when the snail was hold by paguroid ambulatory legs. External lip of shell aperture, operculum and foot of the gastropod were severely damaged.

The population biology and size at sexual maturity of Uca (Uca) maracoani were studied for the first time in a semi-arid tropical estuary of northeastern Brazil. A catch-per-unit-effort (CPUE) technique was used to sample the crabs, on the surface and inside burrows, for 60-min sampling periods by one person on a monthly basis during spring low tide periods from June 2013 to June 2014 in an estuary area of Baixa Grande Beach. A total of 406 crabs were obtained, of which 317 were males, 87 non-ovigerous females, and two ovigerous females. Males were larger than non-ovigerous females. The U. (U.) maracoani population presented unimodal size frequency distribution, which may reflect a continuous recruitment, with no disruption of classes and constant mortality rates, indicating a stable population. The overall sex ratio (3.5 males: 1 female) differed significantly from the expected 1:1 proportion. The major cheliped was on the right side in 45.1% of the males, as reported for other fiddler crabs populations. A total of 294 males and 89 females were used in the allometric study. The specimens were measured at carapace width (CW), the major propodus length (MPL) of males, and abdomen width (AW) of females. In males, the relationship between CW and MPL was 22.3 mm CW, which is considered the functional value at maturity. In females, the size at sexual maturity was 19.3 mm CW based on the relationship between CW and AW. The CPUE method is discussed as one of the reasons of the high sex ratio skewed towards males. This is the first account regarding population structure of U. (U.) maracoani in semi-arid tropical areas.

La estructura poblacional y la madurez sexual morfométrica del cangrejo Uca (Uca) maracoani fueron estudiadas en un manglar tropical en el noreste de Brasil. Los cangrejos fueron colectados mensualmente durante los periodos de marea baja de junio 2013 a junio 2014. Se utilizó la técnica de captura por unidad de esfuerzo (CPUE) con períodos de una hora de captura realizada por una persona. Se obtuvo un total de 406 cangrejos: 317 machos, 87 hembras no-ovígeras y dos hembras ovígeras. El tamaño de los machos fue significativamente mayor que el de las hembras no-ovígeras. La población mostró una distribución unimodal de frecuencias de tamaños, lo que puede reflejar un reclutamiento continuo, sin interrupción de las clases y las tasas de mortalidad constantes, lo que indica una población estable. La proporción sexual (3.5 machos: 1 hembras) se alejó significativamente de la proporción esperada 1:1. El quelípodo mayor estaba en el lado derecho en el 45,1% de los machos, según lo informado por otras poblaciones. Se realizaron mediciones del ancho del caparazón (CW) y longitud del propodio mayor (MPL) de 294 machos, y del ancho del caparazón (CW) y ancho del abdomen (AW) de 89 hembras. En los machos, el punto de inflexión se determinó en 22,3 mm CW, considerado el tamaño morfológico al inicio de la madurez. En las hembras, el tamaño de madurez sexual fue de 19,3 mm CW basado en la relación entre CW y AW. El método CPUE se discute como una de las razones que explican el elevada proporción sexual sesgada hacia los machos. Este es el primer estudio relacionado con la estructura poblacional de U. (U.) maracoani en zonas semiáridas tropicales.

ABSTRACT We report herein the occurrence of the infraorder Polychelida in Potiguar Basin, northeastern Brazil. Specimens were collected by the project "Avaliação da Biota Bentônica e Planctônica na porção offshore das Bacias Potiguar e Ceará", developed by the Brazilian Oil Company (PETROBRAS). Three species were recorded for the first time in this region: Pentacheles validus A. Milne-Edwards, 1880, Polycheles typhlops Heller, 1862, and Stereomastis sculpta (Smith, 1880) at 2000 m, 400 m and 2057 m depth, respectively. The Brazilian deep-sea floor remains poorly known, but progress has been made as a result of collections obtained by oceanographic expeditions and research projects developed by PETROBRAS in Campos Basin (Rio de Janeiro) and Potiguar Basin (Rio Grande do Norte), expanding the knowledge of the distribution area of Polychelidae in Brazilian deep sea waters.

The size at sexual maturity and the allometric growth of the semi-terrestrial crab Sesarma rectum were studied in an impacted tropical mangrove in northeast Brazil. Crabs were monthly collected during spring low-tide periods, from October 2009 through September 2010. A catch-per-unit-effort (CPUE) technique was used to sample the crab population, with two-hour sampling periods, by two people. A total of 492 crabs were obtained, being 262 males and 230 females. The specimens were measured at carapace width (CW), the left and right propodus length and height (RPL, RPH, LPL and LPH), and the gonopod length of males (GL), and abdomen width (AW) of females. In males, the inflection point was at 27.14 mm CW in the relationship between CW and the length of right propodus (LRP), considering the morphological size at the onset of maturity. Based on the relationship between CW and AW, the size at sexual maturity in females was 22.97 mm. In spite of living in an impacted area, this population attained the maturity onset at a bigger size than other localities.

La madurez sexual morfométrica y el crecimiento alométrico del cangrejo semiterrestre Sesarma rectum fueron estudiados en un manglar tropical modificado en el noreste de Brasil. Los cangrejos fueron colectados mensualmente durante los períodos de marea baja desde octubre 2009 a septiembre 2010. Para obtener una muestra representativa de la población se utilizó la técnica de captura por unidad de esfuerzo (CPUE), con períodos de dos horas de captura realizada por dos personas. Se obtuvo un total de 492 cangrejos: 262 machos y 230 hembras. Se realizaron mediciones del ancho del caparazón (AC), longitud y altura del propodio izquierdo y derecho, longitud del gonopodo de los machos (LPI, API, LPD, APD e LG), y ancho del abdomen (AW) de las hembras. En los machos, el punto de inflexión se determinó en 27,14 mm CW en la relación entre CW y la longitud del propodio derecho (LPD), considerado el tamaño morfológico al inicio de la madurez. Basado en la relación entre el CW y AW, el tamaño de madurez sexual de las hembras fue de 22,97 mm. A pesar de vivir en una zona afectada, esta población alcanza el inicio de la madurez sexual a un tamaño mayor que en otras localidades.

The taxonomy of the 11 species of fiddler crabs [Uca (Uca) maracoani (Latreille, 1802-1803), U. (U.) tangeri (Eydoux, 1835), U. (Minuca) burgersi Holthuis, 1967, U. (M.) mordax (Smith, 1870), U. (M.) rapax (Smith, 1870), U. (M.) thayeri Rathbun, 1900, U. (M.) victoriana von Hagen, 1987, U. (M.) vocator (Herbst, 1804), U. (Leptuca) cumulanta Crane, 1943, U. (L.) leptodactyla Rathbun, 1898 and U. (L.) uruguayensis Nobili, 1901] of the South Atlantic Ocean is reviewed. Keys for identification, updating the keys for the Atlantic Ocean are proposed, including the species recently described. Comments reporting morphological variations among types and additional material and among populations of different localities are included. The Atlantic species are divided into three subgenera: Uca s. str., Minuca and Leptuca. The eastern Atlantic species U. (U.)tangeri is included in subgenus Uca s. str. due to the presence of a proximal spine opposing the spoon-tipped setae of the second maxilliped, which is considered an apomorphic character of the subgenus Uca s. str.