Austinixa aidaeinhabits burrows of the ghost shrimpCallichirus majorat Perequê-açu beach, Ubatuba, Brazil. We described the host-use pattern and sexual dimorphism ofA. aidaeto test for monogamy given the generality of this mating system in the subfamily Pinnothereliinae (family Pinnotheridae) to whichA. aidaebelongs. Against expectations,A. aidaelives as solitary individuals within burrows more frequently than expected by chance alone. Additional observations suggested thatA. aidaeexhibits a polygynandrous mating system with males moving among burrows in search of receptive females. First, only 21% of the burrows harboured heterosexual pairs of crabs and the body size of paired crabs was poorly correlated. This suggests pair instability and frequent shifts among burrows by male and/or female crabs, as reported before for other symbiotic crustaceans in which the body size of paired crabs is poorly correlated. Second, males paired with females that were sexually receptive (without embryos) or that have been receptive recently (carrying early embryos) were found more frequently than expected by chance alone. The above agrees with that reported for species in which sexual pairing does not last long. Third, sexual dimorphism in terms of claw size and coloration was evident. Claws were larger in males than in females, a condition that argues in favour of male–male competition inA. aidae. In addition, the body coloration of males was more similar to the sand grains of the beach than that of females. This sex-specific coloration suggests that males are ‘better adapted' than females to roam on the surface of the beach in search of burrows because their coloration should diminish the risk of detection by predators. Experiments are needed to reveal the details of the polygynandrous mating system herein inferred forA. aidaeand to understand those conditions favouring particular reproductive strategies in symbiotic decapod crustaceans.

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The Pinnotheridae family is one of the most diverse and complex groups of brachyuran crabs, many of them symbionts of a wide variety of invertebrates. The present study describes the population dynamics of the pea crab Austinixa aidae (Righi, 1967), a symbiont associated with the burrows of the ghost shrimp Callichirus major (Say, 1818). Individuals (n = 588) were collected bimonthly from May, 2005 to September, 2006 along a sandy beach in the southwestern Atlantic, state of São Paulo, Brazil. Our data indicated that the population demography of A. aidae was characterized by a bimodal size-frequency distribution (between 2.0 and 4.0 mm and between 8.0 and 9.0 mm CW) that remained similar throughout the study period. Sex ratio does not differ significantly from 1:1 (p > 0.05), which confirms the pattern observed in other symbiontic pinnotherids. Density values (1.72 ± 1.34 ind. • ap.-1) are in agreement with those found for other species of the genus. The mean symbiosis incidence (75.6%) was one of the highest among species of the Pinnotheridae family, but it was the lowest among the three studied species of the genus. Recruitment pattern was annual, beginning in May and peaking in July, in both years, after the peak of ovigerous females in the population (from March to May). Our findings describe ecological and biological aspects of A. aidae similar to those of other species of this genus, even from different geographic localities.

As pesquisas sobre insetos aquáticos vem sendo muito difundidas nos últimos anos. Entretanto, existem lacunas sobre o conhecimento de suas relações com macrófitas aquáticas. O objetivo deste trabalho foi analisar a composição e estrutura da entomofauna associada a seis gêneros de macrófitas da represa do Ribeirão das Anhumas (Américo Brasiliense/SP), avaliar as categorias funcionais tróficas dos insetos, comparar as similaridades faunísticas entre os períodos de coletas e entre as macrófitas através das analises PSC (similaridade) e ACP (Análise de Componentes Principais), além de estabelecer a relação entre peso úmido/seco das macrófitas e a fauna associada. Identificamos 1173 espécimes pertencentes a 26 famílias distribuídas em sete ordens. As macrófitas sustentam uma comunidade predominantemente representada por insetos coletores (62% da fauna) seguida por predadores (31%). A análise ACP também não indicou que os diferentes períodos de coleta influenciam a estrutura faunística, entretanto esta análise indicou separação espacial entre algumas macrófitas, o que provavelmente relaciona a diversidade da fauna associada com complexidade espacial das macrófitas. A análise da biomassa das plantas refletiu que o peso seco não exerce influência diretamente relacionada à abundância de insetos.

ABSTRACT. The aim of this study was to describe the population structure and reproduction of Macrobrachium jelskii from a stream in the central region of São Paulo State. A total of 1,215 specimens was collected monthly during one year (February 2008 to January 2009), being 535 males, 578 females and 102 juveniles. The overall sex-ratio was not significantly different from the expected 1:1, but has significantly differed in some months. A total of 136 ovigerous females were collected and the reproductive period was continuous with peak of occurrence on the hottest months. An increase in juveniles following the highest frequency of ovigerous females was observed and characterized the recruitment period. The fecundity was low and varied from 1 to 56 eggs per female. The biological profile observed here matched, in general aspects, with the pattern developed by tropical and subtropical inland populations, with some particularities related with environmental characteristics.

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ABSTRACT. Species of the family Pinnotheridae constitute an ideal group for morphometric studies due to their complex morphological adaptations. These adaptations respond to the selective pressure of a symbiotic life style. This study describes the relative growth and morphometric features of the symbiotic pea crab Austinixa aidae (associated with the ghost shrimp Callichirus major), from the sandy beaches in the southwest Atlantic, Brazil. Significant differences were detected in the biometric proportions, particularly the chelar propodus length and carapace width, of each sex. These dimensions were also related to the size at which the individuals reached morphological sexual maturity (5.1 mm of carapace width for both sexes). Males and females were 2.4 times wider than long, which corresponds to the principal adaptation developed by Austinixa species to live in cryptic environments. Moreover, juveniles were proportionally more rounded. The changes in the biometric proportions of carapace length and width of A. aidae were more pronounced in males and females, adaptations that facilitate roaming within the galleries of their hosts. Keywords: pinnotherid crabs, traditional morphometry, size-at-maturity, sexual dimorphism, southwestern Atlantic.Crecimiento relativo y dimorfismo sexual en Austinixa aidae (Barchyura: Pinnotheridae): un simbionte del camarón fantasma Callichirus major del Atlántico sudoccidental RESUMEN. Las especies de la familia Pinnotheridae constituyen un grupo ideal para la realización de estudios morfométricos, debido a sus complejas adaptaciones morfológicas. Estas adaptaciones son respuesta a la presión de selección debida a su vida simbionte. En este estudio se describió el crecimiento relativo y las características morfométricas del cangrejo simbionte Austinixa aidae (asociado con el camarón fantasma Callichirus major), de una playa de arena del Atlántico suroeste de Brasil. Se determinaron diferencias significativas en las proporciones biométricas de cada sexo, entre la longitud del propodio y ancho del caparazón. Estas dimensiones estuvieron relacionadas también con la talla en que los individuos muestran cambios morfológicos en su madurez sexual (5.1 mm de ancho del caparazón en ambos sexos). Los machos y hembras fueron 2,4 veces más anchos que largos, lo que corresponde a la adaptación principal que las especies del género Austinixa, han desarrollado para vivir en ambientes crípticos. Además, los juveniles fueron proporcionalmente más redondeados. Los cambios en las proporciones biométricas de longitud y ancho del caparazón de A. aidae, fueron más pronunciados en machos y hembras, adaptaciones que facilitan el desplazamiento al interior de las galerías construidas por sus hospederos. Palabras clave: cangrejos pinnothéridos, morfometría tradicional, talla de madurez, dimorfismo sexual, Atlántico sudoccidental.

More than 5.000 species are described to Class Oligochaeta, and approximately 1650 aquatic species are recognized around the world. Knowledge regarding abundance and composition of limnic oligochaetes can be used as an indicator of water and sediment quality. Thus, this paper aims to summarize all published data on aquatic Oligochaeta from State of Sã o Paulo (Brazil), in order to establish a cheklist of microdrili from the State. The list emphasizes the diversity of limnic oligochaetes and provides a general overview of their distribution and also ecological aspects. Were examined the bibliographical data on Sã o Paulo aquatic Oligochaeta, including species catalogs and taxonomic and ecological literature. Were analyzed a total of 34 academic researches, 32 journal papers and two taxonomic catalogs. This analysis resulted in a list of 75 valid species, distributed in 24 genera and five families. This amount of taxa corresponds to 4.5% of the aquatic Oligochaeta worldwide valid species, and about 87% of the Brazilian species. Keywords: Limnic oligochaetes, Species list, Occurrence, São Paulo.GORNI, G., PEIRÓ , D.F., SANCHES, N. Oligochaeta aquático (Annelida: Clitellata) do Estado de São Paulo: Revisão da Diversidade e Ocorrência.http://dx.doi.org/10.1590/ 1676-06032015006314 Resumo: Mais de 5.000 espécies sã o descritas para a Classe Oligochaeta e aproximadamente 1650 espécies aquá ticas sã o reconhecidas em todo o mundo. O conhecimento sobre a composiçã o e abundâ ncia de oligoquetos límnicos pode ser um indicador de qualidade da á gua e/ou sedimento. Assim, este trabalho teve como objetivo reunir todas as informaçõ es publicadas sobre Oligochaeta aquá tico do Estado de São Paulo (Brasil), a fim de estabelecer uma lista de tá xons de microdrili registrados. A lista destaca a diversidade de oligoquetos límnicos e fornece uma visã o geral de sua distribuiçã o e aspectos ecoló gicos. Para isso, foram examinados dados bibliográ ficos de Oligochaeta aquá ticos em Sã o Paulo, incluindo catá logos de espécies, bem como artigos sobre taxonomia e de ecologia. Foram analisados ??o total de 34 trabalhos acadêmicos, sendo 32 artigos e dois catá logos taxonô micos. Esta aná lise resultou em uma lista de 75 espécies vá lidas, distribuídas em 24 gêneros e cinco famílias. Este montante corresponde a 4,5% das espécies de Oligochaeta aquá tico registradas no mundo, e aproximadamente 87 % das espécies brasileiras.