Este artigo analisou a relação entre mesohabitats e as espécies de oligoquetos aquáticos no Córrego Galharada (Parque Estadual de Campos do Jordão, Estado de São Paulo, Brasil). Entre agosto de 2005 e maio de 2006 um total de 192 amostras foram obtidas em quatro mesohabitats diferentes: folhiço em corredeiras (RL), folhiço em remanso (PL), sedimentos em remanso (PS) e sedimento intersticial de pedras em corredeiras (IS). Nos mesohabitats amostrados, foram identificados 2007 espécimes, pertencentes a duas famílias (Naididae e Enchytraeidae). Entre os oligoquetos identificados, Naididae foi representada por seis gêneros (Allonais, Chaetogaster, Nais, Pristina, Aulodrilus e Limnodrilus). A Análise de Componentes principais (ACP) revelou que os dois primeiros eixos explicaram 85,1% da variabilidade total dos dados. Limnodrilus hoffmeisteri Claparede, 1862 e Aulodrilus limnobius Bretscher, 1899 foram associadas às areas de remanso (PL e PS). A maioria das espécies dos gêneros Pristina e Nais demonstrou aparente afinidade com mesohábitats de corredeira. A análise de espécies indicadoras (IndVal) revelou que Nais communis Piguet, 1906, Pristina leidyi Smith, 1896 and Pristina (Pristinella) jenkinae (Stephenson, 1931) são indicadoras do mesohábitat RL, enquanto a família Enchytraeidae foi considerada indicadora do mesohábitat PL.

This paper analyses the relationship among mesohabitat and aquatic oligochaete species in the Galharada Stream (Campos do Jordão State Park, state of São Paulo, Brazil). Between August 2005 and May 2006 a total of 192 samples were obtained in areas of four different mesohabitats: riffle leaf litter (RL), pool leaf litter (PL), pool sediment (PS) and interstitial sediment from rocky beds in riffle areas (IS). In the mesohabitats sampled, 2007 specimens were identified, belonging to two families (Naididae and Enchytraeidae). Among the oligochaetes identified Naididae was represented by six genera (Allonais, Chaetogaster, Nais, Pristina, Aulodrilus and Limnodrilus). Principal components analysis (PCA) revealed the first two axes explained 85.1% of the total variance of the data. Limnodrilus hoffmeisteri Claparede, 1862 and Aulodrilus limnobius Bretscher, 1899 were associated with the pool areas (PL and PS). Most species of genera Pristina and Nais demonstrated apparent affinity with the riffle mesohabitats. The Indicator Species Analysis (IndVal) revealed that Nais communis Piguet, 1906, Pristina leidyi Smith, 1896 and Pristina (Pristinella) jenkinae (Stephenson, 1931) are indicative of RL mesohabitat, while family Enchytraeidae was considered indicative of PL mesohabitat.

This study describes the composition and structure of the benthic community associated with bryophytes in a first-order stream, located in a biological reserve of the Atlantic Forest, during two seasons. During three months of the dry season of 2007 and three months of the rainy season of 2008, samples of bryophytes attached to stones were collected randomly, along a 100 m stream reach. The structure of the community was analyzed through the mean density of individuals, Shannon's diversity index, Pielou's evenness, family richness, dominance index, and the percentage of Ephemeroptera, Plecoptera and Trichoptera (% EPT). Chironomidae larvae were dominant in the two periods of study, followed by Ceratopogonidae in the rainy season, and Naididae in the dry season. The orders EPT contributed 14 families. The results showed that bryophytes constitute suitable habitat which is able to shelter an abundant and diversified benthic fauna in a small extension of the stream. This habitat provides refuge during spates, and thus minimizes downstream transport of the macroinvertebrate fauna.

In this note, the occurrence of phoresy between larvae of Rheotanitarsus sp. (Diptera: Chironomidae) and larvae of Heteragrion sp. (Odonata: Megapodagrionidae) and of unidentified genera of Calopterygidae (Odonata) collected in a first-order stream in an area of Atlantic Forest in southeastern Brazil is reported. During the dry season of 2007 and the rainy season of 2008, with the aid of a Surber sampler, 15 samples of each of the following mesohabitats were collected: litter from riffle areas, litter from pool areas and sediment in pool areas. Eighty-five Odonata larvae were obtained, 10 (11.76%) with cases of phoresy by Rheotanytarsus sp.. These chironomids were associated with only one specimen of Megapodagrionidae, whereas the other larvae were recorded in association with Calopterygidae. Most of the Odonata with cases of phoresy by Rheotanytarsus sp. were recorded in the dry season. In the present study, the absence of the phoretic association with other potential hosts for Rheotanytarsus sp. found in the samples indicates a possible preference of these larvae for Odonata, which accounted for only 2.42% of the collected macroinvertebrates in litter and sediment.

Branchiura sowerbyi Beddard, 1892 é uma espécie de Tubificidae abundante em ambientes límnicos tropicais, freqüentemente associada a sedimento rico em matéria orgânica e a elevadas temperaturas. O presente estudo teve como objetivo obter informações sobre postura e taxa de eclosão de casulos de B. sowerbyi, em condições laboratoriais. Para isso, exemplares da espécie foram acondicionados em béqueres (250 ml), contendo sedimento argiloso e água destilada, mantidos a 25°C. Os casulos foram separados em béqueres de 100 ml e mantidos em condições similares aos indivíduos adultos. Foram coletados 57 casulos, uma média de 0,13 casulos·indivíduo-1·dia-1, contendo 1,21 (±0,08) ovos·casulo-1 em média. O tempo de eclosão foi aproximadamente duas semanas e a taxa de eclosão foi 44,93%. Os resultados obtidos mostraram-se diferentes daqueles encontrados por outros autores para B. sowerbyi. Os dados gerados no presente estudo podem ser considerados passos importantes para a observação de características da biologia reprodutiva da espécie, B. sowebyi, encontrada no sedimento de ambientes aquáticos brasileiros.

Branchiura sowerbyi Beddard, 1892 is a Tubificidae species abundant in tropical limnic environments and associated with sediments rich in organic matter and elevated temperatures. The present study aimed at obtaining information on laying and hatching rates of B. sowerbyi cocoons under laboratory conditions. In order to do this, specimens of B. sowerbyi were placed in beakers (250 ml) containing clay sediment and distilled water and kept at 25ºC. The obtained cocoons were placed in beakers of 100 ml and kept in conditions similar to the mature individuals. Fifty seven cocoons were collected, with a mean of 0.13 cocoons·individual-1·day-1 and 1.21 (±0.08) eggs·cocoon-1. Hatching time was approximately two weeks and hatching rate was 44.93%. The results obtained were different from the ones found by other authors for B. sowerbyi. According to the literature, different populations of the same species can present distinct biological aspects, such as the number of cocoons, hatching rates and growth.

A família Ampullaridae, pertencente à classe Gastropoda, é caracterizada por organismos de água doce com ampla distribuição na região tropical. Vermes Oligochaeta associados a esses caracóis podem ser encontrados habitando o umbílico de suas conchas. Devido à carência de informação sobre a ecologia desses vermes, o presente trabalho centrou-se em um levantamento de espécies de Oligochaeta associadas ao molusco Pomacea bridgesii (Reeve, 1856). Em amostragens realizadas no inverno e na primavera de 2003 e no verão de 2004, foram observados 209 caracóis, sendo que somente em 58 deles foi detectada a presença de vermes Oligochaeta, correspondendo a uma incidência de 27,75%. Foram encontrados, no total, 89 oligoquetos, todos da família Naididae. As espécies Haemonais waldvogeli Bretscher, 1900, Dero (Dero) nivea Aiyer, 1929 e Dero (Dero) sawayai Marcus, 1943 apresentaram a maior abundância relativa (43,68%, 12,32% e 10,08%, respectivamente). Espécimes de Haemonais waldvogeli foram encontrados em todos os períodos sazonais, o que demonstra sua afinidade com este tipo de substrato. Os resultados indicam que várias espécies de Naididae encontram no umbílico da concha (que contém detrito fino) um habitat favorável para seu estabelecimento.

The family Amplullaridae belongs to this class Gastropoda and is made up of freshwater organisms with a wide geographical distribution in tropical regions. Oligochaeta worms can be found in association with snails of this family, inhabiting the umbilicus of their shells. Due to the lack of information on the ecology of these worms, this work focused on investigating which kind of Oligochaeta species associate with the mollusk Pomacea bridgesii (Reeve, 1856). Samples were collected during winter and spring 2003 and summer 2004. From a total of 209 snails collected, the presence of Oligochaeta worms was observed in only 58 of them (27.75%). In these infected snails, 89 Oligochaeta worms were found, all belonging to the family Naididae. The species Haemonais waldvogeli Bretscher, 1900, Dero (Dero) nivea Aiyer, 1929 and Dero (Dero) sawayai Marcus, 1943 were the most abundant (43.68%, 12.32% and 10.08%, respectively). Haemonais waldvogeli was found in all of the seasons studied, what demonstrates its affinity for this kind of substrate. The results indicate that several Naididae species find in the umbilicus of these snails's shells (which contains fine detritus) a favorable habitat for establishing themselves.