Sônia G. B. C. Lopes

Distribution of wood-boring bivalves in the Mamanguape River estuary, Paraíba, Brazil

Wood-boring bivalves of the families Teredinidae and Pholadidae are reported for the first time in Paraiba State, north-east Brazil. During one year, molluscs were collected from mangrove tree logs and from wood panels, along a salinity gradient. Four teredinid ( Neoteredo reynei , Teredo bartschi , Nausitora fusticula , Bankia fimbriatula ) and one pholad species ( Martesia striata ) were found.

Taxonomic Identity in Microbial Eukaryotes: A Practical Approach Using the Testate Amoeba Centropyxis to Resolve Conflicts Between Old and New Taxonomic Descriptions

ABSTRACT. The present work focuses on 12 taxa of the genus Centropyxis Stein, 1857 to explore the conflict between traditional and contemporary taxonomic practices. We examined the morphology, biometry, and ecology of 2,120 Centropyxis individuals collected from Tiete River, Sao Paulo, Brazil; with these new data we studied the consistency of previously described species, varieties, and forms. We encountered transitional forms of test morphology that undermine specific and varietal distinctions for three species and nine varieties. Biometrical analyses made comparing the organisms at the species level suggest a lack of separation between Centropyxis aculeata and Centropyxis discoides, and a possible distinction for Centropyxis ecornis based on spine characteristics. However, incongruence between recent and previous surveys makes taking any taxonomic–nomenclatural actions inadvisable, as they would only add to the confusion. We suggest an explicit and objective taxonomic practice in order to enhance our taxonomic and species concepts for microbial eukaryotes. This will allow more precise inferences of taxon identity for studies in other areas.

Mantle margin morphogenesis in Nodipecten nodosus (Mollusca: Bivalvia): new insights into the development and the roles of bivalve pallial folds

BackgroundDespite extensive knowledge on bivalve anatomy and development, the formation and differentiation of the mantle margin and its associated organs remain largely unclear. Bivalves from the family Pectinidae (scallops) are particularly promising to cast some light on these issues, because they exhibit a complex mantle margin and their developmental stages are easily obtained from scallop farms. We investigated the mantle margin of the scallop Nodipecten nodosus (L. 1758) during larval and postmetamorphic development.MethodsA thorough analysis of the mantle margin development in Nodipecten nodosus, from veliger larvae to mature adults, was conducted by means of integrative microscopy techniques, i.e., light, electron, and confocal microscopy.ResultsInitially unfolded, the pallial margin is divided into distal and proximal regions by the periostracum-forming zone. The emergence of the pallial musculature and its neural innervation are crucial steps during bivalve larval development. By the late pediveliger stage, the margin becomes folded, resulting in a bilobed condition (i.e., outer and inner folds), a periostracal groove, and the development of different types of cilia. After metamorphosis, a second outgrowth process is responsible for emergence of the middle mantle fold from the outer surface of the inner fold. Once the three-folded condition is established, the general adult features are rapidly formed.ConclusionsOur data show that the middle mantle fold forms from the outer surface of the inner fold after metamorphosis and that the initial unfolded mantle margin may represent a common condition among bivalves. The first outgrowth process, which gives rise to the outer and inner folds, and the emergence of the pallial musculature and innervation occur during larval stages, highlighting the importance of the larval period for mantle margin morphogenesis in Bivalvia.

Functional anatomy of the digestive system of Neoteredo reynei (Bartsch, 1920) and Psiloteredo healdi (Bartsch, 1931) (Bivalvia: Teredinidae)

Abstract Studies on the digestive system of the Teredinidae are useful for a better understanding of the evolution of these bivalves in relation to the xylophagous habit. Neoteredo reynei and Psiloteredo healdi, two common species in Brazilian mangroves, have evolved differently in their methods to use wood as food, despite the similarities in the anatomy and functioning of their globular type II stomachs. N. reynei is predominantly xylophagous throughout its life, while P. healdi, despite its predominant suspension-feeding habit, uses wood more efficiently as the animal grows older. The outstanding differences that allow these conclusions are the large size of the appendix and anal canal in N. reynei, always conspicuous and packed with wood, and the small appendix of P. healdi, which increases in size with age. Based on anatomical data and revision of the literature, it is suggested that in both species the appendix, and also the anal canal in N. reynei, is of primary importance in the digestion of wood and absorption of nutrients, counterbalancing the reduced specialized digestive diverticula.

Levantamento e distribuição das espécies de Teredinidae (Mollusca - Bivalvia) no manguezal da Praia Dura, Ubatuba, São Paulo, Brasil

Realizou-se o levantamento e estudou-se a distribuicao das especies de Teredinidae no manguezal da Praia Dura, Ubatuba, Sao Paulo, Brasil. Investigou-se a abundância das especies nas regioes mais em contato frequente com a agua e as menos atingidas pelas preamares. Determinou-se, tambem, a distribuicao das especies ao longo do Rio Escuro, segundo um gradiente decrescente de salinidade: Nausitora fusticula foi a especie mais abundante ao longo do Rio Comprido, demonstrando que esta especie esta bem adaptada a regiao entremares e a grande variacao de salinidade (0 a 33 S). Na area do bosque em maior contato com a agua N fusticula e encontrada com Bankiafimbriatula, B. gouldi e B. rochi e, nas areas menos atingidas pelas preamares, divide o ambiente com Neoteredo reynei, ocorrendo poucos individuos das especies de Banida ja mencionadas. O limite maximo da ocorrencia de Teredinidae no Rio Comprido, correspondeu ao limite maximo da penetracao da agua do mar durante as preamares. Nas areas menos salinas do rio, praticamente deixam de ocorrer todas as especies de Banida e Neoteredo reynei, comecando a surgir Psiloteredo healdi, com quem N. fusticula passa a dividir o ambiente, sendo posteriormente dominada por aquela.

Development of the pallial eye in Nodipecten nodosus (Mollusca: Bivalvia): insights into early visual performance in scallops

Scallop pallial eyes have been the most studied optical system in bivalve mollusks. Despite recent advances in our understanding of the function and evolution of scallop eyes, little attention has been focused on eye development and early visual performance. Here, the anatomy and development of pallial eyes were investigated in the scallop Nodipecten nodosus (Linnaeus, 1758) by means of integrative microscopy techniques (i.e., light, electron, and confocal microscopy). After metamorphosis, juvenile scallops bear small papillae that rapidly transform into minute ocular organs on the middle mantle fold. The distal epithelium gradually becomes pigmented, except for the cornea formed at the distal center of the eye. Internally, the optic vesicle comprises undifferentiated cells in the distal region, while mirror plates are secreted at the base of the eye, next to pigmented cells. Within the undifferentiated cell mass, the proximal retina is the first to be formed, followed by the distal retina and then by the lens. In this respect, the late development of the scallop lens from retina precursor cells may represent a unique condition among animal eyes. Adult eyes are characterized by large pigment distribution in the epithelium, tall columnar cornea, and lens above a slightly curved double retina. Whereas the pallial eyes from adult scallops are a complex visual system based on a mirror mechanism to form a focused image on the retina, early eye condition suggests a simple degree of directional photoreception, with no spatial vision.

The interference of methods in the collection of teredinids (Mollusca, Bivalvia) in mangrove habitats

In the estuary of the Mamanguape River (Paraiba, Brazil), a new collection technique was developed and applied with virgin poles of mangrove trees Avicennia schaueriana (Verbenaceae), Rhizophora mangle (Rhizophoraceae), and Laguncularia racemosa (Combretaceae), taking into account wood preference, water salinity and depth influence during teredinid larval settlement. Sets of poles were vertically fixed in the riverbed at three sites along a decreasing salinity gradient, where they stayed for four months. The poles were collected and divided into upper, median, and lower segments, in agreement with different immersion regimes. An increase of 239% was obtained in the number of individuals when compared to a previous study in the same area using a different methodology. The species Teredo bartschi (Clapp, 1923), Nausitora fusticula (Jeffreys, 1860) and Bankia fimbriatula Moll & Roch, 1931 were registered in both studies, and the species Psiloteredo healdi (Bartsch, 1931) is here registered for the first time as occurring in that estuary. The species Neoteredo reynei (Bartsch, 1920), previously registered on tree branches of the mangrove habitat, was not found in the present work. Bankia fimbriatula, the most abundant species, did not show preference for any substratum but occurred significantly on the lower segment of the poles. N. fusticula, second in abundance, preferred to settle on poles of A. schaueriana and on any of the three segments. Aiming to assess the habitat variations, a more accurate study on teredinids diversity in mangrove ecosystems should be performed through a concomitant analysis from tree branches of the mangrove habitat, as well as from poles of mangrove trees or panels made of pine wood or mangrove trees wood. These collection devices should be maintained along a decreasing salinity gradient exposed to different tide levels.

Recrutamento larval e crescimento de teredinidae (mollusca-bivalvia) em região entremarés de manguezais

O recrutamento larval e o crescimento de Teredinidae na regiao entremares do manguezal da Praia Dura, Ubatuba, SP, foi acompanhado durante doze meses (08/84 a 08/85) utilizando coletores construidos com madeira de mangue. O tempo decorrido para se detectar a presenca dos primeiros Teredinidae foi de aproximadamente sete meses apos o inicio do experimento e o numero de individuos por coletor foi muito reduzido no periodo de amostragem. Esses resultados contrastam com os obtidos por outros autores que instalaram coletores em ambiente marinho, mas sao semelhantes aos obtidos por autores que instalaram coletores em regioes estuarinas do litoral brasileiro. Essas diferencas nos resultados talvez possam ser explicadas pelo fato da salinidade ser mais baixa e mais variavel nos estuarios que no ambiente marinho. A analise dos dados sobre o recrutamento larval, permite concluir que a especie mais abundante foi Nausitora fustieula (Jeffreys, 1860), com principal epoca de instalacao em marco e taxa inicial de crescimento de 1,86 mm/day. As outras especies de Teredinidae, Bankiaflmbriatula Moll & Roch, 1931, Bankia roehi Moll, 1931 e Neoteredo reynei (Bartsch, 1920), apresentaram pequeno numero de individuos e em funcao disso, nao foi possivel determinar suas epocas de instalacao e respectivas taxas de crescimento.

Ocorrência e recrutamento larval de Teredinidae (Mollusca, Bivalvia) na região do Sistema Costeiro Cananéia-Iguape, São Paulo, Brasil

A ocorrencia e o recrutamento larval de Teredinidae na regiao do Sistema Costeiro Cananeia-Iguape foram acompanhados por doze meses utilizando-se coletores laminados de pinho, instalados em tres estacoes dentro do bosque de mangue (mediolitoral) e em uma estacao, localizada no infralitoral. No manguezal, a colonizacao por larvas de teredinideos ocorreu apos quatro meses de permanencia dos coletores na estacao mais frequentemente inundada pela mare e somente apos oito meses nas duas estacoes com menor frequencia de inundacao. No infralitoral, apos quatro meses, os coletores ja estavam consideravelmente danificados. Ao longo do experimento, houve um decrescimo no numero de teredinideos, especialmente no infralitoral, ocasionado possivelmente pela competicao por alimento e espaco entre teredinideos e foladideos. Foram encontrados 2.658 individuos, sendo 704 de Teredinidae e 1.954 de Pholadidae. Entre os teredinideos, Bankia fimbriatula foi a especie mais abundante tanto no infralitoral quanto no manguezal, seguida de Bankia gouldi e Lyrodus floridanus que ocorreram somente no infralitoral, e Nausitora fusticula encontrada somente no manguezal. Martesia striata, unico foladideo, ocorreu somente no infralitoral.

Conteúdos de biologia em vestibulares seriados

A adocao de novos processos seletivos para o acesso de alunos as universidades so foi possivel com a promulgacao da Lei de Diretrizes e Bases da Educacao Nacional n. 9.394/96. O vestibular seriado e uma dessas propostas alternativas, que preve uma avaliacao sistematica dos alunos ao termino de cada ano do ensino medio. O proposito deste estudo foi caracterizar o vestibular seriado, hoje presente em 22 instituicoes publicas, quanto ao seu objetivo, estilos de avaliacao e conteudos da disciplina de Biologia distribuidos nos modulos referentes as tres series do ensino medio. Averiguamos que os diferentes programas analisados nao apresentam uniformidade em diversos aspectos, tais como numero de vagas, estrutura de avaliacao e conteudo programatico. Verificamos, ainda, a ausencia de consenso sobre a sequencia a ser adotada para o ensino de Biologia e a resultante restricao para que o aluno possa preparar-se para as provas seriadas em mais de uma instituicao.