Molecular phylogeny and evolution of Pulmonata (Mollusca: Gastropoda) on the basis of mitochondrial (16S, COI) and nuclear markers (18S, 28S): an overview

The phylogenetic relationships among the major groups of Pulmonata were studied by the information derived from a concatenated dataset consisting of mitochondrial (16S and COI) and nuclear (18S and 28S) markers. Heterobranchia are recovered as monophyletic. Euthyneura as paraphyletic due to the emergence of taxa from Opisthobranchia and lower Heterobranchia. The major groups of Pulmonata, namely Stylommatophora, Veronicellidae, Onchidiidae, Otinoidea, Siphonarioidea and Hygrophila are recovered as monophyletic. Monophyly of Basommatophora was not confirmed due to the variable position of Siphonarioidea and Amphiboloidea. Evolutionary divergence times for different taxa were also estimated using a relaxed molecular clock method in Bayesian evolutionary analysis by sampling trees (BEAST). The common ancestor of Heterobranchia and Caenogastropoda was originated in the Silurian period and the common ancestors of Euthyneura and Pulmonata were originated in the Carboniferous and lower Triassic periods, respectively.

Reproductive cycle and embryonic development of the gastropod Melampus coffeus (Linnaeus, 1758) (Ellobiidae) in the Brazilian Northeast / Ciclo reprodutivo e desenvolvimento embrionário do gastrópode Melampus coffeus (Linnaeus, 1758) (Ellobiidae) no Nordeste do Brasil

Melampus coffeus belongs to a primitive group of pulmonate mollusks found mainly in the upper levels of the marine intertidal zone. They are common in the neotropical mangroves. Little is known about the biology of this species, particularly about its reproduction. The aim of this study was to 1) characterize the morphology and histology of M. coffeus' gonad; 2) describe the main gametogenesis events and link them to a range of maturity stages; 3) chronologically evaluate the frequency of the different maturity stages and their relation to environmental factors such as water, air and sediment temperatures, relative humidity, salinity and rainfall; and 4) characterize M. coffeus' spawning, eggs and newly hatched veliger larvae. Samples were collected monthly between February, 2007 and January, 2009 from the mangroves of Praia de Arpoeiras, Acaraú County, State of Ceará, northeastern Brazil. The characterization of the gonad development stages was carried out using routine histological techniques. The results of this study show that Melampus coffeus is a simultaneous hermaphrodite. The follicles have masculine and feminine elements, interleaved within the gonad. M. coffeus presents a well-defined synchronous reproductive cycle, showing successive maturation, release and resting periods. The average diameter of the oocytes was negatively correlated with salinity and positively correlated with rainfall. The results show that no reproductive activity occurs during periods of drought. After the dry season, the increasing rainfall levels and reduced salinity lead to the appearance of very dense populations, predominantly composed of small individuals.

Melampus coffeus encontra-se em um grupo primitivo de moluscos pulmonados, primordialmente marinhos, habitantes dos níveis superiores da zona entremarés, comum em manguezais do Oceano Atlântico. Pouco se sabe sobre a biologia da espécie, em especial, sobre a sua reprodução. Os objetivos deste trabalho foram: 1) caracterizar morfo-histologicamente a gônada de M. coffeus; 2) descrever os principais eventos da gametogênese e associá-los a uma escala de estágios de maturidade; 3) avaliar temporalmente a frequência dos estágios de maturidade e sua possível relação com os fatores ambientais, como a temperatura da água, do ar e do sedimento, a umidade relativa, a salinidade e a pluviosidade, e 4) caracterizar a postura, os ovos e a véliger recém-eclodida de M. coffeus. Foram realizadas coletas mensais de fevereiro de 2007 a janeiro de 2009, no manguezal da Praia de Arpoeiras, município de Acaraú-Ceará, na Região Nordeste do Brasil. A caracterização das fases de desenvolvimento da gônada foi realizada utilizando-se técnicas histológicas de rotina. Os resultados deste estudo mostram que Melampus coffeus é um hermafrodita simultâneo. Os folículos apresentam elementos masculinos e femininos, distribuindo-se na gônada intercalados radialmente. M. coffeus apresenta um ciclo reprodutivo sincrônico bem definido, evidenciando-se períodos sucessivos de amadurecimento, de liberação e de repouso. O diâmetro médio dos oócitos apresentou correlação negativa com a salinidade e positiva com a pluviosidade. Os resultados indicam que, nos períodos de estiagem, não há atividade reprodutiva. Após essa estação, quando os valores de pluviosidade aumentam e a salinidade diminui, as populações são bastante densas e predominam indivíduos pequenos.

Dos géneros nuevos de caracoles terrestres (Stylommatophora: Arionacea) de Chile

Two new genera of land snails (Stylommatophora: Arionacea) from Chile. We describe two new genera of land molluscs found under wet leaf litter in isolated fragments of a secondary native forest at the Hualpén Botanical Park (36º45´-36º49´ S, 73º9´-73º13´ W), University of Concepción, Chile. The new taxa are Pichikadi gen.n., of Punctidae, and Chellius gen.n., of Charopidae, with the following new species: Pichikadi hualpensis sp.n., and Chellius piramidalis sp.n. English diagnosis are presented for all taxa, together with an English identification key and English versions of figure captions and table headings. To facilitate subsequent studies and interpretations, we follow recent authors in using mainly shell characters, an approach that has favored the present taxonomic stability of the world’s land micromollusca. The diagnosis and observations are complemented with a key for the species of these families inhabiting continental Chile. Rev. Biol. Trop. 55 (2): 693-708. Epub 2007 June, 29.

El estudio taxonómico y sistemático de ejemplares de moluscos terrestres recolectados bajo hojarasca en fragmentos aislados de bosque nativo secundario, Parque Botánico Hualpén, (36º45´-36º49´ S, 73º9´-73º13´ W), Universidad de Concepción, Chile, permitió describir dos géneros nuevos Pichikadi gen.n. de la familia Punctidae, y Chellius gen.n. de la familia Charopidae, con las siguientes especies nuevas para la ciencia: Pichikadi hualpensis sp.n. y Chellius piramidalis sp.n. Para facilitar interpretaciones y estudios posteriores, se sigue a diversos autores en describir las características de la concha, que como otros caracteres filogenéticos han dado origen a la aparente estabilidad sistemática de los micromoluscos terrestres en el ámbito mundial. Las descripciones y observaciones de cada género y especies se complementan con una clave para las especies de estas familias encontradas en Chile continental.