Semperula wallacei (Mollusca, Veronicellidae) um hospedeiro natural recém-descoberto de Angiostrongylus cantonensis (Nematoda, Angiostrongylidae) na Bacia do Pacífico

Semperula wallacei (Issel, 1874) is a species of terrestrial slug that occurs in southeast China and the Pacific Basin and is the only species of its genus that occurs beyond the Oriental region and to the east of Wallace's line in the Australian region, where it has probably been introduced. In this study, we report for the first time S. wallacei as an intermediate host for Angiostrongylus cantonensis (Chen, 1935) based on histological and molecular analyses of slugs from Tuamasaga, Samoa, deposited at the Medical Malacological Collection (Fiocruz-CMM). DNA was obtained from the deparafinized tissues scraped from specimen slides. Polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) targeted to the internal transcribed spacer 2 (ITS2) region were carried out using the restriction enzyme Cla I. The RFLP profile observed for our larval specimen of S. wallacei was identical to the profile previously established for A. cantonensis, demonstrating that S. wallacei can be naturally infected with A. cantonensis and is likely to be an intermediate host for this parasitic nematode species in the field. The potential for geographical range expansion of S. wallacei in the Pacific Basin, its small size, and the general role of veronicellids as crop pests and hosts of nematodes, indicate the significance of S. wallacei as an invasive species in the Pacific Basin. Our work also highlights the importance of biological collections for investigating the environmental impact of invasive species on agriculture, public health, and biodiversity conservation.

Responses of Leptinaria unilamellata (Gastropoda: Subulinidae) to Novel Micro-Environmental Conditions: Shift in Shell Morphology and the Balance between Protection against Desiccation and Reproductive Success

In the present study, we observed that Leptinaria unilamellata responds to changes in microclimatic conditions through shifts in shell morphology. Over three laboratory generations, shell differences between two populations, representing distinct morphotypes, became less evident. Only F1 generations from both populations showed shell morphometry very similar to the field parental snails, suggesting maternal effect. Snails from the locality with higher values of rainfall, relative humidity and evaporation index and smaller values of temperature and insolation produced more and larger hatchlings. Snails from the locality with less favorable climatic conditions presented shells traits that offer protection against desiccation, but reduce reproductive success. These snails showed smaller offspring production and faster response to a desiccation regime, through changes in conchiometrics. In addition, the results of the present study suggest that the spire index plays a less important role in determining protective properties of the shell of L. unilamellata, in response to desiccation risk, compared to aperture dimension. As shell aperture dimension is an important trait related to resistance to desiccation, and at the same time to reproduction, plastic responses to environmental conditions promoting the balance between survival and reproductive success are critical for the species adaptive success.

Ontogeny and morphological variability of shell in populations of Leptinaria unilamellata (d'Orbigny, 1835) (Mollusca, Pulmonata, Subulinidae)

BACKGROUND

Recent studies concerning species of land snails have revealed that the shell morphometrics can provide evidence of the differentiation among populations. In many cases, the morphologic analysis combined with the investigation of molecular variability, can support changes in taxonomy of studied groups. In this sense, the study of shell morphometry during snail development can contribute to the understanding of the structural mechanisms that creates the diversity observed.

DESCRIPTION

The morphological and ontogenetic pattern differences were collected among snails from four different populations, kept under the same laboratorial conditions. It was possible to distinguish characteristic shell morphometrics for snails from each population. The snails from Barra Mansa and Floriano, locations with smaller precipitation indexes presented smaller shell aperture values. The results are discussed in terms of the role of the reproductive strategy of this species as a factor determining shell shape.

CONCLUSIONS

Differences in growth allometry indicated that the whole shell forming process is different among the populations, not only the final form of the adult's shell. Some allometry relationships indicated that, during the snails' development, the increase in shell width is not proportional to the increase of the width and height of the shell aperture. Thus, there is possibly an antagonism between the adoption of K-strategy and protection against desiccation. Since the spire indices of L. unilamellata morphotypes cannot be explained by physical functional aspects, the most likely explanation is the reproductive strategy of this species.

Spatial distribution of Lymnaeidae (Mollusca, Basommatophora), intermediate host of Fasciola hepatica Linnaeus, 1758 (Trematoda, Digenea) in Brazil

Snails of the family Lymnaeidae act as intermediate hosts in the biological cycle of Fasciola hepatica, which is a biological agent of fasciolosis, a parasitic disease of medical importance for humans and animals. The present work aimed to update and map the spatial distribution of the intermediate host snails of F. hepatica in Brazil. Data on the distribution of lymnaeids species were compiled from the Collection of Medical Malacology (Fiocruz-CMM, CPqRR), Collection of Malacology (MZUSP), “SpeciesLink” (CRIA) network and through systematic surveys in the literature. Our maps of the distribution of lymnaeids show that Pseudosuccinea columella is the most common species and it is widespread in the South and Southeast with few records in the Midwest, North and Northeast regions. The distribution of the Galba viatrix, G. cubensis and G. truncatula showed a few records in the South and Southeast regions, they were not reported for the Midwest, North and Northeast. In addition, in the South region there are a few records for G. viatrix and one occurrence of Lymnaea rupestris. Our findings resulted in the first map of the spatial distribution of Lymnaeidae species in Brazil which might be useful to better understand the fasciolosis distribution and delineate priority areas for control interventions.

Raman spectroscopy as a tool for polyunsaturated compound characterization in gastropod and limnic terrestrial shell specimens

The colours of mollusc shells were determined using the Raman spectroscopy and these analyses suggest that the conjugated polyenes (carotenoids) and psittacofulvins are the organic pigments incorporated into their skeletal structures responsible by their colorations. The symmetric stretching vibration of the carbonate ion gives rise to a very strong Raman band at ca. 1089 cm(-1) and a weak band at 705 cm(-1), for all samples; the second band characterizes the aragonite as the inorganic matrix and can be used as a marker. The specimens show bands at 1523-1500 and at 1130-1119 cm(-1), assigned to the ν1 and ν2 modes of the polyenic chain vibrations, respectively. Another band at 1293 cm(-1), assigned to the CH=CH in-plane rocking mode of the olefinic hydrogen is also observed in all samples, which reinforces the psittacofulvin compound as the main pigment present in the analyzed samples.