World Congress of Malacology Antwerp ... - Unitas Malacologica

Freshwater snail diversity of Grande Island, Angra dos Reis, Rio de Janeiro, southeastern
Brazil
Santos, Sonia B.; Myiahira, Igor C.; Lacerda, Luiz Eduardo M.
Universidade do Estado do Rio de Janeiro, Instituto de Biologia Roberto Alcantara Gomes, Rua São
Francisco Xavier 524, PHLC 525-2, Departamento de Zoologia, Laboratório de Malacologia, CEP:
20550-900. Maracanã, RJ, Brasil,
Email: gundlachia@yahoo.com.br; sbsantos@uerj.br; icmyiahira@yahoo.com.br;
lacerdauerjbio@yahoo.com.br
The main goal of this study was to elaborate a taxonomic list and distribution map of the freshwater
snail biodiversity of Grande Island in order to support future studies on taxonomy, ecology as well as
monitoring biodiversity. Grande Island has protected remnants of tropical forests at highlands and
disturbed habitats at lowlands, being included in the Brazilian Atlantic Rainforest hotspot. The
invertebrate fauna, including freshwater snails is still poorly known. Within 192 km 2 we have 32
catchments including small rivers, waterfalls, wetlands with shallow seasonal waterbodies,
mangroves and two coastal lagoons. Intensive surveys were made since 2000, each catchment were
visited at least two times with five to eight collecting points in each explored waterbody. Three
people searched for snails for 15 minutes in the stream substrate, with a long handled metallic scoop
and by eye for 15 minutes in other possible habitats, as under garbage, stones, decayed leaves and
sticks. A total of nine species were found. Prosobranchia: Melanoides tuberculatus (Müller, 1774),
exotic, introduced perhaps after 2004, only at Vila do Abraão, the most populous village and
principal port of entry into Grande Island; Heleobia australis (d´Orbigny, 1835); Heleobia sp., only
into the two lagoons. Basommatophora: Biomphalaria tenagophila (d´Orbigny, 1835), one of the
natural vectors of Schistosoma mansoni Sambon, 1907, only at Vila do Abraão, recently transplanted,
perhaps after 2004 from continental adjacent areas; Antillorbis nordestensis (Lucena, 1954),
Ferrissia sp., Burnupia sp.; Gundlachia ticaga (Marcus & Marcus, 1962). Bivalvia: Pisidium
punctiferum (Guppy, 1867). Vila do Abraão shows seven of the listed species, probably because
accessibility. The very recent introduction of M. tuberculatus and B. tenagophila, probably by means
of aquarium releases, offers a remarkable opportunity to monitor invasion behavior of introduced
species, and to better understand invasive process, especially of M. tuberculatus, in an insular stream
in southeastern Brazil.
Diversity and altitudinal patterns of land snails in two mountains of Atlantic Rain Forest at
Grande Island, Angra dos Reis, Rio de Janeiro, southeastern Brazil
Nunes, Gleisse K.M.; Santos, Sonia B.
Universidade do Estado do Rio de Janeiro, Instituto de Biologia Roberto Alcantara Gomes, Rua São
Francisco Xavier 524, PHLC 525-2, Departamento de Zoologia, Laboratório de Malacologia, CEP:
20550-900. Maracanã, RJ, Brasil,
gkmnunes@yahoo.com.br; gundlachia@yahoo.com.br; sbsantos@uerj.br
Considering that species richness and density varies along elevational gradients, this study is the first
effort to describe altitudinal patterns of land snail diversity on the mountains of Atlantic Rain Forest,
one of the hotspots of biodiversity, at southeastern Brazil. Two mountains at Grande Island were
studied: one on the oceanic side (Jararaca Trail), other on the continental side (Pico do Papagaio
Trail). On each mountain, five areas with 100m elevation levels from 100m to 500m were chosen and
samples collected from December 2004 to February 2005. At each altitudinal level, terrestrial
molluscs were time searched for 3.5 hours and ten 25 x 75cm quadrats of litter were collected;
environmental data were also obtained. Simple correlation was performed with biological data to
generate the matrix used to cluster analysis. Biological groups identified as similar were used to the
discriminant analysis to point the environmental factor responsible for the clustering. A total of 994
specimens, 14 families and 38 species were collected (50% micromolluscs). The richness was similar
on both sides, but species composition and density were different perhaps due to environmental
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