World Congress of Malacology Antwerp ... - Unitas Malacologica

work consisted on the installation, in October 2001, an experiment in casual blocks where a pasture
of rye-grass and white clover was sown. The experimental units are composed of 20 plots with 3m x
1.3 m area (four replicates by each treatment, at random).
During 2004 and 2005 year, molluscs were sample during the spring and autumn of each one. The
most important parameters in terms of soil were done too. Species Richness and Abundance,
Margalef, Shannon diversity indices and Smith and Wilson evenness index were also used to
analysing possible differences on mollusc community. The results shown that Dairy-sludge
treatment promoted the most species richness and highest diversity (H¨). From un-transformed land
surrounding sward (control), five species were sample: Deroceras reticulatum, Arion ater, Arion
intermedius, Cepaea nemoralis, and Portugala inchoata.
From dairy-sludge amended, four species were found: D. reticulatum, A. ater, A. intermedius and
Ponentina subvirescens.
From the remainder treatments (mineral, poultry dung and cattle slurry) only three species were
found: D. reticulatum, A. ater and A. intermedius.
Dairy-sludge amendment was related with a more Nitrogen addition to soil, and with the lower C/N
ratio.
Taxonomy and phylogenetic relationships of Nicaraguan freshwater mussels (Bivalvia:
Unionidae)
Roe, Kevin J. 1 ; Robinson, Stephen 1 ; Lopez de la Fuente, Adolfo 2
1. Iowa State University, Ames, Iowa 50011, USA,
Email: kjroe@iastate.edu; srobins@iastate.edu
2. University of Central America, Managua, Nicaragua,
Email: alosi@ns.uca.edu.ni
Lake Nicaragua is one of the largest lakes in the Western Hemisphere and was formed due to tectonic
and volcanic activity < 3million years ago. The lake is home to a number of species of freshwater
mussels, found nowhere else in the world, that were described in the middle part of the 19th century.
These descriptions were based on shell characters, and do not allow for clear identification of species
and that make the taxonomic placement of these mussels relative to other unionids difficult to assess.
Following a literature review and examination of existing museum holdings, a collecting trip to Lake
Nicaragua (Cocibolca) and the surrounding area was undertaken in 2006. The purpose of this trip was
to collect materials for a re-description of these taxa, and if possible to make observations on the
natural history of these organisms. Newly collected material will be identified by comparison to type
material and taxonomic descriptions. The revised descriptions of Nicaraguan mussels will be
prepared in a monographic format and include descriptions of soft anatomy, conchology, and
glochidia, observations on natural history and reproductive period. In addition, tissue samples were
taken for molecular phylogenetic analyses to develop hypotheses for relationships between these taxa
and the phylogenetic affinities to North American unionids. Examination of museum specimens has
identified seven nominal unionid species in three genera. Preliminary analysis of DNA sequence data
indicates that Nicaraguan unionids mussels are relatively derived members of two North American
unionid clades: the Amblemini and the Lampsilini, but indicate little genetic differentiation between
putative Nicaraguan species within these clades. These results have implications for the evolution of
reproductive traits with the Unionidae and highlight the need for more extensive taxonomic sampling
in future systematic studies of this diverse group.
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