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The prize sponsored by the Conchological Society of Great Britain and Ireland, for the best student poster on a conservation / biodiversity theme was awarded to Joaquim Reis, a PhD student at the University of Lisbon, Portugal, for his poster (presented jointly with Rafael Araujo from Spain).

The title of the poster was: Unio tumidiformis Castro 1885: A highly endangered endemic species (Bivalvia: Unionidae) from the south-western Iberian Peninsula.

The prize comprised an award of €750 and two years' membership of the Society.

Here is a slightly edited version of his abstract:

There are several endangered species of unionid mussels in Europe, notably Margaritifera margaritifera, M. auricularia, Unio crassus and U. mancus, but our poor knowledge of the systematics and taxonomy of the group jeopardises the efficiency of our conservation efforts.

Following our recognition, using molecular phylogenetic analysis, that Portuguese Unio crassus (sensu Haas) was an endemic form, we redescribed this species that was first designated as Unio tumidiformis Castro, 1885. We revised the collections in the Natural History Museums in Lisbon, Coimbra and Porto (Portugal), Madrid (Spain) and Paris (France). It shares some morphological characters with central and northern European populations of U. crassus, its genetic sister species, but it is clearly distinct from all other European Unio.

We made many samples throughout the Iberian Peninsula, and analysed distribution, morphology and anatomy and life cycle in U. tumidiformis populations, where it was found.

U. tumidiformis is restricted to the southern Atlantic basins of the Iberian Peninsula, mainly in the Guadiana basin. It is a small species, rarely more than 5 cm long, and it is very uncommon; many populations seem to be represented by only a few individuals. It lives in small streams, buried in fine sediment near the banks. Females with glochidia can be found between March and July. The glochidia are 200æm in length, and they are released as a loose conglutinate. Five fish species in the genus Squalius were good hosts for the species. Metamorphosis takes place over 10 days at an average temperature of 22° C.

Neither habitat nor the distributions of the fish hosts explain its restricted distribution, which must have its origin in a long history of isolation.

U. tumidiformis will keep the legal conservation status accorded to U. crassus in the EU Habitats Directive, but its very restricted distribution, its rarity, and the sensitivity of its habitat to more frequent and extreme droughts require that special attention be paid to it.