World Congress of Malacology Antwerp ... - Unitas Malacologica

activity might alter the sex-specific resource allocation towards the female function by reducing the
mating frequency of infected A. arbustorum.
Simultaneous ambivalent reproductive strategy in the sessile gastropod Vermetus rugulosus
Monterosato, 1878 (Gastropoda: Prosobranchia)
Scuderi, Danilo; Cantone, Grazia
Department of Animal Biology – Catania University, via Androne, 81, 95124 Catania, Italy,
Email: danscu@tin.it
Vermetids, worm-like sessile molluscs distributed within a restricted tropical and sub-tropical
latitudinal range, have not been hitherto considered capable of high diffusion: among the very few
papers on the reproductive biology of vermetids, only few species are reported to have planctotrophic
larvae, while direct intracapsular development seems to be the most common strategy adopted by the
majority of the species. These data seem to be in contrast with those of the biogeographical
distribution of the species.
Vermetus rugulosus Monterosato, 1878 is a very small, but well defined Mediterranean species,
whose intracapsular mode of reproduction has olready been described in detail. Along with
reproductive pattern studies conducted by the author on some species of Vermetidae, seasonal
samplings of living V. rugulosus were carried out along the E-Sicily coast: some specimens were
dissected and the capsulae extracted and observed for morphometric analysis; others were stored in
aquaria for observations on spawnings. Summer samples have confirmed the intracapsular mode of
development of this species, while winter samples have revealed to have an ambivalent production of
veligers and crawling juveniles, hatching simultaneously from the same capsule. Considerations on
the real distribution capability of this species are here presented too, in the light of such new
reproductive observations.
Inventories for the Dark Continent: compiling African checklists
Seddon, Mary 1 ; Rowson, Ben 1 ; Tattersfield, Peter 1 ; Lange, Charles 2 ; Ngereza, Christine 3
1. Dept. Biodiversity & Systematic Biology, National Museum of Wales, Cathays Park, Cardiff, UK
CF10 3NP,
Email: Mary.Seddon@museumwales.ac.uk
2. Dept. Invertebrate Zoology, National Museum of Kenya, PO Box 40658-00100, Nairobi, Kenya,
Email: nvazi2001@yahoo.com
3. Village Museum, National Museum of Tanzania, PO Box 511, Dar es Salaam, Tanzania,
Email: cngereza@yahoo.com
We estimate that the land snail fauna of Africa contains over 3400 taxa based on the regional species
inventories. Most of the species descriptions come from the periods of colonial expansion between
1860 and 1960. These are in scattered monographs and papers containing brief descriptions and
drawings with types are widely dispersed in European and American Museums.
Since 1993 we have surveyed sites in Kenya, Tanzania and Uganda. Consequently we know that the
country lists published by Verdcourt are incomplete. We have found morpho-species that represent
either local variants of species known from other mountain ranges or undescribed species; these are
the subject of ongoing research.
At present most new species are micro-molluscs (under 5 mm) rather than the larger shelled taxa.
Many of the recently described species are from the Streptaxidae, a family that dominants the East
African fauna (c. 40% of species). These species have distinctive shell forms as well as distinctive
anatomical characters (see Rowson, this volume). We believe that the Family Punctidae, Subulinidae,
Vertiginidae and Urocyclidae also hold new taxa. Some of these families would benefit from a major
revision across the region as anatomical data is required to define species limits, however alcohol
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