World Congress of Malacology Antwerp ... - Unitas Malacologica

ABSTRACTS
Contribution to the revision of the biodiversity of Tunisian terrestrial Malacofauna
Abbes, Intidhar 1 ; Nouira, Saïd 2
1. Unité de recherches: Biodiversité et Biologie des populations, Institut Supérieur des Sciences
Biologiques Appliquées de Tunis, 9 Rue Mohamed Essafi, la Rabta, 1007, Tunis, Tunisie,
Email: intidharabbes@yahoo.fr
2. Institut Supérieur des Sciences Biologiques Appliquées de Tunis, 9 Rue Mohamed Essafi, la
Rabta, 1007, Tunis, Tunisie,
Email: saidnouira@yahoo.fr
Historical studies and our recent prospections in Tunisia led to the record of twenty-seven species of
terrestrial Gastropoda three of which are reported for the first time: Ponentina subvirescens (Bellamy,
1839), Limax flavus (Linnaeus, 1758) and Obscurella septemspirale (Razoumowsky, 1789). Except
for two prosobranch species (Pomatias sulcata and Obscurella septemspirale), all species belong to
14 families and 21 genera from the Pulmonate sub-class. Moreover, a comprehensive study, based on
recent field work, and conchological and anatomical survey, has been undertaken in order to discuss
the taxonomy of the recorded species, and to set up an updated check list of the Tunisian terrestrial
malacofauna.
Furthermore, the geographical distribution study of the different recorded species in some
heterogeneous biotopes shows a significant variation in the general distribution area in response of
the different abiotic factors. This allows defining some ecological affinities of the species and
showing their abilities to cope with the climatic variability.
Land snails microcosm preserved:
Good news from Mayotte, Comoro Islands
Abdou, Ahmed; Bouchet, Philippe; Muratov, Igor
Muséum National d'Histoire Naturelle, USM 602 Taxonomie et collections, 55 rue Buffon, 75005
Paris, France
Email: abdou@mnhn.fr
Concomittant with habitat loss, numerous species extinctions have taken, and are taking, place in the
land snail faunas of many tropical oceanic islands. Located in the northern part of the Mozambique
Channel, Mayotte, the easternmost island of the Comoros Islands, is also the oldest (7-8 My old) and
has an overall area of 375 km 2 (~ 40x15 km). Ninety native species of land snails and slugs were
historically recorded from Mayotte, of which 41 (46%) are endemic to that single island.
Human pressure on the environment is now considerable: population density is estimated to be
around 700 per sq. km, and fragmented primary forests occupy roughly only 5% of the land. Forest
pockets occupy the steeper slopes and are separated by low rolling hills with secondary agroforests,
cultivated lands, fallows and bad lands. As no recent land snail survey has taken place on Mayotte
since the 1880s, it was to be feared that its rich and unique fauna had followed the fate of many
tropical island land snail faunas. Unexpectedly, a survey carried out in 2001 and 2002 found out that,
despite considerable habitat changes, this faunule has survived well. At least 96 species were
censused, including 56% single-island endemics and ca. 20 new species; species not seen for more
than 100 years were found alive. The extraordinary radiations of Streptaxidae (35 species, 21
endemic), Charopidae (11 species, 9 endemic), Subulinidae (6 species, 3 endemic), and
Cyclophoridae (7 species, 5 endemic) were newly documented.
Mayotte deviates from other tropical islands in that even anthropicized habitats contain endemic
species and secondary forests remain largely dominated by native and/or endemic species.
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