CONSERVATION PRIORITIES FOR FOREST-FLOOR INVERTEBRATES OF THE SOUTHEASTERN HALF OF MADAGASCAR - EVIDENCE FROM 2 LAND-SNAIL CLADES

Leaf litter and soil of tropical forests harbour some of Earth's most diverse, most endangered, yet least understood biological communities. How well do east-southeast Madagascar's reserves protect this resourc e? A preliminary answer is provided by the landsnail genera Cyclophori dae Boucardicus and Charopidae n. gen., as represented by 3680 specime ns in 64 species, collected 1990-1993 from 129 stations in 26 transect s, with nine reserves included. These two genera qualify as indicator/ target taxa because they are endemic, species-rich, well-defined clade s, sensitive to environmental degradation, with species readily identi fiable by shells alone. Indices of diversity and endemism were used to rank 12 bioclimate-latitude regions by priority for conservation/coll ection. The higher-priority regions generally have some forest nominal ly conserved, of which the lowland-rainforest reserves of Manombo, Kia njavato, and Betampona are especially rich. A crucial exception, howev er, is the highest-priority region: the coastal-montane rainforests to the north of Tolagnaro (Fort Dauphin), which are completely unprotect ed and are rapidly being destroyed. (Andohahela Reserve lies westward, where diversity and endemism are 60% and 20% lower, respectively, so it conserves less than a fourth of the general region's endemic divers ity.)