In 2007 an unusual crayfish found in food markets in the capital of Madagascar was preliminarily identified as Procambarus 'Marmorkrebs': a new world taxa and the only decapod known to reproduce by parthenogenesis. We present information on the identity, distribution and ecology of this recent invader and attempt to evaluate the threat it poses to Madagascar's biodiversity and to livelihoods. The species appears to be currently limited to the area close to Antananarivo, but is being sold alive on major transport routes. We present molecular evidence of its taxonomic relationships and confirm that the Procambarus present in Madagascar is indeed the parthenogenic taxa. We investigate its reproductive ecology and find Procambarus 'Marmorkrebs' to have an extremely high fecundity; more than six times that of the native crayfish Astacoides. The limited evidence we have suggests that this species poses a serious threat to freshwater biodiversity and that it is likely to damage human livelihoods (through its impact on fishing and possibly rice agriculture). More research is urgently needed but in the meantime action is needed to reduce the rate of spread before it is too late.

Malagasy poison frogs of the genus Mantella are diurnal and toxic amphibians of highly variable and largely aposematic coloration. Previous studies provided evidence for several instances of homoplastic colour evolution in this genus but were unable to sufficiently resolve relationships among major species groups or to clarify the phylogenetic position of several crucial taxa. Here, we provide cytochrome b data for 143 individuals of three species in the Mantella madagascariensis group, including four newly discovered populations. Three of these new populations are characterized by highly variable coloration and patterns but showed no conspicuous increase of haplotype diversity which would be expected under a scenario of secondary hybridization or admixture of chromatically uniform populations. Several populations of these variable forms and of M. crocea were geographically interspersed between the distribution areas of Mantella aurantiaca and Mantella milotympanum . This provides further support for the hypothesis that the largely similar uniformly orange colour of the last two species evolved in parallel. Phylogenies based on over 2000 bp of two nuclear genes ( Rag-1 and Rag-2 ) identified reliably a clade of the Mantella betsileo and Mantella laevigata groups as sister lineage to the M. madagascariensis group, but did not support species within the latter group as monophyletic. The evolutionary history of these frogs might have been characterized by fast and recurrent evolution of colour patterns, possibly triggered by strong selection pressures and mimicry effects, being too complex to be represented by simple bifurcating models of phylogenetic reconstruction.

Madagascar's endemic freshwater crayfish (Parastacidae: Astacoides) are harvested by local people for both subsistence use and small-scale trade. There has been concern that populations, and even species, are threatened by overexploitation but little is known about the harvest or its economic importance. We studied crayfish exploitation in eastern Madagascar over 3 years. The existence of local taboos (fady) preventing commercial crayfish harvesting, as well as access to markets and forest, influenced involvement in the harvest. All four crayfish species found in the region were harvested, but A. granulimanus provided the majority of the catch. In one harvesting village more than 50% of the 47 households were directly involved in the harvest, which contributed USD 2,382 to the village economy in 2003/2004, an important sum in the context of local incomes. Subsistence use was widespread, particularly by children to whom it may provide an important protein source.Community-based conservation (through transfer of harvesting rights and responsibilities for forest management to local communities) is central to a new conservation paradigm in Madagascar. This recognizes communities' long term interest in their natural resources and offers an ideal opportunity for those concerned with the sustainability of the harvest to implement management tools (such as avoiding reproductive females, size limits and no-take zones). We discuss each tool with respect to biological implications and practical constraints. We note that community-based approaches may not be sufficient to conserve rarer species, which make up a small proportion of the value of the harvest.

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