La taxonomie, la répartition et l'écologie de l'ensemble de la faune ouest-africaine de crabes d'eau douce, complétées par les dernières avancées en phylogénie et en biogéographie. ©Electre 2024

The area of West Africa covered by this book includes eighteen countries from Mauritania to Cameroon and Bioko (Equatorial Guinea). The West African freshwater crab fauna comprises at least thirty-two species in seven genera and two families. This work brings together recent contributions to the taxonomy, distribution, and ecology of the West African freshwater crabs and presents new information on phylogeny and biogeography (in 13 Tables, 69 pages of Figures, and 4 Plates). Four new species are added to the faunal list of the region and a new family, the Platythelphusidae Colosi, 1920 is established.

The phylogenetic relationships of the freshwater crabs of West Africa were examined by means of a cladistic analysis (using PAUP 3.1) that employed thirty-three morphological characters from thirty-two ingroup taxa and five outgroup taxa. Five most parsimonious trees (all with 55 steps, a consistency index of 0.75, and a retention index of 0.79) group the West African species into two lineages, the Potamonautidae and the Globonautinae.

Morphometric relationships of the dimensions and proportions of the carapace revealed trends in changes in the width, length and height of the carapace of species within a genus that could be correlated with the habitat and lifestyle of each species.

The thirty-two species of freshwater crabs found in the West African region are arguably the most diverse in Africa and represent about one-third of the species and subspecies presently known from the continent. Species diversity within the West African region clearly depends on vegetation type, where the highest numbers of species occur in rainforest ecosystems, and the fewest in savanna ecosystems. The species composition of the freshwater crab fauna is distinctly different between the Upper Guinea forest (from Guinea to Togo) and the Lower Guinea forest (Nigeria, Cameroon and Central Africa). The Pleistocene forest refuge hypothesis, which postulates past faunal refuges in small areas of stable, undisturbed forest in West and Central Africa, is supported by distributional data presented here. Aspects of the biology of the West African freshwater crabs, including the respiratory system, reproductive system, growth patterns, development, and ecology are also discussed.