Zimmermann, G., Bosc, P., Valade, P., Cornette, R., Améziane, N. and Debat, V. 2011. Geometric morphometrics of carapace of Macrobrachium australe (Crustacea: Palaemonidae) from Reunion Island. —Acta Zoologica (Stockholm) 93: 492–500.
We investigated the structure of carapace shape variation in six populations of Macrobrachium australeGuérin-Méneville 1838 (Crustacea: Decapoda: Palaemonidae) from Reunion Island (Indian Ocean) freshwaters. The morphometric analysis revealed the occurrence of two morphotypes corresponding to two different types of habitats. Individuals living in lotic habitats present a thick carapace armed with a short, robust and straight rostrum, while individuals from lentic habitats have a slender carapace armed with a thin long rostrum orientated upward. This difference suggests an adaptation to lotic disturbances and is tentatively interpreted as adaptive phenotypic plasticity. In such amphidromous organisms regressing to freshwaters after a marine larval phase, selection for physiological and developmental flexibility might facilitate further adaptation and allows the colonisation of a wide panel of environmentally different and sometimes geographically distant insular streams.