Wolbachia bacteria are obligate intracellular alpha-Proteobacteria of arthropods and nematodes. Although widespread among isopod crustaceans, they have seldom been found in non-isopod crustacean species. Here, we report Wolbachia infection in fourteen new crustacean species. Our results extend the range of Wolbachia infections in terrestrial isopods and amphipods (class Malacostraca ). We report the occurrence of two different Wolbachia strains in two host species (a terrestrial isopod and an amphipod). Moreover, the discovery of Wolbachia in the goose barnacle Lepas anatifera (subclass Thecostraca) establishes Wolbachia infection in class Maxillopoda. The new bacterial strains are closely related to B-supergroup Wolbachia strains previously reported from crustacean hosts. Our results suggest that Wolbachia infection may be much more widespread in crustaceans than previously thought. The presence of related Wolbachia strains in highly divergent crustacean hosts suggests that Wolbachia endosymbionts can naturally adapt to a wide range of crustacean hosts. Given the ability of isopod Wolbachia strains to induce feminization of genetic males or cytoplasmic incompatibility, we speculate that manipulation of crustacean-borne Wolbachia bacteria might represent potential tools for controlling crustacean species of commercial interest and crustacean or insect disease vectors.

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Several morphological races and subspecies have been described and later included within the terrestrial isopod species Porcellionides pruinosus. During our study of this species, we have worked on specimens from France, Greece, Tunisia and Re union island. Laboratory crosses have revealed two separate groups of populations: French populations (four localities) in one group, and those from Tunisia, Re union island and Greece in the other. French individuals were reproductively isolated from those of the other populations. We have undertaken a survey of mitochondrial DNA (mtDNA) polymorphism in these seven populations. We observed two groups of mitotypes corresponding to the two groups of populations. Interfertility experiments between populations and the mitochondrial genetic distances between mitotypes both suggest the presence of two di erent species, one in France and one in Greece, Tunisia and Re union island. The two species harbour, respectively, two di erent Wolbachia lines. Another feature of the molecular genetic analysis was the apparent mitochondrial monomorphism in the French populations and the low variability in the other three populations. The result can be related to the possibility of Wolbachia-induced genetic hitchhiking in these populations.