A total of 17 terrestrial crustacean species aliens to Europe of which 13 isopods (woodlice) and 4 amphipods (lawn shrimps) have established on the continent. In addition, 21 species native to Europe were introduced in a European region to which they are not native. Th e establishment of alien crustacean species in Europe slowly increased during the 20 th century without any marked changes during the recent decades. Almost all species alien to Europe originate from sub-tropical or tropical areas. Most of the initial introductions were recorded in greenhouses, botanical gardens and urban parks, probably associated with passive transport of soil, plants or compost. Alien woodlice are still confi ned to urban habitats. Natural habitats have only been colonized by three amphipod species in the family Talitridae.

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Se describe Porcellio wadianae sp. nov. (Crustacea: Oniscidea: Porcellionidae) de la región de Extremadura, España, Península Ibérica. La nueva especie puede clasificarse dentro del llamado “grupo Atlántico” del género Porcellio, definido por Vandel. Se caracteriza por tener un sistema glandular tegumentario poco común en este género y por otras características que lo diferencian del resto de especies del mismo grupo presentes en la región ibero-macaronésica y norteafricana. Además, presentamos observaciones adicionales sobre otras especies recolectadas en Extremadura, una de las regiones menos conocidas de España en lo que se refiere a su fauna de isópodos terrestres.

Isoprenoid quinones are essential for cellular physiology. They act as electron and proton shuttles in respiratory chains and various biological processes. Escherichia coli and many α-, β-, and γ-proteobacteria possess two types of isoprenoid quinones: ubiquinone (UQ) is mainly used under aerobiosis, while demethylmenaquinones (DMK) are mostly used under anaerobiosis. Yet, we recently established the existence of an anaerobic O 2 -independent UQ biosynthesis pathway controlled by ubiT , ubiU , and ubiV genes. Here, we characterize the regulation of ubiTUV genes in E. coli . We show that the three genes are transcribed as two divergent operons that are both under the control of the O 2 -sensing Fnr transcriptional regulator. Phenotypic analyses using a menA mutant devoid of DMK revealed that UbiUV-dependent UQ synthesis is essential for nitrate respiration and uracil biosynthesis under anaerobiosis, while it contributes, though modestly, to bacterial multiplication in the mouse gut. Moreover, we showed by genetic study and 18 O 2 labeling that UbiUV contributes to the hydroxylation of ubiquinone precursors through a unique O 2 -independent process. Last, we report the crucial role of ubiT in allowing E. coli to shift efficiently from anaerobic to aerobic conditions. Overall, this study uncovers a new facet of the strategy used by E. coli to adjust its metabolism on changing O 2 levels and respiratory conditions. This work links respiratory mechanisms to phenotypic adaptation, a major driver in the capacity of E. coli to multiply in gut microbiota and of facultative anaerobic pathogens to multiply in their host. IMPORTANCE Enterobacteria multiplication in the gastrointestinal tract is linked to microaerobic respiration and associated with various inflammatory bowel diseases. Our study focuses on the biosynthesis of ubiquinone, a key player in respiratory chains, under anaerobiosis. The importance of this study stems from the fact that UQ usage was for long considered to be restricted to aerobic conditions. Here we investigated the molecular mechanism allowing UQ synthesis in the absence of O 2 and searched for the anaerobic processes that UQ is fueling in such conditions. We found that UQ biosynthesis involves anaerobic hydroxylases, that is, enzymes able to insert an O atom in the absence of O 2 . We also found that anaerobically synthesized UQ can be used for respiration on nitrate and the synthesis of pyrimidine. Our findings are likely to be applicable to most facultative anaerobes, which count many pathogens ( Salmonella , Shigella , and Vibrio ) and will help in unraveling microbiota dynamics.