Le corps de cette espèce est allongé, arrondi aux extrémités et sa surface est plus ou moins rugueuse. Le thorax est constitué de 7 segments qui portent chacun une paire de pattes locomotrices, toutes de même longueur. Les segments abdominaux sont en partie soudés et il ne semble y avoir que 2 segments ; l'abdomen se termine postérieurement par le pléotelson dont les bords latéraux sont presque parallèles et l'extrémité est tronquée. Sa couleur est gris-brun à bleu noir. La longueur de cet isopode peut atteindre 3 cm chez le mâle ; la femelle est plus petite.
Détermination et espèces proches.
L'identification de l'espèce est moyennement difficile car il existe plusieurs autres espèces morphologiquement assez voisines.
Période d'observation.
Les adultes de cette espèce s'observent toute l'année.
Biologie-éthologie.
La biologie de cette espèce est mal connue. Après la ponte, la femelle incube sa progéniture entre les pattes. Il n'y a pas de larve planctonique ; la femelle libère des juvéniles.
Écologie et distribution.
L'espèce vit en haute mer sur les objets flottants comme des algues et des bois flottants à la dérive. On la trouve aussi parfois avec les anatifes. On qualifie ce mode de vie de neustonique. L'espèce est quasi cosmopolite : elle a une vaste distribution géographique dans les mers chaudes et tempérées.
P. Noël(UMS 2006 Patrimoine Naturel (AFB / CNRS / MNHN)),2017
The map presents a summary at the 10 x 10 km grid of the observation data for the species transmitted to the SINP. These data have been subjected to validation filters.
Distribution map from the Atlas of Departmental Biodiversity and Marine Sectors program
Current distribution in metropolitan France
The map presents a reference distribution layer of the species at the scale of departments and marine sectors. The presence and absence data were established by expertise within a network of partners. This reference distribution is used in the validation process of the SINP data at the INPN level.
Distribution map from the Atlas of Departmental Biodiversity and Marine Sectors program
Certain presence
Corresponds to a report on the basis of at least one observation proved within a period of 10 years (20 years for little-known invertebrates) preceding the year and no presumption of extinction since obtaining the last data nor doubt on reproductive and implemented nature of this population. For migratory species, the presence indicated concerns areas of reproduction.
Probable presence
This status is based on one or more of the following criteria:
search of species incomplete but presence of supportive environments;
ecology of the species consistent with the hypothesis of his presence;
the last reliable sighting is older than 10 years compared to the reference date, no recent specific research and no presumption of extinction from that date [vertebrates, invertebrates and plants well studied (rhopalocera, grasshoppers, dragonflies ...)] ;
the last reliable observation being older than 20 years, no recent specific research and no presumption of extinction from that date [poorly known taxa: fungus, many invertebrates...].
Probable or certain absence
This point covers the absence, more difficult by nature to demonstrate than presence. This status is based on one or more of the following criteria:
intensive but unsuccessful targeted research;
lack of adequate environments;
unobserved species while its presence is easily detected;
unlikely presence for historical or biogeographical reasons.
This status must be assigned to a department in which the presence of the species is casual.
Absence due to a proven extinction
Particular case of absence due to a proven extinction less than a half century ago (older disappearances are treated as "no probable or definite").
No information
In the state of knowledge, we can not comment on the presence or absence in the current department. This is the default status when not comprised in one of the previous categories or whenever there is doubt.
French Version
