Isopode terrestre de taille moyenne (10 mm) et capable de volvation, A. opacum présente un pattern similaire à celui d'A. vulgare, avec des nuances de brun et de gris. Son telson trapézoïdal et sa lame frontale basse n'apportent pas d'éléments d'identification et il faut regarder précisément le front de l'animal pour observer une fossette profonde entre la lame et le vertex, ce dernier étant orné de deux bosses rondes bien visibles, permettant une identification certaine. Le pléon est également un peu plus aplati que chez A. vulgare.
Détermination :
Détermination possible à vue et sur photo à condition de pouvoir observer correctement le vertex (vue par dessus). Les caractères mâles visibles sous binoculaire (exopodite du pléopode 1, péréiopode VII) permettent de confirmer le cas échéant.
Espèces proches :
Armadillidium vulgare, Armadillidium sordidum (dans le sud de la France)
Période d'observation :
L'espèce est active toute l'année.
Biogéographie et écologie :
Armadillidium opacum est une espèce boréo-alpine qui arrive en limite occidentale de distribution en France. Elle a colonisé une partie de l'Europe occidentale, atteignant la Finlande au nord et la Slovaquie à l'est. Dans notre pays, c'est une espèce sylvicole, plutôt présente dans les Alpes et le Jura et présentant une distribution fragmentaire ailleurs ; elle est récemment trouvée dans les grandes forêts du Loiret, marquant sa limite de distribution occidentale.
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
