Les Cercyon sont de petits Hydrophilidae surtout terrestres, mais semi-aquatiques pour quelques uns. C. ustulatus fait partie de ces derniers et appartient au sous-genre Dicyrtocercyon dont il est le seul représentant en Europe. Il est noir brillant avec la partie postérieure du corps rougeâtre et se reconnait aisément à la convexité très forte du pronotum, différente de celle des élytres. Observé de profil, l'insecte dessine ainsi une courbe discontinue, contrairement à ce qui est constaté chez les autres espèces du genre. La couleur rougeâtre des palpes maxillaires est également un indice complémentaire utile.
Détermination :
Assez difficile sur photo d'ensemble.
Espèces proches :
La convexité particulière du pronotum de C. ustulatus constitue un caractère très distinctif parmi le genre Cercyon et observable relativement facilement, ce qui diminue le risque de confusion.
Période d'observation :
Adulte rencontré presque toute l'année, surtout du printemps à l'automne.
Biologie-éthologie :
Se développe au bord des eaux stagnantes ou courantes, dans la vase, sous les pierres, dans les détritus végétaux en décomposition ou les mousses mais aussi dans les bouses et crottins.
Biogéographie et écologie :
Espèce assez fréquente, présente depuis le Portugal et l'Irlande jusqu'à la Scandinavie, la Russie et la Turquie ainsi qu'en Amérique du Nord.
Queney P. et Prévost P. 2021. Clé d'identification des Coléoptères aquatiques de France métropolitaine Myxophaga, Polyphaga Hydrophiloidea (adultes). Tome 1.
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
