| abstract | Mites of the genus Allothrombium Berlese have repeatedly been reported as predators of various aphid species infesting cultivated lucerne in Mediterranean parts of southern Europe and of the Middle East. Investigations made at sites located in the vicinity of Montpellier (southern France) have shown that the hexapod larvae had a truly epiparasitic behaviour and fed from host aphids of all sizes, whereas the mobile 8-legged deutonymphs and adults were general predators, with a distinct preference, however, for aphids and eggs of phytophagous species. The mite species involved could be reared through several successive generations under laboratory conditions, thus allowing for releable specimens of all developmental stases to be obtained in sufficient number. A detailed study of their morphology has revealed that none of the various stases of this acarian could be adequately correlated with any of the previously published descriptions. The larvae in particular differed so much from all other described species that erection of a new genus could be justified at a later stage. Allothrombium monspessulanum nov. spec. is described in its most typical larval and adult forms, the characters of the larva being particularly emphasized. |