A new phoretic mite species with remarks to the phenomenon “Sporothecae” (Acari, Scutacaridae; Hymenoptera, Aculeata)

We provide the first description of the mite species Imparipes (Imparipes) burgeri n. sp. (Scutacaridae, Heterostigmatina). The species is recorded from localities in Austria, Belgium, Germany, Poland and Slovakia. A total of 759 females have been found phoretic upon 45 host species belonging to ground-nesting or parasitc on ground-nesting hosts apoid bees as well as upon mutillid and pompilid wasps, whereas the latter two groups have not yet been reported as phoretic hosts of scutacarid mites. In contrast to the bee- and wasp associated species Imparipes haeseleri Ebermann & Hall, 2003, I. breganti Ebermann & Hall, 2004 and I. apicola Banks, 1914, I. burgeri has – like the majority of Scutacaridae – no sporotheca. Rearing experiments with I. burgeri carried out on fungal species belonging to the genera Fusarium, Mortierella and some other still unidentified fungi revealed that I. burgeri is a distinct food opportunist. Whereas rearing of I. burgeri was successful, the breeding of the sporotheca possessing Imparipes species failed, presumably due to their high food specificity. These results support our hypothesis that the development of a distinct food specificity in some of the bee associated Imparipes could have led to the evolution of a targeted spore transfer by means of a sporotheca.