Remarks on the morphology, life cycle, distribution and taxonomy of water mites of the subfamily Acherontacarinae in the Western Palaearctic

Abstract

The presence of lateral eyes and glandularia in adult water mites of the genus Acherontacarus is confirmed and several additional morphological particuliarities of adults are briefly discussed. Osmoregulatory acetabular organs are arranged on the coxae near leg insertions of larvae, deutonymphs, and adults. Acherontacarellus Lundblad, 1962, Acherontacaropsis Cook, 1967, and Neoacherontacarus Bader, 1989, are considered as synonyms of Acherontacarus K. Viets, 1932. The geographical distribution of Acherontacarus in the W palaearctic region is reviewed and includes the first records from Greece and Italy. Characters of main importance for species discrimination are the shape of the mouth-parts, the arrangement of idiosomal sclerites and the setation of the male fourth leg. First information is given on the phoresy of Acherontacarus larvae on dytiscid and hydraenid beetles. Significance of this phenomenon for bionomics of Acherontacarus is discussed. The unique larval character set can be considered as a case of ‘adultation’ in the sense of Jägersten (1972).