The water mite family Pontarachnidae, with new data on its peculiar morphological structures (Acari: Hydachnidia)

The water mite family Pontarachnidae Koenike is the only family of the water mites (Hydrachnidia) occurring in the marine environment. Two genera of this family are known, Pontarachna Philippi and Litarachna Walter. Until now, this has been one of the least known water mite families. This paper gives an overview of our knowledge on this enigmatic family. For the first time, ultrastructural details are reported based on a study of Litarachna communis. Peculiarities of the cuticle, the so-called wheel-like acetabula, the glandular systems, the digestive system, the dorsomedian excretory organ, and the male genital system are reported.