ABSTRACT: The crayfish parasite 'Psorospermium haeckeli', which supposedly includes several species, is reported for the first time from the stone crayfish Austropotamobius torrentium. The infected specimens were from the Kammlach river in Bavaria (Germany), a place where A. torrentium and the noble crayfish Astacus astacus have coexisted for more than 20 yr. Screening of the mixed crayfish population for P. haeckeli revealed that both species were infected with the elongate morphotype of P. haeckeli which is typical of A. astacus. The distribution pattern of the parasite was similar in both species; most spores were in the collagenous wall of the blood vessels and the subepidermal connective tissue underneath the carapace. In the noble crayfish there was practically no immune response against P. haeckeli, whereas in the stone crayfish ca 10% of the spores were encapsulated by haemocytes, and approximately 1% were melanised. Since stone crayfish collected from other creeks were free of P. haeckeli, we presume that the parasite may have been transmitted to A. torrentium from A. astacus.

KEY WORDS: Psorospermium haeckeli . Astacus astacus . Austropotamobius torrentium . Crayfish . Parasite

Published in DAO Vol. 25, No. 3 (1996) on June 6
ISSN: 0177-5103. Copyright © Inter-Research, Oldendorf/Luhe, 1996