Rhizocephalan infection in the Patagonian stone crab Danielethus patagonicus (A. Milne-Edwards, 1879)

BARÓN, PJ; LEAL, GA; CARSEN, AE; KROECK, MA; MORSAN, EM

DISEASES OF AQUATIC ORGANISMS

INTER-RESEARCH

Lugar: Oldendorf/Luhe; Año: 2021

0177-5103

The system formed by a still unidentified rhizocephalan infecting the Patagonian stone crab Danielethus (Platyxanthus) patagonicus (A. Milne-Edwards, 1879) was analyzed in northern Patagonia. Out of 3222 crabs sampled, mean prevalence of externae was 2.1 %, while corrected mean prevalence based on observation of externae, scars or other indications of infection was slightly higher (3.01%; N = 2100). Prevalence was higher in males (4.47%) than in females (1.44%). Parasitized males were morphologically feminized, while females showed no hyper-feminization. Although most parasitized crabs showed only one externa, two externae were observed in some individuals. The parasite externae were only present in intermediate-sized crabs (26.6-99.7 cm CW). While SEM images allowed detecting "smooth-surface-ballon" type of retinacula on the inner surface of the externae, typical of the Sacculinidae and Peltogastridae, position of the mantle opening relative to the stalk, receptacle location and shape of the externae suggest that the parasite belongs either to the genera Sacculina or to the recently erected Parassaculina (Polyascidae).