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

BARÓN, PEDRO J.; LEAL, GUSTAVO A.; CARSEN, ANDRES; KROECK, MARINA A; MORSAN, ENRIQUE M.; KROECK, MARINA A.

DISEASES OF AQUATIC ORGANISMS

INTER-RESEARCH

Lugar: Oldendorf/Luhe; Año: 2021

0177-5103

The rhizocephalan parasite-brachyuran host system formed by a still undetermined rhizocephalan and the Patagonian stone crab Danielethus (Platyxanthus) patagonicus (A. Milne-Edwards, 1879) was analyzed northern Patagonia. Out of 3222 crabs sampled, mean prevalence based on the presence of externae was 2.08 %, while corrected mean prevalence based on observation of externae, scars or other indication of infestation 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 of them were observed in some few individuals. The parasite externae were only present in medium-sized crabs. A direct positive relationship was found between the maximum width of the parasite externa and the abdomen width of host crabs. 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 to the genus Sacculina.