A new species of Merizocotyle Cerfontaine 1894 (Monocotylidae) from the nasal tissues of deep-sea rajiform fishes in the Southwest Atlantic Ocean

IRIGOITIA, M.M.; CANTATORE, D.M.P.; DELPIANI, G.E.; LANFRANCHI, A.L.; TIMI, J.T.

Rio de Janeiro

Simposio; 7th International Symposium on Monogenea; 2013

Univ, Fed. Do Parana, Inst. Oswaldo Cruz, Univ. Fed. Rural do Rio de Janeiro

A new species of Merizocotyle (Monogenea: Monocotylidae) is described from specimens foundin the nasal tissues of rajiform skates collected in deep-sea waters of the Argentine Sea,Southwest Atlantic Ocean. In total, 42 adult specimens of Merizocotyle were collected from 128skates of the Family Rajidae, including 52 southern thorny skates Amblyraja doellojuradoi (Pozzi1935), 21 broadnose skates Bathyraja brachyurops (Fowler 1910), 22 shortfin sand skatePsammobatis normani McEachran 1983 and 33 yellownose skate Zearaja chilensis (Guichenot1848). Fourteen worms were found on A. doellojuradoii, 11 on B. brachyurops, 1 on P. normaniand 16 on Z. chilensis. The new species most closely resembles M. amplidiscata, M. diaphanaand M. pugetensis but can be distinguished from them by the number and distribution of thehaptoral loculi and by the morphology of the sclerotized male copulatory organ. According to thehaptoral morphology, species of Merizocotyle sensu Chisholm and Whittington (1999) aregrouped in 5 types. The new species represents a sixth haptoral type, which is characterized by 1central, 6 peripheral asymmetrical (one of them much smaller) and 18 marginal loculi.Furthermore, male copulatory organ of the new species is a straight sclerotized tube as in otherspecies, but is unique by having a complete loop in the distal end. With the purpose of analyzingwhether the specimens of different hosts are conspecific, comparisons among the morphologicalmeasures (taking as co-variable parasite Total Lenght) were carried out and no significantdifferences were found (p > 0,01). A new species of Merizocotyle is proposed, which represents a new record for this genus in the Southwest Atlantic Ocean.