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

IRIGOITIA, MANUEL; CANTATORE, DELFINA; DELPIANI, GABRIELA; LANFRANCHI, ANA L.; TIMI, JUAN TOMÁS

Rio de Janeiro

Simposio; 7th Internacional Symposium on Monogenea, 4 al 9 de Agosto de 2013, Rio de Janeiro, Brasil; 2013

A new species of Merizocotyle (Monogenea: Monocotylidae) is described from specimens found in 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 128 skates of the Family Rajidae, including 52 southern thorny skates Amblyraja doellojuradoi (Pozzi 1935), 21 broadnose skates Bathyraja brachyurops (Fowler 1910), 22 shortfin sand skate Psamobatis normani McEachran 1983 and 33 yellow nose skate Zearaja chilensis (Guichenot 1848). Fourteen worms were found on A. doellojuradoi, 11 on B. brachyurops, 1 on P. normani and 16 on Z. chilenis. The new species most closely resembles M. amplidiscata, M. diaphana and M. pugetensis but can be distinguished from them by the number and distribution of the haptoral loculi and by the morphology of the sclerotized male copulatory organ. According to the haptoral morphology, species of Merizocotyle sensu Chisholm and Whittington (1999) are grouped in 5 types. The new species represents a sixth haptoral type, which is characterized by 1 central, 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 other species, but is unique by having a complete loop in the distal end. With purpose of analyzing whether the specimens of different hosts are conspecific, comparisons among the morphological measures (taking as co-variable parasite Total Length) were carried out and no significant differences 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.