The description of two new species of Chloromyxum from skates in the Argentine Sea reveals that a limited geographic host distribution causes phylogenetic lineage separation of myxozoans in Chondrichthyes

CANTATORE, DELFINA M. P.; IRIGOITIA, MANUEL M.; HOLZER ASTRID S.; BARTO?OVÁ-SOJKOVÁ PAVLA ; PECKOVÁ HANA ; FIALA IVAN; TIMI, JUAN T.

PARASITE-JOURNAL DE LA SOCIETE FRANCAISE DE PARASITOLOGIE

PRINCEPS EDITIONS

Lugar: Paris; Año: 2018

1252-607X

During a survey on the myxosporean fauna of Rajiformes from the Argentine Sea (38º-42ºS), the gall bladders of 217 specimens belonging to seven species of skates, representatives of two families were examined. As a result three species of Chloromyxum Mingazzini, 1890 infecting three endemic host species, the spotback skate Atlantoraja castelnaui (Miranda Ribeiro, 1907) (Arhynchobatidae), the yellownose skate Zearaja chilensis (Guichenot, 1848) (Rajidae) and the Rio skate Rioraja agassizii (Müller and Henle, 1841) (Arhynchobatidae) were found. The spore morphology and morphometry characterization, as well as their small subunit ribosomal DNA (SSU rDNA) sequences reveal the presence of two new and one previously described species. The later, Chloromyxum riarajum Azevedo, Casal, Garcia, Matos, Teles-Grilo and Matos, 2009 is recorded for the first time in Argentine Sea parasitizing its type host. The SSU rDNA-based phylogenetic analyses showed that these three species constituted a well-established monophyletic subclade within marine Chloromyxum clade, while branches subtending the other species were poorly resolved or unresolved, independently of the host taxonomic identities (Carchariniformes, Myliobatiformes, Orectolobiformes, Pristiophoriformes, Rajiformes, Squaliformes and Torpediniformes) and/or host geographic distribution (Atlantic coast of Portugal, Atlantic coast of USA, Australian waters or Mediterranean Sea). The possible causes of these discrepancies are discussed, providing new insights into the phylogeny of the marine Chloromyxum clade.