A new schistosome from nasal tissue of the black-necked swans, Cygnus melancorhyphys (Anatidae)

VELEIZAN A.; BRANT S. V.; FLORES V.; CASALINS L.; VIOZZI G.; LOKER E. S.

San Antonio, Texas

Congreso; 92nd Annual Meeting of the American Society of Parasitologists and the 12th International Coccidiosis Conference; 2017

American Asosiation of Parasitologists

In the family Schistosomatidae, 9 schistosome species have been reported from nasal tissues of their hosts,2 from mammals and 7 from birds, with all the avian representatives thus far placed in the genusTrichobilharzia. All previous reports of avian nasal schistosomes have been reported from the EasternHemisphere, 4 species from Rwanda (Africa), 2 from Australia (Oceania) and 1 from Europe/Middle East.A recent parasitological survey of Cygnus melancoryphus, an anatid endemic to South America, revealedthe first adult nasal schistosome worms from the Western Hemisphere. To characterize this new species,worms were described both morphologically and genetically. Some worms were fixed in in hotformaldehyde 4% for morphological studies and others were stored in 96% ethanol for genetic analysis ofthe nuclear 28S and ITS as well as the mitochondrial cox1 gene regions. The combination of diagnosticmorphological features does not match with any described avian schistosome genus. These worms have afiliform body with spiny tegument, a rounded posterior end, two muscular suckers, a robust but shortgynaecophoric canal with thickened cross bands, and more than 100 testes. The longest worm fragmentwas 9.6 mm. The genetic results confirm their distinctiveness and place them at the base of the large avianschistosome clade, and not with the more commonly found genera, Allobilharzia, Anserobilharzia,Trichobilharzia, Dendritobilharzia or Gigantobilharzia. In fact, these worms grouped with a previouslyundescribed clade, designated ?lineage 1? of larval schistosomes from the Patagonian freshwater snailChilina gibbosa. Chilinid snails comprise a distinctive family endemic to southern South America. Thisfirst reported nasal schistosome from the western Hemisphere represents a new genus, with both itsdefinitive and intermediate hosts being species endemic to South America