First record of ancyrocephalid monogeneans of Cheirodon interruptus (Characidae), from a shallow lake in the Pampasic region of Argentina, with the description of three new species

ROSSIN M. ALEJANDRA; TIMI JUAN TOMÁS

Rio de Janeiro

Simposio; 7th Iternational Symposium on Monogenea; 2013

Universidad Federal Do Paraná, Instituto Oswaldo Cruz,Universidad Federal Rural Do Rio de Janeiro

Cheirodon interruptus is the smallest, but more abundant fish species inhabiting shallow lakes and streams of Argentine Pampasic region. At present the parasite fauna of this species is unknown. During a parasitological survey of specimens of C. interruptus captured at Nahuel Rucá lake (Buenos Aires province, Argentina) during 2012-2013, ancyrocephalid monogeneans were found in the gills. A close examination of these parasites, using standard parasitological procedures, showed that 4 species, 3 of them new, belonging to 4 genera were represented. One of them is referable to the new genus proposed in this Symposium for ancyrocephalid monogenean parasites of Oligosarcus jenynsii by the authors, with which this new species shares a series generic characteristics, such as 14 marginal hooks similar in shape and size, with dilated shank; ventral anchor longer than dorsal anchor, ventral and dorsal bars V-shaped, MCO as a coiled tube with counter clockwise rings, accessory piece clamp-shaped, base of MCO articulated to accessory piece by a twisted articulation process lying within rings of MCO and sinistral sclerotized vagina. On the other hand it can be differentiated from its congeners by the length and number of MCO rings, by the morphology of accessory piece and anchors, and by the length and morphology of vagina. The second species possesses a haptor lacking anchors and transversal bars, so it could be included in the genera Anacanthorus or Anacanthoroides. However the presence of 16 marginal hooks (1 pair reduced), the absence of metraterm, the MCO as a counter-clockwise coiled tube, the accessory piece composed by two subunits and clamp-shaped, do not allow its inclusion in these genera. More detailed studies of internal morphology are necessary to confirm the generic status of this species. The third species belongs to the genus Diaphorocleidus, which comprises 6 species, however the new material can be differentiated from its congeners mainly by the shape and size of sclerotized structures, especially by size of MCO and accessory piece, relative to body length; hence a new species is proposed. The last species present in C. interruptus is Characithecium costarricensis. Morphology and morphometry of new material fully agree whit this species, so far known from species of Astyanax (Characidae) from Mexico, Panama, Colombia and Brazil. Therefore, both the range of hosts and geographic distribution of this species are broadened. All species are described and illustrations of sclerotized structures are provided.