Characithecium (Monogenoidea: Dactylogyridae) parasitic on the Neotropical fish Oligosarcus jenynsii (Teleostei: Characidae) from the Pampasic region, Argentina, with the emendation of the genus

Abstract

Presently, only 2 species of dactylogyrid monogeneans have been reported Characidae inhabiting lakes and streams from the Pampasic region (central Argentina). During a parasitological survey on the characid Oligosarcus jenynsii, from Nahuel Rucá Lake (Buenos Aires province, Argentina), dactylogyrids were found on the gills. Specimens were identified as members of Characithecium: C. chascomusensis n. comb, C. longianchoratum n. sp., C. robustum n. sp., C. quadratum n. sp. and C. chelatum n. sp. These species can be distinguished from each other mainly by differences in the shape of the accessory piece of the male copulatory organ, morphology of anchors and ventral bars as well as position of vaginal aperture. The observation of some additional features present in all species studied, such as the vaginal aperture position (as midventral, lateroventral or lateromarginal) and the variability in the morphology of ventral bar (posteromedial projection present or absent) justified an emended diagnosis of Characithecium.

A new species of Characithecium (Monogenea: Dactylogyridae) from external surface and gills of two species of Astyanax (Ostariophysi: Characidae) in southern Brazil

“…Data on ecological parameters of infestations are only available from Mendoza-Franco et al (2003), Rossin and Timi (2014) and Acosta et al (2015). The low sample size (n = 2 and n = 1) of C. costaricensis parasitizing A. fasciatus collected in 2 rivers in Nicaragua by Mendoza-Franco et al (2003) prevents the comparison with the findings of the current study.…”

“…In Brazil, C. costaricensis was recorded in A. fasciatus (Acosta, Queiroz, Brandão, & Silva, 2015;Gioia et al, 1988), A. scabripinnis (Gioia et al, 1988), and A. altiparanae (Azevedo et al, 2007). The other congeners (C. chascomusensis, C. longianchoratum, C. robustum, C. quadratum, and C. chelatum) were recorded in Oligosarcus jenynsii (Günther, 1864) in Argentina (Rossin & Timi, 2014).…”

“…The low sample size (n = 2 and n = 1) of C. costaricensis parasitizing A. fasciatus collected in 2 rivers in Nicaragua by Mendoza-Franco et al (2003) prevents the comparison with the findings of the current study. Rossin and Timi (2014) report the ecological parameters of Characithecium spp. from a subsample (n = 10) of the 54 collected O. jenynsii.…”

“…Characithecium Mendoza-Franco, Reina, & Torchin, 2009 was proposed to include Urocleidoides costaricensis (Price & Bussing, 1967) Kristky & Leiby, 1972, a species considered as incertae sedis by Kritsky, Thatcher, and Boeger (1986) due to the presence of overlapping gonads, mid-ventral vagina, ventral anchor larger than the dorsal, and ventral bar showing a median posterior projection (Mendoza-Franco et al, 2009). Rossin and Timi (2014) revised the diagnosis of Characithecium to include 4 new species collected in Argentina and 1 new combination. The genus currently comprises 6 species: Characithecium chascomusensis (Suriano, 1981) Rossin & Timi, 2014, Characithecium costaricensis (Price & Bussing, 1967) Mendoza-Franco, Reina, & Torchin, 2009, Characithecium longianchoratum Rossin & Timi, 2014, Characithecium robustum Rossin & Timi, 2014, Characithecium quadratum Rossin & Timi, 2014 and Characithecium chelatum Rossin & Timi, 2014. Urocleidoides astyanacis Gioia, Silva & Artigas, 1988 was described from specimens parasitizing the gills of Astyanax fasciatus (Cuvier, 1819) and Astyanax scabripinnis (Jenyns, 1842) in Brazil (Gioia, Cordeiro, & Artigas, 1988).…”

“…Rossin and Timi (2014) revised the diagnosis of Characithecium to include 4 new species collected in Argentina and 1 new combination. The genus currently comprises 6 species: Characithecium chascomusensis (Suriano, 1981) Rossin & Timi, 2014, Characithecium costaricensis (Price & Bussing, 1967) Mendoza-Franco, Reina, & Torchin, 2009, Characithecium longianchoratum Rossin & Timi, 2014, Characithecium robustum Rossin & Timi, 2014, Characithecium quadratum Rossin & Timi, 2014 and Characithecium chelatum Rossin & Timi, 2014. Urocleidoides astyanacis Gioia, Silva & Artigas, 1988 was described from specimens parasitizing the gills of Astyanax fasciatus (Cuvier, 1819) and Astyanax scabripinnis (Jenyns, 1842) in Brazil (Gioia, Cordeiro, & Artigas, 1988). This species was also recorded in Astyanax altiparanae Garutti &Britski, 2000 by Azevedo, Madi, andUeta (2007).…”