A New Species of Rhinergasilus Boeger et Thatcher, 1988 (Copepoda: Ergasilidae) from Gills of Astyanax fasciatus (Cuvier, 1819) (Actinopterygii: Characidae)



To describe a new species of a parasitic copepod, Rhinergasilus digitus n. sp. (Cyclopoida, Ergasilidae), collected from the gills of the red-tailed lambari Astyanax fasciatus (Characiformes, Characidae) in two tributaries of the Jurumirim Reservoir (Upper Paranapanema River), São Paulo State, Brazil: Ribeirão dos Veados and Paranapanema River.


Fish were collected using multi-panel gills nets. The gill of each fish was washed and examined in a stereo microscope for copepods. The copepods found were stored in 70% ethanol, cleared in lactic acid, and mounted in Hoyer’s medium. Drawings were made with the aid of a Leica microscope DMLS equipped with a drawing tube.


The new species differs from its congeneric species, Rhinergasilus piranhus (type-species), in having comparatively biggest body size (body length: 535–598 µm in the new species vs. 237–282 µm in R. piranhus); second antennary segment armed with a minute sensillum near middle of inner margin and a row of spinules on outer margin; third exopodal segment of leg 1 with digitiform process; interpodal plates two and three both ornamented with spinules along posterior margin; leg 5 reduced and represented by two unequal setae.


Based on the morphological differences described above, we erected a new species of Rhinergasilus. Rhinergasilus digitus n. sp. is the second ergasilid described from A. fasciatus, as well as it represents the first report of this genus in a characid fish.

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This study was supported by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) (Proc. N°: 11/24159-3). R.B.N thanks the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for the financial support given to the study (132844/2018-4). R.J.S. is supported by FAPESP #2016/50377-1; CNPq #309125/2017–0; CNPq-PROTAX #440496/2015-2.

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Correspondence to Rodrigo Bravin Narciso.

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Narciso, R.B., Brandão, H., Perbiche-Neves, G. et al. A New Species of Rhinergasilus Boeger et Thatcher, 1988 (Copepoda: Ergasilidae) from Gills of Astyanax fasciatus (Cuvier, 1819) (Actinopterygii: Characidae). Acta Parasit. 65, 327–334 (2020). https://doi.org/10.2478/s11686-020-00168-4

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  • Cyclopoida
  • Crustacea
  • Ectoparasite
  • Jurumirim
  • Paranapanema
  • Ribeirão dos veados