Abstract
The parasitic copepod Gauchergasilus euripedesi (Montú, 1980) Montú & Boxshall, 2002 was described from plankton samples and specimens found in four fish species from the estuarine area of Patos Lagoon, state of Rio Grande do Sul (RS), Brazil. Later, one different fish species was reported parasitized with G. euripedesi in the same locality. Species of Astyanax Baird & Girard, 1854 (Astyanax henseli Melo & Buckup, 2006 and Astyanax lacustris (Lütken, 1875)) and Psalidodon Eigenmann, 1911 (Psalidodon eigenmanniorum (Cope, 1894) and Psalidodon aff. fasciatus (Cuvier, 1819)) were collected in two environments (Pintada Island, municipality of Porto Alegre and Itapeva Lagoon, municipality of Terra de Areia, RS) to investigate their parasites. The copepods found in the gill arches were counted, processed, mounted in permanent slides, and photographed using light microscopy, or processed for observation in scanning electron microscopy. Specimens of P. eigenmanniorum from Pintada Island, A. lacustris and P. aff. fasciatus from Itapeva Lagoon, were parasitized by G. euripedesi, with prevalences of 29.03% (A. lacustris), 10.34% (P. eigenmanniorum), and 9.68% (P. aff. fasciatus). Measurements obtained for specimens of G. euripedesi were similar to those found in the literature, except for egg sacs which were larger in the specimens examined in the present study. In addition to being the first report of G. euripedesi parasitizing species of fish (A. lacustris, P. eigenmanniorum, and P. aff. fasciatus), the results presented here also extend the known geographic distribution of the copepod species.
Highlights
The copepod genus Gauchergasilus Montú & Boxshall, 2002 was proposed to accommodate the species Gauchergasilus euripedesi (Montú, 1980) Montú & Boxshall, 2002, anteriorly included in the genus Ergasilus von Nordmann, 1832 (Montú 1980; Montú and Boxshall 2002)
The specimens of G. euripedesi found in this study presented all of the traits described by Montú (1980) and Montú and Boxshall (2002) as well as presented the measurements similar to those specimens reported by the two studies
Considering the tolerance to salinity variations, G. euripedesi prefers low salinity levels found in the Patos Lagoon estuary (Velloso and Pereira Jr. 2010), the infestations found in Guaíba Lake and Itapeva Lagoon should be higher than those reported by Velloso and Pereira Jr. (2010) and Rassier et al (2015)
Summary
The copepod genus Gauchergasilus Montú & Boxshall, 2002 was proposed to accommodate the species Gauchergasilus euripedesi (Montú, 1980) Montú & Boxshall, 2002, anteriorly included in the genus Ergasilus von Nordmann, 1832 (Montú 1980; Montú and Boxshall 2002). In the original description of G. euripedesi, the specimens were collected from plankton samples and from larvae of the following estuarine and marine fish species: Brevoortia pectinata (Jenyns, 1842), Gobiesox sp., Lycengraulis grossidens (Agassiz, 1829), and Micropogonias furnieri (Desmarest, 1823) in the estuarine area of the Patos Lagoon (Montú 1980). Redescription of females and corrected description of males, were based on plankton samples collected in the estuarine area of Patos Lagoon (Montú and Boxshall 2002). Females of G. euripedesi were found in M. furnieri by Velloso and Pereira Jr. Araujo and Boxshall (2001) reported G. euripedesi obtained from plankton samples collected in the Piauí River estuary. The genus Gauchergasilus is monotypic (Montú and Boxshall 2002; Luque et al 2013)
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