The genus Gymnotus (Gymnotiformes: Gymnotidae) in Argentina. How bad taxonomy results in poor regulations and no conservation

Abstract

Summary Four species of the genus Gymnotus are present in Argentina: G. inaequilabiatus, G. omarorum, G. pantanal, and G. sylvius, the last three species being recorded for the first time in freshwater courses. Gymnotus omarorum, G. pantanal, and G. sylvius together with others of the genus Brachyhypopomus are the group of fishes that bear the greatest impact in the trade as live bait for sport fishing in the northeastern region of Argentina. Within this large area, only the provinces of Chaco, Corrientes, and Formosa have regulations for the catch, trade, and sale of species as live bait. Unfortunately, the species covered by legal regulations are Gymnotus carapo and Brachyhypopomus brevirostris, neither of which occurs in freshwater habitats of Argentina. Comments are included as to how this bad taxonomy affects the regulations and conservation status of these species.

IsNematocharax(Actinopterygii, Characiformes) a monotypic fish genus?

“…Besides taxonomic implications, the recognition of species or evolutionary units is critical for ecology, biogeography, and conservation of biodiversity (Sites and Marshall 2004;Casciotta et al 2013). However, discriminating species based only on morphological features is particularly difficult for some groups, such as Neotropical fish because of their richness (Lévêque et al 2008), remarkable phenotypic plasticity (Wimberger 1992), and high number of cryptic species (Piggott et al 2011).…”

Fish fauna from Río Pilcomayo National Park and Ramsar Site and its surroundings, Formosa, Argentina

“…Samples were fixed in 10% formaldehyde and stored in 70% ethyl alcohol. Fish identification were determined to the species level whenever possible, recognition were made using the following references: López and Castello (1966), Ringuelet et al (1967), Géry (1977), Reis et al (1990), Azpelicueta and Braga (1991), Azpelicueta and Yanosky (1992), López and Miquelarena (1991), Lucena and Kullander (1992), Braga (1993Braga ( , 1994, Mago-Leccia (1994), Lucena (2003), Malabarba and Weitzman (2003), Malabarba (2004), Azpelicueta 2005, Miquelarena andMenni (2005), Almirón et al (2005), Kullander and Lucena (2006), Mirande et al (2006), Lucena (2007), Miquelarena et al (2008), Brancolini et al (2011) and Casciotta et al (2012). Fish classification follows Eschmeyer (2014…”

Characterization of the agonistic behavior of the weakly electric fish Gymnotus sylvius

“…Only four species of Gymnotus occur in the southernmost freshwater environments of Argentina. Gymnotus inaequilabiatus is found in lotic environments and cannot survive in poorly oxygenated waters, whereas Gymnotus omarorum , Gymnotus pantanal , and Gymnotus sylvius usually inhabit in sympatry in environments such as marshes or ponds with dense floating aquatic vegetation and poorly oxygenated water (Casciotta et al., 2013; Rezende et al., 2009).…”

“…Although all species of the genus Gymnotus are considered aggressive and territorial, Gymnotus omarorum is the only species inhabiting the southernmost boundary of gymnotiforms in South America in which its agonistic behavior has been carefully addressed (Batista et al., 2012; Perrone & Silva, 2018; Quintana et al., 2016). In contrast, little is known about the natural history and social behavior of the sexually monomorphic Gymnotus sylvius , which occurs in sympatry with Gymnotus omarorum in freshwater environments of Argentina (Albert et al., 1999; Casciotta et al., 2013; Rezende et al., 2009). In this study, we describe the agonistic behavior of Gymnotus sylvius in dyadic encounters in laboratory settings.…”