Issue
If confirmed as having been actually made available before Gymnotus electricus Linnaeus (1766), Gymnotus tremulus Houttuyn (1764) should be regarded as the senior synonym. However, following Articles 23.9.1 and 23.9.2 of the Code (ICZN, 1999), Gymnotus electricus must be regarded as the valid name, and qualified as a nomen protectum, and Gymnotus tremulus as a nomen oblitum. It seems that both Houttuyn’s (1764) and Linnaeus’ (1766) descriptions were based on previous descriptions by other authors (i.e., primarily, Gronovius and Seba), and that no specimens were actually examined by these authors regarding their proposals of new species. Gronovius’ specimen (or specimens) is currently probably lost, but Seba’s specimen (which apparently have come from the Essequibo river; Seba, 1758, III, p.108, pl. 34, fig. 6) is probably housed in the Rijksmuseum van Natuurlijke Historie, Leiden (Netherlands). That should, then, be considered the remaining name-bearing type for both species above (ICZN, 1999, Article 72.5.6).
