Nomenclatural problems raised by the recent description of a new anaconda species (Squamata, Serpentes, Boidae), with a nomenclatural review of the genus Eunectes

A recent paper proposing taxonomic changes in the South American snake genus Eunectes Wagler, 1830 (anacondas) is analysed. This paper raises an unusually high number of taxonomic and nomenclatural problems. The work does not rely on an explicit species concept, the analysis of the molecular data based on three mitochondrial genes is shown to be unreliable, and the validity of the ‘clades’ proposed in this work is questioned. The nomen proposed for a purported new species is a nomen nudum (nomenclaturally unavailable), and the designation of a ‘lectotype’ for the nominal species Eunectes murinus (Linnaeus, 1758) is invalid. We provide a review of the nomenclatural status of 18 nominal species (including four unavailable ones) once or still now referred to the genus Eunectes, we identify their ‘types’ (nomen-bearing specimens), we designate five lectotypes, which are all specimens figured and briefly described in ancient publications, and we explain the rationale behind this action, which will allow the subsequent designation as neotypes of recently collected specimens associated with precise type localities and molecular data. We show that the generic nomen Eunectes Wagler, 1830 does not apply to the taxonomic genus accommodating anacondas but, this nomen having been used for these giant and spectacular snakes for about 200 years and being well-known even outside the field of taxonomy, we argue that its traditional use should be maintained through an action of the International Commission of Zoological Nomenclature using its plenary power. Finally, we provide various recommendations regarding nomenclatural actions and publications presenting them.