On the importance of types and the perils of “en passant” taxonomy: a brief history of the typification of Coluber naja Linnaeus, 1758 (Serpentes: Elapidae) and its implications, with the designation of a lectotype

Abstract

In response to the recent in passing (“en passant”) taxonomic decision to split Naja naja (Linnaeus) and recognise the Sri Lankan populations as a separate species, N. polyocellata Deraniyagala, we analyse the evidence underlying the proposal and its nomenclatural implications. The proposed split is weakly supported by the available evidence, so that retaining N. naja as a single species seems appropriate until further analysis. Moreover, the proposal raises several issues concerning types, type locality and nomenclature. Linnaeus’ description of Coluber naja was based on a single preserved specimen seen by him (now lost) and several illustrations in Seba’s Thesaurus. The specimens that were the basis of these illustrations constitute part of the type series. Two of the latter specimens, ZMB 2795 and 2796, have been rediscovered in the collections of the Museum für Naturkunde, Berlin. Here, we describe them, and determine that both are of Sri Lankan origin. To settle the question of the type and type locality of this iconic taxon, we designate ZMB 2796 as lectotype for the species, thereby implicitly restricting the type locality to Sri Lanka. The name “polyocellata” thus becomes a subjective junior synonym of Coluber naja, and the name Naja brasiliensis Laurenti, 1768 an objective junior synonym thereof. Any taxonomic recognition of additional diversity within N. naja would thus require the renaming of Indian, not Sri Lankan spectacled cobras, but should await a significant body of convincing evidence. We caution against taxonomic decisions taken “in passing”, based on limited evidence and without in-depth assessment of their nomenclatural implications.