A review of geographic variation in the monocled cobra, Naja kaouthia Lesson, 1831 (Serpentes: Elapidae) with the designation of a neotype

The monocled cobra (Naja kaouthia Lesson, 1831) is a medically important elapid snake with substantial geographic variation across South and Southeast Asia. Throughout its broad distribution, spanning various major ecoregions and habitat types, N. kaouthia displays a great amount of phenotypic variation. Recent taxonomic developments in the Asiatic cobras (Naja, subgenus Naja), namely the description of a new species (Naja fuxi Shi et al. 2022), have resulted in confusion regarding the affinities of non-spitting cobras across Indochina.

Due to close morphological resemblances and poorly resolved phylogenetic relationships among three sympatric and/or parapatric taxa (N. atra, N. fuxi, and N. kaouthia), additional research is needed to disentangle species limits, evolutionary history, ecology, and distribution of these species from one another. A long history of taxonomic confusion and ambiguity in this group, combined with the suggestion of additional cryptic and unrecognized diversity, underscores a need for continued study of the Asiatic cobras.

Consequently, we summarize information on N. kaouthia, compiling data on geographic distribution, phylogenetic relationships, phenotypic variation, venom variation, and venom spitting behavior. While distribution-wide trends do appear to be present for some characteristics (i.e., regional trends in venom spitting behavior, body coloring and patterns), they are apparently lacking or poorly defined for others (i.e., trends in venom composition).

In view of future study on N. kaouthia, and accounting for the missing holotype, we designate a neotype for the species, thereby restricting the type locality to 24 Parganas, West Bengal, India, within the original ambiguous type locality of “Bengale, Inde”. Future taxonomic treatments resulting in the recognition of additional diversity within N. kaouthia will thus require that the name be maintained for snakes from the newly restricted type locality.

We encourage detailed investigation on the Asiatic cobras using integrative lines of evidence combining mitochondrial, nuclear, and morphological datasets, but emphasize that nomenclatural decisions should only be made with a large body of supporting evidence.