Cranial Signals, Genetic Noise: Untangling the Occipital‑Lobed Calumma Lineages

A new study re‑evaluates the occipital‑lobed chameleons traditionally grouped as the Calumma cucullatum complex. The authors show that this phenetic assemblage is not monophyletic. Instead, the C. furcifer group is recovered as sister to C. cucullatum, while C. malthe forms the sister lineage to a clade containing the C. nasutum group and the C. brevicorne group, which together include the remaining species previously treated as the cucullatum group.

Genomic analyses indicate that some taxa in this radiation carry signatures of ancestral introgressive hybridization, yet most currently recognized species remain supported as deep, monophyletic lineages. One taxonomic change is made: northern populations of C. malthe are separated and described as Calumma krystalae.

The study also challenges current interpretations of the C. brevicorne / C. crypticum complex. Museomic data place the brevicorne type within a cluster containing Ranomafana specimens usually identified as C. crypticum, while specimens from the crypticum type locality and from Andasibe fall within a cluster containing the type of C. gularis. Although this pattern suggests that the two‑species framework may not reflect true diversity, the authors refrain from taxonomic changes pending deeper future analysis.

The paper clearly demonstrates that cranial appendages, although evolutionarily important, are not reliable markers for taxonomic grouping. They are not evolutionarily neutral, and their use in species identification becomes problematic when DNA data are unavailable in the field. Morphology alone no longer resolves these lineages. An enigma.

Webmaster's note: 

The separation of C. malthe and the population previously assigned to this species on Marojejy, as well as the dubiosity of C. crypticum, were for years indicated on this page. This paper validates those long‑standing suggestions.

Original citation:

Vences, M., Rothe, L.-D., Glaw, F., Scherz, M.D., Gehring, P.-S., Hawlitschek, O., Kuhn, A., Multzsch, M., Petzold, A., Preick, M., Rakotoarimalala, F., Raselimanana, A.P., Ratsoavina, F.M., Ruane, S., Vieites, D.R., Hofreiter, M., Dufresnes, C. (2026). Genome-scale molecular systematics of Madagascar's occipital-lobed chameleons reveals polyphyly and mito-nuclear discordances. Molecular Phylogenetics and Evolution. https://doi.org/10.1016/j.ympev.2026.108689

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