Universiteit Leiden

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Research project

Cryptic species discovery

Do understudied animals contain hidden species?

Ben Wielstra

Part of the work conducted in the Wielstra lab involves diagnosing and describing overlooked species. Cryptic species are distinct species that previously went unrecognized due to their morphological similarity. Yet, cryptic species can be picked out by studying genetic data. In fact, once such genetically distinct species have been defined, it is often possible to go back to study their morphology and find ways to tell them apart based on their phenotype. Several newts have recently become recognized as distinct species based on Wielstra’s work.


  • Kalaentzis, K., Arntzen, J.W. Avcı, A., van den Berg, V., Beukema, W. France, J., Olgun, K., van Riemsdijk, I., Üzüm, N., de Visser, M.C., Wielstra, B. (2023). Hybrid zone analysis confirms cryptic species of banded newt and does not support competitive displacement since secondary contact. Ecology and Evolution 13(9): e10442
  • van Riemsdijk, I. Arntzen, J.W., Babik, W., Bogaerts, S., Franzen, M., Kalaentzis, K., Litvinchuk, S.N., Olgun, K. Wijnands, J.W.P.M., Wielstra, B. (2022). Next-generation phylogeography of the banded newts (Ommatotriton): a phylogenetic hypothesis for three ancient species with geographically restricted interspecific gene flow and deep intraspecific genetic structure. Molecular Phylogenetics and Evolution 167: 107361.
  • Wielstra, B., Arntzen, J.W. (2016). Description of a new species of crested newt, previously subsumed in Triturus ivanbureschi (Amphibia: Caudata: Salamandridae). Zootaxa 4109(1): 73-80.
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