Wood White (Leptidea sinapis)
A pair of L. sinapis (male above) exhibiting courtship behaviour.
Uncovering cryptic biodiversity is essential for understanding evolutionary processes and patterns of ecosystem functioning, as well as for nature conservation. European butterflies are arguably the best-studied group of invertebrates in the world. The discovery, some twenty years ago, of a cryptic species within the Wood White, L. sinapis, was a significant event and, since then, these butterflies have become a model to study speciation. Cryptic species are not separable based on their external morphology but can often be distinguished by dissection of the male and / or female genitalia. In addition, genetic data also supports species level separation.
In the 1940s Williams investigated the identity of the Irish Wood White L. sinapis. From looking at subtle differences between voucher specimens, he came to the conclusion that Irish examples were distinct from those found on mainland Britain and, as such, proposed that the Irish butterfly should be given the status of subspecies, which he named juvernica.
Across Europe, seven species of Leptidea have now been described: sinapis, reali, juvernica, duponcheli, amurensis, morsei and lactea. The last three are essentially Asian species but duponcheli, a butterfly of Eastern Europe and Asia Minor, is found very locally as far west as the South of France. L. sinapis appears quite widespread on the continent as well as occurring in both Britain and Ireland. In the 1970s and 1980s Réali, and later Lorković, undertook research involving dissections of sinapis. They concluded that sinapis was not a single species but was really two cryptic species. Both species looked identical to the naked eye, did not interbreed and only upon dissection of their genitalia were they found to be separable. The new species was named Leptidea reali, Réal’s Wood White.
More recent investigations of museum specimens by Spanish and Russian lepidopterists (Dincă and colleagues) have thrown further light on the identity and distributions of the Wood Whites across Europe, using techniques based on chromosome counts and DNA analysis. Their conclusions are that reali is not in fact a single species but is itself made up of two distinct species - now named reali and juvernica. They are separate entities from sinapis. Therefore, with the benefit of access to museum specimens, what was previously thought to be a single species of Wood White is, in fact, three species - sinapis, reali and juvernica. The Cryptic Wood White, juvernica, is found across Ireland with the exception of the Burren. Current evidence suggests that there is no overlap in distribution between sinapis and juvernica; sinapis being confined to areas of the Burren limestone district in Clare and southeast Galway in the west of Ireland.
Dincă, V., Lukhtanov, V.A., Talavera, G. and Vila, R. (2011). Unexpected layers of cryptic diversity in wood white Leptidea butterflies. Nature Communications, 2, p. 324, DOI: 10.1038/ncomms1329.
Sachanowicz, K., Wower, A. and Buszko, J. (2011). Past and present distribution of the cryptic species Leptidea sinapis and L. reali (Lepidoptera: Pieridae) in Poland and its implications for the conservation of these butterflies. European Journal of Entomology, 108, pp. 235-242.