Elucidating cryptic sympatric speciation in terrestrial orchids

PREMISE: Cryptic sympatric speciation occurs when closely related species arises with no geographic or spatial isolation. Since cryptic species can not usually be detected when investigations are based exclusively on classical plant taxonomy, molecular markers and integrative taxonomy are important tools to elucidate the identity of cryptic taxa. METHODS: In this paper we aimed to provide a detailed investigation based on molecular data and experimental taxonomy conducted on populations of a plant model occurring inside mesophytic forests and a supposed cryptic sympatric species that is found in marshy areas. Furthermore, a phylogeny was reconstructed by using nrDNA and cpDNA sequences in order to ascertain the position of both sympatric species within Liparis. The divergence among sequences of the putative cryptic sympatric species and related taxa was also verified based on DNA barcoding. KEY RESULTS: Our results reveal cryptic sympatric speciation in the orchid genus Liparis. Differences in microhabitat, flowering phenology, morphology of leaves and flowers, and reproductive strategies support the taxon occurring in marshy areas is a cryptic species. The molecular analyses reveal the cryptic species is closely related to L. nervosa. CONCLUSIONS: Paludal Liparis is a sympatric cryptic species distinguishable from L. nervosa by differences in habitat, phenology and breeding system. Our conclusions are supported by the molecular investigations. The cryptic Liparis emerges as sister to L. nervosa, within a clade with terrestrial habitat and plicate leaves. The discovery of sympatric cryptic speciation in orchids provides increase on the knowledge of diversification and reproductive isolation in flowering plants.