Cryptic diversity within the rotifer Polyarthra dolichoptera along an altitudinal gradient

1. Cryptic species (species that are difficult or impossible to distinguish morphologically) are found worldwide and neglecting them may hamper our understanding of species-environment relationships. The rotifer Polyarthra dolichoptera occurs across wide environmental gradients, indicating the potential for a cryptic species complex. We used P. dolichoptera as a model to investigate spatial patterns and relationships of cryptic species with environmental variables along a broad altitudinal gradient.