One Nerite, or Two?
The introduction of DNA sequencing as a taxonomic tool in the 1980s started a revolution that keeps transforming the classification of mollusks and opening the way for better species delimitations. Molecular systematics has shown time after time not only that what we believe to be separate species are just one and the same, but also that what may be perceived as a single species may actually be two or more! Take, instance, the article by Cristiane Barroso, from the Universidade Federal do Ceará (Brazil) and her collaborators recently published in the journal Zookeys.
The authors examined northeastern Brazilian populations of two very similar nerite species, Vitta virginea and Vitta meleagris. (The authors used the synonym names Neritina virginea and Neritina usnea.) Both species have very variable shell-color patterns, and have been considered by some researchers to be one and the same entity. Using a molecular approach, Barroso and her collaborators have confirmed the existence of the genetically distinguishable, but less common, Vitta meleagris. Based on their results, the authors have then outlined subtle but consistent color patterns and other anatomical features that may help in the separation of the two species by field workers. Read the paper here.