The importance of molecular characters when morphological variability hinders diagnosability: systematics of the moon jellyfish genus<i>Aurelia</i>(Cnidaria: Scyphozoa)

Cryptic species have been detected across Metazoa, and while no apparent morphological features distinguish them, it should not impede taxonomists from formal descriptions. We accepted this challenge for the jellyfish genus Aurelia , which has a long confusing taxonomic history. demonstrate that variability in medusae overlaps very distant geographic localities. Even though some seem responsible most of variation, regional patterns dissimilarities are lacking. This is further emphasized by differences found when comparing lab-cultured coerulea with diagnostic its recent redescription. Previous studies also highlighted difficulties distinguishing polyps ephyrae, their plasticity. Therefore, mostly based on genetic data, we recognize 28 seven were already described, 10 formally described herein, four resurrected remain undescribed. present characters all designate type materials newly species. Recognizing moon diversity names vital conservation efforts other studies. work clarifies practical implications molecular data as characters, sheds light processes generate crypsis.