The impact of jellyfish blooms on fisheries and other human activities renewed scientific attention to the most
conspicuous taxon of marine gelatinous organisms, the Scyphozoa (Boero 2013). In the Mediterranean Sea, the
mauve stinger Pelagia noctiluca (Forskål 1775) occurred in mass throughout the western and central basins
including the Adriatic Sea since the early 1980s, becoming the most important jellyfish because of its widespread
distribution, high abundance, and ecological role (CIESM 2001; Brotz 2012; Canepa et al. 2014). However, the
overall biodiversity of Scyphozoa remains poorly understood, with several unknown life cycles, multiple
taxonomic synonymies, and assumptions of cosmopolitan species that either under-estimate or over-estimate
diversity. Species new to science (Galil et al. 2010) and the description of new anatomical internal structures in
well known taxa, such as the quadralinga in the Pelagiidae (Gershwin & Collins 2002), are common, suggesting
much remains to be learned.