Cotylorhiza erythraea Stiasny, 1920 (Scyphozoa: Rhizostomeae: Cepheidae), yet another erythraean jellyfish from the Mediterranean coast of Israel

An unfamiliar scyphozoan jellyfish species has been observed along the Mediterranean coast of Israel since 2003. Morphological characters such as the densely anastomosed radial canals and the stalked cupped appendages on the oral arms identified it as closely allied to Cotylorhiza. Comparison with the type of C. erythraea, collected over a century ago in the Suez Canal, shows close similarity. Molecular analyses based on the mitochondrial barcoding gene cytochrome oxidase sub unit I (COI) and 28S ribosomal DNA support its placement among the Cepheidae. This is the fifth-introduced scyphozoan species recorded along the Mediterranean coast of Israel. The presence of sexually mature specimens detected as far back as 2003, and the occurrence of the species in the past summer at sites nearly 90 kms apart, indicate the existence of widespread, established populations.