The pelagic Cnidaria of the Gulf of Mexico: zoogeography, ecology and systematics

Abstract

Zoogeographic, ecologic and systematic studies conducted on the pelagic Cnidaria of the Gulf of Mexico revealed 18 species of scyphozoans (including an undescribed species of Nausithoe), approximately 56 species of hydromedusae (including six new species and one new genus) and 45 species of siphonophores. Eight species of siphonophores (Amphicaryon ernesti, A. peltifera, Claasophyes ovata, Maresearsia praeclara, Marrus orthocannoides, Nectopyramis diomedeae, N. natans and Praya dubia) previously known only from the Indo-Pacific are reported for the first time for the western Atlantic. Other records of forms previously known only from the Indo-Pacific include the scyphozoans Deepstaria enigmatica and Periphyllopsis braueri as well as the deep water continental shelf hydromedusae Bythotiara depressa and Calycopsis simulans. The hydromedusan genus Halistaura previously known only from three Pacific species now includes a new species from the Gulf of Mexico. East Atlantic medusae reported for the western Atlantic for the first time include the hydromedusae Dipurena ophiogaster, Sarsia gemmifera, Steenstrupia nutans and Zygocanna vagans and the scyphomedusa Atolla vanhoeffeni. In addition to the well defined bathypelagic cnidarian assemblage the Gulf of Mexico cnidarian fauna may be divided zoogeographically into a northern Gulf neritic and estuarine assemblage, which appears to be a Pleistocene relict fauna, and a tropical neritic and epipelagic fauna of the southern Gulf which is primarily of West Indian origin, but includes also some Indo-Pacific and East Atlantic components. ...