Memoirs of the Queensland Museum | Nature (ISSN 0079-8835)

A cubozoan jellyfish, Morbakka fenneri gen. nov., sp. nov. is described. Morbakka differs from other genera and species in the Carybdeida by having a large, warty body; flat, ribbon-shaped tentacles; a prominent upward-pointing ‘thorn’ at the bend of the pedalial canal, and conspicuous broadening of the canal where it meets the tentacle; frown-shaped or dumbbell-shaped rhopalial niche ostium; long, straight, rabbit-ear shaped rhopalial horns; lack of non-lensed eye spots on the rhopalia; and three types of tentacular nematocysts and two types of bell nematocysts. Its morphology, genetics and sting symptoms clearly put it in the Irukandji group (i.e., Carukia, Malo, Gerongia), most closely related to Gerongia rifkinae. A larger northern Queensland form, and a smaller New South Wales form of Morbakka may also prove to be specifically distinct. Morbakka has been associated with severe Irukandji syndrome. q Cnidaria, Cubozoa, Tamoyidae, Irukandji syndrome, fire jelly, jellyfish, marine stingers, Queensland, Australia. A large and conspicuous eastern Australian cubozoan commonly called ‘morbakka’, ‘fire jelly’ or ‘tamoya’, has been well known to marine scientists, and to Queensland Surf Life Savers, for more than 20 years. Curiously it has never been properly classified or formally described, and this is finally undertaken in the present paper. Morbakka was first described in the nontaxonomic sense by Southcott (1985), and has been extensively discussed by Fenner (1985, 1986b), Williamson et al. (1996), and others (see litera ture compilation under genus Remarks). How ever, more than 20 years later, our knowledge of this conspicuous and important animal has progressed little. Fenner (1986b, 1991, 1997) demon strated that it can give systemic symp toms similar to Irukandji syndrome, and Little et al. (2006) recently implicated it (as ‘fire jelly’) in a serious sting resulting in heart failure. How ever, its reproductive biology, predator-prey ecology, and seasonal patterns have never been investigated, and nor have its toxins been studied. Hopefully, the first formal description of the genus that is presented here, and the summary of current knowledge included, will help to stimulate further taxonomic investigation, as well as essential research into ecology, toxin ology, and basic biology. MATERIALS AND METHODS All taxonomic observations and measurements were made on preserved material unless other wise noted. Measurements were made with Max-Cal digital calipers to the nearest 0.01 mm. Bell height (BH) was measured from the apex of the bell to the velarial turnover. Diagonal bell width (DBW) was measured across diagonal pedalia on a flattened specimen, at the height where the pedalium joins the exumbrella of the bell. Interrhopalial width (IRW) was measured between adjacent rhopalia, with the specimen flattened. Tentacle base width (TBW) was measured at the uppermost part of the tentacle, immediately below the pedalium; if the tentacle was flattened, width was measured across the widest points. In opaque specimens, a search Memoirs of the Queensland Museum — Nature Ÿ 2008 Ÿ 54(1) Ÿ www.qm.qld.gov.au 23 Citation: Gershwin, L. 2008 12 01. Morbakka fenneri, A new genus and species of Irukandji jellyfish (Cnidaria: Cubozoa). In, Davie, P.J.F. & Phillips, J.A. (Eds), Proceedings of the Thirteenth International Marine Biological Workshop, The Marine Fauna and Flora of Moreton Bay, Queensland. Memoirs of the Queensland Museum — Nature 54(1): 23–33. Brisbane. ISSN 0079-8835. for phacellae was made by making a small incision in the upper corners of the bell, and then pulling back a small amount of mesoglea to expose the floor of the stomach, or by open ing up the full length of the body wall to expose the stomach, and then opening the stomach in the same manner. In transparent specimens, absence of phacellae was obvious. Nematocysts were examined and measured with a Leica DMLB compound microscope and Leica IM-50 Image Manager v. 1.20 for Windows; all obser vations and photographs were made through a 40x objective (i.e., 400 x magnification). Nemato cysts were identified following the keys of Calder (1974), Mariscal (1971), Williamson et al. (1996), and Gershwin (2006a). Abbreviations used. Australian Museum, Sydney (AM); Museum of Tropical Queensland, Towns ville (MTQ); Queensland Museum, Brisbane (QM); and South Australian Museum, Adelaide (SAM). Specimens from the Peter J. Fenner inter national cubozoan collection are indicated with his initials (PJF), and are housed in the Queens land Museum; specimens from the Ronald V. Southcott collection are indicated with his initials (RVS) and correspond to extensive notes archived in the South Australian Museum. Everywhere in the text that ‘morbakka’ is not italicised, it is being used as a common name.