Two new species of jellyfish – Keesingia gigas and Malo bella, both believed to cause Irukandji syndrome, have been discovered off Western Australia’s central coast by Dr Lisa-Ann Gershwin of CSIRO Marine and Atmospheric Research.

Irukandji jellyfish are able to fire their stingers into their victim. They are highly venomous and dangerous, hospitalizing up to 100 people annually in Australia.

Their stings are only moderately painful. However, 20-30 min later some patients may develop systemic symptoms collectively known as Irukandji syndrome.

The condition can cause severe abdominal pain, back, limb or joint pain, nausea and vomiting, profuse sweating and agitation. The patients may also experience numbness or paraesthesia. More severe reactions to Irukandji stings can include hypertension and tachycardia.

The symptoms last from hours to weeks, and victims usually require hospitalization.

The two newly discovered jellyfish, Keesingia gigas and Malo bella, bring the total species known or believed to cause Irukandji syndrome to at least 16.

The first species, Keesingia gigas, also represents a new genus.

“The genus name, Keesingia, is named to honor Dr John Keesing of CSIRO Marine and Atmospheric Research, who not only provided the holotype for this species, but has been of great assistance and inspiration to the author for nearly 20 years,” Dr Gershwin wrote in a paper published in the Records of the Western Australian Museum (full text in .pdf).

“The species name, gigas, is in reference to the enormous size of this species.”

While Irukandji jellyfish range from 5 mm to 2.5 cm in bell height, the size of Keesingia gigas can reach about 50 cm.

According to Dr Gershwin, three juvenile leatherjacket fish were captured with one specimen of this species, living inside the subumbrellar cavity.

“While the tendency of young leatherjackets to shelter with medusas has been previously reported, this is the first report of fish sheltering in an Irukandji species.”

To date, only two cases of stinging by Keesingia gigas have been documented – one produced severe Irukandji syndrome, whilst the other caused only local and groin pain.

The second newly discovered species, Malo bella, belongs to a previously known genus of Irukandji jellyfish.

“The species name, bella, is in triple reference to its small bell-like shape, its beauty, and the Montebello Islands in the Pilbara region of Western Australia, where the species was first found.”

Malo bella has a small, bell-shaped body, about 19 mm in bell height. It is the smallest species yet described in the genus Malo.

“This species is not associated with any particular stings, but its phylogenetic affinity would suggest that it may be highly toxic.”

“Research into the biology and ecology of these species should be considered a high priority, in order to manage their potential impacts on public safety,” Dr Gershwin concluded.

_____

Gershwin, Lisa-Ann. 2014. Two new species of box jellies (Cnidaria: Cubozoa: Carybdeida) from the central coast of Western Australia, both presumed to cause Irukandji syndrome. Records of the Western Australian Museum 29 (1): 10-19