Family LOBONEMATIDAE Stiasny, 1921

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Introduction

The family Lobonematidae includes two genera, Lobonema Mayer, 1910 and Lobonemoides Light, 1914; only Lobonema has been reported from Australian waters. The genus Lobonema was first reported in Australian waters by Alderslade (in Williamson et al. 1996), from medusae captured at Darwin, NT. The animals were originally reported as Lobonema smithii, but when later compared with type material, they were shown to be Lobonema mayeri (Gershwin & Alderslade pers. comm.). Originally described from the Philippines, Lobonema smithii has been subsequently reported by numerous authors from the Philippines, and from the Indian Ocean by Rao (1931).

Lobonema smithii and L. mayeri have been variously regarded as synonymous or as separate species by different authors. Gershwin (pers. comm.), after re-examination of the type species of L. smithii, considers L. smithii and L. mayeri (as described) to be morphologically distinct and are here treated as separate species.

Differs from L. smithii in that it has 12-16 rhopalia instead of eight, in that the circular muscle is completely interrupted in the ocular radii, in that it has a false ostium in each interostial pillar, and in that the inter-rhopaliar canals do not reach the bell margin.

Outside Australia, lobonematids have been found from the Philippines to the Indian Ocean. They may occasionally occur in dense swarms. In the Philippines, they have been thought to be quite dangerous (Smith, in Mayer, 1910; but see Light, 1914), but the Australian medusae merely give a painful sting.

Jellyfish in this family are quite distinctive. They have scattered erect, gelatinous papillae on the exumbrellar surface and frilly, floppy oral arms with windows along the fleshy portion. A key defining character of the group is the presence of 'pseudo-tentacles', i.e., tentacle-like structures that have been formed from elongation of marginal lappets.

The group appears to be highly desireable to commensals. An unidentified lobonematid with numerous ophiuroid hitch-hikers was photographed by Clay Bryce at the Western Australian Museum, and another series of photographs by an unknown photographer showed an unidentified lobonematid with gooseneck barnacles hanging from the margin of the bell. It seems likely that fish and crabs also may associate with lobonematids, since they are common associates of rhizostome medusae.

Diagnosis

Inscapuatae with intracircular network of anastomosing canals communicating with the ring canal and with some or all of the 16-32 radial canals, but not with the stomach; with window-like openings in the membranes of the mouth-arms; marginal lappets elongated, tentacle-like.

Diagnosis References

Kramp, P.L. 1961. Synopsis of the medusae of the world. Journal of the Marine Biological Association of the United Kingdom 40: 1-469 [375]

General References

Light, S.F. 1914. Some Philippine Scyphomedusae, including two new genera, five new species, and one new variety. Philippine Journal of Science D 9: 195–231

Mayer, A.G. 1910. Medusae of the World. Vol. 1 and 2, The Hydromedusae. Vol. 3, The Scyphomedusae. Washington, D.C. : Carnegie Institution 735 pp., 76 pls. [reprinted by A. Asher & Co., 1977]

Rao, H.S. 1931. Notes on Scyphomedusae in the Indian Museum. Records of the Indian Museum 33: 25-55, pls 3-4

Williamson, J., Fenner, P., Burnett, J. & Rifkin, J. (eds) 1996. Venomous and Poisonous Marine Animals: a medical and biological handbook. Sydney, Australia : NSW University Press 800 pp.

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