Family LINUCHIDAE Haeckel, 1880

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Introduction

At first glance, linuchids look like thimbles. They have a cup-shaped body that is flat on top with vertical sides, and eight rhopalia alternating with eight short tentacles. Species are distinguished on the basis of the arrangement of subumbrellar protuberances, and on number of gonads.

Eschscholtz (1829: 86, 91) originally placed the genus Linuche in the family Geryonidae, which is comprised largely of hydromedusae. Haeckel (1880: 494), however, placed the genus Linuche into the subfamily Linuchidae, in the family Linergidae, whereas Mayer (1910: 557) placed Linuche in the family Ephyropsidae along with the genera Palephyra and Nausithoe.

Kramp (1961: 313) listed two genera in the Linuchidae — Linantha Haeckel, 1880, which he regarded as doubtful, and Linuche Eschscholtz, 1829, for which he listed two species, L. draco (Haeckel, 1880) and L. unguiculata (Schwartz, 1788).

There has been much debate through the years about species limitations in the genus Linuche, with some recognising the Atlantic L. unguiculata with subumbrellar protuberances in three circles as separate from the Pacific L. aquila with subumbrellar protuberances in two circles, whereas others merge the two forms, recognising only the older L. unguiculata. A good account of the morphology of the Pacific and Atlantic forms was given by Mayer (1910). The systematics of thiis group would benefit from a modern morphological/molecular re-examination.

Both forms of Linuche have been reported in Australian waters; however, the specimens identified as L. unguiculata have been re-examined and they bear the two whorls of protuberances characteristic of the Pacific L. aquila.

Diagnosis

Coronatae with eight rhopalia, eight tentacles, and 16 marginal lappets; with zones of subumbrellar hernia-like protuberances; 16 radiating stomach pouches break up into numerous ragged-edged branches in the marginal lappets.

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 [313]

General References

Eschscholtz, F. 1829. System der Acalephen. Eine ausführliche Beschreibung aller medusenartigen Strahltiere. Berlin : F. Dummlert.

Haeckel, E. 1880. System der Acraspeden. Zweite Halfte des System der Medusen. Jena : G. Fischer.

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

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]

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