Family THYSANOSTOMATIDAE Stiasny, 1940

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Introduction

The genus Thysanostoma was proposed by Agassiz (1862: 153) for the species to which he gave the name T. lessoni; this was a replacement name for Lesson's Melitea brachyura (1830: 227, pl. 80), based on the incompatability of a species with very long arms being named brachyura. Lesson's M. brachyura had originally been named as Rhizostoma brachyura Lesson (1829: 120).

Subsequently, Haeckel (1880: 625) added the species T. thysanura from Australia, and renamed Lesson's R. brachyura (= Agassiz's T. lessoni) as Thysanostoma melitea.

Mayer (1910: 691) made T. thysanura the type species, and speculated that R. brachyura might be the same species.

Diagnosis

Kolpophorae with annular subumbrellar muscles. With eight rhopalar radial canals. With ring canal. With a continuous genital porticus. Subgenital ostia very broad. Arm-disk quadratic, with four primary canals. With very elongate, narrow, lash-like mouth-arms, triangular or three-winged in cross-section, without clubs or filaments.

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 [364]

General References

Agassiz, L. 1862. Contributions to the Natural History of the United States of America. Second monograph. In five parts — Pt. I Acalephs in general. Pt. II Ctenophore. Pt. III. Discophorae. Pt. IV. Hydroidae. Pt. V. Homologies of the Radiata. Boston, London : Little Brown, Trubner Vol. IV i-viii, 380 pp. + (1-10), pls 20-35. [153]

Haeckel, E. 1880. System der Acraspeden. Zweite Halfte des System der Medusen. Jena : G. Fischer. [625]

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] [691]

History of changes