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Classification


Geographic Distribution

Antarctic Convergence illustration Antarctic convergence

Bathymetric Specimen Dispersal

7 individual specimens found for Stygiomedusa gigantea.

Stygiomedusa gigantea (Browne)  Species

Original Description
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Original Description
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“Umbrella to 1.4 m in diame­r. Exumbrella: smooth, with thick mesoglea (2-4 cm) centrally and thinning peripherally; margin scalloped into 20 lobes each with pair of thickened rhopaliar lappets. Subumbrella: with thickened central disc containing 4 oval to round subgenital ostia (5-10 mm in diamet­er). Rhopalia: 20. Oral arms: 4, singly folded, ribbonlike, extremely long (about 11 m as noted by Borchgrevink [1901], or 10 m as noted by J. Mead (personal communication, 1978), with each fold 3-5 mm thick and 10-20 cm broad, with abaxial midrib (circular in cross section). Gonads: 4 (only known from females), forming brood pouches with reproduct­ive cysts containing developing medusae. (Note: No male specimens have been described.) Gastrovascular canals: total 40; rhopaliar canals: 20, lacelike branching, peripherally decreasing in size particularly beyond subumbrellar disc but tending to in­crease in size near margin, resultant pattern of radiating canals forming pie-shaped mesh-works; interrhopaliar canals: 20, unbranched for proximal one-half of length but anastomos­ing distally with rhopaliar canals. Ring canal: wavy appearance, following scalloped margin (at 5-10 mm inward of margin, except at rhopalia where they coincide). Color of um­brella and oral arms: pinkish-purple (accord­ing to J. Mead's photographs of live medusa); pink or white in preserved specimens.”

(Larson, 1986)

Remarks

Stygiomedusa gigantea was apparently first collected in the Antarctic. Borchgrevink [1901] reported the capture of a ‘large jellyfish,’ its weight was ’90 pounds,’ ‘with arms or extremities about 12 yards long.’ An accompanying photograph, showing the distinct meshwork of anastomosing canals, leaves little doubt that the giant medusa is S. gigantea.

The second known specimen was a large (50 cm) medusa from the Southern Cross collection [Browne, 1910]. Browne thought that the specimen was fragmentary because it lacked tentacles; he noted the following morphological features: oral arms which were greater than 2 m in length, subgenital pits (small and oval), and a gastrovascular system of canals. He provisionally placed this medusa in the genus Diplulmaris.

I was kindly allowed to examine this specimen in the British Museum (Natural History) and subsequently determined that Browne’s Diplulmaris ? gigantea was, in fact, a Stygiomedusa. It was a darkly colored specimen, and although fragmentary and very brittle, there were fragments of the margin which were obviously scalloped. Other diagnostic features included portions of the oral arms that had the characteristic midrib, as well as the umbrellar cavity that contained the unique cystlike structures.

This evidence, when compared to Russell’s [1959b] original description of Stygiomedusa, reveals that Diplulmaris ? gigantea Browne and Stygiomedusa fabulosa Russell are conspecific. The valid combination is Stygiomedusa gigantea (Browne).

Stygiomedusa gigantea has been photographed in Antarctic waters at least twice. The first photographs of S. gigantea were published by Borchgrevink [1901]. The second documentation was made by J. Mead of the Smithsonian Institution, who kindly loaned me his color slides of S. gigantea photographed in situ, February 1973, Antarctic Peninsula.

Mead’s slides show a large specimen (approximately 50 cm in diameter) swimming at the surface. One of these slides shows the extremely long and folded oral arms trailing behind the medusa. The arms, about 10 m long, resemble extended, flattened rubber tubes. Underwater slides of the same specimen show a noticeably contracted umbrella, which is hat-shaped, with a high central dome and shelflike brim. Another slide clearly shows the anastomosing radial canal system peculiar to S. gigantea.

(Larson, 1986)

Specimens

Type Status Catalog No. Date Collected Location Coordinates Depth (m) Vessel
  58763 3/14/1964 Antarctic Ocean 61.9° S, 55.9° W 732 – 1373 Eltanin R/V
  58764 7/16/1968 Antarctic Ocean 60.1° S, 145° E 500 Eltanin R/V
  58765 5/27/1964 South Pacific Ocean 59.6° S, 89.1° W 476 Eltanin R/V
  58766 5/24/1963 Scotia Sea 57.3° S, 24.5° W 6661 – 6669 Eltanin R/V
  58767 10/23/1963 Antarctic Ocean 62.5° S, 83.1° W 3660 – 4099 Eltanin R/V
  58768 8/15/1965 Antarctic Ocean 60.8° S, 140.4° W 265 – 375 Eltanin R/V

View additional taxa  View all species collected at same locations as Stygiomedusa gigantea