Discomedusa lobata

Discomedusa lobata Claus 1877 *

Characteristics of the species (from Pagès et al. 1992)

With usually 8 and occasionally 9 rhopalia; between 8 and 40 tentacles, the number generally increasing with bell diameter; between 32 and 48 lappets, the number generally increasing with bell diameter; the 8 perradial and interradial canals branched and usually anastomosing with the 8 simple adradial canals. Up to approximately 150 mm wide, disc-shaped.

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Meristics and morphometric features

Pagès et al. (1992) reported the bell diameters and the numbers of lappets, tentacles, and rhopalia for each of 14 medusae sampled in the Benguela Current during 1981-1982 (see Fig.). They noted that no medusae fitted completely the diagnosis of Kramp (1961) while some features were characteristic of Undosa undulata Haeckel 1880. On the basis of these measurements and those made previously by Thiel (1966), Pagès et al. (1992) concluded that U. undulata was a junior synonym of D. lobata.

Notes

Pagès et al. (1992) noted that no medusae they measured fitted completely the diagnosis of Kramp (1961; see below). They also noted that some features were characteristic of Undosa undulata Haeckel 1880 (see below). On the basis of their measurements and those made previously by Thiel (1966) on medusae 40-100 mm from the Gulf of Guinea, Pagès et al. (1992) concluded that U. undulata is a junior synonym of D. lobata. The "characteristics of the species" given above therefore reflect the range of measurements made for features clearly reported for both species.

Diagnosis of D. lobata following Kramp (1961) With 8 rhopalia, 24 tentacles, 32 lappets; the 8 perradial and interradial canals branched, the 8 adradial canals simple. 150 mm wide, disc-shaped, the 16 rhopalar lappets are as wide as, but somewhat longer than, the 16 tentacular lappets, without centrifugal canals; the terminal ramifications of the perradial and interradial canals fuse with the adradial canals.

Diagnosis of U. undulata following Kramp (1961) With 8 rhopalia, 40 tentacles, 48 lappets; the 8 perradial and interradial canals branched, the 8 adradial canals simple and a ring canal. 120 mm wide, 40 mm high; a brown 16-rayed, star-like figure on exumbrella.

Prepared by M. N. Dawson