Medusina atava (Pohlig, 1892) Walcott, 1898

Moreau, Jean-David & Gand, Georges, 2022, New data on the Permian ecosystem of the Rodez Basin: ichnofauna (traces of protostomians, tetrapods and fishes), jellyfishes and plants from Banassac-Canilhac (Lozère, southern France), Geodiversitas 44 (31), pp. 975-987 : 978

Medusina atava (Pohlig, 1892) Walcott, 1898 ( Fig. 3A, B )

MATERIAL EXAMINED. — One specimen; M486_ 2022.1.9.

DESCRIPTION

The specimen is umbrella-shaped and 16 mm in diameter. The velum is locally visible, forming an up to 3.3 mm wide marginal thickening. The jellyfish bears 10, thin, quite straight and radially arranged furrows originating from the centre and corresponding to radial canals ( Fig. 3A, B ). Most furrows join the periphery of the jellyfish. The centre of the jellyfish shows an up to 8 mm wide, star-shaped and concave structure corresponding to the manubrium ( Fig. 3A, B ).

REMARKS Medusina atava was reported in Permian deposits from France ( Gand et al. 1996), Germany ( Schüppel 1984) and Italy ( Ronchi & Santi 2003). In the Saint-Affrique Basin, both species Medusina atava and Medusina limnica Müller, 1978 are known from some Permian sites ( Gand et al. 1996). However, Medusina is for the first time reported in the Permian deposits of the Rodez Basin. M. limnica is mainly distinguished from M. atava by showing a maximum of four radial canals. Amongst M. atava the number of radial canals is variable and can reach a number of ten ( Schüppel 1984; Gand et al. 1996).

Figures

FIG. 3. — Jellyfish and protostomian traces:A, B, Medusina atava(Pohlig,1892) Walcott,1898,photograph (A) and interpretative sketch (B),specimen M486_2022.1.9; C, D, Diplopodichnus biformis Brady, 1947 (Di.) and Scoyenia gracilis White, 1929 (Sc.); photograph (C) and interpretative sketch, specimen M486_2022.1.2. Abbreviations: Ma., manubrium; Ra., radial canals; Ve., velum. Scale bars: 1 cm.