Ilymatogyra (Afrogyra) africana ( Lamarck, 1801 )

Musavu Moussavou, Benjamin, 2017, Systematics, palaeoecology and taphonomy of Turonian oysters from the northern Gabon Coastal Basin, Geodiversitas 39 (2), pp. 213-224 : 216

Ilymatogyra (Afrogyra) africana ( Lamarck, 1801)

( Fig. 3 I-M)

Gryphaea africana Lamarck, 1801 : 399, pl. 189, figs 5, 6.

Ostrea auressensis Coquand, 1862 : 233, pl. 22, figs 12, 13.

Ostrea africana – Coquand 1869: 134, pl. 39, figs 5, 6; pl. 55, figs 10-12.

Exogyra africana – Trevisan 1937: 72, pl. 3, fig. 18; pl. 5, figs 1-4.

Ilymatogyra (Afrogyra) africana ‘forma crassa’ – Malchus 1990 : 121- 124, pl. 7, figs 6, 8, 9, 11, 12, 14-20; pl. 8, figs 1-3.

Ilymatogyra (Afrogyra) africana – Seeling & Bengtson 1999 : 58, fig. 9d-g. — Berndt 2002: 110; pl. 3, figs 5-7. — Ayoub-Hannaa 2011: 84, pl. 7, figs 4-6; text-fig. 3.7.

MATERIAL. — 6 specimens (MDG/LBV/Lm-8.1 to Lm-8.6).

OCCURRENCE. — Cenomanian of North Africa ( Coquand 1862; Ayoub-Hannaa 2011), Europe ( Trevisan 1937), Brazil ( Seeling & Bengtson 1999). In Gabon, this species is recorded for the first time.

DESCRIPTION

Shell is large, inequivalve, elongated to tear-shaped in outline. Umbo is broken. Left valve is convex. This ornamentation consists of strong scaly growth lamellae. Right valve is flat to moderately convex ornament consisting of fine growth line which becoming lamellose towards ventral margin.

REMARK

Malchus (1990) erected two varieties of Ilymatogyra (Afrogyra) africana, ‘forma typica’ and ‘forma crassa’. For difference between these two varieties, the reader is referred to Malchus (1990). All the specimens from the northern Gabon Coastal Basin seem to correspond to ‘forma crassa’ sensu Malchus (1990).

Figures

FIG. 3. — A, Gyrostrea A MDG/LBV/Lm-13;B, C, Rhynchostreon cf.suborbiculatum (Lamarck,1801) MDG/LBV/Lm-9;D-F, Gryphaeostrea sp.;D-E, MDG/LBV/Lm- 7.1, F. MDG/LBV/Lm-7.2; G, H, Curvostrea tevesthensis (Coquand,1862) MDG/LBV/Lm-11;I-M, Ilymatogyra (Afrogyra) africana (Lamarck, 1801); I, J, MDG/LBV/ Lm-8.3,K.MDG/LBV/Lm-8.2,L-M.MDG/LBV/Lm-8.1;N, Q, Ostreidea gen.et sp.;indet MDG/LBV/Lm-34;O,P.Pycnodonte sp.MDG/LBV/Lm-10.Scale bar:1 cm.