Complexastrea cf. gregaria ( M’Coy, 1848 )

Vasseur, Raphaël & Lathuilière, Bernard, 2021, Pliensbachian corals from the Western Tethys, Geodiversitas 43 (22), pp. 1187-1291 : 1274-1277

Complexastrea cf. gregaria ( M’Coy, 1848)

( Fig. 61 )

Montlivaultia gregaria M’Coy, 1848: 403 .

Thecosmilia gregaria – Milne Edwards & Haime 1851: 135, pl. 28, fig. 1-1a; 1857: 359. — Fromentel 1861: 144. — Duncan 1872: 18, pl. 6, fig. 1-2-3-4. — Tomes 1878: 299. — Meyer 1888: 19, pl. 4, fig. 3-6. — Lang 1917: 93.

Chorisastraea gregaria – Tomes 1882: 429; 1886: 445.

Confusastraea gregaria – Beauvais 1974: 20.

Complexastrea sp. 2 – Vasseur 2018: 147-148, fig. 3.17.

TYPE MATERIAL. — Syntypes Sedgwick Museum Cambridge, J 34976 - J 34978 , J 6116-J 6117. TYPE LOCALITY. — Inferior Oolite of Dundry, Somerset, England and Cheltenham, Gloucester shire, England. STUDIED SAMPLES. — Two specimens:CPUN MA0504E2-3, CPUN MA0504E2-4. GEOGRAPHIC AND STRATIGRAPHIC RANGES. — Pliensbachian of Taililout ( Middle Atlas of Morocco).

DESCRIPTION

Cerio-plocoid massive corallum with subcircular corallites often distorted and fluctuating in diameter. Radial elements are compact, free or joining by their inner edge, often curved costosepta. Lateral faces hold granules with typically montlivaltid distribution and shape. No columella. Endotheca abundant, made of vesicular dissepiments. Incomplete wall made with the external twisted edge of septa, no synapticulae. Some remains of what seems to have been a holotheca have been observed. Calicular diameter: 8 to 23 mm – Distance between calices: 13 to 18 mm – Number of septa:>80 – Septal density: 2 to 4 per 2 mm.

SIMILARITIES AND DIFFERENCES

The Pliensbachian specimens show higher number of septa and septal densities than the Toarcian specimens but the variations of these characters fit with the morphometric variability of Complexastrea gregaria (see Lathuilière1996), a species described up until now in Middle Jurassic that shows important intraspecific variability. We maintain a cf. due to the tendency of calices to be smaller than in Middle Jurassic C. gregaria .

Figures

FIG. 61. — Complexastrea cf. gregaria (M’Coy, 1848): A, distal view of the specimen CPUN MA0504E2-3; B, lateral view of one corallite of the specimen CPUN MA0504E2-3; C, distal view of one calice of the specimen CPUN MA0504E2-3; D, transverse polished section of the specimen CPUN MA0504E2-4;E, transverse polished section of the specimen CPUN MA0504E2-4. Scale bars: A, 2 cm; B, 2 mm; C, 1 cm; D, E, 4 mm.