Orthopsis ovata ( Coquand, 1862 )

Mohamed Abdelhamid, Marouf Abdel-Aty & Moustafa Azab, Mahmoud, 2012, Turonian-Santonian echinoids from Egypt, Geodiversitas 34 (3), pp. 575-615 : 582

Orthopsis ovata ( Coquand, 1862) ( Figs 5F; 6C, D )

Pseudodiadema ovatum Coquand, 1862: 256 , pl. 27, figs 19-21.

Orthopsis ovata – Cotteau 1864: 564, pl. 1132, figs 1-6; 1869: 145, pl. 19, fig. 11. — Petitot 1959: 165.

MATERIAL EXAMINED. —Two specimens from the Turonian of Wadi Abu Qaada (Wata Formation), ASUAQE1-2, Wadi Abu Qaada echinoid horizon 1 ( QEH 1).

DESCRIPTION

Test moderate to large size (D = 21.8-43.7mm). Adapical surface conical- to dome-shaped. Adoral surface strongly depressed around peristome. Ambulacral areas narrow (Wa/Wi = 0.37-0.38). Peristome deeply sunken (Dp/D = 0.34).

REMARKS

The genus Orthopsis has perforate and noncrenulated primary tubercles and this distinguishes it from Pseudodiadema Desor, 1855 , Diplopodia M’Coy, 1848 , and Tetragramma Agassiz, 1840 in which the primary tubercles are perforate and crenulated. This species is distinguished from O. miliaris in having a larger size (D = 21.8-43.7mm against 14.0-15.0mm in O. miliaris ), narrower ambulacra (Wa/Wi = 0.37-0.38 against 0.49-0.52 in O. miliaris ), numerous and well developed tubercles in interambulacra ( Fig. 6A, C ). It is recorded from Algeria, Morocco, and Syria. It is recorded here from Egypt for the first time.

Figures

FIG. 6. — Camera lucida drawings: A, B, plating, tuberculation and poring of ambital interambulacral plates (A) and ambital ambulacral plates (B) in Orthopsis miliaris (d’Archiac, 1835) from the Coniacian-Santonian of Abu Roash; C, D, plating, tuberculation and poring of ambital interambulacral plates (C) and ambital ambulacral plates (D) in Orthopsis ovata (Coquand, 1862) from the Turonian of Wadi Abu Qaada; E, F, plating, tuberculation and poring in Phymosoma abbatei (Gauthier, 1898) from the rudist unit of Abu Roash; E, adapical half ambulacrum; F, adoral half interambulacrum and half ambulacrum; G, plating, tuberculation and poring of adapical half ambulacrum in Phymosoma baylei (Cotteau, 1864) from the Turonian of Wadi Abu Qaada. Scale bars: A, 0.4 mm; B, 0.3 mm; C, D, 1 mm; E, F, 0.8 mm; G, 0.4 mm.