Goniopygus sp.

Mohamed Abdelhamid, Marouf Abdel-Aty & Moustafa Azab, Mahmoud, 2012, Turonian-Santonian echinoids from Egypt, Geodiversitas 34 (3), pp. 575-615 : 595-596

Goniopygus sp. ( Fig. 11A)

MATERIAL EXAMINED. — One specimen from the Coniacian-Santonian of Abu Roash (Ostrea and Plicatula unit), ASUARE72, Abu Roash echinoid horizon 4 ( REH 4).

DESCRIPTION

Test very small (D = 7.5 mm), rounded. Adapical surface dome-shaped (H/D = 0.51). Adoral surface flattened. Apical disc large (La/D = 0.56); both ocular and genital plates ornamented by linear depressions around a point at the middle of each plate; at the middle of each suture and at the contact of every three sutures of the oculogenital plates, there is a small pit; on the inner edges of three plates of the genital plates, there are three granules, each one is surrounded by a shallow semi-lunar depression. Interporiferous zones with two rows of imperforate, non-crenulated, nonconfluent primary tubercles (Na = 8), at the ambitus they are slightly smaller and different from interambulacral tubercles, but near the apical disc they are distinctly smaller than interambulacral tubercles. Major ambulacral plates trigeminate. Interambulacral area with two columns of imperforate, noncrenulated, confluent primary tubercles (Ni = 6). Peristome fairly sunken (Dp/D = 0.52). Gill slits poorly developed.

REMARKS

This specimen is distinguished from G. innesi , G. menardi (Desmarest, 1825) , G. noguesi Cotteau, 1863 and G. major Agassiz, 1838 by the presence of well-developed ambulacral tubercles on adoral surface and ambitus, linear depressions around a point at the middle of each ocular and genital plate, the presence of a small pit at the middle of each suture and at the contact of every three sutures of the oculogenital plates, and in having poorly developed gill slits.

Order HOLECTYPOIDA Duncan, 1889