Coenholectypus roachensis ( Fourtau, 1914 ) Mohamed Abdelhamid & Moustafa Azab, 2012

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

Coenholectypus roachensis ( Fourtau, 1914) n. stat. ( Figs 11 B-D; 12)

Holectypus excisus race roachensis Fourtau, 1914: 44 , pl. 3, fig. 7; 1921: 55.

Coenholectypus excisus roachensis – Abdelhamid 1997: 146, fig. 5 (10).

MATERIAL EXAMINED. — 12 specimens from the Coniacian-Santonian of Abu Roash (Ostrea and Plicatula unit), ASUARE73-84, Abu Roash echinoid horizons 4 and 5 ( REH 4, REH 5).

MEASUREMENTS. — See Table 8.

DESCRIPTION

Outline sub-round to subpentagonal. Adapical surface high. Adoral surface concaved around peristome. Apical disc composed of five genital plates with five genital pores and five ocular plates with five ocular pores. Madreporite large swollen, extended to the other genital plates. Ambulacral area wide, feebly swollen. Peristome large, conspicuously sunken. Periproct large, oval, extending between peristome and mid-distance between apical disc and ambitus.

REMARKS

This subspecies is common in the Coniacian- Santonian of Egypt. Abdelhamid (1997) discussed the difference between Coenholectypus excisus (Desor, 1847) sensu stricto from the Cenomanian and C. excisus roachensis ( Fourtau, 1914) from the Coniacian-Santonian. Coenholectypus excisus roachensis ( Fourtau, 1914) is distinguished from C. excisus (Desor, 1847) in having wider ambulacra, slightly narrower interambulacra, and relatively higher test and wider peristome ( Fig. 12 ). In the present work, the authors think that these differences elevate the rank of this subspecies to species level.

Figures

FIG. 12. — Comparison of Coenholectypus roachensis (Fourtau, 1914) n. stat. (filled quadrangles, dashed line) from the Coniacian- Santonian of Abu Roash and Coenholectypus excisus (Desor,1847) (empty quadrangles,solid line) from the Cenomanian of Saint Paul, north Eastern Desert. The scatter plots show the relation between test length (L) and each of test height (H), width of ambulacrum (Wa), width of interambulacrum (Wi), width of periproct (Wk) and diameter of peristome (Dp).