Petalobrissus humei ( Fourtau, 1906 ) 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 : 598-599

Petalobrissus humei ( Fourtau, 1906) n. comb. ( Figs 11J, K; 14 )

Echinobrissus humei Fourtau, 1906: 148 , pl. 2, figs5-10.

Nucleopygus humei – Lambert & Thiery 1921: 349.

MATERIAL EXAMINED. — 40 specimens from the Turonian of Wadi Abu Qaada (Wata Formation), ASUAQE76-115, Wadi Abu Qaada echinoid horizon 3 ( QEH 3).

MEASUREMENTS. — See Table 10.

DESCRIPTION

Apical disc slightly eccentric forwards. Ends of posterior petals lies at or slightly exceeds the adapical end of periproct. All ambulacral plates beyond petals single-pored; peristome faintly eccentric forwards.

REMARKS

This species is distinguished from P. waltheri in having small-sized test, petals II, III are relatively longer with larger number of pore pairs ( Fig. 14 ), and relatively less eccentric apical disc and peristome. Abdelhamid (1997) discussed the difference between the genera Petalobrissus , Nucleopygus Agassiz, 1840 , and Echinobrissus Gray, 1825 (= Nucleolites Lamarck, 1801 ). Due to the occurrence of a single pore in all ambulacral plates outside the petals, the present species refers to the genus Petalobrissus .

Figures

FIG. 14. — Comparison of Petalobrissus humei (Fourtau, 1906) n. comb. from the Turonian of Wadi Abu Qaada (filled quadrangles, dashed line) and Petalobrissus waltheri (Gauthier, 1900) from the Coniacian Santonian of Wadi Abu Qaada (empty quadrangles, solid line). The scatter plots show the relation between test length (L) and each of test width (W), test height (H), length of petal I or V (LI), number of pore pairs in petal I or V (NI), length of petal II or IV (LII), number of pore pairs in petal II or IV (NII), length of petal III (LIII) and number of pore pairs in petal III (NIII).