Hemiaster barthouxi Lambert, 1931

Mohamed Abdelhamid, Marouf Abdel-Aty & Moustafa Azab, Mahmoud, 2012, Turonian-Santonian echinoids from Egypt, Geodiversitas 34 (3), pp. 575-615 : 602-604

Hemiaster barthouxi Lambert, 1931 ( Fig. 15G, H)

Hemiaster barthouxi Lambert, 1931: 196 , pl. 5, figs18, 19.

MATERIAL EXAMINED. — Five specimens from theTuronian of Wadi Abu Qaada (Wata Formation), ASUAQE144-148, Wadi Abu Qaada echinoid horizon 1 ( QEH 1).

25

20

15

10

5

5 10 15 20 25 10

8

6

4

2

0

5 10 15 20 25

7

5

3

1

5 10 15 20 25

7

5

3

1

5 10 15 20 25 14

12

10

8

6

4

2

5 10 15 20 25 40

35

30

25

20

15

10

5 10 15 20 25 35

30

25

20

15

10

5 10 15 20 25 35

30

25

20

15

length 10

5 10 15 20 25

DESCRIPTION

Test length attaining 23.0- 28.1 mm. Outline oval to sub-round, markedly wide at anterior (W/L = 0.91-1.0). Posterior margin straight. Adapical surface high, culminate behind the apical disc (H/L = 0.66-0.76). Adoral surface convex, swollen at the plastron. Posterior surface with oblique truncation. Apical disc centric, semi-ethmolytic. Frontal ambulacrum narrow and deep near apical disc, flush to very shallow at the ambitus. Paired ambulacra petaloid, relatively short and deep. Posterior paired petals shorter and less divergent than the posterior ones (LI/LII = 0.72-0.77, NI = 23-29, NII = 28-39). Fascioles are a narrow band of peripetalous parafasciole (sensu Néraudeau et al. 1998).

REMARKS

This species is characterized by its globular test with short petals and flush frontal ambulacrum at the ambitus. It is distinguished from H. gauthieri Péron, 1877 from the Turonian and Santonian of France and Spain in having relatively longer and deeper petals.