Characters of Nummulites multiplicutiospiralis n.sp.from the Qarara Formation,Maghagha,Nile Valley,Egypt

• 作者: Safia AL MENOUFY
• 来源期刊: 地质学报（英文版）
• 年，卷（期）: 2021,（2）
• 所属期刊栏目: ORIGINAL ARTICLES
• 页码范围: 342-347
• 页数: 6页
• 语种: 英文

摘要

Nummulites multiplicutiospiralis n.sp.is described and illustrated for both generations from a claystone of Lutetian age in the Middle Eocene Qarara Formation,Maghagha,Nile valley,Egypt.Previously considered to be Nummulites gizehensis,we describe this form as a new species based on diameter of the test and protoconch sizes,septal shape and granulations.The primary feature of this species is spiral multiplication,seen in spiral section.The species is also characterized morphologically by lenticular to flat tests with rounded periphery,wrinkled to broadly meandering septal filaments and few granules on the periphery in microspheric forms.The granules are spirally arranged on the septal filaments in megalospheric forms.Chambers are longer than high and the spire is irregular.The new taxon belongs to the Nummulites partschi Group,Subgroup N.gizehensis.Reflexive coiling in the spiral may develop through ontogeny as in N.rollandi,the species which was considered to be an index species in the southern Tethys(Boukhary et al.,1982 and Boukhary et al.2010).The characters of the new species,as well as its retrogenesis and reflexive coiling,should be further studied in general in Nummulites spp.,to understand the importance of such characters phylogenetically.