n6 UPPER CRETACEOUS-LOWER TERTIARY FORAMINIFERA 



umbilicus roughly quadrate in outline, relatively wide, deep, and covered by complex 

 tegilla of which remnants are still preserved ; primary apertures interiomarginal, 

 umbilical ; tegilla with accessory apertures only poorly preserved ; wall calcareous, 

 perforate except for the imperforate keel and tegilla ; surface on the dorsal side 

 rough in the early part, covered with numerous small papillae which decrease 

 gradually towards the last chamber ; on the ventral side the surface is very rough, 

 heavily papillose or even nodose. 



Dimensions of holotype. 



Maximum diamter = 0-48 mm. 



Minimum diameter = 0-33 mm. 



Thickness = 0-28 mm. 



Main variation. 



1. Chambers 13-18, arranged in 2§~3 whorls, generally dextrally coiled. 



2. Chambers in the last whorl 4-5, flat to slightly inflated, slightly to moderately 



imbricate, increasing slowly in size except for the last, which is either 

 slightly smaller or slightly larger than the penultimate. 



3. The surface can either be rough throughout, heavily nodose or even spinose, 



or it can be delicately papillose in the early part and smooth later. 



Remarks. Gandolfi (1955) described as G. gansseri gansseri Bolli from the 

 Colon shale of northeastern Colombia, a form which differs from the holotype of 

 Bolli (1951). Such a form is abundant in the samples studied; its morphological 

 characters and stratigraphical range warrant its separation from the central type 

 and therefore it is here considered as a new subspecies of G. gansseri Bolli. It is 

 named G. gansseri gandolfii, after Dr. R. Gandolfi. It is believed to have evolved from 

 either G. gansseri gansseri (Bolli) or G. gansseri dicarinata Pessagno, as suggested by 

 the morphological features and stratigraphical ranges of these forms. On the other 

 hand, G. gansseri gandolfii is morphologically related to Globotruncana arabica sp. 

 nov. which appears slightly higher in the section and thus may possibly represent 

 its direct descendant. 



Holotype. P. 45541. 



Paratypes. P. 45542. 



Horizon and locality. Holo- and paratypes, from sample No. 21, W. El- 

 Sharawna section, Esna-Idfu region. 



Stratigraphical range. In the Esna-Idfu region G. gansseri gandolfii appears 

 as a common to a flood form in the upper part of the Middle Maestrichtian G. gansseri 

 Zone, and continues as a rare to a common form in the overlying G. esnehensis Zone 

 where it dies out completely immediately below the disconformity separating this 

 zone from the overlying basal Tertiary. All records of G. gansseri gansseri Bolli 

 from rocks younger than the Middle Maestrichtian (e.g. Gandolfi 1955 and Berggren 

 1962) most probably refer to the present subspecies. 



