Aioloceras morganiforme  (Collignon, 1963)

Measurements	D mm	H/D	T/D	O/D	H/T	Ribs
CP-720	52.9	0.48	0.34	0.22	1.42	26
CP-21	56	0.52	0.34	0.18	1.53	25
CP-719 figured	68.1	0.49	0.30	0.24	1.64	32
CP-719	(56)	0.50	0.35	0.26	1.41	32
Holotype	79	0.49	0.32	0.22	1.56	>34
CP-159	93 (86)	0.47	0.32	0.23	1.45	38

Age	Origin
A. besairiei Malagasy zone Lower Albian	Ambatolafia Boeny Region Madagascar

Description. Discoid phragmocone in a green, glauconitic siltstone with its pearly test. The upper part of one flank is crushed near the aperture. The whorls, 70% covered, have an ogival section, with flanks diverging up to the inner third, then converging towards an arched venter. The umbilicus has a low, straight wall, sloping at 80°, and a narrowly rounded rim. The thickness continues to increase beyond the umbilical margin. Low, rounded ribs gradually arise near the umbilical rim. They are sigmoid, projecting forward at the top of flanks, and cross venter with a marked attenuation and a strong, rounded, proverse sinus at a 90° angle. A few shorter ribs arise above mid-flank. Five slightly stronger ribs begin closer to the umbilicus. They are followed and preceded by a slight constriction, the rear one being wider. There are a total of 38 ribs on venter. The umbilical suture line of the missing portion of the spiral is visible on the last whorl. It shows that the overlap of the whorls drops to 55%.

Remarks. A species closely related to Aioloceras besairiei, but thicker (see its entry and H/T ratio), with more convex and divergent lower flanks, a less narrow venter, and a slightly more open umbilicus. The ribs, fewer in number, persist longer during growth and are projected forward near the venter. The name derives from its resemblance to Cleoniceras morgani Spath, 1927, from the English Albian, but which has umbilical bullae. According to Riccardi & Medina (2002) and Kennedy & Klinger (2014), A. morganiforme may be a variant of A. besairiei.