Catalog - Globorotalia quinifalcata

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Globorotalia quinifalcata

Citation: Globorotalia quinifalcata Saito & Maiya 1973

Type specimens: PI. 18, figs. 5a-c, 6a-c

Type sample (& lithostrat): Sample N-H-13, middle part of the Hojuji Formation, in a dark grey diatomaceous mudstone.

Type locality: small road-side cliff in the village of Go, on the north side of the road, about 3 km west of the Ukai railroad station, Ukai City, Kanazawa Prefecture, Japan

Type repository: Tokyo; National Science Museum, Tokyo, Japan. Duplicate paratypes are deposited in the, U.S.N.M. Washington, D.C.

Test low trochospiral, umbilico-convex, spiral side slightly convex, umbilical side vaulted; spire opening fairly rapidly, with four to five chambers in the last whorl; equatorial periphery weakly lobulate, Uniformly perforate, without carina or pseudocarina; axial periphery rounded; sutures of the spiral side depressed and strongly curved; sutures of the umbilical side depressed, slightly sinuous to radial; chambers almost crescent-shaped as seen from the spiral side; aperture interiomarginal, umbilical-extraumbilical, a low arch with a distinct lip; wall calcareous, perforate.

Maximum diameter of holotype 0.24 mm; paratype (fig. 6a-c) 0.25 mm.

The specific name is from the Latin quini, five and falcata, sickle-shaped, referring to the five tangentially elongate chambers of the last whorl as seen from the spiral side

Globorotalia scitula (BRADY) subsp. praescitula BLOW. JENKINS, 1960, p. 366, pI. 5, fig. 62a-c.
Globorotalia scitula praescitula BLOW. SAITO, 1963, p. 181, pI. 53, fig. 6a-c.

Remarks:-This species differs from G. peripheroronda in having chambers more tangentially elongate, a more strongly vaulted umbilical side, and gently curving sutures on the spiral side. This form has frequently been misidentified as G. praescitula BLOW by previous authors. Our examination of Blow's holotype indicates that G. praescitula is a rather unique form having four strongly lobulate chambers in the last whorl (pI. 18, fig. 7a-c). It differs from G. quinifalcata, n. sp. in having more strongly lobulate chambers on the spiral side, a distinctly lobate equatorial periphery and more strongly curved sutures on the spiral side, and a much deeper umbilicus. The specimen described as G. scitula praescitula by PARKER (1964) from the Experimental Mohole core is, in our opinion, not G. praescitula BLOW but synonymous with G. quinifalcata because of its distinctly umbilicoconvex test and the last whorl consisting of five, rather than four, less lobulate chambers. This new species is widely distributed over the Japanese Islands and occurs commonly in association with G. peripheroronda BLOW and BANNER. G. quinifalcata closely resembles Globorotalia canariensis (O'ORBIGNY) var. minima AKERS, the holotype of which is here re-illustrated (pI. 18, fig. 8a-c). However, G. minima can be distinguished by having a distinctly compressed periphery, and a pseudocarina in the earlier chambers of the last whorl.

Since the specimens of this species are poorly preserved in the Nishikurosawa Formation, the types of G. quinifalcata are chosen from the Hojuji Formation of the Noto Peninsula, Japan. The foraminiferal assemblage of the Hojuji Formation is closely comparable with the present Nishikurosawa fauna in species composition.

References:

Saito, T. & Maiya, S. (1973). Planktonic foraminifera of the Nishikurosawa Formation, northeast Honshu, Japan. Transactions and Proceedings of the Palaeontological Society of Japan. 91(1): 113-125. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Globorotalia quinifalcata Saito & Maiya 1973

Globorotalia quinifalcata

References:

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