Catalog - Hastigerinella riedeli

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Hastigerinella riedeli

Citation: Hastigerinella riedeli Rögl & Bolli 1973

Type age (chronostrat): Type sample: Deep Sea Drilling Project, Leg 15, Site 147. Core 6, core-catcher (51.00 m). Type stratum: Late Pleistocene; Globorotalia truncatulinoides truncatulinoides Zone, Globigerinacalida calida Subzone; Zone X after Ericson and Wollin.

Type locality: Cariaco Basin, Caribbean Sea, lat 10°42,48'N; long65°10,48'W.

Type repository: Basel, CH; Natural History Museum

Test very small, low trochospiral to fairly streptospiral. Twelve subglobular chambers in slightly over two whorls. Chambers increase slowly and regularly in size, are attached to each other fairly loosely and separated by distinct, deeply incised sutures. Last chamber slightly tilted towards the umbilicus, which is small and shallow. The final chamber possesses a small, low arched, umbilical aperture with a narrow, raised lip. The wall is delicate, transparent, smooth and shiny, with very small, widely spaced pores. Clusters of triangular, strong spines are positioned at the peripheral ends of chambers. At their base, the spines are surrounded by small, irregular, conical cuffs formed by calcite crystals.

Largest diameter 0.172 mm; height of spira 0.111 mm.

Paratypes: Sixty-four specimens. Leg 15, Site 147, Core 2, Section 1 (top): NMB C-27162, 27224/1-4; Core 3, Section 1(100-102 cm): NMB C-27224/5-6; Core 4 (core-catcher): NMB C-27224/7-12; Core 5, Section 2 (114-116 cm): NMB C-27224/13-17; Core 6 (core-cather): NMB C-27163, 27165, 27170, 27224/18-60.

Dimensions (paratypes): Diameter 0.088-0.182 mm; height of spire 0.052-0.126 mm; average diameter 0.141 mm; average height of spire 0.084 mm.
Number of chambers (paratypes): 10-17, average 12.16.

The variability of the species is largely restricted to the test size and the number of chambers, which are arranged in two to two and a half, exceptionally, three whorls. High spired specimens are rare. The five chambers of the last whorl are distinctly larger and are on a lower plane than those of the inner portion (Plate 4, Figures 3 and 5). This is caused by a streptospiral arrangement of chambers, which is also apparent in the position of the apertures (Plate 4, Figure 4; Plate 14, Figure 3).

Remarks: The species is placed in Hastigerinella because of its spine development and also because of the slight tendency to streptospiral coiling. The concentration of the spines at the distal ends of chambers is also typical for the genus. The new species is close to Hastigerinella rhumbleri Galloway, which has a similar arrangement of spines, but differs from it in the much smaller size. Hastigerinellar humbleri is not present in Site 147. Occasionally specimens may have a reduced final chamber showing that the end of growth has been reached. The species differs from five chambered Globigerinas such as Globigerina quinqueloba in the robust triangular spines concentrated at the distal end of chambers and in the mode of coiling.

Distribution: The species is present throughout the section of Site 147, from the Globorotalia hessi to the Globorotalia fimbriata Subzone of the Globorotalia truncatulinoides truncatulinoides Zone, Pleistocene to Holocene.

References:

Rögl, F. & Bolli, H. M. (1973). Holocene to Pleistocene planktonik foraminifera of LEG 15, site 147 (Cariaco Basin (Trench), Caribbean Sea) and their climatic interpretation. Initial Reports of the Deep Sea Drilling Project. 15: 553-579. gs O

CATALOG OF ORIGINAL DESCRIPTIONS: Hastigerinella riedeli Rögl & Bolli 1973

Hastigerinella riedeli

References:

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