Catalog - Streptochilus mascarenensis

CATALOG OF ORIGINAL DESCRIPTIONS: Streptochilus mascarenensis Smart and Thomas (2007)

This page provides data from the catalog of type descriptions. The catalog is sorted alphabetically. Use the current identification link to go back to the main database.


Higher levels: pf_cat -> S -> Streptochilus -> Streptochilus mascarenensis
Other pages this level: S. cetacensis, S. dubeyi, S. globiger infirmirugosus, S. inglei, S. latum, S. macdougallae, S. mascarenensis, S. pristinum, S. rockallkiddensis, S. subglobigerum, S. tasmanensis, S. tokelauae flexiserialis

Streptochilus mascarenensis

Citation: Streptochilus mascarenensis Smart and Thomas (2007)
Rank: Species
Type specimens: Holotype BM(NH) PF 68152; Paratypes BM(NH) PF68153-68191, BM(NH) PF 68252-68279
Type sample (& lithostrat): DSDP 24-237-18-6, 69-71cm, 166.69 mbsf.
Type age (chronostrat): Lower Miocene
Type locality: NW Indian Ocean, DSDP Site 237 (Table 1). Also reported from ODP Site 709.
Type repository: London, UK; NHM

Current identification/main database link: Streptochilus mascarenense Smart and Thomas 2007


Original Description

Diagnosis. Test small, elongate, laterally compressed, commonly flared with distinct chambers and curved and depressed sutures.

Description. Test small, elongate, increasing regularly in size,flared and occasionally almost parallel-sided, laterally compressed, periphery broadly rounded and lobulate, rarely twisted,biserial; 5-7 pairs of chambers,wider than high, increasing gradually in size as added; sutures distinct, curved and slightly depressed; aperture high arch-shaped, offset slightly to one side of test, extending from the base of the last chamber onto apertural face, bordered by a thickened rim/collar along the top and outer side of the arch, the opposite side is turned inward to a plate connecting with the top of the collar and the inturned portion of the preceding foramen; wall smooth to finely granular, very finely perforate; no obvious differences between micro- and megalospheric specimens.

Dimensions. Length, 260-110μm (mean 169μm, St. Dev. 30, n = 106); maximum width, 120-80μm (mean 98μm, St. Dev. 8, n= 106); thickness, 60-45μm (mean 50μm, St. Dev. 3, n = 20).

Etymology. Named after the area where it has been found, i.e.the Mascarene Plateau, NW Indian Ocean (DSDP Site 237).

Size:
Dimensions. Length, 260-110μm (mean 169μm, St. Dev. 30, n = 106); maximum width, 120-80μm (mean 98μm, St. Dev. 8, n= 106); thickness, 60-45μm (mean 50μm, St. Dev. 3, n = 20).

Etymology:
From the Mascarene Plateau

Extra details from original publication
Remarks. Streptochilus mascarenensis was called Bolivina sp. and specimens from DSDP Site 237 are illustrated
in Smart (2002, Fig. 3.1, 2) and Smart and Thomas (2006, fig. 2,C, D).

Early Miocene Streptochilus spp. occurred coevally at various sites in the Atlantic and Indian Oceans, but the species differ morphologically from site to site.
Streptochilus mascarenensis closely resembles Streptochilus cetacensis, but Streptochilus mascarenensis is consistently more laterally compressed (thickness 50μm compared with 62μm), its periphery is more lobulate, and its pores are smaller. Streptochilus cetacensis is typically ‘triangular’ in shape and flared, and is clearly different from S.rockallkiddensis.Specimens of S.cetacensis at Site 667 are overall smaller than those from the southeastern Atlantic (Sites 529 and 1264), and have distinctive pores over all chambers of the test. The differences in pore distribution and size of S. cetacensis between the equatorial Atlantic specimens (Site 667) and southeastern Atlantic specimens might be due to differential dissolution.
Streptochilus cetacensis closely resembles S. mascarenensis , but S. cetacensis is consistently less laterally compressed (thickness 62μm compared with 50μm), becomes thicker towards the apertural end, its periphery is less lobulate, and is more ‘triangular’ in shape. S. mascarenensis is clearly different from S. rockallkiddensis in its general shape, its more pronounced chambers, and absence of a coarsely roughened test. For all three new species,differentiating between microspheric and megalospheric specimens in non-sectioned specimens is often unclear and speculative, although in sectioned/polished specimens it is possible to distinguish between specimens that have relatively small (microspheric) or large (megalospheric) proloculi.

Editors' Notes
Orthography: Streptochilus is a neuter noun (Smart & Thomas 2018, p.501) so the correct form of the species name is mascarenense, although it was given as mascarenensis in the original description.

References:

Smart, C. W. & Thomas, E. (2007). Emendation of the genus Streptochilus Brönnimann and Resig 1971 (Foraminifera) and new species from the lower Miocene of the Atlantic and Indian Oceans. Micropaleontology. 53(1-2): 73-103, 103 figures, 113 lates, 101 table. gs

Smart, C. W. & Thomas, E. (2018). Taxonomy, biostratigraphy, and phylogeny of Oligocene Streptochilus. In, Wade, B. S., Olsson, R. K., Pearson, P. N., Huber, B. T. & Berggren, W. A. (eds) Atlas of Oligocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication . 46(Chap 19): 495-511. gs V O


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Streptochilus mascarenensis compiled by the pforams@mikrotax project team viewed: 30-11-2022

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