Catalog - Streptochilus tasmanensis

CATALOG OF ORIGINAL DESCRIPTIONS: Streptochilus tasmanensis Smart & Thomas 2018

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 tasmanensis
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 tasmanensis

Citation: Streptochilus tasmanensis Smart & Thomas 2018
Rank: Species
Type specimens: Plate 19.2, Figures 16-31; Plate 19.3, Figures 1-26
Type sample (& lithostrat): ODP Hole 1170A/43X/3, 56-57 cm
Type age (chronostrat): Upper Oligocene Zone O7,
Type locality: South Tasman Rise, off Tasmania.

Current identification/main database link: Streptochilus tasmanense Smart and Thomas, 2018


Original Description

Type of wall: Microperforate, surface scattered with circular pore mounds.

Test morphology: Test small, biserial, elongate, increasing regularly in size, often narrowing towards apertural end, occasionally flared, rarely twisted, occasionally slightly curved; laterally compressed, periphery broadly rounded and lobulate; usually 5-8 pairs of chambers, rarely more, slightly inflated, wider than high, increasing gradually in size as added; sutures slightly curved and 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 in-turned portion of the preceding foramen; no obvious differences between micro- and megalospheric specimens.

Size:
Holotype length 0.20 mm, width 0.10 mm; length range 0.10-0.32 mm (mean 0.16 mm, St. Dev. 0.033, n = 207), width range 0.07-0.14 mm (mean 0.09 mm, St. Dev. 0.011, n = 207), thickness range 0.04-0.07 (mean 0.05 mm, St. Dev. 0.007, n = 42).

Etymology:
Named after the area where it has been found, i.e. South Tasman Rise, off Tasmania (ODP Site 1170).

Extra details from original publication
Distinguishing features: Distinguished by often becoming narrower towards apertural end, occasionally flared, laterally compressed, surface ornamentation with scattered circular pore mounds. According to the terminology of Georgescu and others (2011), S. tasmanensis n. sp. displays scattered incipient to well-developed pore mounds (2.8-3.7 μm) with circular pores (0.8-1.8 μm). Streptochilus tasmanensis n. sp. is distinguished from Chiloguembelina ototara by the more compressed test, surface ornamentation of scattered pore mounds, and presence of a toothplate. Streptochilus tasmanensis n. sp. differs from S. martini, S. pristinum and S. rockallkiddensis by surface ornamentation of scattered pore mounds. It differs from S. martini and S. pristinum by the narrowing of the test towards the apertural end.

Discussion: Similar to the Miocene S. mascarenensis Smart and Thomas, but S. tasmanensis n. sp. does not become parallel-sided, has less curved sutures and has pore mounds.

Pylogenetic relationships.— It has been shown that some Recent biserial foraminifera are able to live tychopelagically implying a similar lifestyle for fossil species, and polyphyletic evolution of planktonic from benthic biserial groups (Darling and others, 2009). It is likely that the distribution of S. tasmanensis n. sp. represents a separate expatriation event from the coastal benthos to the pelagic zone (Darling and others, 2009).

Stratigraphic range: Upper Oligocene Zone O7 to lower Miocene (Zone M1) (ODP Hole 1170A), pending further investigations.

Geographic distribution: Currently only known from South Tasman Rise, off Tasmania (ODP Site 1170).

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

References:

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

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