CATALOG OF ORIGINAL DESCRIPTIONS: Streptochilus inglei Miranda-Martínez et al. 2017

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 inglei
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 inglei

Citation: Streptochilus inglei Miranda-Martínez et al. 2017
Rank: Species
Type locality: Loc. IGM-3971. 25°58′24.60′′ N, 111°04′33.27′′ W. Punta Perico, Del Carmen Island, Baja California Sur, México.
Type age: PP-1, Unit III Marlstone and Mudstone (Dorsey et al., 2001)
Type sample and level: Carmen Formation.
Holotype Repository: Mexico City; Colecci0n Nacional del Museo de Paleontolog’a Mar’a del Carmen Perrilliat, Instituto de Geolog’a, Universidad Nacional Autonoma de Mexico.
Type & figured specimens: Holotype IGM-1576-Mi (Pl. III, Fig. 3). Paratypes. IGM-1577-Mi (Pl. III, fig. 2); IGM-1578-Mi (Pl. III, fig. 5), IGM-1579-Mi (not illustrated).

Current identification/main database link: Streptochilus inglei Miranda-Martínez, Carreño and McDougall 2017


Original Description
Biserial, small to medium size test, somehow twisted in the initial portion. Periphery lobulated. Commonly with seven to eight pairs of chambers, rare specimens with six pairs. Chambers increase moderately in size as added, in the last mid-portion expands regularly giving a triangular outline. Initial chambers subquadrate and slightly inflated, being subglobose as added and the last two chambers are globose (Pl. III, figs. 2 and 3). Sutures straight and strongly depressed, forming a zigzag feature in the middle line of the test due to the strong overlap of the chambers (Pl. III, fig. 1). Wall, smooth, finely and sparsely perforate (Pl. III, fig. 3b). Aperture, located perpendicular to the middle plane of the test, consists of a wide and elongate high arch, offsets moderately to one side of test, bordered by a thick rim/collar along the outer side of the arch (Pl. III, fig. 9c), which is turned inward and connects with the collar of the previous aperture with presence of an internal plate (Pl. III, fig. 10).

Size: Holotype: Length 176 μm, maximum width 100 μm, minimum width 22.4 μm. Size range: Length 164–306 μm (mean 218 μm, n = 24); max- imum width 99–134 μm (mean 112 μm, n = 16); minimum width 13–23 μm (mean 19 μm, n = 16), maximum thickness 56–90 μm (70 μm, n = 16); minimum thickness 13–21 μm (mean 17 μm, n = 16).

Etymology: In honor of Prof. J. Ingle, Stanford University, CA, for contribution towards knowledge of the fossil foraminifera of the ancient Gulf of California and Pacific Ocean.

Extra details from original publication
Remarks. New species differs from other smooth walled Streptochilus such as S. pristinum Brönnimann and Resig (1971) in having a lobulate periphery with straight sutures, being subglobose in the early stage becoming globose on the last two chambers, instead of have a straight profile with slightly curved sutures, no chamber inflation and the last two formed chamber slightly inflated. Brönnimann and Resig (1971) illustrated a slender specimen of S. pristinum; nevertheless, Resig (1989) shows subglobose specimens, but always with a straight profile and with the last two former chambers subglobose. Aperture of S. pristinum has not been extensively described or illustrated, but from Resig and Kroopnick (1983; Pl. 1; figs. 19, 20) aperture seems to be an arch higher and wider that the observed in new species here described.
Streptochilus latus Brönnimann and Resig is similar to the new species except that sutures are slightly curved and sloping to the periphery, chambers are rectangular and the last formed chambers are subglobose and bigger (Pl. I). Aperture has not been extensively described but Resig and Kroopnick (1983; figs. 5–9) showed it as a larger aperture bordered by a rim/collar that is turned inward to a plate connecting with the collar of the preceding aperture, similar to Streptochilus inglei sp. nov.
Streptochilus cetacensis Smart and Thomas, another smooth-walled species, is similar to the new species except for its typically triangular outline, sutures curved, slightly inflated chambers and not so globose character of the last two formed chambers.
Only in Streptochilus cetacensis the number of chambers is established in the original diagnosis of between five and eight pairs. S. pristinum and S. latus holotypes have seven pairs of chambers (Brönnimann and Resig, 1971), however S. latus specimens with eight pairs in the Gulf of California (Plate I) and Pacific Ocean have been illustrated (Resig and Kroopnick, 1983; Resig, 1989). Holotype of Streptochilus globulosus also has seven pairs of chambers (Cushman, 1933), but fossil specimens with five or six pairs of chambers and recent specimens with eight to nine pairs have been illustrated (Boersma et al., 1969; Brönnimann and Resig, 1971; Resig and Kroopnick, 1983; Resig, 1989; Darling et al., 2009). Number of chambers recorded for Streptochilus inglei sp. nov., is similar to those present in smooth-walled Streptochilus, suggesting that the number of chambers is not a diagnostic feature.

Stratigraphic occurrence. The latest part of the Miocene, from ~ 6 to 5.3 Ma. From upper part of N17b to the basal part of N18/19 zones of Blow (1979 sensu Gradstein et al., 2012), equivalent to the M14 to the base of PL1 zones of Wade et al. (2011).

References:

Miranda-Martinez, A. Y., Carreño, A. L. & McDougall, K. (2017). The Neogene genus Streptochilus (Brönnimann and Resig, 1971) from the Gulf of California. Marine Micropaleontology. 132: 35-52. gs


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Streptochilus inglei compiled by the pforams@mikrotax project team viewed: 16-12-2019

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