Catalog - Globigerinoides eoconglobatus

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.

Globigerinoides eoconglobatus

Citation: Globigerinoides eoconglobatus Stainbank, Spezzaferri, Kroon, de Leau & Rüggeberg, 2018

Type specimens: Figs. 1 and 2; Holotype (MHNF32906) and Paratypes (MHNF32907, MHNF32908, MHNF32909).

Type sample (& lithostrat): IODP 359 Hole U1467B-3H-3, 69–71cm. Pleistocene, PT1 [top of Zone NN19, ca 0.5Ma]

Type locality: Maldives, Inner Sea. Recovered at 4°51.026 N, 073°17.020 E at 487.5 m water depth.

Type repository: Fribourg; Natural History Museum of Fribourg (NHMF), Switzerland.

Type of wall: Normal perforate, cancellate, spinose, ruber/sacculifer-type wall texture and conglobatus-type wall texture of Hemleben et al. (2017, in press). The primary wall texture of G. eoconglobatus n. sp. is ruber/sacculifer type. However, similarly to G. conglobatus, individuals were found with calcitic crusts with a conglobatus-type wall texture (Hemleben et al. 2017, in press) (Fig. 2, 5–6). This texture represents a modification of the external ruber/ sacculifer-type wall texture: the high density of thin spines supported by short spine collars are partly covered by calcite crusts during gametogenesis. The result is a hummocky texture of overgrown spine collars, which occasionally show spine holes that may further develop in a thick euhedral calcite crust (Hemleben et al. 2017, in press).

Test morphology: Low to moderately high trochospiral consisting of two whorls, quadrangular to circular in outline and markedly lobate. Chambers are subspherical, four in the last whorl gradually increasing in size. The last chamber is slightly laterally compressed. Sutures depressed and straight on both sides. Umbilicus open and deep. Primary aperture umbilical to slightly extraumbilical, medium-sized to high and a wide arch. Several small to moderately high and rounded sutural supplementary aper- tures on the spiral side. It has a high density of thin spines

This morphospecies is generally larger than 250 µm. Maximum diameter of the holotype is 548 µm.

Named eoconglobatus as in ‘early or dawn’ as it is the ancestor of G. conglobatus

Distinguishing features: It is distinguished from G. obliquus by its last chamber, which is less laterally compressed. It also has numerous supplementary apertures. It differs from G. conglobatus primarily by its wide, high aperture and inflated final chamber in adult specimens. An additional distinguishing feature is the coiling, which is tight and streptospiral in G. conglobatus and loosely coiled in G. eoconglobatus n. sp.

Discussion: To identify G. conglobatus we have strictly followed the ‘‘morphospecies’’ concept used in Wade et al. (2017, in press). We have defined it by a series of morphological characters that are shared with the holotype. Consequently, G. eoconglobatus n. sp., having different characters has been identified as a new morphospecies. Therefore, both G. conglobatus and G. eoconglobatus n. sp. may or may not represent true biological species. Forms similar to G. eoconglobatus n. sp. have been identified as G. conglobatus or its synonyms by several authors (e.g., Bé and Tolderlund 1971; Fordham 1979; Rillo 2016; Rillo et al. 2016). Yet, due to the lack of accompanying figures in the majority of publications, it is difficult to ascertain the true extent of this morphospecies distribution. Currently, based on this study and images from Rillo (2016) we can state it is found in the Indian and Pacific Oceans.

Phylogenetic relationship: Aze et al. (2011) reported the evolution of G. conglobatus from G. obliquus in the Late Miocene. As such, it is inferred that G. eoconglobatus n. sp. evolved from G. obliquus in Subzone M13a and gives origin to G. conglobatus in Zone PL1.

Stratigraphic range: From Subzone M13a to Holocene.

Geographic distribution: This morphospecies is present in the Indian Ocean Sites drilled during IODP expedition 359. Rillo (2016) also reports it in the Indian and Pacific Oceans, yet it is identified as G. conglobatus. Further studies are, therefore, needed to confirm its presence at other locations, as the true geographical extent of this species is presently unresolved.

Stable isotope paleobiology: Surface mixed layer (tropical/subtropical).

References:

Stainbank, S., Spezzaferri, S., Kroon, D., de Leau, E. S. & Rüggeberg, A. (2018). The Planktonic foraminifera Globigerinoides eoconglobatus n. sp. in a glacial–interglacial context: IODP359 Sites U1467 and U1468. Swiss Journal of Geosciences. 111(3): 511-522. gs

Comments (2)

François

ref: Stainbank, S.; Spezzaferri, S.; Kroon, D.; De Leau, E. S.; Rüggeberg, A. (2018). The Planktonic foraminifera Globigerinoides eoconglobatus n. sp. in a glacial–interglacial context: IODP359 Sites U1467 and U1468. Swiss Journal of Geosciences. 111(3): 511-522.

7 January 2019 14:32

Jeremy Young(UK)

corrected, thanks Jeremy

7 January 2019 20:50

CATALOG OF ORIGINAL DESCRIPTIONS: Globigerinoides eoconglobatus Stainbank, Spezzaferri, Kroon, de Leau & Rüggeberg, 2018

Globigerinoides eoconglobatus

References:

Add Comment

Comments (2)