Catalog - Globigerina rubescens

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Globigerina rubescens

Citation: Globigerina rubescens Hofker 1956

Type locality: Malaya-Indonesian Archipelago area; found in deep water.

Type repository: Depository not given.

Small trochoid test, beginning with small proloculus of 10µm diameter. Chambers four in the last-formed whorl. Pores relatively small, with honeycomb structure between. Aperture open, rounded, totally umbilical and central at ventral side, relatively small, often with thickened border. Pore index 6-1. Wall of last-formed chambers reddish or pinkish.

In many samples from the eastern part of the Malayan Archipelago a small reddish Globigerina occurs which at first glance may have been attributed to Globigerina rubra. When comparing young specimens of real Globigerina rubra from the West Indies with those small specimens from the Pacific, I found, however, that we here deal with a quite different species. Young specimens of Globigerina rubra d'Orbigny, with a diameter of test of about 0.10 mm. and a proloculus of 10µm diameter, all showed already the triloculine arrangement of the last-formed chambers; the new species from the Pacific shows four or even five chambers in the last-formed whorl.
"Globigerina rubra of full-grown size has an average diameter of 0.50 mm. The specimens from the Pacific invariably show a size of about 0.12-0.15 mm., and these adult forms never occur in the samples. The Pacific species shows an index of 6-1. The ornamentation of young Globigerina rubra is smooth, with only very few pustules between the pores; the Pacific species shows the honeycomb type.
The aperture of Globigerina rubra is a wide, arched opening in the young one, though the dorsal part of the aperture is not yet formed; the specimens from the Pacific never show indications of a dorsal aperture, whereas the aperture is much smaller and provided with a conspicuous thickened lip. All these differences enable us to create a new specific name for the Pacific species, and I therefore chose the name Globigerina rubescens. The species seems closely allied with Globigerina rubra."

Lectotype designation by Brummer & Kucera 2022
Hofker did not designate a holotype, neither in his original description of this species (Hofker, 1956), nor when describing the genus Globoturborotalita of which G. rubescens is the type species (Hofker, 1976). Hofker (1956) noted that the specimens that lead him to erect G. rubescens were derived from recent sediments from western Indonesia (Malay Archipelago) collected during the Dutch Siboga expedition (1899–1900). The location of this material is unclear, but we have located in the Hofker collection (originally deposited at the Zoological Museum in Amsterdam, and then transferred in 2011 to the Naturalis Biodiversity Center, Leiden, the Netherlands, and curated there) a slide registered as RGM 538508 with a written note on the slide apparently in Hofker’s handwriting, stating that the sample contains “Globigerina rubescens Hofker” (Fig. 5c). The slide contains a sieved residue from a sediment collected during the Snellius expedition (Snellius station 190) off Sulawesi, i.e. from the same region as the Siboga material. It is impossible to establish when the labelling of the slide occurred, but because of the genus name it must have been before 1976. Since it appears likely that Hofker considered this material when he established G. rubescens in 1956 and because of the clear labelling by Hofker, the specimens in the sample can be considered syntypic, and the sample represents in our opinion the best available material to select a type. The residue contained a rich and well preserved assemblage of planktonic foraminifera from which we were able to extract 15 specimens of G. rubescens. From among those, we here designate specimen RGM 1333481 as the lectotype, and specimens RGM 1333482–1333495 as paralectotypes (Fig. 5). [Brummer & Kucera 2022]

References:

Brummer, G-J. A. & Kucera, M. (2022). Taxonomic review of living planktonic foraminifera. Journal of Micropalaeontology. 41: 29-74. gs

Hofker, J. (1956c). Foraminifera Dentata, foraminifera of Santa Cruz and Thatch-Island, Virginia-Archipelago West-Indies. Copenhagen Univ. Zool. Mus. Spolia (Skrifler). 15: 1-237. gs

Hofker, J. (1976). La famille Turborotalitidae. Revue de Micropaléontologie. 19: 47-53. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Globigerina rubescens Hofker 1956

Globigerina rubescens

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