Leptammina grisea

Cedhagen, Tomas, Gooday, Andrew J. & Pawlowski, Jan, 2009, A new genus and two new species of saccamminid foraminiferans (Protista, Rhizaria) from the deep Southern Ocean *, Zootaxa 2096, pp. 9-22: 12-15

publication ID

http://doi.org/ 10.5281/zenodo.187761

persistent identifier

http://treatment.plazi.org/id/03F387BC-4845-FF82-EEFA-4D00389B474B

treatment provided by

Plazi

scientific name

Leptammina grisea
status

 

Leptammina grisea  gen. et sp. nov.

( Figs 1–2View FIGURE 1View FIGURE 2)

Material: Polarstern Station 102 # 11 (Agassiz trawl) 25 specimens; Station 102 # 13 (Epibenthic sledge) 2 specimens; Station 110 # 8 (Epibenthic sledge) 1 specimen; Station 133 # 2 (Epibenthic sledge) 1 specimen.

Derivation of name: grisea  is the Medieval Latinization of the French word gris, and means grey. It refers to the colour of the test.

Diagnosis. Approximately spherical species of Leptammina  , up to 2 mm diameter, characterized by soft, delicate, finely agglutinated test, grayish or violet-grey in colour and opaque, with dull, non-reflective surface. Single, prominent circular aperture. Cell body dark greenish, with single nucleus. Peduncular sheath well developed.

Deposition of type material: The holotype from Station 102 # 11 and paratypes from Stations 102 # 11, 102 # 13, 110 # 8, and 133 # 2 are deposited in the Forschungsinstitut Senckenberg, Frankfurt am Main, Germany, under reg. no. SMF XXVII 7537.

Description. General morphology. The test is free and a distinctive grey or violet-grey colour. Unfixed specimens are roughly spherical, occasionally more elongate, and often somewhat irregular in shape ( Figs 1View FIGURE 1 A –D). The diameter ranges from 620 to 1360 µm (mean 0.91 mm; median 0.91 mm; n= 24 individuals). There is one round aperture on a short neck and surrounded by a thin raised collar.

Test wall. The wall is soft, delicate and easily detached. The surface has a dull, non-reflective appearance. It is smooth when viewed under the light microscope but slightly rough when viewed at higher magnifications (1,000 X – 5,000 X) in the SEM. The wall includes a thin, outer agglutinated layer, up to 30 µm thick, and an inner organic lining, ~ 3 µm thick ( Figs 1View FIGURE 1 E –F; 2 F). The outer layer is composed of small mineral particles varying in size from ~ 10 µm maximum dimension to 1 µm or less ( Figs 2View FIGURE 2 A –B). Many of these particles are angular in shape.

Cell body. In fresh, newly collected individuals, the cell body is a dark green or brownish green and entirely fills the test ( Fig. 1View FIGURE 1 E –F). A distinct peduncular sheath (stomostyle) is located immediately inside the aperture and may extend into the apertural neck and cover the rim of the aperture ( Fig. 2View FIGURE 2 C). It is also continuous with the inner organic lining of the test wall. Light microscopic sections reveal one large nucleus, up to 240 µm diameter, of the granular type with numerous nucleoli, located within an exonuclear vacuole. The center of the nucleus is occupied by a vacuole, up to 200 µm wide ( Fig. 2View FIGURE 2 F). Large vacuoles are also visible within the cytoplasm of sectioned individuals. Pseudopodia were not observed, although a thin string of cytoplasm projects along the central axis of the peduncular sheath ( Fig. 2View FIGURE 2 C). However, in critical-point dried individuals studied by SEM, the cell body consists of a dense network of fine pseudopodia (reticulopodia) that incorporate stercomata, mineral particles, diatoms, and other foreign particles ( Fig. 2View FIGURE 2 D).

Remarks: Leptammina grisea  gen. et sp. nov. closely resembles Saccammina alba  in the general form and construction of the test. The main differences are that the test is larger (620 to 1360 µm compared to a maximum size of 400 µm in S. alba  ), the test wall is thicker, and the surface is greyish rather than white. It should also be noted that S. alba  was described from an intertidal setting whereas the new species occurs at bathyal and abyssal depths. Leptammina grisea  gen. et sp. nov. differs from Pilulina argentea  in having a dull grey rather than reflective, silvery surface. See also “Remarks” under L. flavofusca  gen. et sp. nov.

Distribution: Weddell Sea, central part at 4795, 4822, and 4698 m depth, northwestern part at 1580 m depth.

SMF

Forschungsinstitut und Natur-Museum Senckenberg