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Selenopemphix antarctica
Selenopemphix antarctica Marret and de Vernal, 1997, p.389,391, pl.5, figs.1–5.
Holotype: Marret and de Vernal, 1997, pl.5, fig.2.
Age: Holocene.
Original description (Marret and de Vernal, 1997)
Etmology: Named antartica from its distibution in the Antarctic Ocean.
Diagnosis: Proximate cyst, extremely compressed apically-antapically, with a short apical horn and two short antapical horns. Archeopyle is intercalary.
Description: The proximate cyst is compressed apically-antapically. The periphragm is faintly ornamented, with granulations concentrated around and on the top of both apical and antapical horns. Both apical and antapical horns present rounded tips (Figs. 2 and 4). The two antapical horns are close to each other. The paratabulation is indicated by an intercalary (hexa) archeopyle, offset laterally to the left of the longitudinal axis. The operculum is free or sometimes remains attached along one parasuture. The paracingulum is expressed by low, parallel,
transverse equatorial folds or ridges. The parasulcus is mostly indicated by a moderate indentation on the ventral surface, although some specimens show a deeper depression. Holotype: Plate V, 2, sample KRSS-18, UQP
773-5, England Finder reference R39/4. Repository: GEOTOP, Universite du Quebec a Montreal (Canada).
Dimensions: Holotype 66 x 62 pm in apical view. Range in maximum diameter 40 (60) 102 pm. Number of specimens measured 69.
Comparisons: S. antarctica sp. nov. differs from S. nephroides in having two antapical horns, and granulations concentrated around and on the top of both apical and antapical horns. The wall surface of S. antarctica sp. nov. lacks the wrinkles that ornament the wall surface of S. nephroides. In contrast with the usual brown colour of S. nephroides, the cyst wall of S. antarctica sp. nov. is thin and has a pale brown colour to semi-transparent at the light microscope. Occurrence: Surface sediments samples of the southern Indian Ocean (south of 405). S. antarctica sp. nov. dominates assemblages of the Antarctic and Subantarctic domains and where sea-surface temperatures average - 1.8 and 0°C in summer, and freeze in winter (e.g. Zwally et al., 1983). Percentages of
S. antarctica sp. nov. decrease from south to north as sea-surface temperatures and salinities increase. S.
antarctica sp. nov. is rare in the Subtropical domain. The occurrence of this species can be related to cold water and seasonal sea-ice cover. S. antarctica sp. nov. is probably an endemic species to high polar environments of the Southern Ocean.
Holotype: Marret and de Vernal, 1997, pl.5, fig.2.
Age: Holocene.
Original description (Marret and de Vernal, 1997)
Etmology: Named antartica from its distibution in the Antarctic Ocean.
Diagnosis: Proximate cyst, extremely compressed apically-antapically, with a short apical horn and two short antapical horns. Archeopyle is intercalary.
Description: The proximate cyst is compressed apically-antapically. The periphragm is faintly ornamented, with granulations concentrated around and on the top of both apical and antapical horns. Both apical and antapical horns present rounded tips (Figs. 2 and 4). The two antapical horns are close to each other. The paratabulation is indicated by an intercalary (hexa) archeopyle, offset laterally to the left of the longitudinal axis. The operculum is free or sometimes remains attached along one parasuture. The paracingulum is expressed by low, parallel,
transverse equatorial folds or ridges. The parasulcus is mostly indicated by a moderate indentation on the ventral surface, although some specimens show a deeper depression. Holotype: Plate V, 2, sample KRSS-18, UQP
773-5, England Finder reference R39/4. Repository: GEOTOP, Universite du Quebec a Montreal (Canada).
Dimensions: Holotype 66 x 62 pm in apical view. Range in maximum diameter 40 (60) 102 pm. Number of specimens measured 69.
Comparisons: S. antarctica sp. nov. differs from S. nephroides in having two antapical horns, and granulations concentrated around and on the top of both apical and antapical horns. The wall surface of S. antarctica sp. nov. lacks the wrinkles that ornament the wall surface of S. nephroides. In contrast with the usual brown colour of S. nephroides, the cyst wall of S. antarctica sp. nov. is thin and has a pale brown colour to semi-transparent at the light microscope. Occurrence: Surface sediments samples of the southern Indian Ocean (south of 405). S. antarctica sp. nov. dominates assemblages of the Antarctic and Subantarctic domains and where sea-surface temperatures average - 1.8 and 0°C in summer, and freeze in winter (e.g. Zwally et al., 1983). Percentages of
S. antarctica sp. nov. decrease from south to north as sea-surface temperatures and salinities increase. S.
antarctica sp. nov. is rare in the Subtropical domain. The occurrence of this species can be related to cold water and seasonal sea-ice cover. S. antarctica sp. nov. is probably an endemic species to high polar environments of the Southern Ocean.