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Selenopemphix undulata

Selenopemphix undulata Verleye et al., 2011, p.71–72, pl.1, figs.1–9; p,.2, figs.1–3.
Holotype: Verleye et al., 2011, pl.1, figs.2–3.
Age: Holocene.

Original description (Verleye et al., 2011)
Holotype. Specimen IRSNB b5176 (Plate 1, figs. 2 and 3). Slide 1233C-2H-1, 112–114, 7.59 mcd P1; England Finder Reference C43-4. Repository. Royal Belgian Institute for Natural Sciences, Brussels, Belgium.
Type locality and type stratum. SE Pacific, offshore central-south
Chile (41°S), ODP Leg 202, ODP Site 1233, Hole C, section 2H-1, 7.59
mcd (6.2 cal ka BP; Holocene).
Diagnosis. A large cyst with a pale brown to brown colour and a reniform, subcircular to circular ambitus in polar view. The epicyst is conical and the hypocyst carries distally two weakly developed rounded horns. Strongly developed, wide cingulum formed by two parallel ridges, with undulating margins. The large rounded archeopyle is simple and offset to the left of the dorsal midline. The operculum is free.
Description. A large, polar compressed cyst with a pale brown to brown colour (Plate 1, fig. 9; Plate 2, fig. 1). In polar view, the cyst has a reniform, subcircular to circular outline (Plate 1, figs. 2–8). The cyst is often folded
because of the thin cyst wall (b0.3 μm). The epicyst and hypocyst are almost equally sized (Plate 1, fig. 9). The epicyst is conical (Plate 1, fig. 9; Plate 2, figs. 1 and 2) while the hypocyst carries distally two small equally
sized rounded horns positioned close to each other (Plate 1, fig. 9; Plate 2, fig. 3). The wall thickens up to 0.9 μm at the apical boss and the tips of each antapical horn. The epicyst and hypocyst are separated by a well developed, deeply indented (4–5 μm), wide (8–11 μm) cingulum (Plate 1, fig. 9; Plate 2, fig. 1). The cingulum is characterised by two parallel, distally undulated ridges (i.e., changes in crest height) (Plate 1, figs. 2–8; Plate 2, fig. 3). The sulcus is well defined by an indentation of the cyst wall, and two flagellar scars are often visible within the sulcal area (Plate 1, fig. 6; Plate 2, figs. 1 and 2). The shagreenate cyst wall is occasionally faintly striated. Striae run from the polar areas toward the cingulum (Plate 1, fig. 8). No tabulation pattern is observed with the
exception of the archeopyle, the cingulum and the sulcus. The archeopyle is simple and is formed by the loss of the second anterior intercalary plate (2a) (Plate 1, figs. 3, 5 and 8). The archeopyle is iso-deltalinteloid hexa with a trithigmate posterior interseries boundary contacting 3'. The archeopyle has rounded margins and is offset to the left of the dorsal midline (Plate 1, fig. 1). The operculum is free and sometimes found within the cyst.
Dimensions. Holotype: cyst diameter 64.6 × 58.2 μm, archeopyle 21.8 × 19.9 μm. Range (Plate 1, fig. 1): width ‘a’ 49.5–89.4 μm (mean: 64.3 μm; SD= 7.6; n= 187); width ‘b’ 37.9-82.3 μm (mean: 60.6 μm; SD= 7.1; n= 107); archeopyle width 16.9–38.4 μm (mean 24.7 μm; SD= 3.4; n= 81); archeopyle height 12–24.3 μm (mean 17.1 μm;
SD= 2.8; n= 79) (see supplementary data E). Comparison with other taxa. Selenopemphix alticinctum Bradford,
1975 is distinguished from S. undulata sp. nov. by its much smaller size (30–39 μm) and its smooth cyst wall. S. undulata sp. nov. differs from Selenopemphix antarctica Marret and de Vernal, 1997 in having no granulations concentrated around and on the top of both apical and antapical horns (Plate 2, figs. 4 and 5). Furthermore, the thin, pale brown to semi-transparent cyst wall of S. antarctica contrasts with the usual brown colour of S. undulata sp. nov. Selenopemphix bothrion Harland and Pudsey, 2002 differs from S. undulata sp. nov. by its conspicuous slit-like negative ornament on both the epicystal and hypocystal margins. These may appear as a series of interconnecting radially aligned basin-like depressions. The size of both cysts is, however, very similar. Selenopemphix nephroides Benedek, 1972 is distinguished from S. undulata sp. nov. by the smooth cyst wall and the absence of undulated cingular margins (Plate 2, figs. 6–9). No striae occur on the cyst wall. The cyst wall of Selenopemphix sp. 1 Esper and Zonneveld, 2007 has granulations concentrated around and on the top of both apical and antapical horns, similar to S. antarctica Marret and de Vernal, 1997.
Remarks. Cyst analysis with an epifluorescent microscope showed no autofluorescence, suggesting a heterotrophic affinity (Brenner and Biebow, 2001).
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