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Selenopemphix conspicua
Selenopemphix conspicua (de Verteuil and Norris, 1992, p.399–401, pl.2, figs.2–8; pl.10, figs.1–4; pl.11, figs.1–2; text-fig.5) Louwye et al. 2004, p.378. Holotype: de Verteuil and Norris, 1992, pl.2, figs.2–3. Originally Selenopemphix brevispinosa subsp. conspicua, subsequently (and now) Selenopemphix conspicua. Age: late middle-late Miocene.
Original diagnosis: De Verteuil and Norris, 1992, p. 400
A subspecies of Selenopemphix brevispinosa Head et al. 1989 with a reniform outline in apical view. Two cingular margins are marked by discontinuous, short, broad adcingular processes that are more or less equally spaced and of equal height (1-3 µm). Processes may bifurcate asymmetrically and are distally denticulate.
Original description: De Verteuil and Norris, 1992, p. 400
The epicyst is concave low conical with a small apical horn 3-6 µm long. The hypocyst also is reduced but is without horns. The cingulum is broad (approximately 15% of major equatorial diameter in height) and level, and has a continuous anterior margin in the ventral region, beneath which the sulcus is located. The ends of the posterior cingular margin curve towards the antapex before terminating. The wall is pigmented and psilate. The archeopyle is intercalary and offset on the left anterior dorsal surface.
Dimensions. Equatorial diameter excluding processes: major, 40(49)62 µm; holotype, 50 µm; minor, 30(36)45 µm; holotype, 36 µm. Process length 1-3 µm. Twenty-two specimens measured.
Discussion. In separate samples, two consistently distinctive collections of S. brevispinosa subsp. conspicua have been found. One morphotype is strongly pigmented with a psilate or nannogranulose (sensu Jarzen and Norris, 1973) ornament (Plate 2, figs. 2-3; Plate 10, figs. 1-2, Plate 11, figs. 1-2), and the other is visibly microgranulose (0.1-0.2 µm) and lacks pigment (Plate 2, figs. 7-8; Plate 10, figs. 3-4). We consider the latter morphotype to be the result of post depositional alteration of originally brown pigmented, psilate cysts. This interpretation is supported by similar observations of pigment loss and selective safranin-o stain uptake in other protoperidiniacean species, a phenomenon discussed earlier in this paper. This micro-ornament variability has also been observed for S. dionaeacysta and Quadrina? condita, but the contrast between the pristine and altered states was not as obvious.
Affinities:
De Verteuil and Norris, 1992, p. 400-401: S. brevispinosa subsp. conspicua is distinguished from S. brevispinosa Head et al. 1989 subsp. brevispinosa by the nature of its adcingular processes, which are wider, usually chorter and distally more complex. S. brevispinosa subsp. conspicua differs from S. dionaeacysta Head et al. 1989 in having relatively shorter processes whose length is always less than 50% of the cingulum height. S. crenata Matsuoka & Bujak 1988 has a very low, continuously serrated cingular margin.
Original diagnosis: De Verteuil and Norris, 1992, p. 400
A subspecies of Selenopemphix brevispinosa Head et al. 1989 with a reniform outline in apical view. Two cingular margins are marked by discontinuous, short, broad adcingular processes that are more or less equally spaced and of equal height (1-3 µm). Processes may bifurcate asymmetrically and are distally denticulate.
Original description: De Verteuil and Norris, 1992, p. 400
The epicyst is concave low conical with a small apical horn 3-6 µm long. The hypocyst also is reduced but is without horns. The cingulum is broad (approximately 15% of major equatorial diameter in height) and level, and has a continuous anterior margin in the ventral region, beneath which the sulcus is located. The ends of the posterior cingular margin curve towards the antapex before terminating. The wall is pigmented and psilate. The archeopyle is intercalary and offset on the left anterior dorsal surface.
Dimensions. Equatorial diameter excluding processes: major, 40(49)62 µm; holotype, 50 µm; minor, 30(36)45 µm; holotype, 36 µm. Process length 1-3 µm. Twenty-two specimens measured.
Discussion. In separate samples, two consistently distinctive collections of S. brevispinosa subsp. conspicua have been found. One morphotype is strongly pigmented with a psilate or nannogranulose (sensu Jarzen and Norris, 1973) ornament (Plate 2, figs. 2-3; Plate 10, figs. 1-2, Plate 11, figs. 1-2), and the other is visibly microgranulose (0.1-0.2 µm) and lacks pigment (Plate 2, figs. 7-8; Plate 10, figs. 3-4). We consider the latter morphotype to be the result of post depositional alteration of originally brown pigmented, psilate cysts. This interpretation is supported by similar observations of pigment loss and selective safranin-o stain uptake in other protoperidiniacean species, a phenomenon discussed earlier in this paper. This micro-ornament variability has also been observed for S. dionaeacysta and Quadrina? condita, but the contrast between the pristine and altered states was not as obvious.
Affinities:
De Verteuil and Norris, 1992, p. 400-401: S. brevispinosa subsp. conspicua is distinguished from S. brevispinosa Head et al. 1989 subsp. brevispinosa by the nature of its adcingular processes, which are wider, usually chorter and distally more complex. S. brevispinosa subsp. conspicua differs from S. dionaeacysta Head et al. 1989 in having relatively shorter processes whose length is always less than 50% of the cingulum height. S. crenata Matsuoka & Bujak 1988 has a very low, continuously serrated cingular margin.