Back
Enneadocysta brevistila
Enneadocysta brevistila Fensome et al., 2007, p.397,398,400,402, pl.4, figs.1–4,7,8.
Holotype: Fensome et al. 2007, pl.4, figs.1,2.
Age: early Priabonian.
Original description (Fensome et al., 2007):
Enneadocysta brevistila Fensome, Guerstein and Williams, n. sp. Plate 4, figures 1-4, 7-8
Areosphaeridium sp. A of COCOZZA and CLARKE 1992, fig 4b.
Enneadocysta sp. 2 of LEVY and HARWOOD 2000, plate 4, figs d-g.
Enneadocysta partridgei “Short processes (Areosphaeridium ebdoniistyle)” of BRINKHUIS et al. 2003 figures 68-69.
Derivation of name: From the Latin, brevis, short, and stilus, stake or pen, in reference to the ragged clypeate processes, similar to those of Enneadocysta dictyostila, but considerably shorter.
Diagnosis: A species of Enneadocysta with short (up to 15µm) processes, including 6 precingulars and 3-5 cingulars. Processes with ragged clypeate to licrate processes.
Description: Shape: Cyst proximochorate with a slightly dorso-ventrally flattened, subspherical central body that may be symmetrical or slightly asymmetrical in outline. Wall relationships: Autophragm up to 1.5µm thick. Wall features: Autophragm smooth to faintly granulate, occasionally pitted. Central body bears 22 to 24 processes mostly mesotabular, but at least three (the two antapical and the posterior sulcal) are apparently obtabular to penitabular. Process distribution as follows: 10 on epicyst, 9 on hypocyst and 3-5 (usually 4) indicating cingulum. Processes short, not exceeding 15µm in length, and distally ragged clypeate. Process stems solid, of variable width (up to 12µm, with cingulars thinner), occasionally faintly fibrous, perforate or fenestrate. Archeopyle: Apical, type (tA), tetratabular; operculum simple, free. Tabulation: Indicated by processes and archeopyle margin. Each of the precingular plates has a mesotabular process, with the sixth and first precingular processes and plates being of equal size. The anterior sulcal plate never has a process. The three to five cingular processes are obtabular, appearing to have “migrated” toward the ambitus. On the hypocyst, there are six postcingular processes, one per plate, a process that we interpret as the posterior sulcal, and two antapical processes. The two antapical processes are penitabular being near the lateral boundaries. Process formula: 4', 6'', 3-5c, 6''', ps, 2''''.
Dimensions: Range of 18 specimens except where noted: central body width 50 (52) 67µm; central body length without operculum 37 (46) 55µm (12 specimens); process length up to 5 (11) 15µm; width of processes stems (excluding cingular processes) 3 to 12µm.
Holotype: Pl. 4, figs. 1-2. Location: sample PT 57, slide P36632-1: 32.7 x 105.0, England Finder P44/0. Repository: Laboratory of Palynology, Universidad Nacional del Sur, Bahía Blanca, Argentina. Dimensions: central body width 51µm; central body length 38µm; process length 7-9µm.
Stratigraphic and geographic occurrence: Lb member of the Leticia Formation, La Despedida Group (Olivero and Malumián 1999) at Cabo Campo del Medio, southeastern Tierra del Fuego, Argentina. Age: Mid Eocene, based on information in Olivero and Malumián (1999).
Occurrence: Enneadocysta brevistila was recorded by one of us (GLW) from ODP Site 1172 core 40, sections 2, 3 and 4. This interval, according to Brinkhuis et al. (2003), is from magnetochron 16 r2r, equivalent to 36.4 Ma or early Priabonian.
Comparison: Enneadocysta brevistila differs from Enneadocysta dictyostila in having much shorter, wider processes. Like Enneadocysta brevistila, Areosphaeridum ebdonii has short processes, including six precingulars but no anterior sulcal; it differs, however, in having only five postcingular processes, one antapical process, and usually no cingular processes, although Bujak (1994) stated that there may be one or two cingular processes. Enneadocysta brevistila always has at least three cingular processes.
Holotype: Fensome et al. 2007, pl.4, figs.1,2.
Age: early Priabonian.
Original description (Fensome et al., 2007):
Enneadocysta brevistila Fensome, Guerstein and Williams, n. sp. Plate 4, figures 1-4, 7-8
Areosphaeridium sp. A of COCOZZA and CLARKE 1992, fig 4b.
Enneadocysta sp. 2 of LEVY and HARWOOD 2000, plate 4, figs d-g.
Enneadocysta partridgei “Short processes (Areosphaeridium ebdoniistyle)” of BRINKHUIS et al. 2003 figures 68-69.
Derivation of name: From the Latin, brevis, short, and stilus, stake or pen, in reference to the ragged clypeate processes, similar to those of Enneadocysta dictyostila, but considerably shorter.
Diagnosis: A species of Enneadocysta with short (up to 15µm) processes, including 6 precingulars and 3-5 cingulars. Processes with ragged clypeate to licrate processes.
Description: Shape: Cyst proximochorate with a slightly dorso-ventrally flattened, subspherical central body that may be symmetrical or slightly asymmetrical in outline. Wall relationships: Autophragm up to 1.5µm thick. Wall features: Autophragm smooth to faintly granulate, occasionally pitted. Central body bears 22 to 24 processes mostly mesotabular, but at least three (the two antapical and the posterior sulcal) are apparently obtabular to penitabular. Process distribution as follows: 10 on epicyst, 9 on hypocyst and 3-5 (usually 4) indicating cingulum. Processes short, not exceeding 15µm in length, and distally ragged clypeate. Process stems solid, of variable width (up to 12µm, with cingulars thinner), occasionally faintly fibrous, perforate or fenestrate. Archeopyle: Apical, type (tA), tetratabular; operculum simple, free. Tabulation: Indicated by processes and archeopyle margin. Each of the precingular plates has a mesotabular process, with the sixth and first precingular processes and plates being of equal size. The anterior sulcal plate never has a process. The three to five cingular processes are obtabular, appearing to have “migrated” toward the ambitus. On the hypocyst, there are six postcingular processes, one per plate, a process that we interpret as the posterior sulcal, and two antapical processes. The two antapical processes are penitabular being near the lateral boundaries. Process formula: 4', 6'', 3-5c, 6''', ps, 2''''.
Dimensions: Range of 18 specimens except where noted: central body width 50 (52) 67µm; central body length without operculum 37 (46) 55µm (12 specimens); process length up to 5 (11) 15µm; width of processes stems (excluding cingular processes) 3 to 12µm.
Holotype: Pl. 4, figs. 1-2. Location: sample PT 57, slide P36632-1: 32.7 x 105.0, England Finder P44/0. Repository: Laboratory of Palynology, Universidad Nacional del Sur, Bahía Blanca, Argentina. Dimensions: central body width 51µm; central body length 38µm; process length 7-9µm.
Stratigraphic and geographic occurrence: Lb member of the Leticia Formation, La Despedida Group (Olivero and Malumián 1999) at Cabo Campo del Medio, southeastern Tierra del Fuego, Argentina. Age: Mid Eocene, based on information in Olivero and Malumián (1999).
Occurrence: Enneadocysta brevistila was recorded by one of us (GLW) from ODP Site 1172 core 40, sections 2, 3 and 4. This interval, according to Brinkhuis et al. (2003), is from magnetochron 16 r2r, equivalent to 36.4 Ma or early Priabonian.
Comparison: Enneadocysta brevistila differs from Enneadocysta dictyostila in having much shorter, wider processes. Like Enneadocysta brevistila, Areosphaeridum ebdonii has short processes, including six precingulars but no anterior sulcal; it differs, however, in having only five postcingular processes, one antapical process, and usually no cingular processes, although Bujak (1994) stated that there may be one or two cingular processes. Enneadocysta brevistila always has at least three cingular processes.