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Senoniasphaera tabulata
Senoniasphaera tabulata Backhouse and Helby in Helby, 1987
Taxonomic senior synonym: Muderongia simplex, according to Riding et al. (2001), p.29.
Holotype: Backhouse and Helby in Helby, 1987, fig.21A-B
Paratypes: Backhouse and Helby in Helby, 1987
Locus typicus: Australia
Stratum typicum: Hauterivian
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Senoniasphaera tabulata Backhouse and Helby in Helby, 1987. Senoniasphaera tabulata is large, not obviously cavate and has distinctive parasutural ridges. It possesses cingular protrusions and two antapical horns. Size: overall width is 76-125 µm, width endocyst 70-107 µm, loisthocyst length 75-140 µm, length endocyst less operculum 60-108 µm, length endocyst with operculum 82-120 µm.
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Original description: Backhouse and Helby in Helby, 1987, p. 317-317
Proximate cyst, lenticular to compressed peridinioid, with a short, anteriorly rounded, apical horn, equatorial paracingular protrusion and 2 antapical horns. Left antapical horn larger and further from the paracingulum. In apical-antapical view, ventral surface markedly concave, and the distal surface convex (Fig.21C,D). Cyst wall 2-layered, circumcavate; outlines of endophragm and periphragm essentially similar; pericoel without supports and wider beneath horns and paracingular protrusions than elsewhere. Wall layers appear appressed in parasulcal area. Endophragm is smooth to scabrate; periphragm smooth, scabrate or perforate between parasutural features, namely, low ridges of thickened scabrogranulate material. Paratabulation clearly expressed by parasutural ridges and by principal and accessory archeopyle sutures. Parasulcal plates not delineated. Paratabulation formula 4', 6'', 6c, 6''', 1p, 1''''(Fig.23). Archeopyle is apical, type [tA], principal archeopyle suture zigzag with offset parasulcal notch; operculum free. Paracingulum marked by distinctive protrusion of periphragm (Fig.21B), both equatorially and across dorsal surface. Parasulcus a depressed, strongly convex, relatively broad, midventral feature on hypocyst continuing to left of centre on epicyst.
Measurements. See Fig.24 for key to measurements. Twenty-five specimens from Plover-2 well at 612.6m in the M. testudinaria Zone were measured as:--A, 76(97)125µm; B, 70(85)107µm; C, 75(99)140µm; D, 60(82.5)108µm; E, 125 (137.8)145µm (4 specimens measured); F, 82(101)120µm.
Affinities:
Backhouse and Helby in Helby, 1987, p. 319: Senoniasphaera ptomatis, is smaller, has less obvious paratabulation and exhibits more extensive cavation than S. tabulata. Senoniasphaera protrusa Clarke & Verdier 1967 is distinguished by its lack of/or poor development of paratabulation features and its periphragm supports. Senoniasphaera rotundata Clarke & Verdier 1967 lacks apical and antapical horns on its endocyst. Forms apparently identical to S. tabulata have been reported from the Wealdean of Great Britain (David Batten, American Association Stratigraphic Palynologists Meeting, Dallas, Texas 1979).
Taxonomic senior synonym: Muderongia simplex, according to Riding et al. (2001), p.29.
Holotype: Backhouse and Helby in Helby, 1987, fig.21A-B
Paratypes: Backhouse and Helby in Helby, 1987
Locus typicus: Australia
Stratum typicum: Hauterivian
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Senoniasphaera tabulata Backhouse and Helby in Helby, 1987. Senoniasphaera tabulata is large, not obviously cavate and has distinctive parasutural ridges. It possesses cingular protrusions and two antapical horns. Size: overall width is 76-125 µm, width endocyst 70-107 µm, loisthocyst length 75-140 µm, length endocyst less operculum 60-108 µm, length endocyst with operculum 82-120 µm.
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Original description: Backhouse and Helby in Helby, 1987, p. 317-317
Proximate cyst, lenticular to compressed peridinioid, with a short, anteriorly rounded, apical horn, equatorial paracingular protrusion and 2 antapical horns. Left antapical horn larger and further from the paracingulum. In apical-antapical view, ventral surface markedly concave, and the distal surface convex (Fig.21C,D). Cyst wall 2-layered, circumcavate; outlines of endophragm and periphragm essentially similar; pericoel without supports and wider beneath horns and paracingular protrusions than elsewhere. Wall layers appear appressed in parasulcal area. Endophragm is smooth to scabrate; periphragm smooth, scabrate or perforate between parasutural features, namely, low ridges of thickened scabrogranulate material. Paratabulation clearly expressed by parasutural ridges and by principal and accessory archeopyle sutures. Parasulcal plates not delineated. Paratabulation formula 4', 6'', 6c, 6''', 1p, 1''''(Fig.23). Archeopyle is apical, type [tA], principal archeopyle suture zigzag with offset parasulcal notch; operculum free. Paracingulum marked by distinctive protrusion of periphragm (Fig.21B), both equatorially and across dorsal surface. Parasulcus a depressed, strongly convex, relatively broad, midventral feature on hypocyst continuing to left of centre on epicyst.
Measurements. See Fig.24 for key to measurements. Twenty-five specimens from Plover-2 well at 612.6m in the M. testudinaria Zone were measured as:--A, 76(97)125µm; B, 70(85)107µm; C, 75(99)140µm; D, 60(82.5)108µm; E, 125 (137.8)145µm (4 specimens measured); F, 82(101)120µm.
Affinities:
Backhouse and Helby in Helby, 1987, p. 319: Senoniasphaera ptomatis, is smaller, has less obvious paratabulation and exhibits more extensive cavation than S. tabulata. Senoniasphaera protrusa Clarke & Verdier 1967 is distinguished by its lack of/or poor development of paratabulation features and its periphragm supports. Senoniasphaera rotundata Clarke & Verdier 1967 lacks apical and antapical horns on its endocyst. Forms apparently identical to S. tabulata have been reported from the Wealdean of Great Britain (David Batten, American Association Stratigraphic Palynologists Meeting, Dallas, Texas 1979).