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Thalassiphora decrementa
Thalassiphora decrementa Islam, 1983
Holotype: Islam, 1983, pl.4, figs.4-5; text-fig.7
Locus typicus: Hampshire Basin, S England
Stratum typicum: Middle Eocene
Original diagnosis: Islam, 1983, p. 344
Cyst ellipsoidal to subspherical, proximate camocavate and biphragmal; sometimes possessing only an apical, or an apical, antapical and two paracingular bulges or protrusions in the pericyst; endocyst sometimes with polar protrusions only; endophragm 1 µm thick and reticulate; periphragm very thin, puncto-reticulate, adpressed to endophragm on dorsal side of cyst and separated elsewhere to a maximum pericoelar separation of 12 µm, sometimes almost no cavation in extreme forms but minor partial cavation always; periphragmal thickening, defining paratabulation of 4", ?1a, 5", 4c, 5""", ?1p, 1"""", xs; archeopyle precingular type P representing paraplate 3", operculum attached.
Dimensions: Holotype: endocyst 68 x 57 µm, maximum pericoelar separation 11 µm. Range: endocyst length 78(69)54 µm, breadth 78(62)52 µm, maximum pericoelar separation 12(6.4)5 µm, length of periapical horn 0-14 µm. Specimens measured: 13.
Affinities:
Islam, 1983, p. 344: This species differs from others of the genus in the reduced pericoel. Its periphragm resembles that of Thalassiphora patula (Williams and Downie) Bujak et al. 1980 and it is a derivative of that species resulting from progressive reduction of pericoel and development of polar and lateral features. Maximum pericoelar separation of 12 µm is set for delimiting the two species. Near-acavate forms resemble Spongodinium Deflandre, emend. Stover and Evitt 1978 and Muratodinium Drugg 1970 but these genera possess autocysts only.
Holotype: Islam, 1983, pl.4, figs.4-5; text-fig.7
Locus typicus: Hampshire Basin, S England
Stratum typicum: Middle Eocene
Original diagnosis: Islam, 1983, p. 344
Cyst ellipsoidal to subspherical, proximate camocavate and biphragmal; sometimes possessing only an apical, or an apical, antapical and two paracingular bulges or protrusions in the pericyst; endocyst sometimes with polar protrusions only; endophragm 1 µm thick and reticulate; periphragm very thin, puncto-reticulate, adpressed to endophragm on dorsal side of cyst and separated elsewhere to a maximum pericoelar separation of 12 µm, sometimes almost no cavation in extreme forms but minor partial cavation always; periphragmal thickening, defining paratabulation of 4", ?1a, 5", 4c, 5""", ?1p, 1"""", xs; archeopyle precingular type P representing paraplate 3", operculum attached.
Dimensions: Holotype: endocyst 68 x 57 µm, maximum pericoelar separation 11 µm. Range: endocyst length 78(69)54 µm, breadth 78(62)52 µm, maximum pericoelar separation 12(6.4)5 µm, length of periapical horn 0-14 µm. Specimens measured: 13.
Affinities:
Islam, 1983, p. 344: This species differs from others of the genus in the reduced pericoel. Its periphragm resembles that of Thalassiphora patula (Williams and Downie) Bujak et al. 1980 and it is a derivative of that species resulting from progressive reduction of pericoel and development of polar and lateral features. Maximum pericoelar separation of 12 µm is set for delimiting the two species. Near-acavate forms resemble Spongodinium Deflandre, emend. Stover and Evitt 1978 and Muratodinium Drugg 1970 but these genera possess autocysts only.