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Pyxidinopsis
From Williams et al., 2017:
[Pyxidinopsis, Habib, 1976, p. 382
Type species: Pyxidinopsis challengerensis, Habib, 1976 (pl.1, figs.1a–b)]
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Original description: [Habib, 1975]:
Diagnosis:
Proximate dinoflagellate cysts. Outline in lateral, dorsal and ventral views oval to elliptical; longer than wide with rounded polar areas. Discrete apical and antapical horns lacking. Autoblast two-layered with periphragm and endophragm in contact. Evidence of cyst tabulation, cingulum or sulcus lacking.
Archeopyle large and precingular, formed by loss of a single plate (Type P). Operculum simple and free.
Periphragm texture variable, processes always wider or longer than high.
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Modified description:
Stover and Evitt 1978, p. 183-184:
Synopsis:
Cysts proximate, subspherical; autophragm; surface reticulate, archeopyle precingular, Type P.
Modified description: Shape: Subspherical.
Wall relationships: Autophragm only, or appressed endophragm and periphragm.
Wall features: Surface reticulate (See Comment below).
Paratabulation: Indicated by archeopyle only.
Archeopyle: Precingular, Type P (3`` only); operculum free.
Paracingulum: Not indicated.
Parasulcus: Not indicated.
Size: Intermediate.
Remark:
Although proposed as monotypic, Habib (1975, p. 382) remarked that undescribed species with granulate and vermiculate ornamentation will eventually be placed in Pyxidinopsis.
Affinities:
Pyxidinopsis differs from Tectatodinium in having a reticulate surface and a simpler wall. Scriniocassis, which is also reticulate, has an ectophragm covering the reticulum and a Type 2P rather than Type P archeopyle.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Pyxidinopsis Habib, 1976. Synopsis from Stover and Evitt (1978, p.183), Cysts proximate, subspherical; autophragm only, or appressed endophragm and periphragm; surface reticulate, archeopyle precingular, type P.
[Pyxidinopsis, Habib, 1976, p. 382
Type species: Pyxidinopsis challengerensis, Habib, 1976 (pl.1, figs.1a–b)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Habib, 1975]:
Diagnosis:
Proximate dinoflagellate cysts. Outline in lateral, dorsal and ventral views oval to elliptical; longer than wide with rounded polar areas. Discrete apical and antapical horns lacking. Autoblast two-layered with periphragm and endophragm in contact. Evidence of cyst tabulation, cingulum or sulcus lacking.
Archeopyle large and precingular, formed by loss of a single plate (Type P). Operculum simple and free.
Periphragm texture variable, processes always wider or longer than high.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Evitt 1978, p. 183-184:
Synopsis:
Cysts proximate, subspherical; autophragm; surface reticulate, archeopyle precingular, Type P.
Modified description: Shape: Subspherical.
Wall relationships: Autophragm only, or appressed endophragm and periphragm.
Wall features: Surface reticulate (See Comment below).
Paratabulation: Indicated by archeopyle only.
Archeopyle: Precingular, Type P (3`` only); operculum free.
Paracingulum: Not indicated.
Parasulcus: Not indicated.
Size: Intermediate.
Remark:
Although proposed as monotypic, Habib (1975, p. 382) remarked that undescribed species with granulate and vermiculate ornamentation will eventually be placed in Pyxidinopsis.
Affinities:
Pyxidinopsis differs from Tectatodinium in having a reticulate surface and a simpler wall. Scriniocassis, which is also reticulate, has an ectophragm covering the reticulum and a Type 2P rather than Type P archeopyle.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Pyxidinopsis Habib, 1976. Synopsis from Stover and Evitt (1978, p.183), Cysts proximate, subspherical; autophragm only, or appressed endophragm and periphragm; surface reticulate, archeopyle precingular, type P.