Back
Alterbidinium papillatum
Alterbidinium papillatum, Khowaja-Ateequzzaman et al., 1991
Holotype: Khowaja-Ateequzzaman et al., 1991, pl.1, figs.4-7; text-figs.1A-B
Locus typicus: Kunnam Village, India
Stratum typicum: Turonian-Santonian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Khowaja-Ateequzzaman et al., 1991, p. 38-41]:
Diagnosis:
Cyst proximate, dorso-ventrally compressed, circumcavate, pericyst ambitus pentagonal with an apical horn and two symmetrically placed unequal antapical horns, right antapical horn reduced; periphragm thin, papillate, papillae more pronounced on dorsal surface, intratabular; endocyst subpentagonal, endophragm thicker than periphragm, smooth; periparacingulum annulate;
paratabulation peridinioid, ?4", 3a, 7", Xc, 5""", 1p, 2"""";
archaeopyle intercalary, independently developed on periphragm and endophragm, periarchaeopyle hexa 2a, steno-deltaform, perioperculum adnate, endoarchaeopyle hexa 2a, eury-deltaform, endoperculum adnate.
Description:
Shape: Cyst proximate, dorso-ventrally compressed; pericyst ambitus pentagonal with a broad based apical horn having a short apicular process at the tip (sensu Wiggins, 1975, p. 98) and two symmetrically placed unequal antapical horns, right antapical horn reduced; endocyst subpentagonal.
Wall relationship: Apical and antapical pericoels prominent connected through ambital pericoel (circumcavate ), endocyst shifted more towards dorsal side where periphragm and endophragm appressed in the precingular and postcingular areas.
Wall features: No parasutural features; periphragm thin, papillate, papillae intratabular, pronounced on perioperculum, precingular, postcingular and antapical paraplate areas on dorsal surface (Text-figs lA, 2A-B); ventral surface bears numerous irregular folds (Text-fig. lB); periparacingulum marked by two parallel ridges and a furrow running high over endocyst, bearing papillae arranged in two single discontinuous rows on the margins of the ridges, paracingular paraplates indiscernible; endophragm thicker than periphragm, smooth; perisulcus marked by a depression.
Paratabulation: Peridinioid, incompletely discernible on individual specimens; pericyst paratabulation formula ?4", 3a, 7", Xc, 5""", 1p, 2"""" (Text-fig. 3A-B).
Archaeopyle: Intercalary, independently developed on periphragm and endophragm, periarchaeopyle hexa 2a, steno-deltaform, perioperculum adnate (adnation along adcingular margin); endoarchaeopyle hexa 2a, eury-deltaform, endoperculum adnate (adnation along adcingular -margin ).
Dimensions:
Holotype; Range
Pericyst: 70x52 µm; 68-75x50-58 µm
Endocyst: 46x46 µm; 45-48x46-52 µm
Periarchaeopyle: transverse archeopyle index (TAI) 0.33, longitudinal archaeopyle index (LAI) 0.46, archaeopyle ratio (AR) 1.1, archaeopyle signum (AS) 2.5
Endoarchaeopyle: transverse archaeopyle index (TAI) 0.32, longitudinal archaeopyle index (LAI) 0.44, archaeopyle ratio (AR) 0.56, archaeopyle signum (AS) 1.8
Affinities:
Alterbidinium papillatum is characterized mainly in having intratabular papillate ornamentation on pericyst which differentiates it from all the known species of the genus. Manum (1963, p. 58-59, pl. 2, figs 1-S; text-fig. 2 ) described some dinoflagellate cysts as Deflandrea cf. scheii from the Cretaceous of Graham Island, Arctic Canada. These forms resemble the present specimens in having intratabular ornamentation and overall shape but differ mainly in having parasutural ridges.
Holotype: Khowaja-Ateequzzaman et al., 1991, pl.1, figs.4-7; text-figs.1A-B
Locus typicus: Kunnam Village, India
Stratum typicum: Turonian-Santonian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Khowaja-Ateequzzaman et al., 1991, p. 38-41]:
Diagnosis:
Cyst proximate, dorso-ventrally compressed, circumcavate, pericyst ambitus pentagonal with an apical horn and two symmetrically placed unequal antapical horns, right antapical horn reduced; periphragm thin, papillate, papillae more pronounced on dorsal surface, intratabular; endocyst subpentagonal, endophragm thicker than periphragm, smooth; periparacingulum annulate;
paratabulation peridinioid, ?4", 3a, 7", Xc, 5""", 1p, 2"""";
archaeopyle intercalary, independently developed on periphragm and endophragm, periarchaeopyle hexa 2a, steno-deltaform, perioperculum adnate, endoarchaeopyle hexa 2a, eury-deltaform, endoperculum adnate.
Description:
Shape: Cyst proximate, dorso-ventrally compressed; pericyst ambitus pentagonal with a broad based apical horn having a short apicular process at the tip (sensu Wiggins, 1975, p. 98) and two symmetrically placed unequal antapical horns, right antapical horn reduced; endocyst subpentagonal.
Wall relationship: Apical and antapical pericoels prominent connected through ambital pericoel (circumcavate ), endocyst shifted more towards dorsal side where periphragm and endophragm appressed in the precingular and postcingular areas.
Wall features: No parasutural features; periphragm thin, papillate, papillae intratabular, pronounced on perioperculum, precingular, postcingular and antapical paraplate areas on dorsal surface (Text-figs lA, 2A-B); ventral surface bears numerous irregular folds (Text-fig. lB); periparacingulum marked by two parallel ridges and a furrow running high over endocyst, bearing papillae arranged in two single discontinuous rows on the margins of the ridges, paracingular paraplates indiscernible; endophragm thicker than periphragm, smooth; perisulcus marked by a depression.
Paratabulation: Peridinioid, incompletely discernible on individual specimens; pericyst paratabulation formula ?4", 3a, 7", Xc, 5""", 1p, 2"""" (Text-fig. 3A-B).
Archaeopyle: Intercalary, independently developed on periphragm and endophragm, periarchaeopyle hexa 2a, steno-deltaform, perioperculum adnate (adnation along adcingular margin); endoarchaeopyle hexa 2a, eury-deltaform, endoperculum adnate (adnation along adcingular -margin ).
Dimensions:
Holotype; Range
Pericyst: 70x52 µm; 68-75x50-58 µm
Endocyst: 46x46 µm; 45-48x46-52 µm
Periarchaeopyle: transverse archeopyle index (TAI) 0.33, longitudinal archaeopyle index (LAI) 0.46, archaeopyle ratio (AR) 1.1, archaeopyle signum (AS) 2.5
Endoarchaeopyle: transverse archaeopyle index (TAI) 0.32, longitudinal archaeopyle index (LAI) 0.44, archaeopyle ratio (AR) 0.56, archaeopyle signum (AS) 1.8
Affinities:
Alterbidinium papillatum is characterized mainly in having intratabular papillate ornamentation on pericyst which differentiates it from all the known species of the genus. Manum (1963, p. 58-59, pl. 2, figs 1-S; text-fig. 2 ) described some dinoflagellate cysts as Deflandrea cf. scheii from the Cretaceous of Graham Island, Arctic Canada. These forms resemble the present specimens in having intratabular ornamentation and overall shape but differ mainly in having parasutural ridges.