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Hystrichosphaeropsis obscura
Hystrichosphaeropsis obcura Habib, 1972
Holotype: Habib, 1972, pl. 21, fig. 1
Locus typicus: DSDP-Site 104, W North Atlantic
Stratum typicum: Late Miocene
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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.
Hystrichosphaeropsis obscura Habib, 1972. Habib (1972) noted that this species is bicavate with an essentially rectangular outline and a epi and hypotract of more or less equal size. There is always a short apical horn. Endocyst ovoidal and densely granular. Pericyst smooth or scabrate. Archeopyle precingular, resulting from the loss of the 3" paraplate. Size: length 70-95 µm.
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Original description: Habib, 1972, p. 379-380: Hystrichosphaeropsis obcurum
Bicavate dinoflagellate cysts. Outline of compressed specimens essentially rectangular, and longer than wide; hypotract is rectangular, and is the same size or slightly larger than epitract; epitract rectangular or broadly triangular, always with a short rounded horn appearing arched at the apex. Internal capsule oval and commonly closely appressed to outer membrane in the area of the cingulum. Antapical pericoel and apical pericoel well-developed; the former is usually larger than the latter. Tabulation of cysts imperfect, varying from distinguishing only a cingular series and several plates of the hypotract, for example, pl. 21, fig. 3, to the formula 3?', 5 or 6'', 5 or 6c, 5''', ?P, 1'''', such as pl. 21, fig. 1. Tabulation of the cingulum is usually best expressed; it is difficult to determine the formula for the ventral surface because of the very poor definition of the sulcus. The apical series is vague, and varies from a single 'plate area' in the poorly tabulated specimens to 3?' in the well tabulated. Precingular archeopyle (3'') is large and rectangular. Surface of internal capsule is densely granular; the outer membrane is smooth or scabrate.
Twenty measured specimens range in maximum length from 70 to 95 Ám.
Affinities:
Habib, 1972, p. 380
Remarks: This species is distinguished from Hystrichosphaeropsis borussica (Cookson and Eisenack) and H. ovum Deflandre by its lack of furcate processes arising from the cingulum and elsewhere on the periphragm. It is the same species as that described as Hystrichosphaeropsis sp. cf. H. ovum by Habib (MS) from late Miocene sediments near Tabiano, Italy (Tabianian stratotype). Gerlach (1961) illustrated a Miocene-?Oligocene species as H. ovum, which is similar to H. obscurum. Graham Williams reported specimens which are considered to be conspecific in Late Miocene to Late Eocene assemblages from shallow cores recovered from the Grand Banks, Newfoundland.
Holotype: Habib, 1972, pl. 21, fig. 1
Locus typicus: DSDP-Site 104, W North Atlantic
Stratum typicum: Late Miocene
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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.
Hystrichosphaeropsis obscura Habib, 1972. Habib (1972) noted that this species is bicavate with an essentially rectangular outline and a epi and hypotract of more or less equal size. There is always a short apical horn. Endocyst ovoidal and densely granular. Pericyst smooth or scabrate. Archeopyle precingular, resulting from the loss of the 3" paraplate. Size: length 70-95 µm.
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Original description: Habib, 1972, p. 379-380: Hystrichosphaeropsis obcurum
Bicavate dinoflagellate cysts. Outline of compressed specimens essentially rectangular, and longer than wide; hypotract is rectangular, and is the same size or slightly larger than epitract; epitract rectangular or broadly triangular, always with a short rounded horn appearing arched at the apex. Internal capsule oval and commonly closely appressed to outer membrane in the area of the cingulum. Antapical pericoel and apical pericoel well-developed; the former is usually larger than the latter. Tabulation of cysts imperfect, varying from distinguishing only a cingular series and several plates of the hypotract, for example, pl. 21, fig. 3, to the formula 3?', 5 or 6'', 5 or 6c, 5''', ?P, 1'''', such as pl. 21, fig. 1. Tabulation of the cingulum is usually best expressed; it is difficult to determine the formula for the ventral surface because of the very poor definition of the sulcus. The apical series is vague, and varies from a single 'plate area' in the poorly tabulated specimens to 3?' in the well tabulated. Precingular archeopyle (3'') is large and rectangular. Surface of internal capsule is densely granular; the outer membrane is smooth or scabrate.
Twenty measured specimens range in maximum length from 70 to 95 Ám.
Affinities:
Habib, 1972, p. 380
Remarks: This species is distinguished from Hystrichosphaeropsis borussica (Cookson and Eisenack) and H. ovum Deflandre by its lack of furcate processes arising from the cingulum and elsewhere on the periphragm. It is the same species as that described as Hystrichosphaeropsis sp. cf. H. ovum by Habib (MS) from late Miocene sediments near Tabiano, Italy (Tabianian stratotype). Gerlach (1961) illustrated a Miocene-?Oligocene species as H. ovum, which is similar to H. obscurum. Graham Williams reported specimens which are considered to be conspecific in Late Miocene to Late Eocene assemblages from shallow cores recovered from the Grand Banks, Newfoundland.