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Chatangiella mcintyrei
Chatangiella mcintyrei, Nohr-Hansen 1996
Holotype: Nohr-Hansen 1996: Plate 2, Fig. 4
Locus typicus: Core hole GGU 400711, Enclosure 10, Svartenhuk, West Greenland
Occurrence: from the Coniacian Arvalidium cheii and Laciniadinium arcticum intervals on Svartenhuk (Enclosures 1, 8,10).
Stratum typicum: Upper Cretaceous
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Original description: [Nohr-Hansen 1996, p. 31, 32]:
Description:
Cyst type: Circumcavate, peridinioid.
Shape: Dorso-ventrally compressed cyst, elongate, almost box-shaped. The width of the cyst is almost the same from the broad apical shoulders to the antapical "horns", except from the areas at the apical and antapical ends of the endocyst, where the periphragm has slightly concave sides. The epicyst and hypocyst are almost the same length. The apical horn is broad-based, short and blunt, with slightly concave sides. The left antapical horn is short and pointed, the right antapical horn is only represented by a bulge.
Wall relationship: The cyst is composed of a smooth to scattered granulate box shaped pericyst and a spherical to slightly apical-antapical compressed endocyst, equatorially centered. Both pericyst and endocyst are rather thin-walled and almost hyaline, which occasionally makes it difficult to distinguish the outline of the endocyst.
Tabulation: Paratabulation is indicated only by the archeopyle and the cingulum, which on both anterior and posterior margins is bordered by discontinuous ridges with tubercles. Five pairs of ridges have been observed; but more likely 7 pieces of anterior ridges and 5 pieces of postcingular ridges should be expected, as in most Chatangiella species. A large wide sulcus is present on the ventral surface.
Archeopyle: Intercalary (2a) rounded iso-omegaform archeopyle. Operculum often attached at posterior margin. One example of a 31 endoarcheopyle with the three plates attached along their posterior margins has been observed (Plate 2, Fig. 7). The complete archeopyle formula for the species is of type l/I or seldom type I/3I.
Dimensions:
Holotype: length of pericyst 101 µm, width of pericyst 70 µm, length of endocyst 52 µm, width of endocyst 56 µm, length of apical horn 11 µm. Size range. Length of pericyst 87 (95) 108 µm, width of pericyst 53 (61) 70 µm, length of endocyst 36 (45) 52 µm, width of endocyst 40 (47) 56 µm, (15 specimens) length of apical horn 10 (11) 12 µm (14 specimens).
Affinities/Discussion:
The pericyst size and shape in the new species Chatangiella mcintyrei are quite similar to that of C. granulifera and C. verrucosa, from which it is easily distinguished by being circumcavate. The box-shaped outline of C. mcintyrei distinguishes it from the rhombic-shaped, circumcavate species C. spectabilis.
Holotype: Nohr-Hansen 1996: Plate 2, Fig. 4
Locus typicus: Core hole GGU 400711, Enclosure 10, Svartenhuk, West Greenland
Occurrence: from the Coniacian Arvalidium cheii and Laciniadinium arcticum intervals on Svartenhuk (Enclosures 1, 8,10).
Stratum typicum: Upper Cretaceous
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Nohr-Hansen 1996, p. 31, 32]:
Description:
Cyst type: Circumcavate, peridinioid.
Shape: Dorso-ventrally compressed cyst, elongate, almost box-shaped. The width of the cyst is almost the same from the broad apical shoulders to the antapical "horns", except from the areas at the apical and antapical ends of the endocyst, where the periphragm has slightly concave sides. The epicyst and hypocyst are almost the same length. The apical horn is broad-based, short and blunt, with slightly concave sides. The left antapical horn is short and pointed, the right antapical horn is only represented by a bulge.
Wall relationship: The cyst is composed of a smooth to scattered granulate box shaped pericyst and a spherical to slightly apical-antapical compressed endocyst, equatorially centered. Both pericyst and endocyst are rather thin-walled and almost hyaline, which occasionally makes it difficult to distinguish the outline of the endocyst.
Tabulation: Paratabulation is indicated only by the archeopyle and the cingulum, which on both anterior and posterior margins is bordered by discontinuous ridges with tubercles. Five pairs of ridges have been observed; but more likely 7 pieces of anterior ridges and 5 pieces of postcingular ridges should be expected, as in most Chatangiella species. A large wide sulcus is present on the ventral surface.
Archeopyle: Intercalary (2a) rounded iso-omegaform archeopyle. Operculum often attached at posterior margin. One example of a 31 endoarcheopyle with the three plates attached along their posterior margins has been observed (Plate 2, Fig. 7). The complete archeopyle formula for the species is of type l/I or seldom type I/3I.
Dimensions:
Holotype: length of pericyst 101 µm, width of pericyst 70 µm, length of endocyst 52 µm, width of endocyst 56 µm, length of apical horn 11 µm. Size range. Length of pericyst 87 (95) 108 µm, width of pericyst 53 (61) 70 µm, length of endocyst 36 (45) 52 µm, width of endocyst 40 (47) 56 µm, (15 specimens) length of apical horn 10 (11) 12 µm (14 specimens).
Affinities/Discussion:
The pericyst size and shape in the new species Chatangiella mcintyrei are quite similar to that of C. granulifera and C. verrucosa, from which it is easily distinguished by being circumcavate. The box-shaped outline of C. mcintyrei distinguishes it from the rhombic-shaped, circumcavate species C. spectabilis.