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Alterbidinium ulloriaq
From Fensome et al., 2019:
Alterbidinium? ulloriaq, Nøhr-Hansen, 1996, p.28–29, pl.14, figs.4–12.
Holotype: Nøhr-Hansen, 1996, pl.14, fig.4.
Questionable assignment: Nøhr-Hansen (1996, p.28).
Age: earliest Paleocene.
Locus typicus: Annertuneq section, north coast of Nuussuaq, West Greenland
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Original description: [Nohr-Hansen 1996, p. 28-29]:
Description:
Cyst type: Circumcavate to cornucavate.
Shape: Star-like; dorso-ventrally compressed elongate pericyst with 3 horns and an extended cingulum. The shape of the endocyst is ellipsoidal to spherical, and equatorially centred. The apical horn is broad based, elongate and often broken distally, as illustrated on the holotype. The two; more or less equal antapical horns are also relatively broad based, elongate, with a blunt to pointed tip. The angle between the base of the antapical horns is usually 90¦ or more. The lateral extension of cingulum are short (4-10 µm), with weak indented termination.
Wall relationship: The cyst is composed of a smooth to scattered granulate pericyst and endocyst. Both pericyst and endocyst are rather thin-walled and almost hyaline.
Tabulation: Paratabulation is indicated by the archeopyle and the pronounced cingulum. Granulae on the surface of the pericyst occasionally occur in rows indicating a peridinioid tabulation pattern and defining the cingulum
Archeopyle: Periarcheopyle, intercalary (2a) steno- to iso-deltaform, operculum free. The form of the endoarcheopyle seems to be broader and not as elongate as the periarcheopyle, the exact form is difficult to distinguish (Plate 14, Figs 7, 12), the endoarcheopyle is most likely of type I.
Dimensions.
Holotype: length of pericyst 104 µm (tips of apical and antapical horns broken), width of pericyst 76 µm, width of endocyst 58 µm, length of endocyst 51 µm.
Range: Length of pericyst 108 (120) 132 µm (2 specimens); width of pericyst 68 (75) 84 µm (10 specimens), length of endocyst 47 (53) 59 µm (10 specimens), width of endocyst 57(60)68 µm (10specimens), length of apical horn 10(11)12 µm (14 specimens).
Discussion/Affinities:
The genus: The combination of the characteristic star-like shape of the cyst and a 2a archeopyle may indicate that this new species represents a new genus.
The species has questionably been placed in the genus Alterbidinium due to the presence of a 2a hexa periarcheopyle of steno- to iso-deltaform type. This periarcheopyle shape is one of the characteristics for the genus Alterbidinium (Khowaja-Ateequzzaman et al., 1991). The shape of the periarcheopyle in the new species A. ? ulloriaq may suggest a placement in the genera Cerodinium or Deflandrea; the two genera have an iso-deltaform (C. ) or a lati-deltaform (D.) periarcheopyle (Lentin & Williams, 1987). However the presence of the distinct lateral extension of the cingulum differentiates the new species from previously described species of the genera Cerodinium and Deflandrea. The distinctive outline of A. ? ulloriaq is similar to the outline of some Muderongia species, which differ by having an apical archeopyle. The outline of the new species also has some similarities with the genus Rhombodinium, however Rhombodinium differs by its quadraform archeopyle and by its very reduced or vestigial right antapical horn. The species. Alterbidinium? ulloriaq sp. nov. has almost the same distinctive outline of the pericyst and almost the same periarcheopyle form as described for Deflandrea pentaradiata (now Alterbidinium? pentaradiatum pentaradiatum) by Cookson & Eisenack (1965). However A.? p. pentaradiatum differs by the shape of the endocyst which is roughly oval in outline or tends to follow the outline of the pericyst, by the surface of the periphragm which is smooth or with fine longitudional striae, especially in the vicinity of the cingulum, by having almost parallel antapical horns and by the size: length of pericyst 159-171 µm, width of pericyst 116-130 µm, length of endocyst 76-97 µm, width of endocyst 82-96 µ Lentin & Williams (1976, p. 49) questionably included the species in the genus Alterbia (now Alterbidinium) and mentioned that "the distinctive outline of the pericyst suggests it may be better placed in the genus Rhombodinium; however, the distinctively hexa archeopyle excludes it from that genus". The questionable placement of the two species with pentaradiate shape in the genus Alterbidinium, may advocate the establishment of a new genus. However the author has not examined the type specimen of Alterbidinium? pentaradiatum pentaradiatum and the available specimens ( 10) of Alterbidinium? ulloriaq are considered too few to erect a new genus.
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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.
Alterbidinium? ulloriaq Nøhr-Hansen, 1996 has a star-shaped, elongate pericyst with an extended cingulum. The endocyst is ellipsoid to spherical and equatorially centred. The apical horn is often broken. The two antapical horns are more or less equal. The angle between these two horns is usually 90 degrees or more.
Size: pericyst length 108-132 µm, width 68-84 µm: endocyst length 47-59 µm, width 57-68 µm. Length of apical horn 10-12 µm.
Alterbidinium? ulloriaq, Nøhr-Hansen, 1996, p.28–29, pl.14, figs.4–12.
Holotype: Nøhr-Hansen, 1996, pl.14, fig.4.
Questionable assignment: Nøhr-Hansen (1996, p.28).
Age: earliest Paleocene.
Locus typicus: Annertuneq section, north coast of Nuussuaq, West Greenland
---------------------------------------------------------------------------------------------------
Original description: [Nohr-Hansen 1996, p. 28-29]:
Description:
Cyst type: Circumcavate to cornucavate.
Shape: Star-like; dorso-ventrally compressed elongate pericyst with 3 horns and an extended cingulum. The shape of the endocyst is ellipsoidal to spherical, and equatorially centred. The apical horn is broad based, elongate and often broken distally, as illustrated on the holotype. The two; more or less equal antapical horns are also relatively broad based, elongate, with a blunt to pointed tip. The angle between the base of the antapical horns is usually 90¦ or more. The lateral extension of cingulum are short (4-10 µm), with weak indented termination.
Wall relationship: The cyst is composed of a smooth to scattered granulate pericyst and endocyst. Both pericyst and endocyst are rather thin-walled and almost hyaline.
Tabulation: Paratabulation is indicated by the archeopyle and the pronounced cingulum. Granulae on the surface of the pericyst occasionally occur in rows indicating a peridinioid tabulation pattern and defining the cingulum
Archeopyle: Periarcheopyle, intercalary (2a) steno- to iso-deltaform, operculum free. The form of the endoarcheopyle seems to be broader and not as elongate as the periarcheopyle, the exact form is difficult to distinguish (Plate 14, Figs 7, 12), the endoarcheopyle is most likely of type I.
Dimensions.
Holotype: length of pericyst 104 µm (tips of apical and antapical horns broken), width of pericyst 76 µm, width of endocyst 58 µm, length of endocyst 51 µm.
Range: Length of pericyst 108 (120) 132 µm (2 specimens); width of pericyst 68 (75) 84 µm (10 specimens), length of endocyst 47 (53) 59 µm (10 specimens), width of endocyst 57(60)68 µm (10specimens), length of apical horn 10(11)12 µm (14 specimens).
Discussion/Affinities:
The genus: The combination of the characteristic star-like shape of the cyst and a 2a archeopyle may indicate that this new species represents a new genus.
The species has questionably been placed in the genus Alterbidinium due to the presence of a 2a hexa periarcheopyle of steno- to iso-deltaform type. This periarcheopyle shape is one of the characteristics for the genus Alterbidinium (Khowaja-Ateequzzaman et al., 1991). The shape of the periarcheopyle in the new species A. ? ulloriaq may suggest a placement in the genera Cerodinium or Deflandrea; the two genera have an iso-deltaform (C. ) or a lati-deltaform (D.) periarcheopyle (Lentin & Williams, 1987). However the presence of the distinct lateral extension of the cingulum differentiates the new species from previously described species of the genera Cerodinium and Deflandrea. The distinctive outline of A. ? ulloriaq is similar to the outline of some Muderongia species, which differ by having an apical archeopyle. The outline of the new species also has some similarities with the genus Rhombodinium, however Rhombodinium differs by its quadraform archeopyle and by its very reduced or vestigial right antapical horn. The species. Alterbidinium? ulloriaq sp. nov. has almost the same distinctive outline of the pericyst and almost the same periarcheopyle form as described for Deflandrea pentaradiata (now Alterbidinium? pentaradiatum pentaradiatum) by Cookson & Eisenack (1965). However A.? p. pentaradiatum differs by the shape of the endocyst which is roughly oval in outline or tends to follow the outline of the pericyst, by the surface of the periphragm which is smooth or with fine longitudional striae, especially in the vicinity of the cingulum, by having almost parallel antapical horns and by the size: length of pericyst 159-171 µm, width of pericyst 116-130 µm, length of endocyst 76-97 µm, width of endocyst 82-96 µ Lentin & Williams (1976, p. 49) questionably included the species in the genus Alterbia (now Alterbidinium) and mentioned that "the distinctive outline of the pericyst suggests it may be better placed in the genus Rhombodinium; however, the distinctively hexa archeopyle excludes it from that genus". The questionable placement of the two species with pentaradiate shape in the genus Alterbidinium, may advocate the establishment of a new genus. However the author has not examined the type specimen of Alterbidinium? pentaradiatum pentaradiatum and the available specimens ( 10) of Alterbidinium? ulloriaq are considered too few to erect a new genus.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Alterbidinium? ulloriaq Nøhr-Hansen, 1996 has a star-shaped, elongate pericyst with an extended cingulum. The endocyst is ellipsoid to spherical and equatorially centred. The apical horn is often broken. The two antapical horns are more or less equal. The angle between these two horns is usually 90 degrees or more.
Size: pericyst length 108-132 µm, width 68-84 µm: endocyst length 47-59 µm, width 57-68 µm. Length of apical horn 10-12 µm.