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Cantulodinium arthuriae
Cantulodinium arthuriae, van Helden, 1986
Holotype: van Helden 1986: Plate 1, figs. 1, 2; Text-Figure 5b.
Locus typicus: Jeanne d'Arc Sub-basin
Stratum typicum: Amphorula metaelliptica assemblage zone (Portlandian to early Berriasian)
Occurrence: Amphorula metaelliptica assemblage zone
Strat. range: Portlandian to early Berriasian
Age: Portlandian-Early Berriasian
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Original description: [van Helden 1986, p. 192, 194]:
Diagnosis:
Proximate cyst, pear-shaped, with pronounced apical horn. Antapical area widens significantly, skirt-like, near the base of the hypocyst.
Wall consisting of autophragm only. Antapical surface covered with a fine irregular network of penicillium-like trabeculate ornamentation.
No paratabulation visible.
Small accessory archeopyle sutures indicate the position of the adjacent precingular and apical paraplates. Archeopyle intercalary, 3I. Operculum free.
Paracingulum sometimes indicated by faint, fold-like ridges on the autophragm towards the antapical region, just above the skirt-like widening of the autophragm. A parasulcal region may be indicated by an interruption of the fold-like paracingular ridges.
Description:
Shape: pear-shaped with a long, slender apical horn; significant, skirt-like widening of the autophragm in the antapical area into two lateral lobes, roughly triangular in outline (often folded), near the base of the hypocyst, possibly analogous to the hornlike appendages in Cantulodinium speciosum Alberti 1961.
Wall structure: thin-walled proximate cyst; wall consisting of autophragm only.
Archeopyle: large, wide, involving three elongate intercalary paraplates (3I); operculum free.
Paratabulation: not visible; the position of precingular and apical paraplates adjacent to the archeopyle is indicated by its angular wall outline and small accessory archeopyle sutures (Plate 1, figs. 1-3; Plate 2, figs. 1-6; Text-Figure Sa-e).
Paracingulum: narrow, indicated by low, fold-like ridges on the autophragm; located just above the skirt-like widening of the hypocyst; the presence of a parasulcal area may be indicated by a discontinuation of these ridges and by low, fold-like ridges approximately perpendicular to the paracingular area (Plate 2, fig. 5; Text-Figure Sa).
Ornamentation: the antapical area is unevenly covered with small, irregular, very finely trabeculate to scabrate or tuberculate penicillium-like ornaments up to 5 µm in length, which may occupy a substantial part of the antapical region (Plate 2, figs. 7,8).
Dimensions:
length of overall cyst 89 µm to 110 µm (holotype: 98 µm); width of cyst at base of hypocyst 67 µm to 71 µm (holotype: 68 µm); five specimens measured.
Remarks:
Cantulodinium arthuriae sp. nov. differs from C. speciosum Alberti 1961 in possessing a distinct skirt-like widening of the hypocyst in the antapical region, developed into two triangular lateral lobes and in lacking distinct antapical hornlike appendages. In addition, the base of the hypocyst of C. arthuriae sp. nov. is covered with fine, penicillium-like ornamentation. As the generic definition of Cantulodinium was restricted to forms possessing three or more antapical hornlike appendages (Stover and Evitt, 1978, p. 97-98), forms with differently shaped antapical ornaments but similar in all other aspects would be excluded from the genus. By restricting the presence of hornlike appendages to a diagnostic feature at species level (C. speciosum), the emended generic diagnosis of Cantulodinium allows for the accommodation of such forms as Cantulodinium arthuriae sp. nov.
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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.
Cantulodinium arthuriae van Helden, 1986. This is proximate, pear-shaped with pronounced apical horn. Antapical area widens significantly, skirt-like, near the base of the hypocyst. Wall consisting of autophragm only. Antapical surface covered with a fine irregular network of penicillium-like trabeculate ornamentation. No paratabulation visible. Small accessory archeopyle sutures indicate the position of the adjacent precingular and apical paraplates. Archeopyle intercalary 3I, may be 2I. Opercula free. Paracingulum sometimes indicated by faint, fold-like ridges on the autophragm towards the antapical region, just above the skirt-like widening of the autophragm.
Holotype: van Helden 1986: Plate 1, figs. 1, 2; Text-Figure 5b.
Locus typicus: Jeanne d'Arc Sub-basin
Stratum typicum: Amphorula metaelliptica assemblage zone (Portlandian to early Berriasian)
Occurrence: Amphorula metaelliptica assemblage zone
Strat. range: Portlandian to early Berriasian
Age: Portlandian-Early Berriasian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [van Helden 1986, p. 192, 194]:
Diagnosis:
Proximate cyst, pear-shaped, with pronounced apical horn. Antapical area widens significantly, skirt-like, near the base of the hypocyst.
Wall consisting of autophragm only. Antapical surface covered with a fine irregular network of penicillium-like trabeculate ornamentation.
No paratabulation visible.
Small accessory archeopyle sutures indicate the position of the adjacent precingular and apical paraplates. Archeopyle intercalary, 3I. Operculum free.
Paracingulum sometimes indicated by faint, fold-like ridges on the autophragm towards the antapical region, just above the skirt-like widening of the autophragm. A parasulcal region may be indicated by an interruption of the fold-like paracingular ridges.
Description:
Shape: pear-shaped with a long, slender apical horn; significant, skirt-like widening of the autophragm in the antapical area into two lateral lobes, roughly triangular in outline (often folded), near the base of the hypocyst, possibly analogous to the hornlike appendages in Cantulodinium speciosum Alberti 1961.
Wall structure: thin-walled proximate cyst; wall consisting of autophragm only.
Archeopyle: large, wide, involving three elongate intercalary paraplates (3I); operculum free.
Paratabulation: not visible; the position of precingular and apical paraplates adjacent to the archeopyle is indicated by its angular wall outline and small accessory archeopyle sutures (Plate 1, figs. 1-3; Plate 2, figs. 1-6; Text-Figure Sa-e).
Paracingulum: narrow, indicated by low, fold-like ridges on the autophragm; located just above the skirt-like widening of the hypocyst; the presence of a parasulcal area may be indicated by a discontinuation of these ridges and by low, fold-like ridges approximately perpendicular to the paracingular area (Plate 2, fig. 5; Text-Figure Sa).
Ornamentation: the antapical area is unevenly covered with small, irregular, very finely trabeculate to scabrate or tuberculate penicillium-like ornaments up to 5 µm in length, which may occupy a substantial part of the antapical region (Plate 2, figs. 7,8).
Dimensions:
length of overall cyst 89 µm to 110 µm (holotype: 98 µm); width of cyst at base of hypocyst 67 µm to 71 µm (holotype: 68 µm); five specimens measured.
Remarks:
Cantulodinium arthuriae sp. nov. differs from C. speciosum Alberti 1961 in possessing a distinct skirt-like widening of the hypocyst in the antapical region, developed into two triangular lateral lobes and in lacking distinct antapical hornlike appendages. In addition, the base of the hypocyst of C. arthuriae sp. nov. is covered with fine, penicillium-like ornamentation. As the generic definition of Cantulodinium was restricted to forms possessing three or more antapical hornlike appendages (Stover and Evitt, 1978, p. 97-98), forms with differently shaped antapical ornaments but similar in all other aspects would be excluded from the genus. By restricting the presence of hornlike appendages to a diagnostic feature at species level (C. speciosum), the emended generic diagnosis of Cantulodinium allows for the accommodation of such forms as Cantulodinium arthuriae sp. nov.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Cantulodinium arthuriae van Helden, 1986. This is proximate, pear-shaped with pronounced apical horn. Antapical area widens significantly, skirt-like, near the base of the hypocyst. Wall consisting of autophragm only. Antapical surface covered with a fine irregular network of penicillium-like trabeculate ornamentation. No paratabulation visible. Small accessory archeopyle sutures indicate the position of the adjacent precingular and apical paraplates. Archeopyle intercalary 3I, may be 2I. Opercula free. Paracingulum sometimes indicated by faint, fold-like ridges on the autophragm towards the antapical region, just above the skirt-like widening of the autophragm.