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Yalkalpodinium playfordii
From Fensome et al., 2019:
Yalkalpodinium Mantle, 2009b, p.98–100, pl.7, figs.1–5; text-figs.1A,B.
Holotype: Mantle, 2009b, pl.7, fig.3.
Age: Callovian.
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Original description: [Mantle, 2009b]:
Yalkalpodinium playfordii sp. nov.
Plate 7, Figs 1-5; Text-fig. 1A, B
Diagnosis: Cysts proximate, camocavate to almost circumcavate, medium-sized with a subcircular or asymmetrical subovoidal, dorso-ventral outline. Cyst broadest at paracingulum and commonly with a relatively narrow antapex. Endocyst subcircular to subovoidal, attached laterally and possibly dorsoventrally to pericyst; widest separation at antapex. Endophragm thick, robusq laevigate to granulate; periphragm thinner, commonly folded, laevigate, scabrate, or microreticulate and occasionally torn. Subcircular claustra rare in periphragm at antapex. Paratabulation partially indicated by archeopyle margin and low, narrow ridges on the pericyst that border the paracingulum and rarely the pre- and postcingular paraplates. Paratabulation formula gonyaulacalean: ?pr, 4', 6", ?6c, ?6"', ?1"". Archeopyle apical; operculum free, compound.
Description: Most specimens are clearly camocavate, exhibiting a broad separation of the endocyst and the pericyst at the antapex (up to 12 μm). In ventral orientation, the cavation extends only a very short distance away from the antapex on the right side of the cyst but continues to or near to the apex on the left side; i.e., the two wall layers are typically attached at the left paracingular margin and separated by ca. 5 μm
at the right paracingular margin (Text-fig. 1A). Cavation is only apparenr on rwo opercula. The endocyst (1-1.5 μm thick) is generally featureless, other than exhibiting sporadic, well-spaced grana and occasional verrucae at the antapex. The thin pericyst (< 0.5 μm thick) is laevigate or microreticulate, is commonly extended into a rounded antapical protuberance (Pl. 7, Fig. 3), and is surmounted by narrow elongate ridges that partially delimit the paratabulation. The paracingulum (4-7 μm wide) is well-marked dorsally with some division into paraplates. It divides the epi- and hypocysts unequally; the hypocyst being 1.5-2 times longer. The broad, deep sulcal notch formed by the loss of the operculum is a prominent feature. However, the parasulcus is not otherwise indicated. Other narrow ridges depicting paratabulation are typically
discontinuous but indicate 6 large precingular paraplates and probably 6 very large postcingular paraplates. The paratabulation is less distinct on the central area o{ the ventral surface. The pericyst may bear minor folds or be folded along almost.the entire length of the cyst. The archeopyle margin, other than the parasulcal notch, is commonly serrate; the apical border of the precingular paraplate, bearing very fine, triangular spines or denticles, 0.5-1.5 μm long and ca. 0.5 μm wide.
Dimensions (14 specimens): Length of pericyst (including operculum) 71 (79) 81 μm; length of pericyst (excluding opercuIum) 57 (70) 80 μm; width of pericyst 55 (65) 79 μm; length of endocyst (excluding operculum) 49 (60) 68 pm; width of endocyst 50 (58) 69 μm; thickness of cyst wall 1-2 pm.
Holotype: Slide no.2, EF L30/3. CPC no. 39382; Pl. 7, Fig. 3. Length of cyst (excluding operculum) 80 μm; length of endocyst 67 μm; overall width of cyst 62 μm; width of endocyst 53 μm.
Type locality: Timor Sea, Bayu-Undan Field, Bayu-4, core 2 at 3090.3 m (Elang Formation).
Etymology: in honour of Professor Geoffrey Playford.
Remarks: Other genera of cavate, gonyaulacoid dinoflagellate cysts include Ambonosphaera FENSOME 1979 (pp. 50-51), Polygonifera HABIB 1972 (p. 376), Senoniasphaera CLARKE & VERDIER 1967 (p. 61), Sirmiodiniopsis DRUGG 1978 (p.73), and Sirmiodinium ALBERTI emend. WARREN 1973 (p. 22). Ambonosphaera apparently lacks antapical claustra and is usually bicavate or camocavate. Such claustra are rarely visible on Yalkalpodinium playfordii sp. nov., often due to poor preservation, bur specimens lacking this feature could easily have been referred to Ambonosphaera. Polygonifera is camocavate with a subpolygonal dorso-ventral outline but typically lacks any indication of paratabulation other than the paracingulum.
Senoniasphaera is readily distinguished as it is typically circumcavate rather than camocavate to bicavate and is markedly lenticular with a parasulcal notch offset to the left from the median line. Sirmiodiniopsis features a pair of claustra bordering an antapical protuberance; and Sirmiodinium has a combination archeopyle that may involve the loss of one or more precingular paraplates.
Comparison: Yalkalpodinium elangianum RIDING & HELBY 2001 (2001d:101-102;figs 20A-P), with which Y. playfordii co-occurs, possesses a narrower but prominent midventral parasulcal notch similar to that of the new species. However, RIDING & HELBY's species clearly differs in outline (being symmetrically subcircular to ellipsoidal with a broader antapex; see Text-fig. 13); in the circumcavate arrangement of its wall
layers; and by its clearer indications of paratabulation. The type species, Y. scutum MONTEIL 1980 (p. 34; pl. 31, figs 15-18) is considerably larger than Y. playfordii, exhibits paracingular protrusions, and is circumcavate. Yalkalpodinium playfordii is also very similar to several species
of Ambonosphaera; A. calloviana FENSOME 1979 (pp. 51-54; pl. 7, figs 3, 5, 6, 8, 9; text-figs 16A-D, 17A, B) is smaller, spherical and bi- to
suturocavate and possesses obvious parasutural crests; A. bavarica LUND & ECKE 1988 (pp. 348, 351; pl. 1, figs. 2a, b, 4; text-figs. 3a, b) is strictly bicavate; A. hemicavata PRAUSS 1989 (pp. 31-32; pl. 10, figs. 8-15; textfig. 9) is almost holocavate (the pericyst is supported by a number of columellae); and A? staffinensis (GITMEZ) POULSEN & RIDING 1992 (pp.26-28; pl. 1, figs 1-6; text-fig. 1) is considerably larger with more prominent camocavation and a broader antapical pericoel.
Local occurrence: Elang Formation; Ternia balmei Interval Zone (Subzone TBs) through Voodooia tabulata Interval Zone (Subzone VT5); rare to common.
Yalkalpodinium Mantle, 2009b, p.98–100, pl.7, figs.1–5; text-figs.1A,B.
Holotype: Mantle, 2009b, pl.7, fig.3.
Age: Callovian.
----------------------------------------------------------------------------------------------------------------------------------
Original description: [Mantle, 2009b]:
Yalkalpodinium playfordii sp. nov.
Plate 7, Figs 1-5; Text-fig. 1A, B
Diagnosis: Cysts proximate, camocavate to almost circumcavate, medium-sized with a subcircular or asymmetrical subovoidal, dorso-ventral outline. Cyst broadest at paracingulum and commonly with a relatively narrow antapex. Endocyst subcircular to subovoidal, attached laterally and possibly dorsoventrally to pericyst; widest separation at antapex. Endophragm thick, robusq laevigate to granulate; periphragm thinner, commonly folded, laevigate, scabrate, or microreticulate and occasionally torn. Subcircular claustra rare in periphragm at antapex. Paratabulation partially indicated by archeopyle margin and low, narrow ridges on the pericyst that border the paracingulum and rarely the pre- and postcingular paraplates. Paratabulation formula gonyaulacalean: ?pr, 4', 6", ?6c, ?6"', ?1"". Archeopyle apical; operculum free, compound.
Description: Most specimens are clearly camocavate, exhibiting a broad separation of the endocyst and the pericyst at the antapex (up to 12 μm). In ventral orientation, the cavation extends only a very short distance away from the antapex on the right side of the cyst but continues to or near to the apex on the left side; i.e., the two wall layers are typically attached at the left paracingular margin and separated by ca. 5 μm
at the right paracingular margin (Text-fig. 1A). Cavation is only apparenr on rwo opercula. The endocyst (1-1.5 μm thick) is generally featureless, other than exhibiting sporadic, well-spaced grana and occasional verrucae at the antapex. The thin pericyst (< 0.5 μm thick) is laevigate or microreticulate, is commonly extended into a rounded antapical protuberance (Pl. 7, Fig. 3), and is surmounted by narrow elongate ridges that partially delimit the paratabulation. The paracingulum (4-7 μm wide) is well-marked dorsally with some division into paraplates. It divides the epi- and hypocysts unequally; the hypocyst being 1.5-2 times longer. The broad, deep sulcal notch formed by the loss of the operculum is a prominent feature. However, the parasulcus is not otherwise indicated. Other narrow ridges depicting paratabulation are typically
discontinuous but indicate 6 large precingular paraplates and probably 6 very large postcingular paraplates. The paratabulation is less distinct on the central area o{ the ventral surface. The pericyst may bear minor folds or be folded along almost.the entire length of the cyst. The archeopyle margin, other than the parasulcal notch, is commonly serrate; the apical border of the precingular paraplate, bearing very fine, triangular spines or denticles, 0.5-1.5 μm long and ca. 0.5 μm wide.
Dimensions (14 specimens): Length of pericyst (including operculum) 71 (79) 81 μm; length of pericyst (excluding opercuIum) 57 (70) 80 μm; width of pericyst 55 (65) 79 μm; length of endocyst (excluding operculum) 49 (60) 68 pm; width of endocyst 50 (58) 69 μm; thickness of cyst wall 1-2 pm.
Holotype: Slide no.2, EF L30/3. CPC no. 39382; Pl. 7, Fig. 3. Length of cyst (excluding operculum) 80 μm; length of endocyst 67 μm; overall width of cyst 62 μm; width of endocyst 53 μm.
Type locality: Timor Sea, Bayu-Undan Field, Bayu-4, core 2 at 3090.3 m (Elang Formation).
Etymology: in honour of Professor Geoffrey Playford.
Remarks: Other genera of cavate, gonyaulacoid dinoflagellate cysts include Ambonosphaera FENSOME 1979 (pp. 50-51), Polygonifera HABIB 1972 (p. 376), Senoniasphaera CLARKE & VERDIER 1967 (p. 61), Sirmiodiniopsis DRUGG 1978 (p.73), and Sirmiodinium ALBERTI emend. WARREN 1973 (p. 22). Ambonosphaera apparently lacks antapical claustra and is usually bicavate or camocavate. Such claustra are rarely visible on Yalkalpodinium playfordii sp. nov., often due to poor preservation, bur specimens lacking this feature could easily have been referred to Ambonosphaera. Polygonifera is camocavate with a subpolygonal dorso-ventral outline but typically lacks any indication of paratabulation other than the paracingulum.
Senoniasphaera is readily distinguished as it is typically circumcavate rather than camocavate to bicavate and is markedly lenticular with a parasulcal notch offset to the left from the median line. Sirmiodiniopsis features a pair of claustra bordering an antapical protuberance; and Sirmiodinium has a combination archeopyle that may involve the loss of one or more precingular paraplates.
Comparison: Yalkalpodinium elangianum RIDING & HELBY 2001 (2001d:101-102;figs 20A-P), with which Y. playfordii co-occurs, possesses a narrower but prominent midventral parasulcal notch similar to that of the new species. However, RIDING & HELBY's species clearly differs in outline (being symmetrically subcircular to ellipsoidal with a broader antapex; see Text-fig. 13); in the circumcavate arrangement of its wall
layers; and by its clearer indications of paratabulation. The type species, Y. scutum MONTEIL 1980 (p. 34; pl. 31, figs 15-18) is considerably larger than Y. playfordii, exhibits paracingular protrusions, and is circumcavate. Yalkalpodinium playfordii is also very similar to several species
of Ambonosphaera; A. calloviana FENSOME 1979 (pp. 51-54; pl. 7, figs 3, 5, 6, 8, 9; text-figs 16A-D, 17A, B) is smaller, spherical and bi- to
suturocavate and possesses obvious parasutural crests; A. bavarica LUND & ECKE 1988 (pp. 348, 351; pl. 1, figs. 2a, b, 4; text-figs. 3a, b) is strictly bicavate; A. hemicavata PRAUSS 1989 (pp. 31-32; pl. 10, figs. 8-15; textfig. 9) is almost holocavate (the pericyst is supported by a number of columellae); and A? staffinensis (GITMEZ) POULSEN & RIDING 1992 (pp.26-28; pl. 1, figs 1-6; text-fig. 1) is considerably larger with more prominent camocavation and a broader antapical pericoel.
Local occurrence: Elang Formation; Ternia balmei Interval Zone (Subzone TBs) through Voodooia tabulata Interval Zone (Subzone VT5); rare to common.