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Susadinium pinna
Susadinium? pinna (Below, 1987) Lentin and Williams, 1989
Originally Dodekovia, subsequently (and now) Susadinium?.
At the time of the transfer, Lentin and Williams, 1989 questionably included this species in Susadinium.
Holotype: Below, 1987, pl.14, fig.1,3,5
Locus typicus: Brentshardhaugen Bed, Eastern slope of Knerten Hill near DeGeerdalen, Spitsbergen
Stratum typicum: Toarcian
Translation Below, 1978: Translation Bureau, Secretary of State Canada, 1988, p. 291-293
Original description: Below, 1987, p. 116-118: Dodekovia pinna
Arrangement of vesicles/plates on the dinoflagellate amphiesma cop, pop, cap, 5", 3a, 7""-6"", 7c, 5""", 2"""", as, z, y, ps; 1"""" and 2"""" located symmetrically on either side of the dorsoventral plane.
Cystic habit proximate, acavate, ovoidal to polyhedral, epicyst coniform or tentoriate, apex also tapering into a short, pyramidal apical horn, hypocyst smaller, tentoriate or semispheroidal, epicyst and hypocyst separated by a deeply indented, weakly laevorotatory cingulum; size small; wall composed of thin pedium and firm, prismatic-spongy luxuria with a granular or spongy surface fused along the fines into low ribs; areation marked by different levels of projection of the areae, the homologous area of the overlapping plate being raised above the level of the homologous area of the overlapping plate and descending towards it with a sharp gradient at the finis; areation formula XPR, cop, pop, cap, 5", 3a, 7""-6"", 7c, 5""", 2"""", as, ps, Xs;
- cop very small, circular, shaped like a peg or a ring, pentagonal to horseshoe- shaped pop and small rhombic cap between 1"/5" and pop;
- 5 apicals, steno VI 1" (V), large VI 2" (VL), deltaform inverse-camerate 3" (DL), deltaform inverse-camerate 4" (DR), large VIII 5" (VR); three anterior intercalaries, linteloid 1a (LDL), VI or VII 2a (D), inverse-camerate 3a (DR);
- 7 precingulars, anteriorly geniculate V-nE 1"" (VVL), anteriorly geniculate V-nE 2"" (LVL), anteriorly linear IV-nE 3"" (LDL), anteriorly geniculate V-nE 4"" (DDL), or anteriorly linear IV-nE 4"" with a heptagonal area 2a, anteriorly geniculate VI-nE 5"" (DDR), finis 4""/5"" dorsal, anteriorly geniculate V-nE 6"" (R), anteriorly linear IV-nE 7"" (VVR) only seldom connected with 1"; or anteriorly geniculate V-nE 1"", anteriorly geniculate V-nE 2"", anterioly geniculate V-nE 3"", anteriorly geniculate V-nE 4"", anteriorly geniculate V-nE 5"", anteriorly linear IV-nE 6"";
- cingulum heptaareate, laevorotatory; dextro-camerate V 1c (V), lati fastigiate 2c (VL), lati VII 3c (LDL), lati fastigiate 4c (D), lati VI 5c (DR), lati camerate 6c (VR), VIII
7c (V);
- 5 Postcingulars, V-nE 1""" (VVL), posteriorly linear IV-nE 2""" (L), posteriorly geniculate V-nE 3""" (DDL), posteriorly linear IV-nE 4""" (DR), finis 3"""/4""" dorsal, posteriorly linear V-nE 5""" (VR);
- large V 1"""" (L) and large V 2"""" (R) on each side of the antapex;
- sulcus consisting of large steno VII as usually in contact with 5" and 7"", undivided central sulcus and large steno VI ps; archaeopyle anterior intercalary, 2a;
- operculum monoareate, secate, opercular formula 2as.
Dimensions: Holotype: length 32 µm, breadth 30 µm, thickness 30 µm.
Remarks: This species is important in connection with the reflection of thecal growth structures. So far, it is the only known cyst of the genus Dodekovia from which the overlapping of thecal plates can be largely reconstructed (Figure 65). It is a matter of interest whether, with fully identical tabulations of the Toarcian/ Aalenian species and Recent species of the genus Heterocapsa, the direction of overlap between particular plates could have changed since the Liassic/Dogger. On most specimens the overlapping formula is almost completely readable. The ridge-tile areae (culmen) project far above the surface of the cyst like step-platform.
Along the fines bordering areae of reflected overlapped plates they descend abruptly to the normal level of the cyst surface. All other areae, which reflect overlapped plates, are comparable to a ramp. Each area ascends uniformly from the margin where it reflects overlapping by a plate, and where the height of its periphery is even with the overall surface of the cyst, to the margin where the homologous plate in turn overlaps the neighbouring plate. There it projects far above the surface-level, like the ridge-tile plate. This arrangement can be seen most clearly in a polar aspect of the cyst, in each series on both sides of the ridge-tile area; it is reminiscent of a paddle wheel (Plate 14, Fig. 5, 11). Comparison with the overlapping pattern of the theca of the Recent species Heterocapsa triqueta shows that the structure has remained the same over a period of 170 million years. Hence, the direction of overlap is probably a very stable feature, which has not changed as long as the tabulation has been constant.
The growth of the plates is not clearly reflected. The finate border of the overlapping margin is somewhat more distinct. Perhaps this suggests one-sided growth of the gonyaulacoidal type, in which the directions of growth and overlapping are correlated (see p. 54). However, this interpretation is inconsistent with the observations from other taxa of the subfamily, which indicate peridinoidal growth.
Affinities:
Below, 1987, p. 118: Dodekovia pinna
Dodekovia szygia Dörhöfer and Davies 1980, emend. (synonym: Ovalicysta hiata Bjaerke 1980) is related to Dodekovia pinna n. sp. Both species have a similar habit, areation, type of archaeopyle, and wall structure. However, Dodekovia szygia is not polygonal and the areae do not project like step-platforms.
Originally Dodekovia, subsequently (and now) Susadinium?.
At the time of the transfer, Lentin and Williams, 1989 questionably included this species in Susadinium.
Holotype: Below, 1987, pl.14, fig.1,3,5
Locus typicus: Brentshardhaugen Bed, Eastern slope of Knerten Hill near DeGeerdalen, Spitsbergen
Stratum typicum: Toarcian
Translation Below, 1978: Translation Bureau, Secretary of State Canada, 1988, p. 291-293
Original description: Below, 1987, p. 116-118: Dodekovia pinna
Arrangement of vesicles/plates on the dinoflagellate amphiesma cop, pop, cap, 5", 3a, 7""-6"", 7c, 5""", 2"""", as, z, y, ps; 1"""" and 2"""" located symmetrically on either side of the dorsoventral plane.
Cystic habit proximate, acavate, ovoidal to polyhedral, epicyst coniform or tentoriate, apex also tapering into a short, pyramidal apical horn, hypocyst smaller, tentoriate or semispheroidal, epicyst and hypocyst separated by a deeply indented, weakly laevorotatory cingulum; size small; wall composed of thin pedium and firm, prismatic-spongy luxuria with a granular or spongy surface fused along the fines into low ribs; areation marked by different levels of projection of the areae, the homologous area of the overlapping plate being raised above the level of the homologous area of the overlapping plate and descending towards it with a sharp gradient at the finis; areation formula XPR, cop, pop, cap, 5", 3a, 7""-6"", 7c, 5""", 2"""", as, ps, Xs;
- cop very small, circular, shaped like a peg or a ring, pentagonal to horseshoe- shaped pop and small rhombic cap between 1"/5" and pop;
- 5 apicals, steno VI 1" (V), large VI 2" (VL), deltaform inverse-camerate 3" (DL), deltaform inverse-camerate 4" (DR), large VIII 5" (VR); three anterior intercalaries, linteloid 1a (LDL), VI or VII 2a (D), inverse-camerate 3a (DR);
- 7 precingulars, anteriorly geniculate V-nE 1"" (VVL), anteriorly geniculate V-nE 2"" (LVL), anteriorly linear IV-nE 3"" (LDL), anteriorly geniculate V-nE 4"" (DDL), or anteriorly linear IV-nE 4"" with a heptagonal area 2a, anteriorly geniculate VI-nE 5"" (DDR), finis 4""/5"" dorsal, anteriorly geniculate V-nE 6"" (R), anteriorly linear IV-nE 7"" (VVR) only seldom connected with 1"; or anteriorly geniculate V-nE 1"", anteriorly geniculate V-nE 2"", anterioly geniculate V-nE 3"", anteriorly geniculate V-nE 4"", anteriorly geniculate V-nE 5"", anteriorly linear IV-nE 6"";
- cingulum heptaareate, laevorotatory; dextro-camerate V 1c (V), lati fastigiate 2c (VL), lati VII 3c (LDL), lati fastigiate 4c (D), lati VI 5c (DR), lati camerate 6c (VR), VIII
7c (V);
- 5 Postcingulars, V-nE 1""" (VVL), posteriorly linear IV-nE 2""" (L), posteriorly geniculate V-nE 3""" (DDL), posteriorly linear IV-nE 4""" (DR), finis 3"""/4""" dorsal, posteriorly linear V-nE 5""" (VR);
- large V 1"""" (L) and large V 2"""" (R) on each side of the antapex;
- sulcus consisting of large steno VII as usually in contact with 5" and 7"", undivided central sulcus and large steno VI ps; archaeopyle anterior intercalary, 2a;
- operculum monoareate, secate, opercular formula 2as.
Dimensions: Holotype: length 32 µm, breadth 30 µm, thickness 30 µm.
Remarks: This species is important in connection with the reflection of thecal growth structures. So far, it is the only known cyst of the genus Dodekovia from which the overlapping of thecal plates can be largely reconstructed (Figure 65). It is a matter of interest whether, with fully identical tabulations of the Toarcian/ Aalenian species and Recent species of the genus Heterocapsa, the direction of overlap between particular plates could have changed since the Liassic/Dogger. On most specimens the overlapping formula is almost completely readable. The ridge-tile areae (culmen) project far above the surface of the cyst like step-platform.
Along the fines bordering areae of reflected overlapped plates they descend abruptly to the normal level of the cyst surface. All other areae, which reflect overlapped plates, are comparable to a ramp. Each area ascends uniformly from the margin where it reflects overlapping by a plate, and where the height of its periphery is even with the overall surface of the cyst, to the margin where the homologous plate in turn overlaps the neighbouring plate. There it projects far above the surface-level, like the ridge-tile plate. This arrangement can be seen most clearly in a polar aspect of the cyst, in each series on both sides of the ridge-tile area; it is reminiscent of a paddle wheel (Plate 14, Fig. 5, 11). Comparison with the overlapping pattern of the theca of the Recent species Heterocapsa triqueta shows that the structure has remained the same over a period of 170 million years. Hence, the direction of overlap is probably a very stable feature, which has not changed as long as the tabulation has been constant.
The growth of the plates is not clearly reflected. The finate border of the overlapping margin is somewhat more distinct. Perhaps this suggests one-sided growth of the gonyaulacoidal type, in which the directions of growth and overlapping are correlated (see p. 54). However, this interpretation is inconsistent with the observations from other taxa of the subfamily, which indicate peridinoidal growth.
Affinities:
Below, 1987, p. 118: Dodekovia pinna
Dodekovia szygia Dörhöfer and Davies 1980, emend. (synonym: Ovalicysta hiata Bjaerke 1980) is related to Dodekovia pinna n. sp. Both species have a similar habit, areation, type of archaeopyle, and wall structure. However, Dodekovia szygia is not polygonal and the areae do not project like step-platforms.