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Valvaeodinium armatum
From Fensome et al., 2019:
Valvaeodinium armatum Morgenroth, 1970, p.350–351, pl.11, figs.1–5. Holotype: Morgenroth, 1970, pl.11, figs.1–2; Fensome et al., 1993a, figs.1–2 — p.935; figs.1–2 — p.939. Age: late Pliensbachian.
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Original description: Morgenroth 1970, p. 350-351
Diagnosis: test biconical, epitract and hypotract almost equal in size. Reflected tabulation 4', 2a, 5'', ?5c or ?6c, 5''', 0p, 1''''. Surface of test granular. Plate margins marked by very low thin crests, without spines. Numerous thin fibrous spines, which may be hollow at their base arise from the plates. Distal end of spines capitate or ?bifurcate. Cingulum slightly laevorotatory. Sulcus not subdivided, narrowing towards the antapex. Archaeopyle intercalary (Archaeopyle Type 2I).
Dimensions: holotype: length of test 36 µm, breadth of test 32 µm, length of spines 5-9 µm. Range (14 specimens): length 28(32)36 µm, breadth 25(29)33 µm, spines 3(5)9 µm.
Description: The test (wall 1 µm thick) has an almost biconical shape. The apex is obtusely pointed, without an apical horn. The sides of the epitract and the hypotract are practically straight in outline on most of the specimens. The antapex is flattened. Four reflected apical plates are present. Plate 1' is elongate and occupies the anterior prolongation of the sulcus. In front of 1' lies the minute plate 3' (length 3 µm). The ?pentagonal plates 2' and 4' are symmetrically arranged on both sides of 1' and 3'. They seem to be almost equal in size. Symmetrically above 3', two anterior intercalary plates are reflected. They are mirror images and seem to be pentagonal. On specimens with an archaeopyle developed, both anterior intercalary plates are discarded. The five precingular plates are pentagonal. the laevo-rotatory cingulum is only slightly intruding; its two ends which broaden considerably towards the sulcus differ in antero-posterior position by 1/2-1 cingulum width. The five postcingular plates are all of similar size. the single antapical plate is hexagonal in shape. The sulcus is narrow in its anterior portion, broadening at its contact with the cingulum and becoming narrow again towards the antapex.
Modified description: Below, 1987, p. 66
Arrangement of vesicles/plates of the dinoflagellate amphiesma PR, 4', 1a, 5'' (-6''), 6c, 5''', 1'''', ns. Growth of plates peridinoidal.
Cyst habit proximochorate, acavate, rounded polyhedral, seldom spheroidal or ovaloidal, epicyst and hypocyst of equal size, separated by a centrally located cingulum; wall composed of firm pedium and microlanate luxuria, forming short, intraareate appendages of variable number and constant shape which measure 1/4 to 1/5 of cingular diameter of the cyst and are solid, thin, cylindrical, basally branched and insiderate, distally abruptly bi-, tri, to polyfurcate or caulifloratre; surface areate, fines recognizable within limbate zones free from appendages as angular bends of the adjacent plane or only weakly convex areae; the edges are also reinforced into broad ramparts distinctly elevated in cross sections and often trimmed with granules, with the finis often forming a delicate groove along the vertex; areation formula PR, 4', 1a, 5'' (-6''), Xc/6c, 5''', 1'''', as, Xs. PR a minute planate field.
- 4 apicals: steno omegaform linteloid 1' (V), inverse-camerate 2' (LVL), VI 3' (DL), VI 4' (RVR).
- caroidal 1a (DR).
- 5 anteriorly geniculate precingulars, V-nE 1'' (VVL), V-nE 2'' (LDL), V-nE 3'' (D), V-nE 4'' (RDR), V-nE 5'' (VR).
- cingulum planispiral, nonareate, but with the positions of 6 homologuous thecal plates indicated by alternating wide and narrow spaces between cingular margins, lati 1c-5c, iso 6c.
- 5 posteriorly linear postcingulars: IV-nE 1''' (VL), IV-nE 2''' (LDL), IV-nE 3''' (D), IV-nE 4''' (RDR), IV-nE 5''' (VR) and polar VI 1''''.
- sulcus nonpartite, with steno quasi-trapezoidal as and narrow, steno inverse-trapezoidal posterior sector.
- archaeopyle apical/anterior intercalary, 3'+1a. Operculum solvate, secate, general opercular formula 3'(s)+1a(s).
Affinities:
Below, 1987, p. 66
The surface sculpture, the length and shape of the appendages, and the rounded polyhedral habit of this characteristic species hardly vary. Ideally spheroidal specimens are rare. However, the number of appendages varies individually in many associations. Usually they are numerous and spaced on intraareate regions at uniform density. However, there are also variants with only a few appendages scattered diffusely on the center of the areae (pl.19, fig.12), or with peniareate appendages. The assemblages of Liassic gamma, which number few individuals, consist exclusively of such specimens, but they are always distinct oblong-oval and only very indistinctly p\olyhedral. On the other hand, those specimens designated as Valvaeodinium cf. armatum resemble Valvaeodinium koessenium, which has as its only identifying character a much wider cingular zone without processes. We must assume a development from V. koessenium through V. cf. armatum to V. armatum.
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Valvaeodinium armatum Morgenroth, 1970. Below (1987b, p.66-67) provided a modified description of this species. Arrangement of plates on the dinoflagellate amphiesma PR, 4', 1a, 5(-6"), 6c, 5"’, 1"”, ns; growth of plates peridinioid. Cyst form proximochorate, acavate, rounded-polyhedral, seldom spheroidal or ovaloidal, epicyst and hypocyst of equal size separated by a centrally located cingulum; wall composed of firm pedium and microlanate luxuria forming short, intraareate processes of variable number and constant shape which measure one-quarter to one-fifth of the cingular diameter of the cyst and are solid, thin, cylindrical, basally branched and insiderate, distally abruptly bi-, tri-, to polyfurcate or cauliflorate; surface areate, fines recognizable within limbate zones free from processes as angular bends of the adjacent plate or only weakly convex areae; the edges are also reinforced into broad ramparts distinctly elevated in cross-sections and often trimmed with granules, with the finis often forming a delicate groove along the ridge top..... Archeopyle apical/anterior intercalary, 3' + 1a; operculum solvate, secate, general opercular formula 3' + 1a. Size: length 28-36 µm, width 25-33 µm, length of spines 3-9 µm.
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Valvaeodinium armatum Morgenroth, 1970, p.350–351, pl.11, figs.1–5. Holotype: Morgenroth, 1970, pl.11, figs.1–2; Fensome et al., 1993a, figs.1–2 — p.935; figs.1–2 — p.939. Age: late Pliensbachian.
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Original description: Morgenroth 1970, p. 350-351
Diagnosis: test biconical, epitract and hypotract almost equal in size. Reflected tabulation 4', 2a, 5'', ?5c or ?6c, 5''', 0p, 1''''. Surface of test granular. Plate margins marked by very low thin crests, without spines. Numerous thin fibrous spines, which may be hollow at their base arise from the plates. Distal end of spines capitate or ?bifurcate. Cingulum slightly laevorotatory. Sulcus not subdivided, narrowing towards the antapex. Archaeopyle intercalary (Archaeopyle Type 2I).
Dimensions: holotype: length of test 36 µm, breadth of test 32 µm, length of spines 5-9 µm. Range (14 specimens): length 28(32)36 µm, breadth 25(29)33 µm, spines 3(5)9 µm.
Description: The test (wall 1 µm thick) has an almost biconical shape. The apex is obtusely pointed, without an apical horn. The sides of the epitract and the hypotract are practically straight in outline on most of the specimens. The antapex is flattened. Four reflected apical plates are present. Plate 1' is elongate and occupies the anterior prolongation of the sulcus. In front of 1' lies the minute plate 3' (length 3 µm). The ?pentagonal plates 2' and 4' are symmetrically arranged on both sides of 1' and 3'. They seem to be almost equal in size. Symmetrically above 3', two anterior intercalary plates are reflected. They are mirror images and seem to be pentagonal. On specimens with an archaeopyle developed, both anterior intercalary plates are discarded. The five precingular plates are pentagonal. the laevo-rotatory cingulum is only slightly intruding; its two ends which broaden considerably towards the sulcus differ in antero-posterior position by 1/2-1 cingulum width. The five postcingular plates are all of similar size. the single antapical plate is hexagonal in shape. The sulcus is narrow in its anterior portion, broadening at its contact with the cingulum and becoming narrow again towards the antapex.
Modified description: Below, 1987, p. 66
Arrangement of vesicles/plates of the dinoflagellate amphiesma PR, 4', 1a, 5'' (-6''), 6c, 5''', 1'''', ns. Growth of plates peridinoidal.
Cyst habit proximochorate, acavate, rounded polyhedral, seldom spheroidal or ovaloidal, epicyst and hypocyst of equal size, separated by a centrally located cingulum; wall composed of firm pedium and microlanate luxuria, forming short, intraareate appendages of variable number and constant shape which measure 1/4 to 1/5 of cingular diameter of the cyst and are solid, thin, cylindrical, basally branched and insiderate, distally abruptly bi-, tri, to polyfurcate or caulifloratre; surface areate, fines recognizable within limbate zones free from appendages as angular bends of the adjacent plane or only weakly convex areae; the edges are also reinforced into broad ramparts distinctly elevated in cross sections and often trimmed with granules, with the finis often forming a delicate groove along the vertex; areation formula PR, 4', 1a, 5'' (-6''), Xc/6c, 5''', 1'''', as, Xs. PR a minute planate field.
- 4 apicals: steno omegaform linteloid 1' (V), inverse-camerate 2' (LVL), VI 3' (DL), VI 4' (RVR).
- caroidal 1a (DR).
- 5 anteriorly geniculate precingulars, V-nE 1'' (VVL), V-nE 2'' (LDL), V-nE 3'' (D), V-nE 4'' (RDR), V-nE 5'' (VR).
- cingulum planispiral, nonareate, but with the positions of 6 homologuous thecal plates indicated by alternating wide and narrow spaces between cingular margins, lati 1c-5c, iso 6c.
- 5 posteriorly linear postcingulars: IV-nE 1''' (VL), IV-nE 2''' (LDL), IV-nE 3''' (D), IV-nE 4''' (RDR), IV-nE 5''' (VR) and polar VI 1''''.
- sulcus nonpartite, with steno quasi-trapezoidal as and narrow, steno inverse-trapezoidal posterior sector.
- archaeopyle apical/anterior intercalary, 3'+1a. Operculum solvate, secate, general opercular formula 3'(s)+1a(s).
Affinities:
Below, 1987, p. 66
The surface sculpture, the length and shape of the appendages, and the rounded polyhedral habit of this characteristic species hardly vary. Ideally spheroidal specimens are rare. However, the number of appendages varies individually in many associations. Usually they are numerous and spaced on intraareate regions at uniform density. However, there are also variants with only a few appendages scattered diffusely on the center of the areae (pl.19, fig.12), or with peniareate appendages. The assemblages of Liassic gamma, which number few individuals, consist exclusively of such specimens, but they are always distinct oblong-oval and only very indistinctly p\olyhedral. On the other hand, those specimens designated as Valvaeodinium cf. armatum resemble Valvaeodinium koessenium, which has as its only identifying character a much wider cingular zone without processes. We must assume a development from V. koessenium through V. cf. armatum to V. armatum.
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Valvaeodinium armatum Morgenroth, 1970. Below (1987b, p.66-67) provided a modified description of this species. Arrangement of plates on the dinoflagellate amphiesma PR, 4', 1a, 5(-6"), 6c, 5"’, 1"”, ns; growth of plates peridinioid. Cyst form proximochorate, acavate, rounded-polyhedral, seldom spheroidal or ovaloidal, epicyst and hypocyst of equal size separated by a centrally located cingulum; wall composed of firm pedium and microlanate luxuria forming short, intraareate processes of variable number and constant shape which measure one-quarter to one-fifth of the cingular diameter of the cyst and are solid, thin, cylindrical, basally branched and insiderate, distally abruptly bi-, tri-, to polyfurcate or cauliflorate; surface areate, fines recognizable within limbate zones free from processes as angular bends of the adjacent plate or only weakly convex areae; the edges are also reinforced into broad ramparts distinctly elevated in cross-sections and often trimmed with granules, with the finis often forming a delicate groove along the ridge top..... Archeopyle apical/anterior intercalary, 3' + 1a; operculum solvate, secate, general opercular formula 3' + 1a. Size: length 28-36 µm, width 25-33 µm, length of spines 3-9 µm.
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