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Phanerodinium setosum
Phanerodinium setosum (Sarjeant, 1966b, p.151, pl.16, figs.9–10; text-fig.39) Below, 1987b, p.38. Emendation: Below, 1987b, p.53–54, as Phanerodinium setosum.
Now Microdinium. Originally (and now) Microdinium, subsequently Phanerodinium.
Tax. sr. synonym of Microdinium echinatum Clarke and Verdier, 1967, according to Clarke et al., 1968. Lentin and Williams, 1989 retained the species in Microdinium Cookson and Eisenack, 1960.
Holotype: Sarjeant, 1966, pl.16, figs.9-10
Age: Cenomanian
Original diagnosis: Sarjeant, 1966, p. 151
A Microdinium having an ovoidal shell with somewhat flattened antapex. The epitract considerably smaller than the hypotract; a broad cingulum, weakly spiral, divides them. Tabulation ?1", oa, 6", 6c, 6""", 1p, 1"""": two additional plates present in ventral region between two ends of cingulum. Sutures bearing low crests from which arise spines of moderate length, simple and well spaced; shell surface minutely but densely granular. Apex characteristically lost in the pylome formation.
Dimensions: Holotype: overall length 35m µm, breadth 30 µm; shell length 33 µm, breadth 24 µm. Range of dimensions: overall lengths 33 to 38 µm, breadths 24 to 37 µm.
Original description: Sarjeant, 1966, p. 151
This species is moderately abundant in the lower levels of the Cenomanian of the Fetcham Mill Borehole, over 30 specimens having been seen. The apex is presumed to have consisted of a single plate, but it was lost in the majority of specimens seen. In a few, the archaeopyle " lid " was still attached, but too buckled for its character to be determined.
Six precingular and six postcingular plates are present, the former being consistently smaller than the latter in the proportion that the epitract is smaller than the hypotract. Plates 1""" and 2""" are reduced: a posterior intercalary plate separates plate 2""" from the antapex. As in M. cf. ornatum, plate 1p and the antapical plate are of comparable size and in some specimens look more like paired antapical plates.
The cingulum is broad, not hollowed, and very weakly spiral, its two ends scarcely differing in antero-posterior position. It is divided into six cingular plates; two ventral plates lie between its two ends and divide the sulcus into an epitractal and a hypotractal portion. The crests are low and bear simple, flexuous spines, the crest margin being scalloped between spine bases. The surface bears a uniform, dense cover of minute granules.
Affinities:
Sarjeant, 1966, p. 151: Microdinium setosum sp. nov. differs from M. ornatum in crest character, detail of tabulation, and granular surface. It is placed in Microdinium on the basis of general structure and apical archaeopyle: possession of only one apical plate was presumed but not confirmed.
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Emended description: Below 1987b, p. 53-54: Phanerodinium setosum
Arrangement of vesicles/plates on the dinoflagellate amphiesma cop, pop, cap, 4" 4a, 7"", 7c, 6""", 2"""", as, FM subdivided into several periflasellar platelets, ls, rs, ps; pentagonal 1"""" and hexagonal Z"""" partiform; omegaform ps very large; adelopore on suture 1"/4"; tegulation 6*, 4**, 4***, 2****, 7c, 4*, 4**, 3***, primtegulate epithecal series connected sinistrally with as; 6rowth of plates yonyaulacoidal. Cyst hahit proximate to proximochorate, ovaloidal to polyhedral with tholiform epicyst and tentoriate hypocyst twice as long as the epicyst, equatorial section circular or oval, maximal diameter at the posterior cingular margin; size small; uall composed of thin pedium and spongy luxuria fusing distally into a tegillum, surface scabrate, shagreenate, with very few perforations, each area completely surrounded by a tegillate, low, broad-based ridae bearing spinules and spines, the ridges of neighboring areae fused into ribs exactly on the fines; areation formula XPR/cop, pop, Nrcap/cap, X"/4", Xa/a, 7"", 7c, 6""", 2"""", as, FM, ls, rs, ps; PR undifferentiated or cop very small, circular, surrounded by an annular pop; 4 small apicals often reflected only rudimentarily, steno VII 1" (V), VIII 2" (L), VIII 3" (R), steno V 4" (VVR) also with porichnion on finis 4"/1"; 4 very small anterior intercalaries with their positions only poorly defined by finate rows of granules, or caroidal la (DL), fastigiate 2a (D), deltaform inverse-camerate 3a (DR), V 4a (RVR); 7 precingulars, anteriorly geniculate V-nE l"" (VVL), anteriorly geniculate V-nE 2"" (L), anteriorly geniculate V-nE 3"" (DDL), anteriorly geniculate V-nE 4"" (DDR), finis 3""/4"" dorsal, anteriorly geniculate V-nE 5"" (R), anteriorly geniculate V-nE 6"" (VR), small anteriorly geniculate V-nE 7"" (VVR); cingulum helicoid levorotatory, shallowly indented, heptapartite, lati lc to 6c, iso fastigiate 7c; 6 postcingulars, posteriorly linear V-nE l""" (VVL), posteriorly linear IV-nE 2""" (VL) posteriorly geniculate V-nE 3""" (DL), posteriorly linear IV-nE 4""" (DDR), posteriorly linear IV-nE 5""" (R),
posteriorly linear V-nE 6"""(R); 2 antapicals partiform, V 1"""" descending towards VL, VI, 2"""" towards R; sulcus level or lightly indented on the hypocyst partite, small VI as, small oval FM subdivided into several very small areae, small V ls, small V rs, large omegaform Vl ps; archeopyle apical/anterior intercalary, PR + 1" + 2" + 3" + 4" + la + 2a + 3a + 4a; operculum foederate, adnate, general opercular formula (PR + l" + 2" + 3" + 4" + la + 2a + 3a + 4a)a.
Remarks: Below 1987b
The original description, which diagnoses an areation ?l", Oa, 6"", 6c, 6""", 1p, 1"""" and conjectures a monotabular apical archeopyle, is emended to correspond with the actual areation and archeopyle. In contrast to SARJEANT"s (1966) description, in my material I found chiefly specimens with an adnate, foederate operculum; however, frequently it was flapped inside the cyst. Only a few specimens partially or completely lack the apical calotte. However, in these cases it was detached abiotically, and not ejected alony predetermined archeopyle sutures under the control of the cell. The range of variation of this species extends from forms with alony spines on finate ridges to those with only rows of spinules alone the fines. According to the literature, certain species with finate ridges described as "spiny" could be synonymous with Phanerodinium setosum. However, without SEM analyses to clarify the precise surface structure and the shape of the finate ornaments, this can not be resolved.
Now Microdinium. Originally (and now) Microdinium, subsequently Phanerodinium.
Tax. sr. synonym of Microdinium echinatum Clarke and Verdier, 1967, according to Clarke et al., 1968. Lentin and Williams, 1989 retained the species in Microdinium Cookson and Eisenack, 1960.
Holotype: Sarjeant, 1966, pl.16, figs.9-10
Age: Cenomanian
Original diagnosis: Sarjeant, 1966, p. 151
A Microdinium having an ovoidal shell with somewhat flattened antapex. The epitract considerably smaller than the hypotract; a broad cingulum, weakly spiral, divides them. Tabulation ?1", oa, 6", 6c, 6""", 1p, 1"""": two additional plates present in ventral region between two ends of cingulum. Sutures bearing low crests from which arise spines of moderate length, simple and well spaced; shell surface minutely but densely granular. Apex characteristically lost in the pylome formation.
Dimensions: Holotype: overall length 35m µm, breadth 30 µm; shell length 33 µm, breadth 24 µm. Range of dimensions: overall lengths 33 to 38 µm, breadths 24 to 37 µm.
Original description: Sarjeant, 1966, p. 151
This species is moderately abundant in the lower levels of the Cenomanian of the Fetcham Mill Borehole, over 30 specimens having been seen. The apex is presumed to have consisted of a single plate, but it was lost in the majority of specimens seen. In a few, the archaeopyle " lid " was still attached, but too buckled for its character to be determined.
Six precingular and six postcingular plates are present, the former being consistently smaller than the latter in the proportion that the epitract is smaller than the hypotract. Plates 1""" and 2""" are reduced: a posterior intercalary plate separates plate 2""" from the antapex. As in M. cf. ornatum, plate 1p and the antapical plate are of comparable size and in some specimens look more like paired antapical plates.
The cingulum is broad, not hollowed, and very weakly spiral, its two ends scarcely differing in antero-posterior position. It is divided into six cingular plates; two ventral plates lie between its two ends and divide the sulcus into an epitractal and a hypotractal portion. The crests are low and bear simple, flexuous spines, the crest margin being scalloped between spine bases. The surface bears a uniform, dense cover of minute granules.
Affinities:
Sarjeant, 1966, p. 151: Microdinium setosum sp. nov. differs from M. ornatum in crest character, detail of tabulation, and granular surface. It is placed in Microdinium on the basis of general structure and apical archaeopyle: possession of only one apical plate was presumed but not confirmed.
------------------------------------------------------
Emended description: Below 1987b, p. 53-54: Phanerodinium setosum
Arrangement of vesicles/plates on the dinoflagellate amphiesma cop, pop, cap, 4" 4a, 7"", 7c, 6""", 2"""", as, FM subdivided into several periflasellar platelets, ls, rs, ps; pentagonal 1"""" and hexagonal Z"""" partiform; omegaform ps very large; adelopore on suture 1"/4"; tegulation 6*, 4**, 4***, 2****, 7c, 4*, 4**, 3***, primtegulate epithecal series connected sinistrally with as; 6rowth of plates yonyaulacoidal. Cyst hahit proximate to proximochorate, ovaloidal to polyhedral with tholiform epicyst and tentoriate hypocyst twice as long as the epicyst, equatorial section circular or oval, maximal diameter at the posterior cingular margin; size small; uall composed of thin pedium and spongy luxuria fusing distally into a tegillum, surface scabrate, shagreenate, with very few perforations, each area completely surrounded by a tegillate, low, broad-based ridae bearing spinules and spines, the ridges of neighboring areae fused into ribs exactly on the fines; areation formula XPR/cop, pop, Nrcap/cap, X"/4", Xa/a, 7"", 7c, 6""", 2"""", as, FM, ls, rs, ps; PR undifferentiated or cop very small, circular, surrounded by an annular pop; 4 small apicals often reflected only rudimentarily, steno VII 1" (V), VIII 2" (L), VIII 3" (R), steno V 4" (VVR) also with porichnion on finis 4"/1"; 4 very small anterior intercalaries with their positions only poorly defined by finate rows of granules, or caroidal la (DL), fastigiate 2a (D), deltaform inverse-camerate 3a (DR), V 4a (RVR); 7 precingulars, anteriorly geniculate V-nE l"" (VVL), anteriorly geniculate V-nE 2"" (L), anteriorly geniculate V-nE 3"" (DDL), anteriorly geniculate V-nE 4"" (DDR), finis 3""/4"" dorsal, anteriorly geniculate V-nE 5"" (R), anteriorly geniculate V-nE 6"" (VR), small anteriorly geniculate V-nE 7"" (VVR); cingulum helicoid levorotatory, shallowly indented, heptapartite, lati lc to 6c, iso fastigiate 7c; 6 postcingulars, posteriorly linear V-nE l""" (VVL), posteriorly linear IV-nE 2""" (VL) posteriorly geniculate V-nE 3""" (DL), posteriorly linear IV-nE 4""" (DDR), posteriorly linear IV-nE 5""" (R),
posteriorly linear V-nE 6"""(R); 2 antapicals partiform, V 1"""" descending towards VL, VI, 2"""" towards R; sulcus level or lightly indented on the hypocyst partite, small VI as, small oval FM subdivided into several very small areae, small V ls, small V rs, large omegaform Vl ps; archeopyle apical/anterior intercalary, PR + 1" + 2" + 3" + 4" + la + 2a + 3a + 4a; operculum foederate, adnate, general opercular formula (PR + l" + 2" + 3" + 4" + la + 2a + 3a + 4a)a.
Remarks: Below 1987b
The original description, which diagnoses an areation ?l", Oa, 6"", 6c, 6""", 1p, 1"""" and conjectures a monotabular apical archeopyle, is emended to correspond with the actual areation and archeopyle. In contrast to SARJEANT"s (1966) description, in my material I found chiefly specimens with an adnate, foederate operculum; however, frequently it was flapped inside the cyst. Only a few specimens partially or completely lack the apical calotte. However, in these cases it was detached abiotically, and not ejected alony predetermined archeopyle sutures under the control of the cell. The range of variation of this species extends from forms with alony spines on finate ridges to those with only rows of spinules alone the fines. According to the literature, certain species with finate ridges described as "spiny" could be synonymous with Phanerodinium setosum. However, without SEM analyses to clarify the precise surface structure and the shape of the finate ornaments, this can not be resolved.