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Silicisphaera ramulus
Silicisphaera ramula May, 1980
Now Florentinia. Originally Silicisphaera, subsequently (and now) Florentinia.
Holotype: May, 1980, pl.2, figs.13-14
Locus typicus: Atlantic Highlands, New Jersey
Stratum typicum: Maastrichtian-Campanian
Original description: May, 1980, p.66
Cyst main body spherical to ovoidal, circular in polar view, bearing processes of two sizes. Bilayered; endoblast smooth, slightly thicker than periblast (both layers ca. 2 µm). Periblast includes microreticulate surface, and hollow, generally distally closed, smooth to slightly striate processes of two basic size ranges and types. Broad, roundly-polygonal-based processes bearing a few to several branchlets which are closed at the tips (the branchlets appearing truncate); and slender processes, which may be simple and basally joined by low crests. The larger type processes characterize the pre- and postcingular series, while the slender type characterize the apex, sulcus, cingulum, antapex, la and 6". Cingulum bears paired, slender, basally-joined processes, indicating six cingular plates, and is slightly levorotatory, having ca. 1 cingulum width offset. Sulcus bears four or more slender processes; including anterior and posterior sulcals. Apical series may bear from three to ca. six slender processes; however, apex shape and process arrangement on some specimens indicate four apical plates and an apical pore closing platelet. Each apical plate generally bears a single process; whereas, the apical pore closing platelet may have two or more. Antapex characterized by one to a few slender processes; when more than one is involved, they are closely associated at their bases. Reflected tabulation 4", 6", 6c, 5""", 1p, 1"""", 2-6s. Archeopyle is combination (Type Aa + P): plate equivalent 3" generally missing; apical series dislodged as a unit, but generally remains in place.
Discussion: S. ramulus differs from S. ferox by having more deeply divided branchlets which are distally truncate, as opposed to the pointed or acuminate branchlets seen in S. ferox. It differs from members of the genus Florentinia Davey and Verdier, 1973, by having a slender distally closed, antapical process as opposed to the distinctively large, tubular, antapical process of Florentinia. Characteristic features of S. ramulus are: Gonyaulax-type tabulation; combination archeopyle (Type Aa + P); processes of two sizes, with slender processes at cingulum, sulcus, apex, and antapex.
Dimensions: Holotype L x W main body 51 X 50 µm, process length 17--20 µm. Observed range (9 specimens measured): length main body 47--52 µm, width 47--52 µm; process length 16--20 µm; wall thickness ca. 2 µm, endophragm thicker than periphragm.
Affinities:
May, 1980, p.67: See "Discussion" above. Members of the genus Silicisphaera are considered closely related to those of the genus Florentinia; however, they lack the large antapical process, and have distally closed processes. Members are differentiated from Hystrichokolpoma Klumpp, 1953 by possessing a combination archeopyle.
Now Florentinia. Originally Silicisphaera, subsequently (and now) Florentinia.
Holotype: May, 1980, pl.2, figs.13-14
Locus typicus: Atlantic Highlands, New Jersey
Stratum typicum: Maastrichtian-Campanian
Original description: May, 1980, p.66
Cyst main body spherical to ovoidal, circular in polar view, bearing processes of two sizes. Bilayered; endoblast smooth, slightly thicker than periblast (both layers ca. 2 µm). Periblast includes microreticulate surface, and hollow, generally distally closed, smooth to slightly striate processes of two basic size ranges and types. Broad, roundly-polygonal-based processes bearing a few to several branchlets which are closed at the tips (the branchlets appearing truncate); and slender processes, which may be simple and basally joined by low crests. The larger type processes characterize the pre- and postcingular series, while the slender type characterize the apex, sulcus, cingulum, antapex, la and 6". Cingulum bears paired, slender, basally-joined processes, indicating six cingular plates, and is slightly levorotatory, having ca. 1 cingulum width offset. Sulcus bears four or more slender processes; including anterior and posterior sulcals. Apical series may bear from three to ca. six slender processes; however, apex shape and process arrangement on some specimens indicate four apical plates and an apical pore closing platelet. Each apical plate generally bears a single process; whereas, the apical pore closing platelet may have two or more. Antapex characterized by one to a few slender processes; when more than one is involved, they are closely associated at their bases. Reflected tabulation 4", 6", 6c, 5""", 1p, 1"""", 2-6s. Archeopyle is combination (Type Aa + P): plate equivalent 3" generally missing; apical series dislodged as a unit, but generally remains in place.
Discussion: S. ramulus differs from S. ferox by having more deeply divided branchlets which are distally truncate, as opposed to the pointed or acuminate branchlets seen in S. ferox. It differs from members of the genus Florentinia Davey and Verdier, 1973, by having a slender distally closed, antapical process as opposed to the distinctively large, tubular, antapical process of Florentinia. Characteristic features of S. ramulus are: Gonyaulax-type tabulation; combination archeopyle (Type Aa + P); processes of two sizes, with slender processes at cingulum, sulcus, apex, and antapex.
Dimensions: Holotype L x W main body 51 X 50 µm, process length 17--20 µm. Observed range (9 specimens measured): length main body 47--52 µm, width 47--52 µm; process length 16--20 µm; wall thickness ca. 2 µm, endophragm thicker than periphragm.
Affinities:
May, 1980, p.67: See "Discussion" above. Members of the genus Silicisphaera are considered closely related to those of the genus Florentinia; however, they lack the large antapical process, and have distally closed processes. Members are differentiated from Hystrichokolpoma Klumpp, 1953 by possessing a combination archeopyle.