Back
Filisphaera
From Fensome et al., 2019:
Filisphaera, Bujak, 1984, p.185.
Emendation: Head, 1994b, p.234–235.
Taxonomic junior synonym: Muraticysta, according to Head (1994b, p.234).
Type: Bujak, 1984, pl.1, figs.7–8, as Filisphaera filifera.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Bujak, 1984]:
Diagnosis:
Spherical to ovoidal dinoflagellate cysts, sometimes with small apical lobe. Cyst with thin inner wall and thicker outer wall composed of radiating fibers. Spines and other projections absent. Cingulum and sulcus absent. Archeopyle precingular, formed by loss or displacement of one or more plates.
Affinities:
Filisphaera is characterized by its combination of spherical to ovoidal shape, radiating fibers in the outer wall and precingular archaeopyle. Tapeinosphaeridium Ioannides et al. differs in having a thin single-layered wall. Tectatodinium Wall and Bitectatodinium differ in having a tectate outer wall. Operculodinium Wall differs in having numerous cones, spines or processes. Pyxidiniopsis (sic, should be: Pyxidinopsis) Habib differs in having a periphragm with a reticulate surface.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Williams, 1987, p. 99:
Synopsis:
Cysts proximate, subspherical to ellipsoidal, without spines or other projections; wall layers appressed, periphragm composed of radiating fibers; indications of paratabulation lacking except for the type P or 2P precingular archeopyle.
Description:
Shape: Subspherical to ellipsoidal, with or without an apical lobe.
Wall relationships: Periphragm and ectophragm appressed.
Wall features: Surface without spines or other projecting structures; periphragm with radiating fibers.
Archeopyle: Precingular, simple, type P (3``) or compound, 2P (3`` and ?4``); opercula free.
Paratabulation: Expressed solely by archeopyle.
Paracingulum: Not indicated.
Parasulcus: Not indicated.
Size: Small to intermediate, length 45 to 60 µm.
Affinities:
According to Bujak (1984, p. 185), "Tapeinosphaeridium loannides et al. differs [from Filisphaera] in having a thin single-layered wall. Tectatodinium Wall and Bitectatodinium differ in having a tectate outer wall. Operculodinium Wall differs in having numerous cones, spines or processes. Pyxidiniopsis [sic] Habib differs in having a periphragm with a reticulate surface".
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended description:
Head, 1994b:
Diagnosis:
Cysts spherical to ovoidal, sometimes with small apical lobe. Cyst wall formed of two closely appressed layers, a thin solid endophragm and thicker periphragm of narrow, principally radiating, nontabular septa that form a microreticulum. Other projections absent or weakly expressed. Paracingulum and parasulcus absent or weakly expressed. Archeopyle precingular, with well developed angles, and formed by loss or displacement of one or more plates.
Discussion:
The genus Filisphaera is here emended to accommodate the septate and microreticulate nature of the periphragm in the type species Filisphaera filifera Bujak 1984 emend. nov. The periphragm was originally determined as being composed of radiating fibers (Bujak,1984) and the fibrous appearance of the periphragm is now interpreted to be caused by junctions of the septa. Head et al. (1989a) proposed the genus Muraticysta for otherwise similar cysts that were microreticulate. Muraticysta is now regarded a taxonomic junior synonym of Filisphaera. Hence, an important feature of Filisphaera is its microreticulate periphragm of narrow, predominantly radiating, nontabular septa. However, specimens exhibiting some degree of bifurcation of septa, or possessing certain modifications to the basal part of the periphragm (e.g., a vesicular layer such as occurs in Tectatodinium pellitum Wall and in the specimen illustrated on Plate 5, figs. 4-7) may also be included in Filisphaera. Septa may be of even or uneven height and on some specimens may be highest at the junctions of septa. Specimens with some discontinuous septa may also be included in Filisphaera. The archeopyle in Filisphaera is precingular, formed by loss or displacement of one or more plates. The presence of well defined archeopyle angles, seen on all currently recognized taxa of Filisphaera, is thought to be a feature of generic significance.
Affinities:
The periphragm of Filisphaera is characterized by a more or less continuous microreticulum of high, narrow septa. In contrast, the genus Cerebrocysta Bujak in Bujak et al.,1980 emend. Stover & Williams 1987 has low, discontinuous, sinuous ridges; Tectatodinium Wall 1967 has a typically cancellous to fibroid periphragm (Head, in prep.); Bitectatodinium Wilson, 1973 has a periphragm that lacks a complete reticulate or microreticulate structure, and Habibacysta Head et al.,1989a has a combined tectate/columellate wall structure.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Filisphaera Bujak, 1984, emend. Head, 1994b. According to Head (1994b, p.235), cysts spherical to ovoidal, sometimes with small apical lobe. Cyst wall formed of two closely appressed layers, a thin solid endophragm and thicker periphragm of narrow, principally radiating nontabular septa that form a microreticulum. Other projections absent or weakly expressed. Paracingulum and parasulcus absent or weakly expressed. Archeopyle precingular, with well developed angles, and formed by the loss or displacement of one or more plates.
Filisphaera, Bujak, 1984, p.185.
Emendation: Head, 1994b, p.234–235.
Taxonomic junior synonym: Muraticysta, according to Head (1994b, p.234).
Type: Bujak, 1984, pl.1, figs.7–8, as Filisphaera filifera.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Bujak, 1984]:
Diagnosis:
Spherical to ovoidal dinoflagellate cysts, sometimes with small apical lobe. Cyst with thin inner wall and thicker outer wall composed of radiating fibers. Spines and other projections absent. Cingulum and sulcus absent. Archeopyle precingular, formed by loss or displacement of one or more plates.
Affinities:
Filisphaera is characterized by its combination of spherical to ovoidal shape, radiating fibers in the outer wall and precingular archaeopyle. Tapeinosphaeridium Ioannides et al. differs in having a thin single-layered wall. Tectatodinium Wall and Bitectatodinium differ in having a tectate outer wall. Operculodinium Wall differs in having numerous cones, spines or processes. Pyxidiniopsis (sic, should be: Pyxidinopsis) Habib differs in having a periphragm with a reticulate surface.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Williams, 1987, p. 99:
Synopsis:
Cysts proximate, subspherical to ellipsoidal, without spines or other projections; wall layers appressed, periphragm composed of radiating fibers; indications of paratabulation lacking except for the type P or 2P precingular archeopyle.
Description:
Shape: Subspherical to ellipsoidal, with or without an apical lobe.
Wall relationships: Periphragm and ectophragm appressed.
Wall features: Surface without spines or other projecting structures; periphragm with radiating fibers.
Archeopyle: Precingular, simple, type P (3``) or compound, 2P (3`` and ?4``); opercula free.
Paratabulation: Expressed solely by archeopyle.
Paracingulum: Not indicated.
Parasulcus: Not indicated.
Size: Small to intermediate, length 45 to 60 µm.
Affinities:
According to Bujak (1984, p. 185), "Tapeinosphaeridium loannides et al. differs [from Filisphaera] in having a thin single-layered wall. Tectatodinium Wall and Bitectatodinium differ in having a tectate outer wall. Operculodinium Wall differs in having numerous cones, spines or processes. Pyxidiniopsis [sic] Habib differs in having a periphragm with a reticulate surface".
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended description:
Head, 1994b:
Diagnosis:
Cysts spherical to ovoidal, sometimes with small apical lobe. Cyst wall formed of two closely appressed layers, a thin solid endophragm and thicker periphragm of narrow, principally radiating, nontabular septa that form a microreticulum. Other projections absent or weakly expressed. Paracingulum and parasulcus absent or weakly expressed. Archeopyle precingular, with well developed angles, and formed by loss or displacement of one or more plates.
Discussion:
The genus Filisphaera is here emended to accommodate the septate and microreticulate nature of the periphragm in the type species Filisphaera filifera Bujak 1984 emend. nov. The periphragm was originally determined as being composed of radiating fibers (Bujak,1984) and the fibrous appearance of the periphragm is now interpreted to be caused by junctions of the septa. Head et al. (1989a) proposed the genus Muraticysta for otherwise similar cysts that were microreticulate. Muraticysta is now regarded a taxonomic junior synonym of Filisphaera. Hence, an important feature of Filisphaera is its microreticulate periphragm of narrow, predominantly radiating, nontabular septa. However, specimens exhibiting some degree of bifurcation of septa, or possessing certain modifications to the basal part of the periphragm (e.g., a vesicular layer such as occurs in Tectatodinium pellitum Wall and in the specimen illustrated on Plate 5, figs. 4-7) may also be included in Filisphaera. Septa may be of even or uneven height and on some specimens may be highest at the junctions of septa. Specimens with some discontinuous septa may also be included in Filisphaera. The archeopyle in Filisphaera is precingular, formed by loss or displacement of one or more plates. The presence of well defined archeopyle angles, seen on all currently recognized taxa of Filisphaera, is thought to be a feature of generic significance.
Affinities:
The periphragm of Filisphaera is characterized by a more or less continuous microreticulum of high, narrow septa. In contrast, the genus Cerebrocysta Bujak in Bujak et al.,1980 emend. Stover & Williams 1987 has low, discontinuous, sinuous ridges; Tectatodinium Wall 1967 has a typically cancellous to fibroid periphragm (Head, in prep.); Bitectatodinium Wilson, 1973 has a periphragm that lacks a complete reticulate or microreticulate structure, and Habibacysta Head et al.,1989a has a combined tectate/columellate wall structure.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Filisphaera Bujak, 1984, emend. Head, 1994b. According to Head (1994b, p.235), cysts spherical to ovoidal, sometimes with small apical lobe. Cyst wall formed of two closely appressed layers, a thin solid endophragm and thicker periphragm of narrow, principally radiating nontabular septa that form a microreticulum. Other projections absent or weakly expressed. Paracingulum and parasulcus absent or weakly expressed. Archeopyle precingular, with well developed angles, and formed by the loss or displacement of one or more plates.