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Kleithriasphaeridium
From Williams et al., 2017:
[Kleithriasphaeridium, Davey, 1974, p. 55-56; Emendations: Torricelli, 2001, p. 98; Fensome et al., 2009, p. 40.
Type species: Kleithriasphaeridium corrugatum, Davey, 1974 (pl.5, figs.1–2; text-fig.3)]
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Original description: [Davey, 1974]:
Diagnosis:
The cysts are subspherical and bear one intratabular process per reflected plate area. The processes are hollow, open distally, and may be slightly striated; they vary in width with the smallest occupying the sulcal region (some of these may be solid). Rarely processes may be linked proximally by a membrane. The cyst wall beneath the processes is usually thickened and granular. T
he reflected tabulation appears to be 3-4`. 6``, 6c, 5```, 1p?, 1```` and 2 or more sulcal processes.
The archaeopyle is precingular formed by the loss of plate 3``.
Affinities:
This genus resembles Cordosphaeridium Eisenack, 1963 which differs in possessing a fibro-pitted central body wall and strongly fibrous processes that are often solid and may be compound. As far as can be determined the tabulation exhibited by these two genera are very similar (see Gocht 1969). Cordosphaeridium does not occur until the latest Maastrichtian or Danian and appears to arise from an Exochosphaeridium Davey et al. (1966) ancestor (see Davey 1969). Kleithriasphaeridium differs from Florentinia Davey and Verdier (in press [1973]) in having only undivided processes, which do not bear tubules, no distinctive antapical process and never a combination precingular-apical archaeopyle; both genera do, however, possess a characteristic thickening of the cyst wall beneath the larger process.
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Modified description:
Stover and Evitt 1978, p. 167-168:
Synopsis:
Cysts skolochorate, acavate; body subspherical, bearing 24-27 hollow, intratabular, nonfibrous processes; paratabulation gonyaulacacean, indicated by processes; archeopyle precingular, type P.
Description:
Shape: Body subspherical.
Wall relationships: Endophragm and periphragm appressed between processes.
Wall features: No parasutural features. Intratabular processes hollow, nonfibrous, smooth and faintly striate, expanded and open distally. Surface between processes finely ribbed, corrugate or smooth; low septa may extend between processes.
Paratabulation: Indicated by intratabular processes; gonyaulacacean, process formula: 3-4`, 6``, 6c, 5```, 1p, 1````, 2 or more s.
Archeopyle: Precingular, Type P (3`` only); operculum free.
Paracingulum: Indicated by six processes.
Parasulcus: Indicated by two or more (generally four) slender processes. Size: Intermediate to large.
Affinities:
Kleithriasphaeridium differs from Cordosphaeridium in having hollow nonfibrous processes, which may be connected proximally by low septa. On Cordosphaeridium the processes are fibrous and on some species are solid rather than hollow. Kleithriasphaeridium differs from Hystrichosphaeridium in having a precingular rather than an apical archeopyle.
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Emended descriptions:
Torricelli., 2001:
Diagnosis:
Cysts subspherical bearing one intratabular process per paraplate. The processes are hollow nonfibrous, smooth to faintly striate, open distally; they vary in width with the smallest occupying the sulcal region (some of these may be solid). Rarely processes may be linked proximally by low septa. The cyst wall beneath the processes is unusually thickened and granular. A conical, distally closed protrusion, shorter than the processes, may be present at the apex.
The reflected tabulation appears to be 3-4', 6",6c,5-6"', 1p, 1"" and 2 or more sulcal processes.
The archeopyle is precingular, formed by the loss of plate 3" only.
Discussion:
The overall morphology of cysts hereby assigned to Kleithriasphaeridium atlasiense comb. nov. corresponds to the original description of the genus Kleithriasphaeridium of Davey (1974) except for the presence of a short apical protrusion and of six (instead of five) postcingular paraplates (see Below, 1982). Since the presence of the apical protrusion is not considered sufficient for the erection of a new genus and the presence of five or six postcingular paraplates is consistent with the description of the subfamily Leptodinioideae to which the genus Kleithriasphaeridium belongs (Fensome et al. 1993, p. 86), the present emendation of the generic description is proposed, in order to include also these forms in Kleithriasphaeridium.
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Fensome et al., 2009:
Diagnosis:
Gonyaulacacean (leptodinioid) cysts that are chorate, with a spheroidal central body. Acavate. Atabulate. Processes mesotabular, present on all latitudinal series and sulcals; simple, tubular, hollow and open or closed, sometimes moderately variable in size. Archaeopyle usually precingular but occasionally combination apical precingular, with formulas P3’’ or A(1-4’) + P3’’.
Remarks:
The above emended diagnosis can also serve as a synopsis. Kleithriasphaeridium is here emended to allow for distally closed as well as open processes, and to circumscribe forms with a combination precingular-apical archaeopyle, a type of opening that occurs as an intraspecific variant of some species (Plate 6, fig. d). We agree with Torricelli (2001: 98, who emended this genus) that some forms have a small apical prominence (the basis of his emendation), but do not mention it above since it is not a diagnostic feature of the genus. Kleithriasphaeridium is similar to Cordosphaeridium in being chorate with one process per plate and bearing (usually in the case of Kleithriasphaeridium) a precingular archaeopyle. However, in Cordosphaeridium the processes are fibrous. Florentinia has complex processes that generally do not approach a simple tubular shape; hence, we consider such species as Florentinia cooksoniae and Florentinia perforata that have simple tubular processes to belong to Kleithriasphaeridium and, hence, transfer them to the latter genus here.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Kleithriasphaeridium Davey, 1974. Synopsis from Stover and Evitt (1978, p.167-168). Cysts skolochorate, acavate; body subspherical, bearing 24-27 hollow, intratabular, nonfibrous processes; paratabulation gonyaulacacean, indicated by processes; archeopyle precingular, type P.
[Kleithriasphaeridium, Davey, 1974, p. 55-56; Emendations: Torricelli, 2001, p. 98; Fensome et al., 2009, p. 40.
Type species: Kleithriasphaeridium corrugatum, Davey, 1974 (pl.5, figs.1–2; text-fig.3)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Davey, 1974]:
Diagnosis:
The cysts are subspherical and bear one intratabular process per reflected plate area. The processes are hollow, open distally, and may be slightly striated; they vary in width with the smallest occupying the sulcal region (some of these may be solid). Rarely processes may be linked proximally by a membrane. The cyst wall beneath the processes is usually thickened and granular. T
he reflected tabulation appears to be 3-4`. 6``, 6c, 5```, 1p?, 1```` and 2 or more sulcal processes.
The archaeopyle is precingular formed by the loss of plate 3``.
Affinities:
This genus resembles Cordosphaeridium Eisenack, 1963 which differs in possessing a fibro-pitted central body wall and strongly fibrous processes that are often solid and may be compound. As far as can be determined the tabulation exhibited by these two genera are very similar (see Gocht 1969). Cordosphaeridium does not occur until the latest Maastrichtian or Danian and appears to arise from an Exochosphaeridium Davey et al. (1966) ancestor (see Davey 1969). Kleithriasphaeridium differs from Florentinia Davey and Verdier (in press [1973]) in having only undivided processes, which do not bear tubules, no distinctive antapical process and never a combination precingular-apical archaeopyle; both genera do, however, possess a characteristic thickening of the cyst wall beneath the larger process.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Evitt 1978, p. 167-168:
Synopsis:
Cysts skolochorate, acavate; body subspherical, bearing 24-27 hollow, intratabular, nonfibrous processes; paratabulation gonyaulacacean, indicated by processes; archeopyle precingular, type P.
Description:
Shape: Body subspherical.
Wall relationships: Endophragm and periphragm appressed between processes.
Wall features: No parasutural features. Intratabular processes hollow, nonfibrous, smooth and faintly striate, expanded and open distally. Surface between processes finely ribbed, corrugate or smooth; low septa may extend between processes.
Paratabulation: Indicated by intratabular processes; gonyaulacacean, process formula: 3-4`, 6``, 6c, 5```, 1p, 1````, 2 or more s.
Archeopyle: Precingular, Type P (3`` only); operculum free.
Paracingulum: Indicated by six processes.
Parasulcus: Indicated by two or more (generally four) slender processes. Size: Intermediate to large.
Affinities:
Kleithriasphaeridium differs from Cordosphaeridium in having hollow nonfibrous processes, which may be connected proximally by low septa. On Cordosphaeridium the processes are fibrous and on some species are solid rather than hollow. Kleithriasphaeridium differs from Hystrichosphaeridium in having a precingular rather than an apical archeopyle.
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Emended descriptions:
Torricelli., 2001:
Diagnosis:
Cysts subspherical bearing one intratabular process per paraplate. The processes are hollow nonfibrous, smooth to faintly striate, open distally; they vary in width with the smallest occupying the sulcal region (some of these may be solid). Rarely processes may be linked proximally by low septa. The cyst wall beneath the processes is unusually thickened and granular. A conical, distally closed protrusion, shorter than the processes, may be present at the apex.
The reflected tabulation appears to be 3-4', 6",6c,5-6"', 1p, 1"" and 2 or more sulcal processes.
The archeopyle is precingular, formed by the loss of plate 3" only.
Discussion:
The overall morphology of cysts hereby assigned to Kleithriasphaeridium atlasiense comb. nov. corresponds to the original description of the genus Kleithriasphaeridium of Davey (1974) except for the presence of a short apical protrusion and of six (instead of five) postcingular paraplates (see Below, 1982). Since the presence of the apical protrusion is not considered sufficient for the erection of a new genus and the presence of five or six postcingular paraplates is consistent with the description of the subfamily Leptodinioideae to which the genus Kleithriasphaeridium belongs (Fensome et al. 1993, p. 86), the present emendation of the generic description is proposed, in order to include also these forms in Kleithriasphaeridium.
--------------------------------------
Fensome et al., 2009:
Diagnosis:
Gonyaulacacean (leptodinioid) cysts that are chorate, with a spheroidal central body. Acavate. Atabulate. Processes mesotabular, present on all latitudinal series and sulcals; simple, tubular, hollow and open or closed, sometimes moderately variable in size. Archaeopyle usually precingular but occasionally combination apical precingular, with formulas P3’’ or A(1-4’) + P3’’.
Remarks:
The above emended diagnosis can also serve as a synopsis. Kleithriasphaeridium is here emended to allow for distally closed as well as open processes, and to circumscribe forms with a combination precingular-apical archaeopyle, a type of opening that occurs as an intraspecific variant of some species (Plate 6, fig. d). We agree with Torricelli (2001: 98, who emended this genus) that some forms have a small apical prominence (the basis of his emendation), but do not mention it above since it is not a diagnostic feature of the genus. Kleithriasphaeridium is similar to Cordosphaeridium in being chorate with one process per plate and bearing (usually in the case of Kleithriasphaeridium) a precingular archaeopyle. However, in Cordosphaeridium the processes are fibrous. Florentinia has complex processes that generally do not approach a simple tubular shape; hence, we consider such species as Florentinia cooksoniae and Florentinia perforata that have simple tubular processes to belong to Kleithriasphaeridium and, hence, transfer them to the latter genus here.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Kleithriasphaeridium Davey, 1974. Synopsis from Stover and Evitt (1978, p.167-168). Cysts skolochorate, acavate; body subspherical, bearing 24-27 hollow, intratabular, nonfibrous processes; paratabulation gonyaulacacean, indicated by processes; archeopyle precingular, type P.