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Litosphaeridium
From Williams et al., 2017:
[Litosphaeridium, Davey and Williams, 1966b, p. 79–80; Emendations: Davey and Verdier, 1973, p. 193; Lucas-Clark, 1984, p. 181–182.
Tax. jr. syn.: Conosphaeridium, by implication in Sarjeant (1969, p.14), who transferred the "type species" of Conosphaeridium, Conosphaeridium striatoconum, to Litosphaeridium — however, Lentin and Williams (1973, p.31) retained Conosphaeridium.
Type species: originally as Hystrichosphaeridium siphoniphorum, Cookson and Eisenack, 1958, (pl.11, fig.8)] ; Litosphaeridium siphoniphorum, Davey and Williams, 1966;
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Original description: [Davey and Williams 1966]:
Diagnosis:
Chorate cyst with spherical to sub-spherical central body composed of two membranes. Processes few in number (only one per plate area), hollow and open distally except for sulcal processes which may be closed. Reflected tabulation 3`, 6``, 5```, 1p, 1````, with variable number of sulcal processes. Archaeopyle apical.
Affinities:
The presence of three apical processes and the absence of cingular processes is diagnostic of this genus, and makes it easily recognizable. The sulcal processes may be either absent or few.
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Modified description:
Stover and Evitt 1978, p. 61-62:
Synopsis:
Cysts skolochorate, body subspherical with 16 to 19 intratabular processes; processes hollow, subcylindrical to dome-shaped, tips commonly narrower than bases; paracingular processes absent; paratabulation gonyaulacacean, indicated by intratabular processes; archeopyle apical. Types tA or tAa.
Description:
Shape: Body subspherical.
Wall relationships: Endophragm and periphragm appressed between processes.
Wall features: No parasutural features. Intratabular processes subcylindrical to dome-shaped, usually longer than wide, tips commonly narrower than bases; smaller processes tend to be closed distally.
Paratabulation: Indicated by intratabular processes; gonyaulacacean, process formula: 3-4`, 6``, 0c, 5```, 1p, 1````, 0-2s.
Archeopyle: Apical, Type tA or tAa; operculum free or attached with three or four processes.
Paracingulum: Position indicated by the absence of processes.
Parasulcus: Indicated by the absence of processes, or by the presence of one or two small processes.
Size: Intermediate.
Affinities:
Litosphaeridium differs from Oligosphaeridium in having tubular to dome-shaped processes that are relatively closely spaced proximally and typically not expanded distally, as in Oligosphaeridium.
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Emended description:
Lucas-Clarke, 1984:
Description:
Shape: Body subspherical to ovoid.
Wall relationships: Endophragm and periphragm appressed between processes, i.e., skolochorate, apiculocavate.
Wall features: No parasutural features. Hollow intratabular processes: subcylindrical, bulbous, conical, or goblet-shaped. Process bases subcircular; process tips truncated to constricted and without spines or ornamentation or suggestion of polygonal plate shapes; process shafts subcircular in cross-section. Periphragm smooth or ornamented with features of low relief (usually granular, reticulate, or rugulate) which extend partly onto processes. Endophragm ornament, which differs from that on periphragm, visible only beneath processes.
Paratabulation: Expressed by archeopyle shape, accessory archeopyle sutures, and intratabular processes. Not all paraplates are represented by processes, and some may have more than one process (up to four observed). Processes with double tips or double-bases occasionally observed. Apical processes three or four, the occasional fourth close to the third. Pre- and postcingular paraplates usually represented by one or more processes; multiple processes especially on relatively large paraplates in some species. Single posterior intercalary (X) and antapical (Y) processes consistently present. Inferred thecal tabulation sexiform gonyaulacoid with C divided into Ci and Cu.
Archeopyle: Apical, Type tA; operculum adnate ventrally or free; archeopyle suture zigzag.
Paracingulum: Paraplates without processes or with one or two per paraplate; multiple processes, when present, more common on dorsal and lateral paraplates. Processes generally more slender than those representing pre- and postcingular paraplates.
Parasulcus: Paraplates without processes or with one or two processes representing ai, and single processes representing Z, and Iu.
Size: small to intermediate (20-55 µm total diameter).
Remarks:
This genus is distinguished by simplicity of structure; a central cyst body with hollow, truncated processes, and an apical archeopyle. Its peculiarity is the variation in process number between and within species, but this variation can be resolved into a consistent paratabulation pattern. Important details of process distribution and paratabulation supplement the distinctive combination of archeopyle type and process form in Litosphaeridium. These include: ( 1 ) usual presence of only three processes (lu, B, Ci) on the apical operculum; apparently no process represents A, even when four are present; (2) division of C into Ci and Cu, suggested by archeopyle outline indicating contact of paraplate 5 with two apicals, and by position of occasional fourth process on the operculum; (3) sexiform antapical paratabulation pattern suggested by process arrangement.
Distinction of species within the genus depends upon details of process form and process distribution (both number and arrangement) including the presence of "extra" processes on certain paraplates.
Affinities:
Litosphaeridium is distinguished from Hystrichokolpoma in not having penitabular processes or processes with proximally quadrate cross-sections that reflect paraplate shape. Also, Hystrichokolpoma is described as consistently having 4 apical processes. Kaiwaradinium Wilson, 1978 is distinguished from Litosphaeridium in having a more elongate, ellipsoidal body shape, and in consistently having 4 apical processes. Genera which have similar processes to those of Litosphaeridium, such as Florentinia, Diphyes, Homotryblium, and Conosphaeridium, have precingular, combination, or epicystal archaeopyles.
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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.
Litosphaeridium Davey and Williams, 1966b, emend. Davey and Verdier, 1973, emend. Lucas-Clark, 1984. Lucas-Clark (1984, p. 181-182) noted that Litosphaeridium has a subspherical to ovoid central body with hollow, intratabular, subcylindrical, bulbous, conical or goblet-shaped processes. Processes may vary from 1-4 per plate and not all plates necessarily have processes. Always one process on 1p and 1"'' plates. Inferred to be sexiform. Cingulum devoid of processes or with one or two per plate. Archeopyle apical, type tA. Operculum adnate ventrally or free.
[Litosphaeridium, Davey and Williams, 1966b, p. 79–80; Emendations: Davey and Verdier, 1973, p. 193; Lucas-Clark, 1984, p. 181–182.
Tax. jr. syn.: Conosphaeridium, by implication in Sarjeant (1969, p.14), who transferred the "type species" of Conosphaeridium, Conosphaeridium striatoconum, to Litosphaeridium — however, Lentin and Williams (1973, p.31) retained Conosphaeridium.
Type species: originally as Hystrichosphaeridium siphoniphorum, Cookson and Eisenack, 1958, (pl.11, fig.8)] ; Litosphaeridium siphoniphorum, Davey and Williams, 1966;
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Davey and Williams 1966]:
Diagnosis:
Chorate cyst with spherical to sub-spherical central body composed of two membranes. Processes few in number (only one per plate area), hollow and open distally except for sulcal processes which may be closed. Reflected tabulation 3`, 6``, 5```, 1p, 1````, with variable number of sulcal processes. Archaeopyle apical.
Affinities:
The presence of three apical processes and the absence of cingular processes is diagnostic of this genus, and makes it easily recognizable. The sulcal processes may be either absent or few.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Evitt 1978, p. 61-62:
Synopsis:
Cysts skolochorate, body subspherical with 16 to 19 intratabular processes; processes hollow, subcylindrical to dome-shaped, tips commonly narrower than bases; paracingular processes absent; paratabulation gonyaulacacean, indicated by intratabular processes; archeopyle apical. Types tA or tAa.
Description:
Shape: Body subspherical.
Wall relationships: Endophragm and periphragm appressed between processes.
Wall features: No parasutural features. Intratabular processes subcylindrical to dome-shaped, usually longer than wide, tips commonly narrower than bases; smaller processes tend to be closed distally.
Paratabulation: Indicated by intratabular processes; gonyaulacacean, process formula: 3-4`, 6``, 0c, 5```, 1p, 1````, 0-2s.
Archeopyle: Apical, Type tA or tAa; operculum free or attached with three or four processes.
Paracingulum: Position indicated by the absence of processes.
Parasulcus: Indicated by the absence of processes, or by the presence of one or two small processes.
Size: Intermediate.
Affinities:
Litosphaeridium differs from Oligosphaeridium in having tubular to dome-shaped processes that are relatively closely spaced proximally and typically not expanded distally, as in Oligosphaeridium.
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Emended description:
Lucas-Clarke, 1984:
Description:
Shape: Body subspherical to ovoid.
Wall relationships: Endophragm and periphragm appressed between processes, i.e., skolochorate, apiculocavate.
Wall features: No parasutural features. Hollow intratabular processes: subcylindrical, bulbous, conical, or goblet-shaped. Process bases subcircular; process tips truncated to constricted and without spines or ornamentation or suggestion of polygonal plate shapes; process shafts subcircular in cross-section. Periphragm smooth or ornamented with features of low relief (usually granular, reticulate, or rugulate) which extend partly onto processes. Endophragm ornament, which differs from that on periphragm, visible only beneath processes.
Paratabulation: Expressed by archeopyle shape, accessory archeopyle sutures, and intratabular processes. Not all paraplates are represented by processes, and some may have more than one process (up to four observed). Processes with double tips or double-bases occasionally observed. Apical processes three or four, the occasional fourth close to the third. Pre- and postcingular paraplates usually represented by one or more processes; multiple processes especially on relatively large paraplates in some species. Single posterior intercalary (X) and antapical (Y) processes consistently present. Inferred thecal tabulation sexiform gonyaulacoid with C divided into Ci and Cu.
Archeopyle: Apical, Type tA; operculum adnate ventrally or free; archeopyle suture zigzag.
Paracingulum: Paraplates without processes or with one or two per paraplate; multiple processes, when present, more common on dorsal and lateral paraplates. Processes generally more slender than those representing pre- and postcingular paraplates.
Parasulcus: Paraplates without processes or with one or two processes representing ai, and single processes representing Z, and Iu.
Size: small to intermediate (20-55 µm total diameter).
Remarks:
This genus is distinguished by simplicity of structure; a central cyst body with hollow, truncated processes, and an apical archeopyle. Its peculiarity is the variation in process number between and within species, but this variation can be resolved into a consistent paratabulation pattern. Important details of process distribution and paratabulation supplement the distinctive combination of archeopyle type and process form in Litosphaeridium. These include: ( 1 ) usual presence of only three processes (lu, B, Ci) on the apical operculum; apparently no process represents A, even when four are present; (2) division of C into Ci and Cu, suggested by archeopyle outline indicating contact of paraplate 5 with two apicals, and by position of occasional fourth process on the operculum; (3) sexiform antapical paratabulation pattern suggested by process arrangement.
Distinction of species within the genus depends upon details of process form and process distribution (both number and arrangement) including the presence of "extra" processes on certain paraplates.
Affinities:
Litosphaeridium is distinguished from Hystrichokolpoma in not having penitabular processes or processes with proximally quadrate cross-sections that reflect paraplate shape. Also, Hystrichokolpoma is described as consistently having 4 apical processes. Kaiwaradinium Wilson, 1978 is distinguished from Litosphaeridium in having a more elongate, ellipsoidal body shape, and in consistently having 4 apical processes. Genera which have similar processes to those of Litosphaeridium, such as Florentinia, Diphyes, Homotryblium, and Conosphaeridium, have precingular, combination, or epicystal archaeopyles.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Litosphaeridium Davey and Williams, 1966b, emend. Davey and Verdier, 1973, emend. Lucas-Clark, 1984. Lucas-Clark (1984, p. 181-182) noted that Litosphaeridium has a subspherical to ovoid central body with hollow, intratabular, subcylindrical, bulbous, conical or goblet-shaped processes. Processes may vary from 1-4 per plate and not all plates necessarily have processes. Always one process on 1p and 1"'' plates. Inferred to be sexiform. Cingulum devoid of processes or with one or two per plate. Archeopyle apical, type tA. Operculum adnate ventrally or free.