Back
Rhaetogonyaulax
From Williams et al., 2017:
[Rhaetogonyaulax, Sarjeant, 1966b, p. 152–153; Emendations: Harland et al., 1975, p. 860; Fisher and van Helden, 1979, p. 270, 272; Below, 1987a, p. 101–102.
Type species: originally as Gonyaulax rhaetica, Sarjeant, 1963b (text-figs.1–2 (left))] ; Rhaetogonyaulax rhaetica, Loeblich and Loeblich, 1968; emend. Harland et al., 1975; emend. Below, 1987.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Sarjeant, 1966]:
Diagnosis:
Proximate dinoflagellate cysts, spindle-shaped or biconical, typically with the tabulation 4`, 1a, 6``, 6```, 1p, 1````: tabulation well or poorly marked by ridges or partially or entirely indeterminable. Cingulum strongly or weakly spiral, laevo-rotatory, divided into plates (?6c) or without such division. Surface smooth, granular, nodose, punctate or reticulate; ornamentation may mask the tabulation.
Archeopyle (where present) epitractal, formed by the schism of shell immediately anterior to cingulum.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended descriptions:
Harland et al., 1975:
Diagnosis:
Cyst proximate, elongate-biconical to spindle-shaped, with rudimentary or pronounced apical and antapical horns. Wall apparently single-layered, smooth, rough; punctate, granulate or reticulate. Cingulum helicoid, laevorotatory, moderately indented; cingulum and sulcus generally defined by ridges. tabulation 4`-?6`, 5-?6a, 1av, 7``, 7c, 7```, 1p, 3s, 3````; boundaries of plate-areas marked by raised lines, lines of short processes, or rupture. Processes, where developed, may be sutural or intratabular, simple or furcate.
Archaeopyle development by progressive loss of all plates anterior to the precingular series.
-------------------------------------------
Fisher and van Helden, 1979:
Diagnosis:
Proximate cysts, biconical to fusiform, with one apical and one antapical horn or protrusion; in some assemblages a second vestigial antapical protrusion may be observed. Paracingulum well defined. Wall single-layered, variously ornamented, including granulate, scabrate, reticulate and spinose ornamentation.
Paratabulation 1(?2)pr, 6`, 5a, 7``, 7c, 7```, ?2```, ?5s.
Archaeopyle formed by the progressive loss of pre-apical, apical and intercalary paraplates to produce an A(4`)+5I type archaeopyle whereby the opercular paraplates are individually separated, leaving the extreme, conical, apical part of the cyst attached to the precingular series, or to produce a 6A5I type archaeopyle with an undivided operculum whereby all paraplates of the intercalary and apical series are united in a single piece, separated along the archaeopyle suture from the precingular paraplates.
-------------------------------------------
Below, 1987: (Translation: Translation Bureau of the Secretary of State, Canada.)
Diagnosis:
Arrangement of vesicles/plates on the dinoflagellate amphiesma cop, pop, cap, 5`, 4a, 7``, 8c, 7```-8```, 3````, ns; as connected dextrally with5` and 7``; growth type of thecal plates peridinoidal.
Cyst habit proximate, proximochotrate, chorate, fusiform, peridinoidal, poles rounded, acuminate or with apical horn and one or two antapical horns, acavate to cavate, size variable; wall composed of pedium, also with luxuria; surface smooth or ornamented, areate or nonareate; areation marked by finate ornaments or limbi; areation formula NR PR/cop, pop, cap, NR`/5`, NRa/4a, NR``/7``, NRc/Xc/8c, NR```/7```-8```, NR````/3````, NRs/Xs/ns; archaeopyle apical/anterior intercalary, PR+1`+2`+3`+4`+5`+1a+2a+3a+4a; operculum partially solvate, partially foederate, foederate opercular pieces adnate or secate, general opercular formula 3(s)+5(s)+1a(s)+2a(s)+3a(s)+4a(s)+[PR+1`+2`+4`](a/s).
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Evitt 1978, p. 218-219:
Synopsis:
Cysts proximate, elongate ellipsoidal to biconical, typically with single apical and antapical horns or lobes; autophragm smooth or variously ornamented with features of low relief; paratabulation typically indicated incompletely by parasutural features, formula: ?1pa, 4-?6`, 5-?6a, 7``, X-7c, 7```, 0-1p, 3````, 2-4s; combination archeopyle, generally Type tAtI.
Description:
Shape: Elongate ellipsoidal to biconical, generally with single pointed to blunt apical an antapical horns or lobes; antapical horn medial or offset to one side.
Wall Relationships: Autophragm only.
Wall Features: Parasutural features consist of low smooth or ornamented ridges, discontinuous rows of granules or spinules, and sutures. Autophragm of variable thickness, variously ornamented with features of generally low relief, which tend to be arranged in intratabular clusters separated by ill-defined pandasuturate areas.
Paratabulation: Typically incompletely expressed by edge of archeopyle, by vague pandasuturate areas, or by faint parasutural features. Paratabulation formula: ?1pa, 4-?6`, 5-?6a, 7``, X-7c, 7```, 0-1p, 3````, 2-4s; paratabulation generally indicated more clearly on epicyst than on hypocyst and in precingular-postcingular area than at apices. First precingular paraplate only slightly wider than adjacent parasulcal notch.
Archeopyle: Combination, generally Type tAtI; operculum free, usually conical, although one or more of the intercalary opercular pieces may separate from the others or adhere to subjacent precingular paraplates. Paracingulum: Indicated by low, transverse, parallel, equatorial ridges separated by a shallow to moderately deep concavity.
Parasulcus: Indicated by offset in paracingulum and by shallow depression on hypocyst, which may be delimited by low parasutural features and may be subdivided.
Size: Intermediate.
Affinities:
Rhaetogonyaulax differs from Sverdrupiella, which may also be biconical, in having an autophragm only and in having a combination Type tAtI archeopyle rather than a simple or compound intercalary archeopyle.
[Rhaetogonyaulax, Sarjeant, 1966b, p. 152–153; Emendations: Harland et al., 1975, p. 860; Fisher and van Helden, 1979, p. 270, 272; Below, 1987a, p. 101–102.
Type species: originally as Gonyaulax rhaetica, Sarjeant, 1963b (text-figs.1–2 (left))] ; Rhaetogonyaulax rhaetica, Loeblich and Loeblich, 1968; emend. Harland et al., 1975; emend. Below, 1987.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Sarjeant, 1966]:
Diagnosis:
Proximate dinoflagellate cysts, spindle-shaped or biconical, typically with the tabulation 4`, 1a, 6``, 6```, 1p, 1````: tabulation well or poorly marked by ridges or partially or entirely indeterminable. Cingulum strongly or weakly spiral, laevo-rotatory, divided into plates (?6c) or without such division. Surface smooth, granular, nodose, punctate or reticulate; ornamentation may mask the tabulation.
Archeopyle (where present) epitractal, formed by the schism of shell immediately anterior to cingulum.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended descriptions:
Harland et al., 1975:
Diagnosis:
Cyst proximate, elongate-biconical to spindle-shaped, with rudimentary or pronounced apical and antapical horns. Wall apparently single-layered, smooth, rough; punctate, granulate or reticulate. Cingulum helicoid, laevorotatory, moderately indented; cingulum and sulcus generally defined by ridges. tabulation 4`-?6`, 5-?6a, 1av, 7``, 7c, 7```, 1p, 3s, 3````; boundaries of plate-areas marked by raised lines, lines of short processes, or rupture. Processes, where developed, may be sutural or intratabular, simple or furcate.
Archaeopyle development by progressive loss of all plates anterior to the precingular series.
-------------------------------------------
Fisher and van Helden, 1979:
Diagnosis:
Proximate cysts, biconical to fusiform, with one apical and one antapical horn or protrusion; in some assemblages a second vestigial antapical protrusion may be observed. Paracingulum well defined. Wall single-layered, variously ornamented, including granulate, scabrate, reticulate and spinose ornamentation.
Paratabulation 1(?2)pr, 6`, 5a, 7``, 7c, 7```, ?2```, ?5s.
Archaeopyle formed by the progressive loss of pre-apical, apical and intercalary paraplates to produce an A(4`)+5I type archaeopyle whereby the opercular paraplates are individually separated, leaving the extreme, conical, apical part of the cyst attached to the precingular series, or to produce a 6A5I type archaeopyle with an undivided operculum whereby all paraplates of the intercalary and apical series are united in a single piece, separated along the archaeopyle suture from the precingular paraplates.
-------------------------------------------
Below, 1987: (Translation: Translation Bureau of the Secretary of State, Canada.)
Diagnosis:
Arrangement of vesicles/plates on the dinoflagellate amphiesma cop, pop, cap, 5`, 4a, 7``, 8c, 7```-8```, 3````, ns; as connected dextrally with5` and 7``; growth type of thecal plates peridinoidal.
Cyst habit proximate, proximochotrate, chorate, fusiform, peridinoidal, poles rounded, acuminate or with apical horn and one or two antapical horns, acavate to cavate, size variable; wall composed of pedium, also with luxuria; surface smooth or ornamented, areate or nonareate; areation marked by finate ornaments or limbi; areation formula NR PR/cop, pop, cap, NR`/5`, NRa/4a, NR``/7``, NRc/Xc/8c, NR```/7```-8```, NR````/3````, NRs/Xs/ns; archaeopyle apical/anterior intercalary, PR+1`+2`+3`+4`+5`+1a+2a+3a+4a; operculum partially solvate, partially foederate, foederate opercular pieces adnate or secate, general opercular formula 3(s)+5(s)+1a(s)+2a(s)+3a(s)+4a(s)+[PR+1`+2`+4`](a/s).
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Evitt 1978, p. 218-219:
Synopsis:
Cysts proximate, elongate ellipsoidal to biconical, typically with single apical and antapical horns or lobes; autophragm smooth or variously ornamented with features of low relief; paratabulation typically indicated incompletely by parasutural features, formula: ?1pa, 4-?6`, 5-?6a, 7``, X-7c, 7```, 0-1p, 3````, 2-4s; combination archeopyle, generally Type tAtI.
Description:
Shape: Elongate ellipsoidal to biconical, generally with single pointed to blunt apical an antapical horns or lobes; antapical horn medial or offset to one side.
Wall Relationships: Autophragm only.
Wall Features: Parasutural features consist of low smooth or ornamented ridges, discontinuous rows of granules or spinules, and sutures. Autophragm of variable thickness, variously ornamented with features of generally low relief, which tend to be arranged in intratabular clusters separated by ill-defined pandasuturate areas.
Paratabulation: Typically incompletely expressed by edge of archeopyle, by vague pandasuturate areas, or by faint parasutural features. Paratabulation formula: ?1pa, 4-?6`, 5-?6a, 7``, X-7c, 7```, 0-1p, 3````, 2-4s; paratabulation generally indicated more clearly on epicyst than on hypocyst and in precingular-postcingular area than at apices. First precingular paraplate only slightly wider than adjacent parasulcal notch.
Archeopyle: Combination, generally Type tAtI; operculum free, usually conical, although one or more of the intercalary opercular pieces may separate from the others or adhere to subjacent precingular paraplates. Paracingulum: Indicated by low, transverse, parallel, equatorial ridges separated by a shallow to moderately deep concavity.
Parasulcus: Indicated by offset in paracingulum and by shallow depression on hypocyst, which may be delimited by low parasutural features and may be subdivided.
Size: Intermediate.
Affinities:
Rhaetogonyaulax differs from Sverdrupiella, which may also be biconical, in having an autophragm only and in having a combination Type tAtI archeopyle rather than a simple or compound intercalary archeopyle.