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Gonyaulacysta sp. b of davey 1982b
Gonyaulacysta sp. B of Davey, 1982b
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Genus: Gonyaulacysta Deflandre, 1964; emend. Sarjeant, 1966; emend. Sarjeant, 1969; emend. Stover and Evitt, 1978; emend. Sarjeant, 1982
Tax. sr. synonym of Rhynchodiniopsis Deflandre, 1935, according to Millioud, 1969; howecer, Rhynchodiniopsis would be the sr. synonym. Lentin and Williams, 1973, retained Gonyaulacysta and Rhynchodiniopsis as separate genera.
Tax. sr. synonym of Nelchinopsis Wiggins, 1972, according to Duxbury, 1977. Stover and Williams, 1987, retained Nelchinopsis as a separate genus.
Tax. sr. synonym of Psaligonyaulax Sarjeant, 1966, according to Below, 1981. Lentin and Williams, 1981, retained Psaligonyaulax as a separate genus.
Type species: Gonyaulacysta jurassica (Deflandre, 1938) Norris and Sarjeant, 1965; emend. Sarjeant, 1982
Translation Deflandre, 1964: Stover and Evitt, 1978, p. 157
Original description: Deflandre, 1964, p. 5030
Diagnosis: I place in the genus Gonyaulacysta nov. gen. all the fossil species with Gonyaulax-like tabulation represented by thecae with projecting, more or less strongly ornamented crests (pectinate, spiny, denticulate, etc....) and provided with an archaeopyle (3rd pre-equatorial plate).
Emended diagnosis: Sarjeant, 1966, p. 111
Proximate dinoflagellate cysts, spherical, ovoidal, ellipsoidal or polyhedral, with the tabulation 3-4", 0-1a, 6"", 6c, 6""", 1p, 0-1 p.v., 1"""". Cingulum strongly or weakly helicoid. Cingular plates (6c) well or poorly marked; ventral surface may show division into additional small plates. Sulcus generally but not constantly extending onto epitract. Apical horn frequently, but not constantly present; median and antapical horns lacking. Sutures in form of low ridges; bearing crests of varied form (smooth denticulate or spinous; perforate or imperforate); or marked by lines of spines of varied form. Height of spines or crests always less than 1/4 of shell width. A precingular archaeopyle formed by loss of plate 3"". (Archaeopyle not always present.) Surface smooth, granular, nodose, punctate or reticulate.
Emended diagnosis: Sarjeant, 1969, p. 8
Proximate dinoflagellate cysts, spherical, ovoidal, ellipsoidal or polyhedral, with an apical horn and the reflected tabulation 3-4", 0-1a, 6"", 6c, 5-6""", 1p, 0-1p.v, 1"""", 0-xs. Cingulum strongly or weakly helicoid; cingular plates well or poorly marked. Sulcus generally but not constantly extending on to the epitract; undivided or subdivided into a variable number of small plates. Apical horn typically formed from the periphragm only, less frequently from both shell layers; rarely, an apical or antapical pericoel is present (but not both), but the two layers are most often otherwise in continuous contact. Median and antapical horns lacking. Sutures marked by low ridges; bearing crests of varied form (smooth, denticulate or spinous, perforate or imperforate); or marked by lines of spines of varied form. Height of spines or crests always less than 1/4 of shell width. A precingular single-plate archaeopyle, formed by loss of plate 3"", is developed, the operculum typically becoming wholly detached: in some individual specimens, the archaeopyle may not be developed. Surface of periphragm smooth, granular, nodose, punctate or reticulate; forms with a general spine cover are excluded.
Emended description: Stover and Evitt 1978, p. 158
Synopsis: Cysts typically bicavate; endocyst subspherical to ellipsoidal; pericyst subpolygonal and generally elongate longitudinally, with a short to long apical horn. Partabulation gonyaulacacean, indicated by parasutural septa with denticulate to spinulate crests; archeopyle precingular, Type P.
Modified description:
Shape: Elongate ellipsoidal to subpolygonal with a short to long apical horn; antapical end generally truncate.
Wall relationships: Cysts typically bicavate, although developed of epipericoel or hypopericoel may be lacking or reduced. In addition, tunnellike cavaties may extend toward paracingulum along parasutures.
Wall features: Parasutural septa with characteristic denticulate to spinulate crests; areas between septa smooth or punctoreticulate, or with scattered features of low relief; endophragm normally smooth.
Paratabulation: Indicated by parasutural features; gonyaulacacean, formula: 0-2pr, 3-4", 0-1a, 6"", 6c, 5-6""", 1p, 1"""", 0-1s; apical paraplates often difficult to distinguish.
Archeopyle: Precingular, Type P (3"" only); operculum free.
Paracingulum: Indicated by six subrectangular paraplates; ends of paracingulum typically strongly offset ventrally.
Parasulcus: Generally clearly delimited by parasutural septa, straight to S-shaped; posterior paraplate may be differentiated.
Size: Intermediate to large, generally the former.
Emended diagnosis: Sarjeant, 1982, p. 28
Proximate to proximochorate dinoflagellate cysts normally of small or intermediate, rarely of large, size. Ambitus subpolygonal to rounded subpolygonal or lozenge-shaped, consistently with an apical horn or prominence and with parasutural crests of variable form. Development of cavation at the apex universal, at the antapex variable to lacking; individual cysts may be apically cornucavate, epicavate, delphicavate or bicavate. Where a hypopericoel is developed, its length is always less than its breadth and the structure has no modifying effect on the ambitus of the hypotract, no angle being formed between the hypopericoel and the anterior portion of the hypotract. Paratabulation 0-2pa, 3-4", 0-1a, 6"", 6c-?7c, 6""", 1p, 0-1pv, 1""""; the sulcus may also show some division into small paraplates.
Paraplate 4" is elongate and narrow, shorter than 1" and only having a small contact with 6""; the latter paraplate typically exhibits some measure of triangularity. The crest between 4" and 6"" intersects the right lateral crest of 1" in a position anterior, and usually markedly anterior, to the boundary of the latter paraplate with the sulcus. Cingulum strongly or weakly helicoid; between its two ends, the sulcus may be straight or in varying degree sigmoidal. Crests on parasutures raised, smooth, serrate or developed into denticles or spines of regular or irregular length and character; accessory crests feebly developed or (typically) lacking. Height of crests variable, but always less than 1/4 of the cyst width. Gonal spines of small to moderate height present or absent. Surface of periphragm smooth, granular, nodose, punctate or reticulate; endophragm, where separate, typically smooth. Archaeopyle single-plate precingular, formed by loss of paraplate 3""" (sic, but should be 3""); operculum reduced.
Affinities:
Stover and Evitt 1978, p. 158
Gonyaulacysta differs from Rhynchodiniopsis in being cavate and in lacking strongly developed spines at the intersecions of parasutural features. Rhynchodiniopsis has an autophragm, and spinules in the gonal positions are longer (especially along the paracingulum) than those in intergonal locations.
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Genus: Gonyaulacysta Deflandre, 1964; emend. Sarjeant, 1966; emend. Sarjeant, 1969; emend. Stover and Evitt, 1978; emend. Sarjeant, 1982
Tax. sr. synonym of Rhynchodiniopsis Deflandre, 1935, according to Millioud, 1969; howecer, Rhynchodiniopsis would be the sr. synonym. Lentin and Williams, 1973, retained Gonyaulacysta and Rhynchodiniopsis as separate genera.
Tax. sr. synonym of Nelchinopsis Wiggins, 1972, according to Duxbury, 1977. Stover and Williams, 1987, retained Nelchinopsis as a separate genus.
Tax. sr. synonym of Psaligonyaulax Sarjeant, 1966, according to Below, 1981. Lentin and Williams, 1981, retained Psaligonyaulax as a separate genus.
Type species: Gonyaulacysta jurassica (Deflandre, 1938) Norris and Sarjeant, 1965; emend. Sarjeant, 1982
Translation Deflandre, 1964: Stover and Evitt, 1978, p. 157
Original description: Deflandre, 1964, p. 5030
Diagnosis: I place in the genus Gonyaulacysta nov. gen. all the fossil species with Gonyaulax-like tabulation represented by thecae with projecting, more or less strongly ornamented crests (pectinate, spiny, denticulate, etc....) and provided with an archaeopyle (3rd pre-equatorial plate).
Emended diagnosis: Sarjeant, 1966, p. 111
Proximate dinoflagellate cysts, spherical, ovoidal, ellipsoidal or polyhedral, with the tabulation 3-4", 0-1a, 6"", 6c, 6""", 1p, 0-1 p.v., 1"""". Cingulum strongly or weakly helicoid. Cingular plates (6c) well or poorly marked; ventral surface may show division into additional small plates. Sulcus generally but not constantly extending onto epitract. Apical horn frequently, but not constantly present; median and antapical horns lacking. Sutures in form of low ridges; bearing crests of varied form (smooth denticulate or spinous; perforate or imperforate); or marked by lines of spines of varied form. Height of spines or crests always less than 1/4 of shell width. A precingular archaeopyle formed by loss of plate 3"". (Archaeopyle not always present.) Surface smooth, granular, nodose, punctate or reticulate.
Emended diagnosis: Sarjeant, 1969, p. 8
Proximate dinoflagellate cysts, spherical, ovoidal, ellipsoidal or polyhedral, with an apical horn and the reflected tabulation 3-4", 0-1a, 6"", 6c, 5-6""", 1p, 0-1p.v, 1"""", 0-xs. Cingulum strongly or weakly helicoid; cingular plates well or poorly marked. Sulcus generally but not constantly extending on to the epitract; undivided or subdivided into a variable number of small plates. Apical horn typically formed from the periphragm only, less frequently from both shell layers; rarely, an apical or antapical pericoel is present (but not both), but the two layers are most often otherwise in continuous contact. Median and antapical horns lacking. Sutures marked by low ridges; bearing crests of varied form (smooth, denticulate or spinous, perforate or imperforate); or marked by lines of spines of varied form. Height of spines or crests always less than 1/4 of shell width. A precingular single-plate archaeopyle, formed by loss of plate 3"", is developed, the operculum typically becoming wholly detached: in some individual specimens, the archaeopyle may not be developed. Surface of periphragm smooth, granular, nodose, punctate or reticulate; forms with a general spine cover are excluded.
Emended description: Stover and Evitt 1978, p. 158
Synopsis: Cysts typically bicavate; endocyst subspherical to ellipsoidal; pericyst subpolygonal and generally elongate longitudinally, with a short to long apical horn. Partabulation gonyaulacacean, indicated by parasutural septa with denticulate to spinulate crests; archeopyle precingular, Type P.
Modified description:
Shape: Elongate ellipsoidal to subpolygonal with a short to long apical horn; antapical end generally truncate.
Wall relationships: Cysts typically bicavate, although developed of epipericoel or hypopericoel may be lacking or reduced. In addition, tunnellike cavaties may extend toward paracingulum along parasutures.
Wall features: Parasutural septa with characteristic denticulate to spinulate crests; areas between septa smooth or punctoreticulate, or with scattered features of low relief; endophragm normally smooth.
Paratabulation: Indicated by parasutural features; gonyaulacacean, formula: 0-2pr, 3-4", 0-1a, 6"", 6c, 5-6""", 1p, 1"""", 0-1s; apical paraplates often difficult to distinguish.
Archeopyle: Precingular, Type P (3"" only); operculum free.
Paracingulum: Indicated by six subrectangular paraplates; ends of paracingulum typically strongly offset ventrally.
Parasulcus: Generally clearly delimited by parasutural septa, straight to S-shaped; posterior paraplate may be differentiated.
Size: Intermediate to large, generally the former.
Emended diagnosis: Sarjeant, 1982, p. 28
Proximate to proximochorate dinoflagellate cysts normally of small or intermediate, rarely of large, size. Ambitus subpolygonal to rounded subpolygonal or lozenge-shaped, consistently with an apical horn or prominence and with parasutural crests of variable form. Development of cavation at the apex universal, at the antapex variable to lacking; individual cysts may be apically cornucavate, epicavate, delphicavate or bicavate. Where a hypopericoel is developed, its length is always less than its breadth and the structure has no modifying effect on the ambitus of the hypotract, no angle being formed between the hypopericoel and the anterior portion of the hypotract. Paratabulation 0-2pa, 3-4", 0-1a, 6"", 6c-?7c, 6""", 1p, 0-1pv, 1""""; the sulcus may also show some division into small paraplates.
Paraplate 4" is elongate and narrow, shorter than 1" and only having a small contact with 6""; the latter paraplate typically exhibits some measure of triangularity. The crest between 4" and 6"" intersects the right lateral crest of 1" in a position anterior, and usually markedly anterior, to the boundary of the latter paraplate with the sulcus. Cingulum strongly or weakly helicoid; between its two ends, the sulcus may be straight or in varying degree sigmoidal. Crests on parasutures raised, smooth, serrate or developed into denticles or spines of regular or irregular length and character; accessory crests feebly developed or (typically) lacking. Height of crests variable, but always less than 1/4 of the cyst width. Gonal spines of small to moderate height present or absent. Surface of periphragm smooth, granular, nodose, punctate or reticulate; endophragm, where separate, typically smooth. Archaeopyle single-plate precingular, formed by loss of paraplate 3""" (sic, but should be 3""); operculum reduced.
Affinities:
Stover and Evitt 1978, p. 158
Gonyaulacysta differs from Rhynchodiniopsis in being cavate and in lacking strongly developed spines at the intersecions of parasutural features. Rhynchodiniopsis has an autophragm, and spinules in the gonal positions are longer (especially along the paracingulum) than those in intergonal locations.