Back
Dichadogonyaulax
From Fensome et al., 2019:
Dichadogonyaulax, Sarjeant, 1966b, p.153.
Emendations: Sarjeant, 1975a, p.50; Woollam, 1983, p.193; Benson, 1985, p.152.
Taxonomic senior synonym: Ctenidodinium, according to Lentin and Williams (1973, p.46) -- however, Sarjeant (1975a, p.50) and Benson (1985, p.152) retained Dichadogonyaulax.
Taxonomic junior synonyms: Brotzenia, by implication in Fensome and Sarjeant (1982, p.56), who transferred the "type species" of Brotzenia -- Brotzenia cristata -- to Dichadogonyaulax; Avellodinium, by implication in Davey (1982b, p.26), who transferred the "type species" of Dichadogonyaulax, Dichadogonyaulax (originally Gonyaulax) culmula, to Avellodinium -- however, Lentin and Williams (1985, p.31) retained that species in Dichadogonyaulax and retained Avellodinium. Although the "type species" was not validly transferred by Sarjeant (1966b, p.153), the generic name Dichadogonyaulax was validly published by that author since it is based on a previously validly published species name (ICN Article 40.3). Type: Norris, 1965, figs.8–9, as Gonyaulax culmula.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Sarjeant, 1966b]:
Description:
Proximate dinoflagellate cysts, spheroidal, ovoidal, ellipsoidal or polyhedral, having the tabulation 3-5`, 0-?1a, 6", 5-6```, 1p, 1````; sulcus divided into plates or undivided, ventral region may show division into additional small plates. Cingulum strongly or weakly spiral, laevorotatory. Apical horn may be 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. Archaeopyle (where present) epitractal, by schism of shell immediately anterior to cingulum.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended descriptions:
Sarjeant, 1975a:
Diagnosis:
Proximate dinoflagellate cysts, spheroidal or ovoidal to sub-polygonal in shape, with or without an apical horn but without median or antapical horns.
Reflected tabulation 3-6`, 0-2a, 0-1av, 6, 6c, 5-6```, 0-2p, 0-1pv, 1````, plus a variable number of sulcal plate-areas occupying the ventral surface and, in forms with apical horns, one or more pre-apical plates.
Cingulum strongly or weakly helicoid, laevorotatory. Boundaries between plate areas marked by low ridges; in the form of raised crests of variable character; or marked by lines of isolate or linked processes.
Sutural development on either side of cingulum symmetrical.
Archaeopyle (where developed) epitractal, formed by schism along the centre or anterior margin of the cingulum; the resultant hemicysts, in particular the epitract, may break up by further schism along plate-area boundaries.
---------------------------------
Woolam, 1983:
Diagnosis:
Cysts generally proximate, occasionally proximochorate, autophragm only.
Body subspherical to ellipsoidal, generally without an apical horn. Paratabulation gonyaulacoid, 0-3pa, 1`, 0-2a, 6", 6c, x-6s, 6```, 1p, 1````, indicated by parasutural rows of isolated or proximally linked processes or by low, often denticulate crests. Development of parasutural ornament on the paracingulum symmetrical. Parasutural ornament development elsewhere generally of uniform height. Archaeopyle epicystal, formed by schism along a line anterior to the paracingulum, initiated dorsally, operculum (epicyst) attached ventrally at the parasulcus.
Affinities:
Dichadogonyaulax differs from Ctenidodinium primarily in the symmetry of its paracingular crests, which in Ctenidodinium are asymmetrically developed, the posterior larger than the anterior.
---------------------------------
Benson, 1985:
Description:
Proximochorate dinoflagellate cysts constructed of an autophragm only. Subspherical in shape, lacking an apical horn.
Paratabulation formula: 1pr, 4`, 0a, 6", x-6c, 6```, 1p, 1````, x-6s, indicated by parasutural crests, ridges, or rows of processes, crests generally ornamented with spines. Accessory ridges absent. Paraplates of the anterior intercalary series absent. Preapical paraplate reduced in size and displaced posteroventrally, resulting in contact between paraplates 2` and 4`. Combination (epicystal, type E) archeopyle separating from the hypocyst along the posterior margin of the precingular paraplates. Parasutural features on the paracingulum may or may not be reduced on the anterior margin as compared with the posterior margin.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Dichadogonyaulax Sarjeant, 1966b, emend. Sarjeant, 1975a, emend. Woollam, 1983, emend. Benson, 1985. According to Benson (1985), this genus has the tabulation 1p, 4`, 0a, 6", x-6c, 6" ,1p, 1" , x-6s. It differs from Ctenidodinium in not having intercalary plates and in having an off-centre preapical structure which allows contact of 2` and 3`.
Dichadogonyaulax, Sarjeant, 1966b, p.153.
Emendations: Sarjeant, 1975a, p.50; Woollam, 1983, p.193; Benson, 1985, p.152.
Taxonomic senior synonym: Ctenidodinium, according to Lentin and Williams (1973, p.46) -- however, Sarjeant (1975a, p.50) and Benson (1985, p.152) retained Dichadogonyaulax.
Taxonomic junior synonyms: Brotzenia, by implication in Fensome and Sarjeant (1982, p.56), who transferred the "type species" of Brotzenia -- Brotzenia cristata -- to Dichadogonyaulax; Avellodinium, by implication in Davey (1982b, p.26), who transferred the "type species" of Dichadogonyaulax, Dichadogonyaulax (originally Gonyaulax) culmula, to Avellodinium -- however, Lentin and Williams (1985, p.31) retained that species in Dichadogonyaulax and retained Avellodinium. Although the "type species" was not validly transferred by Sarjeant (1966b, p.153), the generic name Dichadogonyaulax was validly published by that author since it is based on a previously validly published species name (ICN Article 40.3). Type: Norris, 1965, figs.8–9, as Gonyaulax culmula.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Sarjeant, 1966b]:
Description:
Proximate dinoflagellate cysts, spheroidal, ovoidal, ellipsoidal or polyhedral, having the tabulation 3-5`, 0-?1a, 6", 5-6```, 1p, 1````; sulcus divided into plates or undivided, ventral region may show division into additional small plates. Cingulum strongly or weakly spiral, laevorotatory. Apical horn may be 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. Archaeopyle (where present) epitractal, by schism of shell immediately anterior to cingulum.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended descriptions:
Sarjeant, 1975a:
Diagnosis:
Proximate dinoflagellate cysts, spheroidal or ovoidal to sub-polygonal in shape, with or without an apical horn but without median or antapical horns.
Reflected tabulation 3-6`, 0-2a, 0-1av, 6, 6c, 5-6```, 0-2p, 0-1pv, 1````, plus a variable number of sulcal plate-areas occupying the ventral surface and, in forms with apical horns, one or more pre-apical plates.
Cingulum strongly or weakly helicoid, laevorotatory. Boundaries between plate areas marked by low ridges; in the form of raised crests of variable character; or marked by lines of isolate or linked processes.
Sutural development on either side of cingulum symmetrical.
Archaeopyle (where developed) epitractal, formed by schism along the centre or anterior margin of the cingulum; the resultant hemicysts, in particular the epitract, may break up by further schism along plate-area boundaries.
---------------------------------
Woolam, 1983:
Diagnosis:
Cysts generally proximate, occasionally proximochorate, autophragm only.
Body subspherical to ellipsoidal, generally without an apical horn. Paratabulation gonyaulacoid, 0-3pa, 1`, 0-2a, 6", 6c, x-6s, 6```, 1p, 1````, indicated by parasutural rows of isolated or proximally linked processes or by low, often denticulate crests. Development of parasutural ornament on the paracingulum symmetrical. Parasutural ornament development elsewhere generally of uniform height. Archaeopyle epicystal, formed by schism along a line anterior to the paracingulum, initiated dorsally, operculum (epicyst) attached ventrally at the parasulcus.
Affinities:
Dichadogonyaulax differs from Ctenidodinium primarily in the symmetry of its paracingular crests, which in Ctenidodinium are asymmetrically developed, the posterior larger than the anterior.
---------------------------------
Benson, 1985:
Description:
Proximochorate dinoflagellate cysts constructed of an autophragm only. Subspherical in shape, lacking an apical horn.
Paratabulation formula: 1pr, 4`, 0a, 6", x-6c, 6```, 1p, 1````, x-6s, indicated by parasutural crests, ridges, or rows of processes, crests generally ornamented with spines. Accessory ridges absent. Paraplates of the anterior intercalary series absent. Preapical paraplate reduced in size and displaced posteroventrally, resulting in contact between paraplates 2` and 4`. Combination (epicystal, type E) archeopyle separating from the hypocyst along the posterior margin of the precingular paraplates. Parasutural features on the paracingulum may or may not be reduced on the anterior margin as compared with the posterior margin.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Dichadogonyaulax Sarjeant, 1966b, emend. Sarjeant, 1975a, emend. Woollam, 1983, emend. Benson, 1985. According to Benson (1985), this genus has the tabulation 1p, 4`, 0a, 6", x-6c, 6" ,1p, 1" , x-6s. It differs from Ctenidodinium in not having intercalary plates and in having an off-centre preapical structure which allows contact of 2` and 3`.