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Gonyaulacysta pectinigera
Gonyaulacysta pectinigera (Gocht, 1970); Emendation: Fensome, 1979, p.43, as Gonyaulacysta pectinigera.
Originally Leptodinium subtile ssp. pectinigerum, subsequently Hystrichogonyaulax pectinigera, thirdly (and now) Gonyaulacysta pectinigera, fourthly Leptodinium pectinigerum.
Lentin and Williams, 1981, retained this taxon in Hystrichogonyaulax Sarjeant, 1969, as Hystrichogonyaulax pectinigera. Jan du Chene et al., 1986, agreed with Fensome (1979). Stover and Evitt, 1978, raised this taxon to the species level.
Holotype: Gocht, 1970, pl.33, fig.1
Age: Early Bathonian
Emended diagnosis: Fensome 1979 p. 43-46: Gonyaulacysta pectinigera
Proximate dinoflagel]ate cysts with a subpolygonal (roughly pentagonal) outline, polygonality being accentuated by the presence of high denticulate parasutural crests which occur dorsally and laterally. Ventrally crests are low and usually spinose. Paratabulation: 1 pr, 4", 6", 7c, 6"", lp, 1"". The cyst wall consists of two layers which separate only at the apex, where the periphragm is drawn out into a short rectangular to irregularly polygonal horn and the endophragm produces a mamelon-like structure. The cyst wall and parasutural crests are foveolate; pandasutural zones with more densely foveolate ornamentation often occur on many of the larger dorsal and lateral paraplates. The archeopyle is precingular, formed by the loss of paraplate 3 "; the operculum is usually detached.
Dimensions: Range; (eight specimens measured) length 58 (77) 96 Ám. breadth 56 (74) 83 Ám, depth (in one specimen only) 38 Ám. Iength of apical horn 5 (10) 15 Ám, height of crests 5 (7) 9 Ám.
Description: Fensome 1979 p. 43-46: Gonyaulacysta pectinigera
The cyst is slightly dorso-ventrally flattened. In ventral or dorsal view it is approximately pentagonal, the corners of the central body being more or less rounded. Polygonality is imparted by the presence of high sutural crests. Many of the lateral and dorsal precingular and postcingular paraplates possess a pandasutural zone of variable breadth in which the foveolate ornament of the cyst wall is denser than elsewhere. The boundary of this zone, where present, is usually or constantly sharp. The cyst wall also appears to be slightly thicker in the pandasutural zones. The dorsal paraplates of G. pectinigera are well delineated by high parasutural crests which have strongly and more or less regularly denticulat,e distal margins. The denticles are usually pointed, but they may occasionally bifurcate distally and more rarely they may be blunt. The parasutural crests on the ventral surface are usually much lower and give rise to short, narrow, pointed spinelets. The apical horn is produced by apical paraplates 1", 2" and 3", none of which extend greatly below the base of the horn. The other apical paraplate, 4", is not involved in the formation of the apical horn. There appears to be a small preapical paraplate at the distal tip of the horn, at least on some of the specimens encountered. The apical horn is variable in shape. In some specimens it was short and rectangular in outline, as in the specimen illustrated by Gocht (1970, text-fig. 11) and in one specimen illustrated in this work (Plate 6, fig.4). In other specimens it tends to be more irregular in shape (Plate 6. fig. 2 and text-fig. 15). There are six precingular paraplates, of which 6" is relatively small owing to the presence of paraplate 4". In all of the specimens encountered paraplate 3" is lost in archeopyle formation. The paracingulum is laevorotatory, its ends being displaced at the parasulcus by about one paracingulum width. Parasutures within the paracingulum indicate seven paraplates; six of these are elongate, but Ic is very short. The paracingular paraplates were often difficult to perceive. The parasulcus extends from the posterior end of apical paraplate 1" to the antapical paraplate. It is straight, broadening slightly on the hypocyst. The specimen illustrated in text-fig. 15A, B has a parasulcus which has collapsed inwards; its morphology in this region is therefore difficult to study in detail. However, other specimens show faint ridges within this region, indicating possible parasutures. One specimen exhibits a faint flagellar marking. There are six postcingular paraplates, 1"" being narrow and generally poorly indicated. It is not shown by Gocht (1970, text-figure 11) but may be discerned on at least one of his photographs (ibid, pl. 33, fig. lb). Also present is a small, triangular posterior intercalary paraplate, inserted between paraplates 1"", 1"" and the parasulcus. There is a single rectangular antapical paraplate (1"").
Remarks: Fensome 1979 p. 43-46
This taxon was originally described by Gocht (1970) as Leptodinium sublile Klement, 1960 subsp. pectinigerum. Although its paratabulation does resemble that of L. subtile, its crests are very distinctive and quite unlike those of L. subtile. Moreover, its possession of an apical horn merits its inclusion in the genus Gonyaulacysta, rather than Leptodinium. G. pectinigera is similar to G. jurassica (Deflandre, 1938b) Norris & Sarjeant, 1965, but it has a distinctive pentagonal shape and is not as elongate as G. jurassica; the overall breadth of G. pectinigera approaches and may occassionally equal or even slightly exceed the overall length. G. pectinigera also resembles G. crassicornuta (Klement, 1960), but has a much shorter apical horn and denticulate and spinose rather than consistently spinose crests. From Klement"s photographs, G. crassicornuta appears to have a much rougher surface ornamentation than G. pectinigera (although Klement comments that G. crassicornuta possesses a smooth to unclearly punctate membrane). G. eisenacki (Deflandre, 1938b) has an antapical pericoel and because of this, its more elongate shape and subconical apex, it is easily distinguished from G. pectinigera. G. cf. G. eisenacki of Valensi (1953, pl. 1, fig. 5) is more similar to G. pectinigera but appears to lack an apical horn; Valensi did not describe its paratabulation. G. aff. G. jurassica of Sarjeant (1972) is also similar to G. pectinigera in general appearance but has only five postcingular paraplates and lower, more irregularly denticulate perasutural crests.
Originally Leptodinium subtile ssp. pectinigerum, subsequently Hystrichogonyaulax pectinigera, thirdly (and now) Gonyaulacysta pectinigera, fourthly Leptodinium pectinigerum.
Lentin and Williams, 1981, retained this taxon in Hystrichogonyaulax Sarjeant, 1969, as Hystrichogonyaulax pectinigera. Jan du Chene et al., 1986, agreed with Fensome (1979). Stover and Evitt, 1978, raised this taxon to the species level.
Holotype: Gocht, 1970, pl.33, fig.1
Age: Early Bathonian
Emended diagnosis: Fensome 1979 p. 43-46: Gonyaulacysta pectinigera
Proximate dinoflagel]ate cysts with a subpolygonal (roughly pentagonal) outline, polygonality being accentuated by the presence of high denticulate parasutural crests which occur dorsally and laterally. Ventrally crests are low and usually spinose. Paratabulation: 1 pr, 4", 6", 7c, 6"", lp, 1"". The cyst wall consists of two layers which separate only at the apex, where the periphragm is drawn out into a short rectangular to irregularly polygonal horn and the endophragm produces a mamelon-like structure. The cyst wall and parasutural crests are foveolate; pandasutural zones with more densely foveolate ornamentation often occur on many of the larger dorsal and lateral paraplates. The archeopyle is precingular, formed by the loss of paraplate 3 "; the operculum is usually detached.
Dimensions: Range; (eight specimens measured) length 58 (77) 96 Ám. breadth 56 (74) 83 Ám, depth (in one specimen only) 38 Ám. Iength of apical horn 5 (10) 15 Ám, height of crests 5 (7) 9 Ám.
Description: Fensome 1979 p. 43-46: Gonyaulacysta pectinigera
The cyst is slightly dorso-ventrally flattened. In ventral or dorsal view it is approximately pentagonal, the corners of the central body being more or less rounded. Polygonality is imparted by the presence of high sutural crests. Many of the lateral and dorsal precingular and postcingular paraplates possess a pandasutural zone of variable breadth in which the foveolate ornament of the cyst wall is denser than elsewhere. The boundary of this zone, where present, is usually or constantly sharp. The cyst wall also appears to be slightly thicker in the pandasutural zones. The dorsal paraplates of G. pectinigera are well delineated by high parasutural crests which have strongly and more or less regularly denticulat,e distal margins. The denticles are usually pointed, but they may occasionally bifurcate distally and more rarely they may be blunt. The parasutural crests on the ventral surface are usually much lower and give rise to short, narrow, pointed spinelets. The apical horn is produced by apical paraplates 1", 2" and 3", none of which extend greatly below the base of the horn. The other apical paraplate, 4", is not involved in the formation of the apical horn. There appears to be a small preapical paraplate at the distal tip of the horn, at least on some of the specimens encountered. The apical horn is variable in shape. In some specimens it was short and rectangular in outline, as in the specimen illustrated by Gocht (1970, text-fig. 11) and in one specimen illustrated in this work (Plate 6, fig.4). In other specimens it tends to be more irregular in shape (Plate 6. fig. 2 and text-fig. 15). There are six precingular paraplates, of which 6" is relatively small owing to the presence of paraplate 4". In all of the specimens encountered paraplate 3" is lost in archeopyle formation. The paracingulum is laevorotatory, its ends being displaced at the parasulcus by about one paracingulum width. Parasutures within the paracingulum indicate seven paraplates; six of these are elongate, but Ic is very short. The paracingular paraplates were often difficult to perceive. The parasulcus extends from the posterior end of apical paraplate 1" to the antapical paraplate. It is straight, broadening slightly on the hypocyst. The specimen illustrated in text-fig. 15A, B has a parasulcus which has collapsed inwards; its morphology in this region is therefore difficult to study in detail. However, other specimens show faint ridges within this region, indicating possible parasutures. One specimen exhibits a faint flagellar marking. There are six postcingular paraplates, 1"" being narrow and generally poorly indicated. It is not shown by Gocht (1970, text-figure 11) but may be discerned on at least one of his photographs (ibid, pl. 33, fig. lb). Also present is a small, triangular posterior intercalary paraplate, inserted between paraplates 1"", 1"" and the parasulcus. There is a single rectangular antapical paraplate (1"").
Remarks: Fensome 1979 p. 43-46
This taxon was originally described by Gocht (1970) as Leptodinium sublile Klement, 1960 subsp. pectinigerum. Although its paratabulation does resemble that of L. subtile, its crests are very distinctive and quite unlike those of L. subtile. Moreover, its possession of an apical horn merits its inclusion in the genus Gonyaulacysta, rather than Leptodinium. G. pectinigera is similar to G. jurassica (Deflandre, 1938b) Norris & Sarjeant, 1965, but it has a distinctive pentagonal shape and is not as elongate as G. jurassica; the overall breadth of G. pectinigera approaches and may occassionally equal or even slightly exceed the overall length. G. pectinigera also resembles G. crassicornuta (Klement, 1960), but has a much shorter apical horn and denticulate and spinose rather than consistently spinose crests. From Klement"s photographs, G. crassicornuta appears to have a much rougher surface ornamentation than G. pectinigera (although Klement comments that G. crassicornuta possesses a smooth to unclearly punctate membrane). G. eisenacki (Deflandre, 1938b) has an antapical pericoel and because of this, its more elongate shape and subconical apex, it is easily distinguished from G. pectinigera. G. cf. G. eisenacki of Valensi (1953, pl. 1, fig. 5) is more similar to G. pectinigera but appears to lack an apical horn; Valensi did not describe its paratabulation. G. aff. G. jurassica of Sarjeant (1972) is also similar to G. pectinigera in general appearance but has only five postcingular paraplates and lower, more irregularly denticulate perasutural crests.