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Cribroperidinium swithini
From Fensome et al., 2019:
Cribroperidinium swithini Williams et al., 1998, p.151. Holotype: Sarjeant, 1984a, pl.3, figs.3–4; text-fig.3; Jan du Chêne et al., 1986a, pl.27, figs.7–10; Brenner, 1988, pl.3, figs.2,5; Fensome et al., 1995, figs.5–6 — p.1525. Originally Meristaulax granulata Brenner (name illegitimate), subsequently Cribroperidinium swithini. Substitute name for Meristaulax granulata Brenner, 1988, p.65–66, pl.3, figs.2,5; the name Cribroperidinium granulatum is preoccupied. Since the epithet is based on a given name, it ends in "i" rather than "ii" (ICN Recommendation
60C.2). Age: Late Jurassic.
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Emended description: [Sarjeant, 1984a] (as Meristaulax granulata):
Emended Diagnosis: Cyst proximate, monocornucavate. Ambitus ovoidal. Apical horn very short and blunt, the development of crests on its flanks imparting a bifid or trifid appearance according to orientation. Epitract and hypotract of similar size and shape. Parasutures marked by low crests giving rise to short spines of variable form, free or united by membranes which may or may not be perforate; accessory crests lower and sometimes discontinuous. Paratabulation ?2 pr, 4, ?0a, 6", 6-?7 c, 6", lp, 1 pv, 1"", ? xs. Cingulum of moderate breadth and spirality, its two ends differing in anteroposterior position by only slightly more than its breadth. Sulcus broad and distinctly indented, most notably in its posterior portion. Paraplate 4' is relatively large and quadrate, having a broad margin with a comparably large 6"; the boundary between these paraplates intersects the right boundary of 1' at a position markedly anterior to the junction of the latter paraplate with the sulcus. Accessory crests well-marked on the larger paraplates (1", 2", 4", 5", 3", 4" and 5"), poorly developed or lacking on the smaller paraplates. Surface of phragma covered by granules, tubercles or bacula. Archaeopyle single-plate precingular, Type P (3* only); operculum free.
Holotype: Specimen Pr1149/49 (S 33/31); illustrated by KLEMENT (1960, pl. 5 figs. 4-5, text-figs. 18-19). [Note: This specimen has
since disintegrated and is no longer suitable for study]. Lectotype: Specimen Pr1149/53 (S 39/41), formerly a paratype; illustrated herein, pl. 3
figs. 3-4, text-fig. 3. Paratypes: Pr 1149/50 (S 34/25), Pr 1149/51 (S 33/36, illustrated by KLEMENT 1960, pl. 4 figs. 12-13) and Pr1149/52
(S 33/15, illustrated by KLEMENT 1960, text-fig. 20). Type material in the KLEMENT Collection, University of Tübingen.
Type Locality and Horizon: Scherstetten 1 borehole, south west Germany, at between 1682.3 and 1683.6 m depth. Malm Lower Delta (Middle Kimmeridgian: Eulepidus Zone).
Dimensions: Holotype; overall length 60 um, overall breadth 63 um. Lectotype: overall length 66 μm, length of apical horn 7 μm, maximum height of crests c. 7 μm. Range of dimensions: Overall length 57-72 μm (mean 63 μm), overall breadth 46-63 μm (mean 60 μm).
Description: The dense surficial ornament a cover of granules of varying size or of bacula, varying in density not only between specimens but also on individual cysts - causes problems in determining the full paratabulation pattern. Since the holotype has broken up, the diagnosis and description are based primarily on the lectotype and paratypes and on KLEMENT'S illustrations of the holotype. A number of features remain uncertain - a first preapical paraplate appears to be present, but the second was not discerned with confidence; dorsal anterior intercalaries were not discerned; and the presence of a posterior ventral paraplate, mentioned by KLEMENT in his diagnosis but not illustrated in his text-figures, could not be confirmed. KLEMENT Specified only six cingulars; I suggest that seven may be present, but cannot be confident.
A feature to be stressed is the variable character of the parasutural crests. These are always of low to moderate height, but may be entire or undulate (and fenestrate) or may approach the echinate, muricate or even hystricate condition in different situations on the same cyst. They appear to be sustained by gonal spines. The accessory crests typically form single lines, but sometimes a partial second line may be developed.
The sixth precingular (6") is smaller than the others, but nevertheless relatively large. 1'" is the smallest of the postcingulars, but 2'" is also reduced, both paraplates being separated from the antapex by the posterior intercalary (1p). The antapical paraplate is relatively small.
Remarks: As noted earlier, the holotype has disintegrated, so that the selection of a new type specimen was necessary. Paratype Pr1149/50 was unsuitable, since it is in polar orientation, and paratypes Pr1149/51 and Pr1149/52 have changed in orientation since they were illustrated by KLEMENT. The former paratype Prl149/53, though in oblique ventral view, was considered by me to be the most suitable for study and is here selected as lectotype, under Article 7.4 of the International Code of Botanical Nomenclature. FISHER & RILEY (1980, p. 321) treat this species as a senior synonym of Rhy nchodiniopsis granuligera; and one of KLEMENT's photographs (1960, pl. 4 fig. 11) does indeed suggest the U-shaped arrangement of paraplates about the posterior end of the sulcus which is so characteristic of that species. However, I consider this to be an
"orientational artifact" resulting from the angle at which the photograph was taken; the holotype itself cannot be reexamined, but neither KLEMENT'S sketches of the holotype (ibid., text-figs. 18-19) nor my own observations accord with their interpretation. Moreover, the overall shape and dimensions of M. granulata are quite different from those of R. granuligera, the apical horn much shorter, the cingulum broader and less strongly helicoid, the ornamentation of the phragma generally coarser, the parasutural crests generally higher and accessory crests clearly
developed. This synonymization accordingly is here rejected. The reported stratigraphical distribution of this species would suggest that it is a long-ranging form; but its morphology hitherto has been misinterpreted and, apart from KLEMENT'S records, only that of DODEKOVA, from the
Tithonian' of Bulgaria, appears reliable. GITMEZ'S specimen appears to exhibit no accessory crests and differs in enough other details to make her identification of it highly questionable, while the Jurassic form illustrated by BEJU and the Oligocene form illustrated by BENEDEK Certainly are not referable to this species. The records from offshore eastern Canada by BARSS et al. and by WLLIAMS & BUJAK are unaccompanied by illustrations and thus cannot be checked.
Cribroperidinium swithini Williams et al., 1998, p.151. Holotype: Sarjeant, 1984a, pl.3, figs.3–4; text-fig.3; Jan du Chêne et al., 1986a, pl.27, figs.7–10; Brenner, 1988, pl.3, figs.2,5; Fensome et al., 1995, figs.5–6 — p.1525. Originally Meristaulax granulata Brenner (name illegitimate), subsequently Cribroperidinium swithini. Substitute name for Meristaulax granulata Brenner, 1988, p.65–66, pl.3, figs.2,5; the name Cribroperidinium granulatum is preoccupied. Since the epithet is based on a given name, it ends in "i" rather than "ii" (ICN Recommendation
60C.2). Age: Late Jurassic.
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Emended description: [Sarjeant, 1984a] (as Meristaulax granulata):
Emended Diagnosis: Cyst proximate, monocornucavate. Ambitus ovoidal. Apical horn very short and blunt, the development of crests on its flanks imparting a bifid or trifid appearance according to orientation. Epitract and hypotract of similar size and shape. Parasutures marked by low crests giving rise to short spines of variable form, free or united by membranes which may or may not be perforate; accessory crests lower and sometimes discontinuous. Paratabulation ?2 pr, 4, ?0a, 6", 6-?7 c, 6", lp, 1 pv, 1"", ? xs. Cingulum of moderate breadth and spirality, its two ends differing in anteroposterior position by only slightly more than its breadth. Sulcus broad and distinctly indented, most notably in its posterior portion. Paraplate 4' is relatively large and quadrate, having a broad margin with a comparably large 6"; the boundary between these paraplates intersects the right boundary of 1' at a position markedly anterior to the junction of the latter paraplate with the sulcus. Accessory crests well-marked on the larger paraplates (1", 2", 4", 5", 3", 4" and 5"), poorly developed or lacking on the smaller paraplates. Surface of phragma covered by granules, tubercles or bacula. Archaeopyle single-plate precingular, Type P (3* only); operculum free.
Holotype: Specimen Pr1149/49 (S 33/31); illustrated by KLEMENT (1960, pl. 5 figs. 4-5, text-figs. 18-19). [Note: This specimen has
since disintegrated and is no longer suitable for study]. Lectotype: Specimen Pr1149/53 (S 39/41), formerly a paratype; illustrated herein, pl. 3
figs. 3-4, text-fig. 3. Paratypes: Pr 1149/50 (S 34/25), Pr 1149/51 (S 33/36, illustrated by KLEMENT 1960, pl. 4 figs. 12-13) and Pr1149/52
(S 33/15, illustrated by KLEMENT 1960, text-fig. 20). Type material in the KLEMENT Collection, University of Tübingen.
Type Locality and Horizon: Scherstetten 1 borehole, south west Germany, at between 1682.3 and 1683.6 m depth. Malm Lower Delta (Middle Kimmeridgian: Eulepidus Zone).
Dimensions: Holotype; overall length 60 um, overall breadth 63 um. Lectotype: overall length 66 μm, length of apical horn 7 μm, maximum height of crests c. 7 μm. Range of dimensions: Overall length 57-72 μm (mean 63 μm), overall breadth 46-63 μm (mean 60 μm).
Description: The dense surficial ornament a cover of granules of varying size or of bacula, varying in density not only between specimens but also on individual cysts - causes problems in determining the full paratabulation pattern. Since the holotype has broken up, the diagnosis and description are based primarily on the lectotype and paratypes and on KLEMENT'S illustrations of the holotype. A number of features remain uncertain - a first preapical paraplate appears to be present, but the second was not discerned with confidence; dorsal anterior intercalaries were not discerned; and the presence of a posterior ventral paraplate, mentioned by KLEMENT in his diagnosis but not illustrated in his text-figures, could not be confirmed. KLEMENT Specified only six cingulars; I suggest that seven may be present, but cannot be confident.
A feature to be stressed is the variable character of the parasutural crests. These are always of low to moderate height, but may be entire or undulate (and fenestrate) or may approach the echinate, muricate or even hystricate condition in different situations on the same cyst. They appear to be sustained by gonal spines. The accessory crests typically form single lines, but sometimes a partial second line may be developed.
The sixth precingular (6") is smaller than the others, but nevertheless relatively large. 1'" is the smallest of the postcingulars, but 2'" is also reduced, both paraplates being separated from the antapex by the posterior intercalary (1p). The antapical paraplate is relatively small.
Remarks: As noted earlier, the holotype has disintegrated, so that the selection of a new type specimen was necessary. Paratype Pr1149/50 was unsuitable, since it is in polar orientation, and paratypes Pr1149/51 and Pr1149/52 have changed in orientation since they were illustrated by KLEMENT. The former paratype Prl149/53, though in oblique ventral view, was considered by me to be the most suitable for study and is here selected as lectotype, under Article 7.4 of the International Code of Botanical Nomenclature. FISHER & RILEY (1980, p. 321) treat this species as a senior synonym of Rhy nchodiniopsis granuligera; and one of KLEMENT's photographs (1960, pl. 4 fig. 11) does indeed suggest the U-shaped arrangement of paraplates about the posterior end of the sulcus which is so characteristic of that species. However, I consider this to be an
"orientational artifact" resulting from the angle at which the photograph was taken; the holotype itself cannot be reexamined, but neither KLEMENT'S sketches of the holotype (ibid., text-figs. 18-19) nor my own observations accord with their interpretation. Moreover, the overall shape and dimensions of M. granulata are quite different from those of R. granuligera, the apical horn much shorter, the cingulum broader and less strongly helicoid, the ornamentation of the phragma generally coarser, the parasutural crests generally higher and accessory crests clearly
developed. This synonymization accordingly is here rejected. The reported stratigraphical distribution of this species would suggest that it is a long-ranging form; but its morphology hitherto has been misinterpreted and, apart from KLEMENT'S records, only that of DODEKOVA, from the
Tithonian' of Bulgaria, appears reliable. GITMEZ'S specimen appears to exhibit no accessory crests and differs in enough other details to make her identification of it highly questionable, while the Jurassic form illustrated by BEJU and the Oligocene form illustrated by BENEDEK Certainly are not referable to this species. The records from offshore eastern Canada by BARSS et al. and by WLLIAMS & BUJAK are unaccompanied by illustrations and thus cannot be checked.