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Clathroctenocystis calabaza
Clathroctenocystis calabaza, Stevens and Helby, 1987
Holotype: Stevens and Helby, 1987, fig.7A-C
Locus typicus: Exmouth Plateau, Australia
Stratum typicum: Early Berriasian
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Original description: [Stevens and Helby, 1987, p.170-172]:
Description:
Cysts proximate, ellipsoidal with a low (4-8 µm) truncate apical perihorn and high (up to 24 µm), irregularly folded, antapical, parasutural septa. Cyst wall 2-layered, appressed; endophragm relatively thick (1.5-3 µm), smooth, with concentration of low, irregular verrucae (1.5 µm in height and diameter) at antapex. Periphragm about 1 µm thick over most of the body with marked thickening at the apices and along some parasutures. Periphragm spongeous with an irregular surface with perforations foveolae and caniculae up to 1.5 µm in diameter.
Archeopyle apical, type [tAI with a zigzag principal suture, short accessory sutures and a relatively deep midventral sulcal notch. Edge of the principal peri-archeopyle suture often finely denticulate. Operculum usually free, comprising a low, truncate perihorn appressed to the gently concave endophragm.
Apart from slight reentrants at the margin of the operculum, apical parasutures not generally evident.
Paratabulation on the cyst may be indicated only by the archeopyle and paracingulum, but commonly marked by incomplete, wavy parasutural septa (generally 2-6 µm high, but up to 24 µm high at the antapex). Parasutural bounding septum most fully developed towards the extremities, height diminishing rapidly towards the paracingulum, giving way to irregular pandasutural bands of perforations and foveolae. Paratabulation gonyaulacacean, 4", 6", 0c, 6""", 1p, 1"""", 0s (Fig.6E,F), but seldom fully evident on individual specimens. The 1p and 1"""" paraplates delineated by flange-like parasutural septa; these septa commonly folded obscuring the paraplates. The 1""" paraplate relatively large (even larger than the 6""" paraplate), with 1p paraplate positioned very close to the antapex. Large size of the 1""" paraplate resulting in an unusual displacement: the 4""" paraplate to the right of mid dorsal, the 3"""/4""" parasutural ridge mid dorsal, and on the dorsal surface, the 2", 3" and 4"" paraplates nearly aligned with the 2""", 3""" and 4""" paraplates.
Paracingulum commonly expressed by the transverse alignment of perforations into a band 4-5 µm wide, dividing the cyst unequally with a slightly longer hypocyst. Ends of the paracingulum offset ventrally by about half the paracingulum width. On some specimens paracingulum not discernible.
Parasulcus not well defined, located anteriorly, identified by the position of the sulcal notch and in the mid ventral region by an elongate (6-10 µm long) smooth flagellar scar, often contrasting with a scabrate surrounding area (Fig.7E,H).
Variability: Cyst size and shape vary considerably depending on the relative sizes of the pericyst, apical horn and antapical flange-like septa (Fig.6A,D). The periphragm ornament varies through irregular perforations (Fig.7G,H), foveolae, caniculae (Fig.7A-C) to scabration or may be relatively smooth (Fig.7D). The paratabulation is seldom complete and may be expressed by the archeopyle, paracingulum and flagellar scar only (Fig.7D), but is generally expressed by parasutural septa of varying lengths and proximity to the paracingulum (Fig.7A-C,E-H). The opercular parasutural septa (Fig.7E,F) are commonly difficult to discern as the operculum maybe compressed and distorted. The Ipand 1"""" paraplates are delineated by, but also partially obscured by the high flange-like antapical parasutural septa (Fig.7C,E,H). The operculum is generally free, but may be in place (Fig.6E,F). The paracingulum is commonly indicated (Fig.7C,D), but it may be absent (Fig.7E,F).
Dimensions:
Endocyst length (dehisced) 58(69)90 µm, length increased by 8-12 µm when operculum present, pericyst length (dehisced) 62(80)110 µm, length increased by 12-18 µm when operculum present, pericyst width 38(48)66 µm (19 specimens).
Affinities:
Clathroctenocystis elegans Wiggins 1972 resembles C. calabaza in having thickened apices, high parasutural septa and a similar paratabulation formula. However, the former species differs in having a fusiform shape, a nontabulate operculum, only five postcingular paraplates (2""" to 6"""), a subdivided paracingulum indicated by incomplete parasutural septa, a short, mostly hypocystal parasulcus, in lacking a flagellar scar and sulcal notch and in having flat anterior margins to the 1", 3", 5"" and 6" paraplates (Wiggins, 1972, fig.3), which are gabled in C.calabaza.
Holotype: Stevens and Helby, 1987, fig.7A-C
Locus typicus: Exmouth Plateau, Australia
Stratum typicum: Early Berriasian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Stevens and Helby, 1987, p.170-172]:
Description:
Cysts proximate, ellipsoidal with a low (4-8 µm) truncate apical perihorn and high (up to 24 µm), irregularly folded, antapical, parasutural septa. Cyst wall 2-layered, appressed; endophragm relatively thick (1.5-3 µm), smooth, with concentration of low, irregular verrucae (1.5 µm in height and diameter) at antapex. Periphragm about 1 µm thick over most of the body with marked thickening at the apices and along some parasutures. Periphragm spongeous with an irregular surface with perforations foveolae and caniculae up to 1.5 µm in diameter.
Archeopyle apical, type [tAI with a zigzag principal suture, short accessory sutures and a relatively deep midventral sulcal notch. Edge of the principal peri-archeopyle suture often finely denticulate. Operculum usually free, comprising a low, truncate perihorn appressed to the gently concave endophragm.
Apart from slight reentrants at the margin of the operculum, apical parasutures not generally evident.
Paratabulation on the cyst may be indicated only by the archeopyle and paracingulum, but commonly marked by incomplete, wavy parasutural septa (generally 2-6 µm high, but up to 24 µm high at the antapex). Parasutural bounding septum most fully developed towards the extremities, height diminishing rapidly towards the paracingulum, giving way to irregular pandasutural bands of perforations and foveolae. Paratabulation gonyaulacacean, 4", 6", 0c, 6""", 1p, 1"""", 0s (Fig.6E,F), but seldom fully evident on individual specimens. The 1p and 1"""" paraplates delineated by flange-like parasutural septa; these septa commonly folded obscuring the paraplates. The 1""" paraplate relatively large (even larger than the 6""" paraplate), with 1p paraplate positioned very close to the antapex. Large size of the 1""" paraplate resulting in an unusual displacement: the 4""" paraplate to the right of mid dorsal, the 3"""/4""" parasutural ridge mid dorsal, and on the dorsal surface, the 2", 3" and 4"" paraplates nearly aligned with the 2""", 3""" and 4""" paraplates.
Paracingulum commonly expressed by the transverse alignment of perforations into a band 4-5 µm wide, dividing the cyst unequally with a slightly longer hypocyst. Ends of the paracingulum offset ventrally by about half the paracingulum width. On some specimens paracingulum not discernible.
Parasulcus not well defined, located anteriorly, identified by the position of the sulcal notch and in the mid ventral region by an elongate (6-10 µm long) smooth flagellar scar, often contrasting with a scabrate surrounding area (Fig.7E,H).
Variability: Cyst size and shape vary considerably depending on the relative sizes of the pericyst, apical horn and antapical flange-like septa (Fig.6A,D). The periphragm ornament varies through irregular perforations (Fig.7G,H), foveolae, caniculae (Fig.7A-C) to scabration or may be relatively smooth (Fig.7D). The paratabulation is seldom complete and may be expressed by the archeopyle, paracingulum and flagellar scar only (Fig.7D), but is generally expressed by parasutural septa of varying lengths and proximity to the paracingulum (Fig.7A-C,E-H). The opercular parasutural septa (Fig.7E,F) are commonly difficult to discern as the operculum maybe compressed and distorted. The Ipand 1"""" paraplates are delineated by, but also partially obscured by the high flange-like antapical parasutural septa (Fig.7C,E,H). The operculum is generally free, but may be in place (Fig.6E,F). The paracingulum is commonly indicated (Fig.7C,D), but it may be absent (Fig.7E,F).
Dimensions:
Endocyst length (dehisced) 58(69)90 µm, length increased by 8-12 µm when operculum present, pericyst length (dehisced) 62(80)110 µm, length increased by 12-18 µm when operculum present, pericyst width 38(48)66 µm (19 specimens).
Affinities:
Clathroctenocystis elegans Wiggins 1972 resembles C. calabaza in having thickened apices, high parasutural septa and a similar paratabulation formula. However, the former species differs in having a fusiform shape, a nontabulate operculum, only five postcingular paraplates (2""" to 6"""), a subdivided paracingulum indicated by incomplete parasutural septa, a short, mostly hypocystal parasulcus, in lacking a flagellar scar and sulcal notch and in having flat anterior margins to the 1", 3", 5"" and 6" paraplates (Wiggins, 1972, fig.3), which are gabled in C.calabaza.