Back
Canningia bassensis
Canningia bassensis, Marshall, 1990
Holotype: Marshall, 1990, figs.9G, 15D-F
Locality: SE Australia
Age: Campanian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Marshall, 1990, p.13-14]:
Description:
Cysts subpentagonal in ventrodorsal view, modified by 1 apical, 2 antapical, and often 2 lateral horns forming broadly rounded, subconical structures.
Cysts holocavate: ectocoel widest around periphery, becoming markedly narrower on mid-dorsal and midventral surfaces. Wall layers separated by numerous, fine, solid pillars arranged normally to either surface. Pillars appearing less than 0.5 µm wide, longest and most common around periphery of cyst, becoming sparsely distributed, and barely discernible on some specimens, on mid-dorsal and midventral surfaces. Ventrodorsal outline of autocyst similar to that of ectocyst; usually having the horns reflected as rounded bulges. Autophragm smooth, c. 0.5 µm thick, bearing numerous, close spaced perforations with irregular distribution and highly variable size. Perforations give ectophragm a fenestrate structure, interconnecting strands within network frequently incomplete and having a strongly dissected appearance. Ectophragm frequently only occurring as discontinuous patches on midventral surface. Ectophragm marked by parasutural folds with rounded to angular crests, and can be split apart slightly along the crests.
Paratabulation incomplete with only fragments of paraplates usually evident; pattern most clear on dorsal surface. Paraplates outlined on examples with clearest paratabulation: 1-4 ", 3-5""", 1"""" (Fig. 9F, G).
Paracingulum defined on dorsal and edges of ventral surface by a shallow groove bordered by two ridges 5-7 µm apart.
Archeopyle apical, Type (tA), weak accessory sutures usually evident on both wall layers of operculum and main body.
Dimensions:
Cyst without operculum: ectocyst length 61(81)92 µm, width 84(94)103 µm; autocyst length 55(68)78 µm, width 66(77)86 µm (13 specimens).
Holotype: (Fig. 15D-F) ectocyst length 76 µm, width 93 µm, autocyst length 68 µm, width 81 µm.
Affinities:
This form is characterised by the numerous fine pillars extending between the wall layers and the fenestrate ectophragm. It is often difficult to view these pillars clearly because they can be partially obscured by the fenestrate ectophragm. On some specimens, it is also difficult to tell if the wall layers are in contact on the mid-dorsal and midventral surfaces. However, the occurrence of scattered pillars within these areas suggests that they are slightly separated.
Holotype: Marshall, 1990, figs.9G, 15D-F
Locality: SE Australia
Age: Campanian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Marshall, 1990, p.13-14]:
Description:
Cysts subpentagonal in ventrodorsal view, modified by 1 apical, 2 antapical, and often 2 lateral horns forming broadly rounded, subconical structures.
Cysts holocavate: ectocoel widest around periphery, becoming markedly narrower on mid-dorsal and midventral surfaces. Wall layers separated by numerous, fine, solid pillars arranged normally to either surface. Pillars appearing less than 0.5 µm wide, longest and most common around periphery of cyst, becoming sparsely distributed, and barely discernible on some specimens, on mid-dorsal and midventral surfaces. Ventrodorsal outline of autocyst similar to that of ectocyst; usually having the horns reflected as rounded bulges. Autophragm smooth, c. 0.5 µm thick, bearing numerous, close spaced perforations with irregular distribution and highly variable size. Perforations give ectophragm a fenestrate structure, interconnecting strands within network frequently incomplete and having a strongly dissected appearance. Ectophragm frequently only occurring as discontinuous patches on midventral surface. Ectophragm marked by parasutural folds with rounded to angular crests, and can be split apart slightly along the crests.
Paratabulation incomplete with only fragments of paraplates usually evident; pattern most clear on dorsal surface. Paraplates outlined on examples with clearest paratabulation: 1-4 ", 3-5""", 1"""" (Fig. 9F, G).
Paracingulum defined on dorsal and edges of ventral surface by a shallow groove bordered by two ridges 5-7 µm apart.
Archeopyle apical, Type (tA), weak accessory sutures usually evident on both wall layers of operculum and main body.
Dimensions:
Cyst without operculum: ectocyst length 61(81)92 µm, width 84(94)103 µm; autocyst length 55(68)78 µm, width 66(77)86 µm (13 specimens).
Holotype: (Fig. 15D-F) ectocyst length 76 µm, width 93 µm, autocyst length 68 µm, width 81 µm.
Affinities:
This form is characterised by the numerous fine pillars extending between the wall layers and the fenestrate ectophragm. It is often difficult to view these pillars clearly because they can be partially obscured by the fenestrate ectophragm. On some specimens, it is also difficult to tell if the wall layers are in contact on the mid-dorsal and midventral surfaces. However, the occurrence of scattered pillars within these areas suggests that they are slightly separated.