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Korystocysta aldridgei
From Fensome et al., 2019:
Korystocysta aldridgei Wiggan et al. 2017, p.82, pl.7, figs.1–6. Holotype: Wiggan et al. 2017, pl.7, figs.1–3. The authors spelled
the epithet "aldridgeii". Age: late Bajocian to early Bathonian.
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Original description: [Wiggan et al., 2017]:
Korystocysta aldridgeii sp. nov. (Plate VII, 1–6).
Diagnosis: A species of Korystocysta with faint to discontinuous sutural ridges which may be capped by short spines, a small, broad apical protuberance, and scabrate to slightly granulate or rugulate autophragm; it is consistently broader than long.
Description: A species of Korystocysta which is primarily dorsoventrally flattened, and with a subovoidal dorsoventral outline. It is large in size. Korystocysta aldridgeii sp. nov. is consistently slightly broader than it is long, and has a short, rounded apical protuberance. The species is acavate, and the autophragm is of moderate thickness and is scabrate to slightly granulate or rugulate. The gonyaulacacean tabulation is indicated by low, and dominantly discontinuous sutural ridges which often bear denticles or small (b5 μm) spines. The cingulum however, is fully indicated by continuous ridges irregularly capped by denticles or small spines. The epicystal archaeopyle is normally clearly expressed.
Dimensions: width: 80 (99) 119 μm, 30 specimens measured.
Holotype: width: 114 μm, length: 103 μm.
Paratype: width: 118 μm, length: 104 μm.
Derivation of name: Korystocysta aldridgeii sp. nov. is named in memory of the late Richard J. Aldridge (1945–2014), who was F.W. Bennett Professor of Geology at the University of Leicester, UK.
Remarks: Korystocysta aldridgeii sp. nov. is a highly distinctive representative of this genus because its width is consistently slightly greater than its length. The size, general morphology, stratigraphical extent and overall similarity to Korystocysta gochtii and Korystocysta pachyderma of this species clearly indicates that it belongs within the genus Korystocysta. Further to its distinctive relatively squat/stout overall shape, it is also characterised by a short, distally-rounded apical protuberance, moderately thick, scabrate to slightly granulate autophragm and discontinuous, sutural ridges which are irregularly ornamented with denticles and small spines. The sutures, despite being markedly discontinuous, clearly indicate a gonyaulacacean tabulation. The autophragm is relatively thin, and specimens are therefore susceptible to mechanical damage, particularly the epicyst which is frequently broken, and rarely encountered intact.
Comparison: Korystocysta aldridgeii sp. nov. is shorter, more squat, and generally larger than the other two valid species of this genus, Korystocysta gochtii and Korystocysta pachyderma. Both the latter are longer than they are broad (Woollam, 1983). Korystocysta gochtii, the type, has a much more pronounced apical horn and whilst Korystocysta pachyderma also bears prominent intratabular ridges and is thick walled (Woollam, 1983, pl. 1, 9).
Stratigraphical range: Korystocysta aldridgeii sp. nov. ranges from the P. parkinsoni to Z. zigzag zones, where it occurs abundantly and is a
good marker for the Bajocian–Bathonian transition. There a questionable occurrence in the G. garantiana zone (sample S89) and the lowermost sample (S102) of the P. parkinsoni zone.
Repository: The type material is curated in the collections of the Sedgwick Museum, Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, UK. Holotype: slide S105-A, England finder co-ordinates: L48/2, museum accession number CAMSM X.50257.1. Paratype: slide S105-B, G36, museum accession number CAMSM X.50257.2.
Korystocysta aldridgei Wiggan et al. 2017, p.82, pl.7, figs.1–6. Holotype: Wiggan et al. 2017, pl.7, figs.1–3. The authors spelled
the epithet "aldridgeii". Age: late Bajocian to early Bathonian.
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Original description: [Wiggan et al., 2017]:
Korystocysta aldridgeii sp. nov. (Plate VII, 1–6).
Diagnosis: A species of Korystocysta with faint to discontinuous sutural ridges which may be capped by short spines, a small, broad apical protuberance, and scabrate to slightly granulate or rugulate autophragm; it is consistently broader than long.
Description: A species of Korystocysta which is primarily dorsoventrally flattened, and with a subovoidal dorsoventral outline. It is large in size. Korystocysta aldridgeii sp. nov. is consistently slightly broader than it is long, and has a short, rounded apical protuberance. The species is acavate, and the autophragm is of moderate thickness and is scabrate to slightly granulate or rugulate. The gonyaulacacean tabulation is indicated by low, and dominantly discontinuous sutural ridges which often bear denticles or small (b5 μm) spines. The cingulum however, is fully indicated by continuous ridges irregularly capped by denticles or small spines. The epicystal archaeopyle is normally clearly expressed.
Dimensions: width: 80 (99) 119 μm, 30 specimens measured.
Holotype: width: 114 μm, length: 103 μm.
Paratype: width: 118 μm, length: 104 μm.
Derivation of name: Korystocysta aldridgeii sp. nov. is named in memory of the late Richard J. Aldridge (1945–2014), who was F.W. Bennett Professor of Geology at the University of Leicester, UK.
Remarks: Korystocysta aldridgeii sp. nov. is a highly distinctive representative of this genus because its width is consistently slightly greater than its length. The size, general morphology, stratigraphical extent and overall similarity to Korystocysta gochtii and Korystocysta pachyderma of this species clearly indicates that it belongs within the genus Korystocysta. Further to its distinctive relatively squat/stout overall shape, it is also characterised by a short, distally-rounded apical protuberance, moderately thick, scabrate to slightly granulate autophragm and discontinuous, sutural ridges which are irregularly ornamented with denticles and small spines. The sutures, despite being markedly discontinuous, clearly indicate a gonyaulacacean tabulation. The autophragm is relatively thin, and specimens are therefore susceptible to mechanical damage, particularly the epicyst which is frequently broken, and rarely encountered intact.
Comparison: Korystocysta aldridgeii sp. nov. is shorter, more squat, and generally larger than the other two valid species of this genus, Korystocysta gochtii and Korystocysta pachyderma. Both the latter are longer than they are broad (Woollam, 1983). Korystocysta gochtii, the type, has a much more pronounced apical horn and whilst Korystocysta pachyderma also bears prominent intratabular ridges and is thick walled (Woollam, 1983, pl. 1, 9).
Stratigraphical range: Korystocysta aldridgeii sp. nov. ranges from the P. parkinsoni to Z. zigzag zones, where it occurs abundantly and is a
good marker for the Bajocian–Bathonian transition. There a questionable occurrence in the G. garantiana zone (sample S89) and the lowermost sample (S102) of the P. parkinsoni zone.
Repository: The type material is curated in the collections of the Sedgwick Museum, Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, UK. Holotype: slide S105-A, England finder co-ordinates: L48/2, museum accession number CAMSM X.50257.1. Paratype: slide S105-B, G36, museum accession number CAMSM X.50257.2.