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Apteodinium larvalis
Plate 4, Figures 3, 4, 8
Holotype: Plate 4, Figure 3
Type Locality: early Hauterivian, Speeton Clay Formation, Speeton. Holotype: Slide baseD2D(2), E.F. K49.4. Derivation of Name: From the Latin larvalis, ghostly - in reference to the insubstantial nature of this species.
Diagnosis: A cyst of moderate size which is very thin-walled and irregularly and finely granular, extending into a prominent, distally-rounded apical horn. Avery low, fragmentary reticulum of variable mesh size covers the cyst, tending to reduce or to be replaced by denser granulation towards the apex. There is a prominent horn extension formed from a tangle of surface ornament. The archeopyle is single-plate mid-dorsal, assumed to involve plate 3".
Dimensions: Holotype: 68 × 56 μm
Overall: 84 (73) 66 μm × 61 (57) 53 μm
Specimens Measured: 6
Remarks: The combination of a very thin cyst wall, fine granules and surface reticulum are particularly characteristic features of this species, combined with its prominent, tangled horn extension. Because of its fragility, this species is invariably folded to some degree.
Specimens assigned to Paragonyaulacysta? borealis in text-figure 9g, h of Nøhr-Hansen et al. 2019 appear to be very similar to A. larvalis, although the LAD of that taxon was illustrated towards the top of the Berriasian (Nøhr-Hansen et al. op. cit., text-fig. 7).
The range of Apteodinium larvalis n. sp. was very restricted in the current study, occurring only in both samples analysed from Speeton Bed D2D, basal Hauterivian, amblygonium ammonite Zone.
Holotype: Plate 4, Figure 3
Type Locality: early Hauterivian, Speeton Clay Formation, Speeton. Holotype: Slide baseD2D(2), E.F. K49.4. Derivation of Name: From the Latin larvalis, ghostly - in reference to the insubstantial nature of this species.
Diagnosis: A cyst of moderate size which is very thin-walled and irregularly and finely granular, extending into a prominent, distally-rounded apical horn. Avery low, fragmentary reticulum of variable mesh size covers the cyst, tending to reduce or to be replaced by denser granulation towards the apex. There is a prominent horn extension formed from a tangle of surface ornament. The archeopyle is single-plate mid-dorsal, assumed to involve plate 3".
Dimensions: Holotype: 68 × 56 μm
Overall: 84 (73) 66 μm × 61 (57) 53 μm
Specimens Measured: 6
Remarks: The combination of a very thin cyst wall, fine granules and surface reticulum are particularly characteristic features of this species, combined with its prominent, tangled horn extension. Because of its fragility, this species is invariably folded to some degree.
Specimens assigned to Paragonyaulacysta? borealis in text-figure 9g, h of Nøhr-Hansen et al. 2019 appear to be very similar to A. larvalis, although the LAD of that taxon was illustrated towards the top of the Berriasian (Nøhr-Hansen et al. op. cit., text-fig. 7).
The range of Apteodinium larvalis n. sp. was very restricted in the current study, occurring only in both samples analysed from Speeton Bed D2D, basal Hauterivian, amblygonium ammonite Zone.