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Exochosphaeridium crassum
From Fensome et al., 2019:
Exochosphaeridium crassum Duxbury, 2019, p.191, pl.13, figs.4–5,7–8. Holotype: Duxbury, 2019, pl.13, figs.4,7. Age: late Barremian.
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Original description Duxbury, 2019:
Plate 13, Figures 4, 5, 7, 8
Holotype: Plate 13, Figures 4, 7.
Paratype: Plate 13, Figure 5, 8.
Type Locality: Well 22/26a-2 at 11,235.00 ft (core chip), late Barremian age. Holotype: E.F. U27.0. Paratype: E.F. V34.3
Derivation of Name: From the Latin crassus, thick, fat, stout - in reference to the main body of this species.
Diagnosis: A thick-walled, spheroidal to ovoidal chorate cyst bearing numerous long, tapering, fairly rigid and acuminate spines of equal length and with a low apical bulge. The surface of the cyst is fibro-perforate with striations running into the spine bases. Spines can merge proximally but only rarely and can form what appear to be intratabular clusters. There is no clear indication of tabulation except for a single plate archeopyle, presumed mid-dorsal precingular (3''). A prominent, solid apical horn is consistently present; this may furcate at any point along its length and commonly displays short spines distally.
Dimensions: Holotype: 76 × 73 μm.
Paratype: Overall - 73 × 63 μm.
All measured specimens: 78 (73) 66 μm × 76 (69) 63 μm.
Specimens Measured: 11.
Remarks: Exochosphaeridium crassum n. sp. is similar in some respects to the holotype of Exochosphaeridium phragmites Davey et al. (1966, Plate 2, Figures 9, 10), although it is thick-walled, significantly smaller and has spines only rarely joined proximally, as opposed to the “often confluent” (Davey et al. 1966, p. 165), proximally joined, blade-like processes of E. phragmites.
The prominent, solid apical projection of E. crassum n. sp. may be formed by the lateral merger of several spines and could therefore be a “false” horn in the sense of Harding (1990, p. 37 - 39). However, Helenes (2000, p. 138) in his generic description notes that in Exochosphaeridium, “The P (1pr) structure is represented by a spine at the tip of the apical horn”, presumably implying a “true” apical horn.
This species has a very restricted range in the present study, being observed only in well 22/26a-2 at 11,235.00 ft and 11,230.00 ft, palynofloral Zone LKP20.
Exochosphaeridium crassum Duxbury, 2019, p.191, pl.13, figs.4–5,7–8. Holotype: Duxbury, 2019, pl.13, figs.4,7. Age: late Barremian.
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Original description Duxbury, 2019:
Plate 13, Figures 4, 5, 7, 8
Holotype: Plate 13, Figures 4, 7.
Paratype: Plate 13, Figure 5, 8.
Type Locality: Well 22/26a-2 at 11,235.00 ft (core chip), late Barremian age. Holotype: E.F. U27.0. Paratype: E.F. V34.3
Derivation of Name: From the Latin crassus, thick, fat, stout - in reference to the main body of this species.
Diagnosis: A thick-walled, spheroidal to ovoidal chorate cyst bearing numerous long, tapering, fairly rigid and acuminate spines of equal length and with a low apical bulge. The surface of the cyst is fibro-perforate with striations running into the spine bases. Spines can merge proximally but only rarely and can form what appear to be intratabular clusters. There is no clear indication of tabulation except for a single plate archeopyle, presumed mid-dorsal precingular (3''). A prominent, solid apical horn is consistently present; this may furcate at any point along its length and commonly displays short spines distally.
Dimensions: Holotype: 76 × 73 μm.
Paratype: Overall - 73 × 63 μm.
All measured specimens: 78 (73) 66 μm × 76 (69) 63 μm.
Specimens Measured: 11.
Remarks: Exochosphaeridium crassum n. sp. is similar in some respects to the holotype of Exochosphaeridium phragmites Davey et al. (1966, Plate 2, Figures 9, 10), although it is thick-walled, significantly smaller and has spines only rarely joined proximally, as opposed to the “often confluent” (Davey et al. 1966, p. 165), proximally joined, blade-like processes of E. phragmites.
The prominent, solid apical projection of E. crassum n. sp. may be formed by the lateral merger of several spines and could therefore be a “false” horn in the sense of Harding (1990, p. 37 - 39). However, Helenes (2000, p. 138) in his generic description notes that in Exochosphaeridium, “The P (1pr) structure is represented by a spine at the tip of the apical horn”, presumably implying a “true” apical horn.
This species has a very restricted range in the present study, being observed only in well 22/26a-2 at 11,235.00 ft and 11,230.00 ft, palynofloral Zone LKP20.