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Apteodinium parvigranulatum
From Fensome et al., 2019:
Apteodinium parvigranulatum Duxbury, 2019, p.180, pl.14, figs.3–4,6. Holotype: Duxbury, 2019, pl.14, fig.4. Age: late
Barremian.
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Original description: [Duxbury, 2019, p. 180]:
Apteodinium parvigranulatum Duxbury n. sp.
Plate 14, Figures 3, 4, 6
Holotype: Plate 14, Figure 4.
Type Locality: Well 22/26a-2 at 11,179.50 ft (core chip), late Barremian age. Holotype: E.F. R50.2.
Derivation of Name: From the Latin parvus, little and granulum, a small seed - in reference to the surface ornament of this species.
Diagnosis: A thin-walled, ovoidal to ellipsoidal species, autophragm only, with a dense, very finely granular surface ornament and a prominent apical horn. The horn is hollow, distally closed, triangular in longitudinal section and can be simple or possess a short apical extension. There is no indication of tabulation, except for the single plate precingular archeopyle (3'').
Dimensions: Holotype: Length - 68 µm. Width - 51 µm.
Overall: 86 (73) 61 µm × 71 (58) 48 µm.
Specimens Measured: 22.
Remarks: This species is restricted to usually small, “simple” forms possessing a thin autophragm covered in small granules and is thereby distinguished from Eisenack’s type material of Apteodinium granulatum, as resolved by Sarjeant (1985). Although the morphology of A. parvigranulatum differs significantly from A. granulatum, it has no doubt been commonly assigned to the latter species by other authors.
Apteodinium parvigranulatum is similar in size to Apteodinium mutabile but the latter species is smooth-walled, highly folded and tends to have variously-developed outgrowths.
In having ornament over the entire surface and in lacking any trace of tabulation (except for the archeopyle), A. parvigranulatum is similar to Apteodinium paeminosum. It differs in being generally smaller, more elongate and in possessing dense, finely granular surface ornament; A. paeminosum has an irregular surface ornament of low relief, consisting of slightly raised maculae, with very rare coni.
Apteodinium parvigranulatum was restricted to the late Barremian here, occurring between 28.00 m and 19.00 m in Heslerton No. 2 and between 11,235.00 ft and 11,179.50 ft in well 22/26a-2.
Apteodinium parvigranulatum Duxbury, 2019, p.180, pl.14, figs.3–4,6. Holotype: Duxbury, 2019, pl.14, fig.4. Age: late
Barremian.
---------------------------------------------------------------------------------------------------
Original description: [Duxbury, 2019, p. 180]:
Apteodinium parvigranulatum Duxbury n. sp.
Plate 14, Figures 3, 4, 6
Holotype: Plate 14, Figure 4.
Type Locality: Well 22/26a-2 at 11,179.50 ft (core chip), late Barremian age. Holotype: E.F. R50.2.
Derivation of Name: From the Latin parvus, little and granulum, a small seed - in reference to the surface ornament of this species.
Diagnosis: A thin-walled, ovoidal to ellipsoidal species, autophragm only, with a dense, very finely granular surface ornament and a prominent apical horn. The horn is hollow, distally closed, triangular in longitudinal section and can be simple or possess a short apical extension. There is no indication of tabulation, except for the single plate precingular archeopyle (3'').
Dimensions: Holotype: Length - 68 µm. Width - 51 µm.
Overall: 86 (73) 61 µm × 71 (58) 48 µm.
Specimens Measured: 22.
Remarks: This species is restricted to usually small, “simple” forms possessing a thin autophragm covered in small granules and is thereby distinguished from Eisenack’s type material of Apteodinium granulatum, as resolved by Sarjeant (1985). Although the morphology of A. parvigranulatum differs significantly from A. granulatum, it has no doubt been commonly assigned to the latter species by other authors.
Apteodinium parvigranulatum is similar in size to Apteodinium mutabile but the latter species is smooth-walled, highly folded and tends to have variously-developed outgrowths.
In having ornament over the entire surface and in lacking any trace of tabulation (except for the archeopyle), A. parvigranulatum is similar to Apteodinium paeminosum. It differs in being generally smaller, more elongate and in possessing dense, finely granular surface ornament; A. paeminosum has an irregular surface ornament of low relief, consisting of slightly raised maculae, with very rare coni.
Apteodinium parvigranulatum was restricted to the late Barremian here, occurring between 28.00 m and 19.00 m in Heslerton No. 2 and between 11,235.00 ft and 11,179.50 ft in well 22/26a-2.