Back
Aptea fragile
From Fensome et al., 2019:
Aptea fragile, (Harris, 1965, p.97, pl.27, figs.4–5) Fensome et al., 2019a, p.15.
Holotype: Harris, 1965, pl.27, fig.5; Fensome et al., 2019a. fig.12A.
Originally Ovoidites (Appendix A), subsequently Cassidium, thirdly (and now) Aptea.
Age: Early Eocene.
---------------------------------------------------------------------------------------------------
Original description as Ovoidites fragilis: [Harris, 1965, p.97]:
Description:
Pollen non-aperturate, exine 2-3 µm thick coarsely rugulate. Rugulae 1 µm high 2 µm wide at base often anastomosing to give a reticulate pattern. Pollen commonly fractured.
Dimensions:
Diameter (10 specimens) 60 (75) 79 µm.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Revised diagnosis:
Drugg, 1967, p. 22:
Diagnosis:
Test circular to slightly angular in outline, usually dorso-ventrally flattened by compression. Weakly developed antapical lobes sometimes present. No girdle or longitudinal furrow visible. Test wall relatively thick- ca. 2 to 3 µm. Outer surface rugulate to imperfectly reticulate, the rugulae being low, thick, and rounded.
The test opens by means of an apical archeopyle, the line of separation being characteristically zigzag.
The test is tabulated but the exact formula is questionable because the peculiar ornamentation tends to obscure the plate boundaries. The tabulation appears to consist of six large equatorial plates below the archeopyle and one large antapical plate. The operculum questionably consists of four plates.
Dimensions:
The size varies from 60 to 92 µm high, and 61 to 97 µm wide.
----------------------------------------------------------------------------------------------------
Comments Fensome et al., 2019a:
1965 Ovoidites fragilis Harris Citation1965, p. 97, pl. 27, figs 4–5.1967 Cassidium fragile (Harris) Drugg, p. 22.
Comments. This species was originally described as pollen by Harris (Citation1965). Drugg (Citation1967, p. 22) recognised the dinoflagellate affinity of the holotype and provided a revised diagnosis. He noted that it had a relatively thick wall (2–3 μm), and that its ‘outer surface [is] rugulate to imperfectly reticulate, the rugulae being low, thick, and rounded’. The cyst surface appears to have ridges that appear initially to be parasutural, but they may not actually reflect tabulation; for example, no paracingulum is evident. The ridges may represent a very coarse reticulation superimposed on a finer rugulate–reticulate pattern that covers the whole surface. The presence of apparent parasutures led Drugg (Citation1967) to compare Cassidium (now Aptea) fragile with Canninginopsis denticulata, noting as differences the lack of a paracingulum and much thicker, rugulate wall in the former.
Although the coarser reticulum of Aptea fragilis may not reflect plate boundaries, the holotype clearly reflects tabulation in the archaeopyle outline and accessory archaeopyle sutures between precingular paraplates. The holotype is bowl shaped rather than lenticular, but the parasulcal notch appears to be offset; Drugg (Citation1967) noted that antapical lobes are sometimes present. Therefore, it seems reasonable to consider this species to be an areoligeracean.
Stratigraphical occurrence. Harris (Citation1965) recorded this species from the Lower Eocene of Victoria, Australia. According to Drugg (Citation1967) it is abundant in the Maastrichtian–Danian interval of California, USA.
Aptea fragile, (Harris, 1965, p.97, pl.27, figs.4–5) Fensome et al., 2019a, p.15.
Holotype: Harris, 1965, pl.27, fig.5; Fensome et al., 2019a. fig.12A.
Originally Ovoidites (Appendix A), subsequently Cassidium, thirdly (and now) Aptea.
Age: Early Eocene.
---------------------------------------------------------------------------------------------------
Original description as Ovoidites fragilis: [Harris, 1965, p.97]:
Description:
Pollen non-aperturate, exine 2-3 µm thick coarsely rugulate. Rugulae 1 µm high 2 µm wide at base often anastomosing to give a reticulate pattern. Pollen commonly fractured.
Dimensions:
Diameter (10 specimens) 60 (75) 79 µm.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Revised diagnosis:
Drugg, 1967, p. 22:
Diagnosis:
Test circular to slightly angular in outline, usually dorso-ventrally flattened by compression. Weakly developed antapical lobes sometimes present. No girdle or longitudinal furrow visible. Test wall relatively thick- ca. 2 to 3 µm. Outer surface rugulate to imperfectly reticulate, the rugulae being low, thick, and rounded.
The test opens by means of an apical archeopyle, the line of separation being characteristically zigzag.
The test is tabulated but the exact formula is questionable because the peculiar ornamentation tends to obscure the plate boundaries. The tabulation appears to consist of six large equatorial plates below the archeopyle and one large antapical plate. The operculum questionably consists of four plates.
Dimensions:
The size varies from 60 to 92 µm high, and 61 to 97 µm wide.
----------------------------------------------------------------------------------------------------
Comments Fensome et al., 2019a:
1965 Ovoidites fragilis Harris Citation1965, p. 97, pl. 27, figs 4–5.1967 Cassidium fragile (Harris) Drugg, p. 22.
Comments. This species was originally described as pollen by Harris (Citation1965). Drugg (Citation1967, p. 22) recognised the dinoflagellate affinity of the holotype and provided a revised diagnosis. He noted that it had a relatively thick wall (2–3 μm), and that its ‘outer surface [is] rugulate to imperfectly reticulate, the rugulae being low, thick, and rounded’. The cyst surface appears to have ridges that appear initially to be parasutural, but they may not actually reflect tabulation; for example, no paracingulum is evident. The ridges may represent a very coarse reticulation superimposed on a finer rugulate–reticulate pattern that covers the whole surface. The presence of apparent parasutures led Drugg (Citation1967) to compare Cassidium (now Aptea) fragile with Canninginopsis denticulata, noting as differences the lack of a paracingulum and much thicker, rugulate wall in the former.
Although the coarser reticulum of Aptea fragilis may not reflect plate boundaries, the holotype clearly reflects tabulation in the archaeopyle outline and accessory archaeopyle sutures between precingular paraplates. The holotype is bowl shaped rather than lenticular, but the parasulcal notch appears to be offset; Drugg (Citation1967) noted that antapical lobes are sometimes present. Therefore, it seems reasonable to consider this species to be an areoligeracean.
Stratigraphical occurrence. Harris (Citation1965) recorded this species from the Lower Eocene of Victoria, Australia. According to Drugg (Citation1967) it is abundant in the Maastrichtian–Danian interval of California, USA.