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Batiacasphaera edwardsiae
Batiacasphaera edwardsiae, Louwye et al., 2008, p.134,136, pl.1, figs.1–9.
Holotype: Louwye et al., 2008, pl.1, figs.1–7.
Type locality: Porcupine Basin, offshore southwest Ireland.
Age: middle Miocene.
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Original description: [Louwye et al., 2008]:
Diagnosis:
Medium-sized spherical to sub-spherical cyst with single-layered wall ornamented with low, discontinuous and anatomizing muri forming an irregular reticulum. Lumina are large and interconnect.
Archeopyle apical, formed by the release of all the apical plates. Outline of archeopyle is distinctly angular. Operculum free.
Description:
Proximate cyst with a circular to subcircular outline.
The cyst wall is simple (not layered), and has a thickness of approximately 0.5–1.0 μm. The autophragm forms an ornamentation of low, discontinuous muri which anastomose. This gives the cyst an irregular, microreticulate appearance.
The geometry of the lumina of the micro reticulum is highly irregular, and the lumina interconnect. The size of the lumina vary considerably; they are typically no smaller than 3 μm. The muri have a maximum height of approximately 2.5 μm, and have a slightly widened base. They thin slightly towards the apex and end distally in rounded crests. The surface of the muri is pitted, while the surface of the autophragm within the lumina is shagreenate to scabrate.
The ornamentation does not reflect a coherent tabulation pattern.
The apical archeopyle is large and involves the entire apical series. The principal archeopyle suture is distinctly angular.
Accessory sutures are often developed, and indicate the location of the precingular plates, a feature already indicated by Edwards (1984). Often, these accessory sutures cause the anterior end of precingular plates to overlap slightly, which hampers the reconstruction of the tabulation pattern in the apical and precingular region. The operculum is always free, and it is not known whether it is compound or not.
The sulcal notch is well developed, and this prominent feature facilitates orientation.
The archeopyle is the only indication of a tabulation pattern.
Dimensions.
Holotype: Length or maximum diameter: 43μm; width or minimum diameter: 42 μm; wall thickness: 2 μm. Range: length: 40(45)49 μm; width: 40(44)47 μm; average thickness of wall including ornamentation: 2.3 μm. Number of specimens measured: 16.
Affinities/Comparison:
Most other species of Batiacasphaera have a significantly more discrete ornamentation, and a thinner wall. Batiacasphaera compta Drugg 1970 possesses a reticulate wall composed of small rod-like elements joined together into muri which form regular polygons. Batiacasphaera cassiculus Wilson 1988 is a larger species (range diameter: 73(85)93 μm) and possesses a thick autophragm ornamented with a dense, irregular reticulum consisting of thick muri separating the lumen. Batiacasphaeraminuta (Matsuoka 1974) Matsuoka & Head 1992 has a thinner wall (1.0–1.5 μm), a smaller diameter (33–29 x 28–27 μm), and a dense microreticulate wall. Batiacasphaera micropapillata Stover 1977 has a thin wall of about 0.5 μm, and a granulate, microreticulate, or papillate ornamentation.
Holotype: Louwye et al., 2008, pl.1, figs.1–7.
Type locality: Porcupine Basin, offshore southwest Ireland.
Age: middle Miocene.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Louwye et al., 2008]:
Diagnosis:
Medium-sized spherical to sub-spherical cyst with single-layered wall ornamented with low, discontinuous and anatomizing muri forming an irregular reticulum. Lumina are large and interconnect.
Archeopyle apical, formed by the release of all the apical plates. Outline of archeopyle is distinctly angular. Operculum free.
Description:
Proximate cyst with a circular to subcircular outline.
The cyst wall is simple (not layered), and has a thickness of approximately 0.5–1.0 μm. The autophragm forms an ornamentation of low, discontinuous muri which anastomose. This gives the cyst an irregular, microreticulate appearance.
The geometry of the lumina of the micro reticulum is highly irregular, and the lumina interconnect. The size of the lumina vary considerably; they are typically no smaller than 3 μm. The muri have a maximum height of approximately 2.5 μm, and have a slightly widened base. They thin slightly towards the apex and end distally in rounded crests. The surface of the muri is pitted, while the surface of the autophragm within the lumina is shagreenate to scabrate.
The ornamentation does not reflect a coherent tabulation pattern.
The apical archeopyle is large and involves the entire apical series. The principal archeopyle suture is distinctly angular.
Accessory sutures are often developed, and indicate the location of the precingular plates, a feature already indicated by Edwards (1984). Often, these accessory sutures cause the anterior end of precingular plates to overlap slightly, which hampers the reconstruction of the tabulation pattern in the apical and precingular region. The operculum is always free, and it is not known whether it is compound or not.
The sulcal notch is well developed, and this prominent feature facilitates orientation.
The archeopyle is the only indication of a tabulation pattern.
Dimensions.
Holotype: Length or maximum diameter: 43μm; width or minimum diameter: 42 μm; wall thickness: 2 μm. Range: length: 40(45)49 μm; width: 40(44)47 μm; average thickness of wall including ornamentation: 2.3 μm. Number of specimens measured: 16.
Affinities/Comparison:
Most other species of Batiacasphaera have a significantly more discrete ornamentation, and a thinner wall. Batiacasphaera compta Drugg 1970 possesses a reticulate wall composed of small rod-like elements joined together into muri which form regular polygons. Batiacasphaera cassiculus Wilson 1988 is a larger species (range diameter: 73(85)93 μm) and possesses a thick autophragm ornamented with a dense, irregular reticulum consisting of thick muri separating the lumen. Batiacasphaeraminuta (Matsuoka 1974) Matsuoka & Head 1992 has a thinner wall (1.0–1.5 μm), a smaller diameter (33–29 x 28–27 μm), and a dense microreticulate wall. Batiacasphaera micropapillata Stover 1977 has a thin wall of about 0.5 μm, and a granulate, microreticulate, or papillate ornamentation.