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Algidasphaeridium spongium
Algidasphaeridium spongium, Zonneveld, 1997, p. 322–323,325, pl.1, figs.1–6; text-figs.3A–B ; Emendation: Zonneveld and Jurkschat, 1999, p.158, as Bitectatodinium spongium.
Holotype: Zonneveld, 1997, pl.1, figs.1,3,5; Zonneveld and Jurkschat, 1999, pl.1, figs.2–4 (not 1).
Stratigraphic range: Late Pleistocene-Recent (Zonneveld, 1996b; Zonneveld et al., 1996a)
Age: Holocene.
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Original description: [Zonneveld, 1997]:
Diagnosis:
Spheroidal cysts with a wall that comprises a thin pedium and a spongy, granulofibrous, distally open luxuria of numerous capitate, solid spines. Archeopyle is chasmic.
There are no ornaments reflecting paratabulation.
Dimensions:
Holotype: body diameter 62 µm; spine length on average 10.5 µm; wall thickness 3.2 µm.
Range: body diameter 48-63 µm (mean = 55.6 µm, n=22); spine length 5-11 µm (mean= 8 µm, n=22); thickness cell wall 1.5-3.5 µm (mean = 2.6 µm, n = 22).
Remarks and Affinities:
The spongy luxuria appears densely fibrous under bright field microscopy. Part of the fibrils project from the surface of the fibrous layer and form capitate spines which have lengths of about three times the thickness of the fibrous layer. The thin pedium is only seen in optical section. The archeopyle is formed by a split along several sutures. Matsuoka and Bujak (1988) defined the cyst wall of Algidasphaeridium as being granular. Since the cyst wall of A.? spongium is formed by spongy, granulo-fibrous luxuria, the assignment to Algidasphaeridium is provisional. The wall structure of A.? spongium is very similar to that of Tectatodinium pellitum Wall, 1967. However, although both species have a cyst wall of spongy, distally open luxuria where fibrils may project from the surface, these fibrils are relatively larger and capitate in cysts of A.? spongium. Beside a small difference in wall morphology T. pellitum differs from A.? spongium in having a precingular archeopyle, formed by the loss of the third precingular paraplate. A.? spongium differs from Algidasphaeridium capillatum Matsuoka et Bujak, 1988 and Algidasphaeridium? minutum (Harland et Reid) Matsuoka et Bujak, 1988 in its larger size and its spongy cyst wall.
Environmental affinity:
In the Arabian Sea A.? spongium is characteristically present in sediments associated with coastal-upwelling during the SW monsoon offshore Somalia and Yemen (Zonneveld, 1996a,b).
Holotype: Zonneveld, 1997, pl.1, figs.1,3,5; Zonneveld and Jurkschat, 1999, pl.1, figs.2–4 (not 1).
Stratigraphic range: Late Pleistocene-Recent (Zonneveld, 1996b; Zonneveld et al., 1996a)
Age: Holocene.
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Original description: [Zonneveld, 1997]:
Diagnosis:
Spheroidal cysts with a wall that comprises a thin pedium and a spongy, granulofibrous, distally open luxuria of numerous capitate, solid spines. Archeopyle is chasmic.
There are no ornaments reflecting paratabulation.
Dimensions:
Holotype: body diameter 62 µm; spine length on average 10.5 µm; wall thickness 3.2 µm.
Range: body diameter 48-63 µm (mean = 55.6 µm, n=22); spine length 5-11 µm (mean= 8 µm, n=22); thickness cell wall 1.5-3.5 µm (mean = 2.6 µm, n = 22).
Remarks and Affinities:
The spongy luxuria appears densely fibrous under bright field microscopy. Part of the fibrils project from the surface of the fibrous layer and form capitate spines which have lengths of about three times the thickness of the fibrous layer. The thin pedium is only seen in optical section. The archeopyle is formed by a split along several sutures. Matsuoka and Bujak (1988) defined the cyst wall of Algidasphaeridium as being granular. Since the cyst wall of A.? spongium is formed by spongy, granulo-fibrous luxuria, the assignment to Algidasphaeridium is provisional. The wall structure of A.? spongium is very similar to that of Tectatodinium pellitum Wall, 1967. However, although both species have a cyst wall of spongy, distally open luxuria where fibrils may project from the surface, these fibrils are relatively larger and capitate in cysts of A.? spongium. Beside a small difference in wall morphology T. pellitum differs from A.? spongium in having a precingular archeopyle, formed by the loss of the third precingular paraplate. A.? spongium differs from Algidasphaeridium capillatum Matsuoka et Bujak, 1988 and Algidasphaeridium? minutum (Harland et Reid) Matsuoka et Bujak, 1988 in its larger size and its spongy cyst wall.
Environmental affinity:
In the Arabian Sea A.? spongium is characteristically present in sediments associated with coastal-upwelling during the SW monsoon offshore Somalia and Yemen (Zonneveld, 1996a,b).