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Echinidinium bispiniformum
Echinidinium bispiniformum Zonneveld, 1997, p.329,331,333, pl.4, figs.1-4; text-figs.7A-B ex Head, 2003a, p.171.
Holotype: Zonneveld, 1997, pl.4, figs.1-3. The holotype is from ocean floor sediment and has a stratigraphic context; hence it may be treated as a fossil, its name not requiring a Latin diagnosis for validation (Head, 2003a, p.171-172). This name was not validly published in Zonneveld (1997) since the generic name was not validated until 2001. By fully citing the basionym, Head (2003a, p.171) validated the name Echinidinium bispiniformum.
Age: Holocene.
(Zonneveld, 1997):
1996a cf. Protoperidinium sp. 4, Zonneveld, pp. 151-152, pl. l, figs. 8, 9.
Holotype: Single Grain ARZE 3. Sample ARZE 303 (Plate IV, 1-3).
Repository: Collection of Fachbereich-5 Geowissenschaften, Universität Bremen, Germany.
Type locality: Offshore Yemen, Arabian Sea.
Etymology: With reference to its two spine types.
Diagnosis: Spheroidal cysts covered with randomly distributed spines of two different types. Cyst wall is pigmented with a smooth pedium. The first spine type is large, hollow, transparent and bulbose or bulbous in outline. It is formed by separation of the luxuria and pedium. This type of spines is flexible and can have fine solid spinules at their closed distal ends. Spine bases are subspherical to ovoidal with a diameter of about 30% of the spine length. The second spine type is small, solid, acuminate and scattered randomly between the large spines. These flexuous spines are pigmented, smooth, have (sub) sphaerical bases and are sharply pointed at their distal ends. No paratabulation is reflected except for the chasmic archeopyle which consists of a split along several sutures.
Additional remarks: The pigmented cysts have a thin cell wall which is easily folded. The form and size of the large spines are not uniform but varies considerably between, and on the individual specimens (Fig. 7B, b). Their height is about 10 to 20% of the cyst diameter. The cysts have about 30-40 of these large spines. The small spines are numerous, very uniform in size and outline, their height never exceeds 5% of the body diameter (Fig. 7B, a). The size of the archeopyle can vary between the different specimens from a split along two sutures to a zigzag split which almost encircles the complete cyst (Fig. 7A; Plate IV, 1, 2). The archeopyle could not be assigned to an equivalent paratabulation.
Dimensions: Holotype: body diameter 46.3 µm; length large spines 6-11.6 µm; base large spines 3.2 5.3 µm; length small spines µm. Range: body diameter 39-48 µm (mean =43.4 µm, n = 14); length large spines 4-12 µm (mean=7.5 µm, n= 14); base large spines 2-6 µm; length small spines 2 µm, n = 14).
Comparison with other taxa: Echinidinium bispiniformum most closely resembles cysts of Protoperidinium monospinum (Paulsen) Zonneveld et Dale, 1994 since they both have spines of two different types. However, the large spines of P. monospinum are brown and capitate, bifurcate or double branched at their distal ends whereas the large spines of E. bispiniformum are hollow, transparent and bulbose or bulbous in outline. Furthermore, the body diameter of E. bispiniformum is much larger than that of P. monospinum. E. bispiniformum differs from all other Echinidinium species, cysts of Diplopelta parva (Abe) Matsuoka, 1988, cysts of Diplopelta symmetrica Pavillard, 1913, cysts of Protoperidinium minutum (Kofoid) Loeblich, 1969 as described by Wall and Dale (1968), Algidasphaeridium? minutum (Harland et Reid) Matsuoka et Bujak, 1988 and by Fukuyo et al. (1977) and Pheopolykrikos hartmannii (Zimmermann) Matsuoka et Fukuyo, 1986 in having two types of spines.
Stratigraphic range: Late Pleistocene-Recent (Zonneveld, 1996b; Zonneveld et al., 1996a).
Environmental affinity: E. granulatum is most abundant in surface sediment samples of the Arabian Sea and Benguela upwelling region where it is found in the coastal regions (Zonneveld, 1996a,b; R. Hoek, pets. commun., 1996) suggesting that E. bispiniformum is associated with tropical eutrophic waters.
Holotype: Zonneveld, 1997, pl.4, figs.1-3. The holotype is from ocean floor sediment and has a stratigraphic context; hence it may be treated as a fossil, its name not requiring a Latin diagnosis for validation (Head, 2003a, p.171-172). This name was not validly published in Zonneveld (1997) since the generic name was not validated until 2001. By fully citing the basionym, Head (2003a, p.171) validated the name Echinidinium bispiniformum.
Age: Holocene.
(Zonneveld, 1997):
1996a cf. Protoperidinium sp. 4, Zonneveld, pp. 151-152, pl. l, figs. 8, 9.
Holotype: Single Grain ARZE 3. Sample ARZE 303 (Plate IV, 1-3).
Repository: Collection of Fachbereich-5 Geowissenschaften, Universität Bremen, Germany.
Type locality: Offshore Yemen, Arabian Sea.
Etymology: With reference to its two spine types.
Diagnosis: Spheroidal cysts covered with randomly distributed spines of two different types. Cyst wall is pigmented with a smooth pedium. The first spine type is large, hollow, transparent and bulbose or bulbous in outline. It is formed by separation of the luxuria and pedium. This type of spines is flexible and can have fine solid spinules at their closed distal ends. Spine bases are subspherical to ovoidal with a diameter of about 30% of the spine length. The second spine type is small, solid, acuminate and scattered randomly between the large spines. These flexuous spines are pigmented, smooth, have (sub) sphaerical bases and are sharply pointed at their distal ends. No paratabulation is reflected except for the chasmic archeopyle which consists of a split along several sutures.
Additional remarks: The pigmented cysts have a thin cell wall which is easily folded. The form and size of the large spines are not uniform but varies considerably between, and on the individual specimens (Fig. 7B, b). Their height is about 10 to 20% of the cyst diameter. The cysts have about 30-40 of these large spines. The small spines are numerous, very uniform in size and outline, their height never exceeds 5% of the body diameter (Fig. 7B, a). The size of the archeopyle can vary between the different specimens from a split along two sutures to a zigzag split which almost encircles the complete cyst (Fig. 7A; Plate IV, 1, 2). The archeopyle could not be assigned to an equivalent paratabulation.
Dimensions: Holotype: body diameter 46.3 µm; length large spines 6-11.6 µm; base large spines 3.2 5.3 µm; length small spines µm. Range: body diameter 39-48 µm (mean =43.4 µm, n = 14); length large spines 4-12 µm (mean=7.5 µm, n= 14); base large spines 2-6 µm; length small spines 2 µm, n = 14).
Comparison with other taxa: Echinidinium bispiniformum most closely resembles cysts of Protoperidinium monospinum (Paulsen) Zonneveld et Dale, 1994 since they both have spines of two different types. However, the large spines of P. monospinum are brown and capitate, bifurcate or double branched at their distal ends whereas the large spines of E. bispiniformum are hollow, transparent and bulbose or bulbous in outline. Furthermore, the body diameter of E. bispiniformum is much larger than that of P. monospinum. E. bispiniformum differs from all other Echinidinium species, cysts of Diplopelta parva (Abe) Matsuoka, 1988, cysts of Diplopelta symmetrica Pavillard, 1913, cysts of Protoperidinium minutum (Kofoid) Loeblich, 1969 as described by Wall and Dale (1968), Algidasphaeridium? minutum (Harland et Reid) Matsuoka et Bujak, 1988 and by Fukuyo et al. (1977) and Pheopolykrikos hartmannii (Zimmermann) Matsuoka et Fukuyo, 1986 in having two types of spines.
Stratigraphic range: Late Pleistocene-Recent (Zonneveld, 1996b; Zonneveld et al., 1996a).
Environmental affinity: E. granulatum is most abundant in surface sediment samples of the Arabian Sea and Benguela upwelling region where it is found in the coastal regions (Zonneveld, 1996a,b; R. Hoek, pets. commun., 1996) suggesting that E. bispiniformum is associated with tropical eutrophic waters.