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Echinidinium transparantum
Echinidinium transparantum Zonneveld, 1997, p.329, pl.3, figs.6-10; text-figs.6A-B.
Name not validly published: no Latin description provided.
Holotype: Zonneveld, 1997, pl.3, figs.6-8; Head, 2003a, pl.2, figs.1-3. The holotype is from a sediment trap and does not have a stratigraphic context; hence it must be treated as an extant form rather than a fossil, its name requiring a Latin diagnosis for validation (Head, 2003a, p.171-173.
Age: Holocene.
(Zonneveld, 1997):
1996a cf. Protoperidinium sp. 3, Zonneveld, p. 151, pl. 1, figs. 7, 10.
Holotype: Single Grain ARZE 2. Sample MST- 8-B6. (Plate III, 6-8).
Repository: Collection of Fachbereich-5 Geowissenschaften, Universit/it Bremen, Germany.
Type locality: Offshore Somalia, Arabian Sea.
Etymology: With reference to its transparent spines.
Description: Spheroidal cysts covered with many randomly distributed spines. Cyst wall is pigmented and formed by a smooth pedium and a smooth luxuria forming the solid, acuminate spines. The spines are rigid and transparent. Their distal ends are sharply pointed. The outline of the spine bases is (sub) sphaerical to unregularly rectangular. The chasmic Archeopyle consists of a split, probably along a single suture. No other paratabulation is reflected
Additional remarks: The thin walled cyst body is strongly pigmented whereas the spines are transparent to yellow. The outline of the process bases may vary from (sub) sphaerical to unregularly rectangular (Fig. 6A). The spine length varies between 25 and 45% of the cyst-body diameter. No variation in relative spine length is observed. The archeopyle is only rarely observed and consists of a single split.
Dimensions: Holotype: body diameter 28.4 µm; process length 11.6 µm; base spines 2 µm. Range: body diameter 22 36 µm (mean =28.7 µm, n = 17); process length 5-14 µm (mean=9.5 µm, n=17); base spines 1.5-2.5 µm (mean 2 µm, n = 17).
Comparison with other taxa: Echinidinium transparantum most closely resembles cysts from Diplopelta parva (Abe) Matsuoka, 1988 but it is smaller and has solid transparent spines. E. transparantum differs from all other Echinidinium species, cysts of Protoperidinium minutum (Kofoid) Loeblich, 1969 as described by Wall and Dale (1968) and Fukuyo et al. (1977), cysts of Diplopelta symmetrica Pavillard, 1913, Protoperidinium monospinum (Paulsen) Zonneveld et Dale, 1994, Algidasphaeridium? minutum (Harland et Reid) Matsuoka et Bujak, 1988 and Pheopolykrikos hartmannii (Zimmermann) Matsuoka et Fukuyo, 1986 in having solid, transparent, acuminate spines.
Stratigraphic range: Late Pleistocene-Recent (Zonneveld, 1996b; Zonneveld et al., 1996a)
Environmental affinity: E. transparantum was recovered from surface sediment samples from the Arabian Sea with exception of the central part of the basin (Zonneveld, 1996a,b). This highest abundance is found in the Somali upwelling region and it may be characteristic for regions with eutropic surface water conditions.
Name not validly published: no Latin description provided.
Holotype: Zonneveld, 1997, pl.3, figs.6-8; Head, 2003a, pl.2, figs.1-3. The holotype is from a sediment trap and does not have a stratigraphic context; hence it must be treated as an extant form rather than a fossil, its name requiring a Latin diagnosis for validation (Head, 2003a, p.171-173.
Age: Holocene.
(Zonneveld, 1997):
1996a cf. Protoperidinium sp. 3, Zonneveld, p. 151, pl. 1, figs. 7, 10.
Holotype: Single Grain ARZE 2. Sample MST- 8-B6. (Plate III, 6-8).
Repository: Collection of Fachbereich-5 Geowissenschaften, Universit/it Bremen, Germany.
Type locality: Offshore Somalia, Arabian Sea.
Etymology: With reference to its transparent spines.
Description: Spheroidal cysts covered with many randomly distributed spines. Cyst wall is pigmented and formed by a smooth pedium and a smooth luxuria forming the solid, acuminate spines. The spines are rigid and transparent. Their distal ends are sharply pointed. The outline of the spine bases is (sub) sphaerical to unregularly rectangular. The chasmic Archeopyle consists of a split, probably along a single suture. No other paratabulation is reflected
Additional remarks: The thin walled cyst body is strongly pigmented whereas the spines are transparent to yellow. The outline of the process bases may vary from (sub) sphaerical to unregularly rectangular (Fig. 6A). The spine length varies between 25 and 45% of the cyst-body diameter. No variation in relative spine length is observed. The archeopyle is only rarely observed and consists of a single split.
Dimensions: Holotype: body diameter 28.4 µm; process length 11.6 µm; base spines 2 µm. Range: body diameter 22 36 µm (mean =28.7 µm, n = 17); process length 5-14 µm (mean=9.5 µm, n=17); base spines 1.5-2.5 µm (mean 2 µm, n = 17).
Comparison with other taxa: Echinidinium transparantum most closely resembles cysts from Diplopelta parva (Abe) Matsuoka, 1988 but it is smaller and has solid transparent spines. E. transparantum differs from all other Echinidinium species, cysts of Protoperidinium minutum (Kofoid) Loeblich, 1969 as described by Wall and Dale (1968) and Fukuyo et al. (1977), cysts of Diplopelta symmetrica Pavillard, 1913, Protoperidinium monospinum (Paulsen) Zonneveld et Dale, 1994, Algidasphaeridium? minutum (Harland et Reid) Matsuoka et Bujak, 1988 and Pheopolykrikos hartmannii (Zimmermann) Matsuoka et Fukuyo, 1986 in having solid, transparent, acuminate spines.
Stratigraphic range: Late Pleistocene-Recent (Zonneveld, 1996b; Zonneveld et al., 1996a)
Environmental affinity: E. transparantum was recovered from surface sediment samples from the Arabian Sea with exception of the central part of the basin (Zonneveld, 1996a,b). This highest abundance is found in the Somali upwelling region and it may be characteristic for regions with eutropic surface water conditions.