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Echinidinium delicatum
Echinidinium delicatum Zonneveld, 1997, p.333-334, pl.4, figs.5-7; text-figs.8A-B ex Head 2003a, p.171.
Holotype: Zonneveld, 1997, pl.4, figs.5-7. 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 delicatum.
Age: Holocene.
(Zonneveld, 1997):
1996a cf. Protoperidinium sp. 6, Zonneveld, p. 154, pl. l, figs. 13-15.
Holotype: ARZE 461 EFC U34/4 (Plate IV, 5-7).
Repository: Collection of Fachbereich-5 Geowissenschaften, Universität Bremen, Germany.
Type locality: Offshore Pakistan, Arabian Sea.
Etymology: With reference to its delicate appearance and small spines.
Description: Spheroidal cysts covered with numerous more or less regularly distributed spines. Cyst wall is pale brown with a smooth pedium. The rigid, hollow spines are formed by separation of the smooth luxuria and pedium. They are acuminate, pigmented, have (sub) sphaerical bases and are sharply pointed and closed at their distal ends. The chasmic archeopyle consist of a split along one or two sutures.
Additional remarks: The pigmented cysts have a thin cyst wall which is easily folded. The form and relative height of the spines is very constant within and between specimens (Fig. 8). Length of the spines do not exceed a third of the cyst diameter. No specimens with reduced spine lengths are observed. The chasmic archeopyle is only seldom observed (Plate IV, 5).
Dimensions: Holotype: body diameter 24.2 µm: spine length 3.2 µm. Range: body diameter 17-25 µm (mean=21.5 µm, n=9); spine length 2-4 µm (mean=3 µm, n=9).
Comparison with other taxa: Echinidinium delicatum most closely resembles AIgidasphaeridium? rninutum (Harland et Reid) Matsuoka et Bujak, 1988 but differs in having completely hollow spines rather than having spines with hollow bases and solid shafts and tips. E. delicatum differs from cysts of Protoperidinium minutum as described by Fukuyo et al. (1977) in having a smaller body diameter (17-22 gm in comparison with 28 32 gm of P. rninutum) and a chasmic archeopyle. E. delicatum differs from E. granulatum in having much smaller regularly distributed spines and a smooth cyst wall. It differs from cysts of Pheopolykrikos hartmannii (Zimmermann) Matsuoka et Fukuyo, 1986 in its smaller size, its smooth cyst wall, absence of striations at the proximal base of the processes and having an archeopyle which is formed by a split along one or two sutures.
Stratigraphic range: Late Pleistocene Recent (Zonneveld, 1996b; Zonneveld et al., 1996a).
Environmental affinity: The occurrence of E. delicatum in surface sediment samples of the Arabian Sea is restricted to the coastal regions. The highest abundance of E. delicatum is observed in sediments of the Oman upwelling region. ( Zonneveld, 1996a,b).
Holotype: Zonneveld, 1997, pl.4, figs.5-7. 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 delicatum.
Age: Holocene.
(Zonneveld, 1997):
1996a cf. Protoperidinium sp. 6, Zonneveld, p. 154, pl. l, figs. 13-15.
Holotype: ARZE 461 EFC U34/4 (Plate IV, 5-7).
Repository: Collection of Fachbereich-5 Geowissenschaften, Universität Bremen, Germany.
Type locality: Offshore Pakistan, Arabian Sea.
Etymology: With reference to its delicate appearance and small spines.
Description: Spheroidal cysts covered with numerous more or less regularly distributed spines. Cyst wall is pale brown with a smooth pedium. The rigid, hollow spines are formed by separation of the smooth luxuria and pedium. They are acuminate, pigmented, have (sub) sphaerical bases and are sharply pointed and closed at their distal ends. The chasmic archeopyle consist of a split along one or two sutures.
Additional remarks: The pigmented cysts have a thin cyst wall which is easily folded. The form and relative height of the spines is very constant within and between specimens (Fig. 8). Length of the spines do not exceed a third of the cyst diameter. No specimens with reduced spine lengths are observed. The chasmic archeopyle is only seldom observed (Plate IV, 5).
Dimensions: Holotype: body diameter 24.2 µm: spine length 3.2 µm. Range: body diameter 17-25 µm (mean=21.5 µm, n=9); spine length 2-4 µm (mean=3 µm, n=9).
Comparison with other taxa: Echinidinium delicatum most closely resembles AIgidasphaeridium? rninutum (Harland et Reid) Matsuoka et Bujak, 1988 but differs in having completely hollow spines rather than having spines with hollow bases and solid shafts and tips. E. delicatum differs from cysts of Protoperidinium minutum as described by Fukuyo et al. (1977) in having a smaller body diameter (17-22 gm in comparison with 28 32 gm of P. rninutum) and a chasmic archeopyle. E. delicatum differs from E. granulatum in having much smaller regularly distributed spines and a smooth cyst wall. It differs from cysts of Pheopolykrikos hartmannii (Zimmermann) Matsuoka et Fukuyo, 1986 in its smaller size, its smooth cyst wall, absence of striations at the proximal base of the processes and having an archeopyle which is formed by a split along one or two sutures.
Stratigraphic range: Late Pleistocene Recent (Zonneveld, 1996b; Zonneveld et al., 1996a).
Environmental affinity: The occurrence of E. delicatum in surface sediment samples of the Arabian Sea is restricted to the coastal regions. The highest abundance of E. delicatum is observed in sediments of the Oman upwelling region. ( Zonneveld, 1996a,b).