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Echinidinium karaense
Echinidinium karaense Head et al., 2001, p.633-634, pl.3, figs.i-o.
Holotype: Head et al., 2001, pl.3, figs.i-k.
Age: Holocene.
(Head et al., 2001):
Multispinula minuta s.l. auct. non Harland and Reid, 1980. Matthiessen, 1991, pl. 4, fig. 12 only.
Algidasphaeridium? minutum s.l. auct. non Harland and Reid, 1980. Matthiessen, 1995, pl. 1, fig. 4.
Algidasphaeridium? minutum Morphotyp C. Kunz-Pirrung, 1998, p. 93, pl. 1, figs 5, 6, 8 and 12.
Algidasphaeridium? Typ C. Kunz-Pirrung, 1999, pl. 1, fig. 5.
Algidasphaeridium? minutum var. cezare auct. non de Vernal et al., 1989. Rochon et al., 1999, pl. 14, figs 10– 12.
Diagnosis. Cysts brown in colour, chorate, having spheroidal central body whose wall is smooth with scattered coni or spinules. Processes numerous, nontabular, robust, conical to tapering, rarely branched, distally solid with pericoels extending variable distance along process length; terminating distally in acuminate or minutely flared tips. Archeopyle theropylic, opening by means of a nearly straight split.
Description. Cysts have a brown wall that does not autofluoresce. The cyst wall is less than 0.5 µm thick, not visibly stratified between processes, and has a smooth surface bearing scattered small coni or spinules of variable length but up to 3 µm high on some specimens. In addition to spinules, slender solid or apiculocavate spines may occur on some specimens but they are somewhat shorter than the processes. Processes are numerous, non-tabular, and are separated from one another at their base by ca. 1.5–3.0 µm, this range of separation being present on most individual cysts. Processes are conical to tapering, and individual specimens show variable width at base, although usually this is not more than about 2.5 µm. Processes are apiculocavate to mostly hollow, with the extent of cavation varying on individual specimens, but most specimens have some processes with pericoels that extend for at least one-third of their length. Processes are solid distally, have a smooth surface, a circular transverse section, and are rarely branched (as on the paratype, Plate 3o). Process tips are either acuminate or minutely expanded and flared, and usually both types of tips are present on the same cyst, although in proportions that vary considerably from cyst to cyst. Where process tips are minutely expanded, aculeae are often discerned. These aculeae rarely exceed 1.0 µm in length, usually are directed away from the cyst wall and are never strongly recurved.
The archeopyle is interpreted as being theropylic, opening by means of a simple, long, nearly straight split. Some slight angulations along its course suggest an opening along plate sutures. An archeopyle was not clearly seen in most specimens, and this probably is a consequence of its indistinct nature. A few specimens have been found with polygonal openings (Plate 3l and m; and the holotype), but these are interpreted as damage to the cyst wall. There is no other evidence of tabulation, but some areas of the cyst wall on several specimens examined (including both holotype and paratype) have slightly darkened lines (slight thickening?) that run between process bases and form a very faint and irregular reticulum. It is uncertain whether this is a preservational feature (a separation of wall layers?) but may be related to the polygonal openings noted above.
Measurements. Holotype: central body diameter, 32 × 32 µm, maximum process length, 6 µm. Range: central body maximum diameter, 29 (32.5) 36 µm; average process length, 5.0(6.1)7.0 µm. Fifteen specimens measured from the Kara Sea (Fig. 9).
Etymology. Named after the Kara Sea, the type locality of this species.
Holotype. Specimen MPK 12443. Sample BP97-52 (74°00 01.2N, 72°39 43.2E), slide 2, EF E40/2 (label to left), from modern sediments of the Kara Sea, Arctic Ocean (Plate 3i–k).
Repository. The holotype (see above) and paratype (specimen MPK 12444; Plate 3l–o) are deposited in the type collection of the British Geological Survey.
Material examined. Modern sediments from the Kara and Laptev seas, Russian Arctic.
Comparison. Echinidinium karaense is most similar to the cyst of Protoperidinium monospinum (see Zonneveld and Dale, 1994), which appears to have more conspicuously branched processes. The cysts of Diplopelta parva (see Matsuoka, 1988) differ in having processes with exclusively acuminate tips. Islandinium minutum differs in having a saphopylic archeopyle; processes that are generally shorter in length, narrower at the base, and always acuminate; and a wall surface that has low granules, and not spinules and coni. Islandinium? cezare differs in having a granulate rather than smooth wall surface, and process terminations that are expanded into platforms with recurved margins rather than being minutely flared. The processes on Islandinium? cezare (morphotype 1) are also more solid. Echinidinium aculeatum Zonneveld 1997, described from modern sediments of the Arabian Sea, differs in its smaller size (body diameter 16–26 µm, mean 20 µm), less densely distributed processes, less solid process stems, and a wall surface lacking spinules and coni (Zonneveld, 1997; MJH personal observation). The paratype of Echinidinium aculeatum has a polygonal opening and reticulum of dark lines as seen in some specimens of Echinidinium karaense (see above). As with Echinidinium karaense, this appears to be preservational because the holotype of Echinidinium aculeatum lacks these features but has a straight, slit-like opening interpreted to be part of the theropylic archeopyle (Zonneveld, 1997, fig. 5a; MJH personal observation).
Holotype: Head et al., 2001, pl.3, figs.i-k.
Age: Holocene.
(Head et al., 2001):
Multispinula minuta s.l. auct. non Harland and Reid, 1980. Matthiessen, 1991, pl. 4, fig. 12 only.
Algidasphaeridium? minutum s.l. auct. non Harland and Reid, 1980. Matthiessen, 1995, pl. 1, fig. 4.
Algidasphaeridium? minutum Morphotyp C. Kunz-Pirrung, 1998, p. 93, pl. 1, figs 5, 6, 8 and 12.
Algidasphaeridium? Typ C. Kunz-Pirrung, 1999, pl. 1, fig. 5.
Algidasphaeridium? minutum var. cezare auct. non de Vernal et al., 1989. Rochon et al., 1999, pl. 14, figs 10– 12.
Diagnosis. Cysts brown in colour, chorate, having spheroidal central body whose wall is smooth with scattered coni or spinules. Processes numerous, nontabular, robust, conical to tapering, rarely branched, distally solid with pericoels extending variable distance along process length; terminating distally in acuminate or minutely flared tips. Archeopyle theropylic, opening by means of a nearly straight split.
Description. Cysts have a brown wall that does not autofluoresce. The cyst wall is less than 0.5 µm thick, not visibly stratified between processes, and has a smooth surface bearing scattered small coni or spinules of variable length but up to 3 µm high on some specimens. In addition to spinules, slender solid or apiculocavate spines may occur on some specimens but they are somewhat shorter than the processes. Processes are numerous, non-tabular, and are separated from one another at their base by ca. 1.5–3.0 µm, this range of separation being present on most individual cysts. Processes are conical to tapering, and individual specimens show variable width at base, although usually this is not more than about 2.5 µm. Processes are apiculocavate to mostly hollow, with the extent of cavation varying on individual specimens, but most specimens have some processes with pericoels that extend for at least one-third of their length. Processes are solid distally, have a smooth surface, a circular transverse section, and are rarely branched (as on the paratype, Plate 3o). Process tips are either acuminate or minutely expanded and flared, and usually both types of tips are present on the same cyst, although in proportions that vary considerably from cyst to cyst. Where process tips are minutely expanded, aculeae are often discerned. These aculeae rarely exceed 1.0 µm in length, usually are directed away from the cyst wall and are never strongly recurved.
The archeopyle is interpreted as being theropylic, opening by means of a simple, long, nearly straight split. Some slight angulations along its course suggest an opening along plate sutures. An archeopyle was not clearly seen in most specimens, and this probably is a consequence of its indistinct nature. A few specimens have been found with polygonal openings (Plate 3l and m; and the holotype), but these are interpreted as damage to the cyst wall. There is no other evidence of tabulation, but some areas of the cyst wall on several specimens examined (including both holotype and paratype) have slightly darkened lines (slight thickening?) that run between process bases and form a very faint and irregular reticulum. It is uncertain whether this is a preservational feature (a separation of wall layers?) but may be related to the polygonal openings noted above.
Measurements. Holotype: central body diameter, 32 × 32 µm, maximum process length, 6 µm. Range: central body maximum diameter, 29 (32.5) 36 µm; average process length, 5.0(6.1)7.0 µm. Fifteen specimens measured from the Kara Sea (Fig. 9).
Etymology. Named after the Kara Sea, the type locality of this species.
Holotype. Specimen MPK 12443. Sample BP97-52 (74°00 01.2N, 72°39 43.2E), slide 2, EF E40/2 (label to left), from modern sediments of the Kara Sea, Arctic Ocean (Plate 3i–k).
Repository. The holotype (see above) and paratype (specimen MPK 12444; Plate 3l–o) are deposited in the type collection of the British Geological Survey.
Material examined. Modern sediments from the Kara and Laptev seas, Russian Arctic.
Comparison. Echinidinium karaense is most similar to the cyst of Protoperidinium monospinum (see Zonneveld and Dale, 1994), which appears to have more conspicuously branched processes. The cysts of Diplopelta parva (see Matsuoka, 1988) differ in having processes with exclusively acuminate tips. Islandinium minutum differs in having a saphopylic archeopyle; processes that are generally shorter in length, narrower at the base, and always acuminate; and a wall surface that has low granules, and not spinules and coni. Islandinium? cezare differs in having a granulate rather than smooth wall surface, and process terminations that are expanded into platforms with recurved margins rather than being minutely flared. The processes on Islandinium? cezare (morphotype 1) are also more solid. Echinidinium aculeatum Zonneveld 1997, described from modern sediments of the Arabian Sea, differs in its smaller size (body diameter 16–26 µm, mean 20 µm), less densely distributed processes, less solid process stems, and a wall surface lacking spinules and coni (Zonneveld, 1997; MJH personal observation). The paratype of Echinidinium aculeatum has a polygonal opening and reticulum of dark lines as seen in some specimens of Echinidinium karaense (see above). As with Echinidinium karaense, this appears to be preservational because the holotype of Echinidinium aculeatum lacks these features but has a straight, slit-like opening interpreted to be part of the theropylic archeopyle (Zonneveld, 1997, fig. 5a; MJH personal observation).