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Filisphaera filifera ssp. filifera
Filisphaera filifera. subsp. filifera Head (ed.) 1993
Only those records confirmed by unequivocal photographic documentation are listed in this synonymy:
Filisphaera filifera Bujak, 1984, p. l 85, pl. 1, figs. 7-12; Mudie, 1987, pl. 4, fig. 6; Mudie, 1989, pl. 5, fig. 14; de Vernal and Mudie, 1989, pl. 4, figs. 1, 2; Head and Wrenn, 1992a, pl.6, figs.7-9, pl.7, figs.1-4; de Vernal et al., 1992, pl. 1, fig. 18.
Holotype: Head (ed.) 1993: pl. 3, fig. 1-3
Locus typicus: Bering Sea, DSDP site 185, core 7, section 4, interval 56-62 cm
Stratum typicum: Upper Pliocene
Diagnosis, Head (ed.) 1993, p. 236:. A subspecies of Filisphaera filifera characterized by relatively high (approximately 1.7-2.2 Ám) periphragmal septa.
Dimensions. Holotype: Length 56 Ám, breadth 47 Ám, wall thickness ca. 1.9 Ám. Range: Length 54 (55.0) 56 Ám, breadth 45 (46.5) 49Ám, wall thickness ca. 1.8 (2.0) 2.3 Ám. Six specimens were measured.
Description: Head (ed.) 1993: p. 236-237
The endophragm is visible only in optical section, appearing as a dark line, and is estimated to be about 0.1-0.2 Ám thick. The periphragm is composed of narrow septa that form a microreticulum (see Plate 3, figs. 1,4,7). Septa are nontabular except presumably where they meet the principal archeopyle suture. The septa impart a radially striate appearance in optical section (see Bujak, 1984), they are very narrow (about 0.2 Ám) and relatively high (about 1.7-2.2 Ám). There is some suggestion, in optical section, that some of these septa bifurcate at low angle--it is not certain if this is an optical effect. On all specimens, many lumina (measured near base of reticulum) are about 1.0-0.5 Ám or less in diameter, and on the holotype many are about 0.5 Ám or less. The larger lumina vary from about 1.0 to 2.0Ám in diameter depending on the specimen, and are about 1.5 Ám on the holotype. The apical lobe is present on at least five of six specimens examined and is about l Ám high (as for the holotype). The archeopyle is formed by loss of a single precingular plate on at least four of the six specimens examined, including the holotype, although Bujak (1984) additionally observed specimens with 2P archeopyles (Bujak,1984). The adapical margin of the archeopyle is irregular, while other margins are smooth to somewhat irregular. Angles of the adcingular margin are well defined on four specimens that permitting such observation.
Comparison. Filisphaera filifera subsp. filifera is distinguished from F. filifera pilosa by its higher periphragmal septa: about 1.7-2.2 Ám. for F. filifera filifera versus about 0.8 Ám for the holotype of F. filifera pilosa. It differs from F. microornata in having finer periphragmal microreticulation: diameter of lumina mostly about 1.5 Ám or less for Filisphaera filifera subsp. filifera versus about 2.0-2.5 Ám for F. microornata. Based on Strauss and Lund (1992), Filisphaera filifera subsp. filifera differs from Filisphaera(?) minuta by its larger size: cyst length 45-60 Ám (Bujak, 1984) for Filisphaera filifera subsp. filifera versus 35-43Ám for Filisphaera(?) minuta, although many details about the morphology of Filisphaera(?) minuta are presently unknown.
Stratigraphic Range. Filisphaera filifera subs p. filifera is known only from higher northern latitudes. It has been recorded from the Middle Miocene of DSDP Site 192, northern North Pacific (Bujak, 1984, table 1). It has a persistent highest occurrence in the Lower Pleistocene of northern high-latitude sites (de Vernal et al., 1992).
Only those records confirmed by unequivocal photographic documentation are listed in this synonymy:
Filisphaera filifera Bujak, 1984, p. l 85, pl. 1, figs. 7-12; Mudie, 1987, pl. 4, fig. 6; Mudie, 1989, pl. 5, fig. 14; de Vernal and Mudie, 1989, pl. 4, figs. 1, 2; Head and Wrenn, 1992a, pl.6, figs.7-9, pl.7, figs.1-4; de Vernal et al., 1992, pl. 1, fig. 18.
Holotype: Head (ed.) 1993: pl. 3, fig. 1-3
Locus typicus: Bering Sea, DSDP site 185, core 7, section 4, interval 56-62 cm
Stratum typicum: Upper Pliocene
Diagnosis, Head (ed.) 1993, p. 236:. A subspecies of Filisphaera filifera characterized by relatively high (approximately 1.7-2.2 Ám) periphragmal septa.
Dimensions. Holotype: Length 56 Ám, breadth 47 Ám, wall thickness ca. 1.9 Ám. Range: Length 54 (55.0) 56 Ám, breadth 45 (46.5) 49Ám, wall thickness ca. 1.8 (2.0) 2.3 Ám. Six specimens were measured.
Description: Head (ed.) 1993: p. 236-237
The endophragm is visible only in optical section, appearing as a dark line, and is estimated to be about 0.1-0.2 Ám thick. The periphragm is composed of narrow septa that form a microreticulum (see Plate 3, figs. 1,4,7). Septa are nontabular except presumably where they meet the principal archeopyle suture. The septa impart a radially striate appearance in optical section (see Bujak, 1984), they are very narrow (about 0.2 Ám) and relatively high (about 1.7-2.2 Ám). There is some suggestion, in optical section, that some of these septa bifurcate at low angle--it is not certain if this is an optical effect. On all specimens, many lumina (measured near base of reticulum) are about 1.0-0.5 Ám or less in diameter, and on the holotype many are about 0.5 Ám or less. The larger lumina vary from about 1.0 to 2.0Ám in diameter depending on the specimen, and are about 1.5 Ám on the holotype. The apical lobe is present on at least five of six specimens examined and is about l Ám high (as for the holotype). The archeopyle is formed by loss of a single precingular plate on at least four of the six specimens examined, including the holotype, although Bujak (1984) additionally observed specimens with 2P archeopyles (Bujak,1984). The adapical margin of the archeopyle is irregular, while other margins are smooth to somewhat irregular. Angles of the adcingular margin are well defined on four specimens that permitting such observation.
Comparison. Filisphaera filifera subsp. filifera is distinguished from F. filifera pilosa by its higher periphragmal septa: about 1.7-2.2 Ám. for F. filifera filifera versus about 0.8 Ám for the holotype of F. filifera pilosa. It differs from F. microornata in having finer periphragmal microreticulation: diameter of lumina mostly about 1.5 Ám or less for Filisphaera filifera subsp. filifera versus about 2.0-2.5 Ám for F. microornata. Based on Strauss and Lund (1992), Filisphaera filifera subsp. filifera differs from Filisphaera(?) minuta by its larger size: cyst length 45-60 Ám (Bujak, 1984) for Filisphaera filifera subsp. filifera versus 35-43Ám for Filisphaera(?) minuta, although many details about the morphology of Filisphaera(?) minuta are presently unknown.
Stratigraphic Range. Filisphaera filifera subs p. filifera is known only from higher northern latitudes. It has been recorded from the Middle Miocene of DSDP Site 192, northern North Pacific (Bujak, 1984, table 1). It has a persistent highest occurrence in the Lower Pleistocene of northern high-latitude sites (de Vernal et al., 1992).