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Exochosphaeridium bifidum
Exochospaeridium bifidum (Clarke and Verdier, 1967) Clarke et al., 196; Emendation: Davey, 1969b, p.26,28, as Exochosphaeridium bifidum.
Originally Baltisphaeridium, subsequently (and now) Exochosphaeridium.
Taxonomic senior synonym: Hystrichosphaeridium (now Exochosphaeridium) majus according to Peyrot (2011, p.284).
The emendation by Davey (1969b) was given under the heading for the species but probably more appropriately applies to the autonym. Davey (1969b, p.27,29) also proposed this combination, considering it to be not validly published in Clarke et al. (1968).
Holotype: Clarke and Verdier, 1967, pl. 17, fig. 5
Paratype: Clarke and Verdier, 1967
Locus typicus: Culver Cliff, Isle of Wight, S England
Stratum typicum: Cenomanian-Campanian
Translation Marheinecke, 1992: LPP
Original description: Clarke and Verdier, 1967, p. 72-73: Baltisphaeridium bifidum
Diagnosis: A species of Baltisphaeridium diagnosed by the thick wall and long processes which have slightly bifid or expanded tops. The base of the processes and the body generally exhibit a striate appearance.
Description (annotated): Main body circular, wall 2-3 µm thick, bearing long distinct processes. Processes generally discrete, only occasionally being joined at their bases. Each process widens at its base and possesses a short bifurcation or expansion distally. The sculpture of the body, which extends in some cases onto the base of the processes, consists of elongated perforations which imparts a striate appearance to the wall and especially to the proximal part of the processes. An apical opening is present on some specimens.
Dimensions: Holotype: diameter of body, 66 µm, length of processes, 22 µm. Range: diameter of body, 44-72 µm, length of processes, 13-34 µm.
Clarke et al., 1968, p. 182
Baltisphaeridium bifidum Clarke and Verdier, 1967 is now considered to have a precingular archaeopyle. Its transfer to Exochosphaeridium Davey et al., 1966, as Exochosphaeridium bifidum is therefore proposed.
Revised description: May, 1980, p.52
Cyst main body ovoidal. Bilayered; endophragm ca. 1.5 Ám thick, formed of vertical fibers or bacula; periphragm ca. 0.5 Ám thick, formed of short fibers matted or arranged into a fine reticulum (lacunae measuring ca. 0.4 Ám across). Processes formed of periphragm, generally spaced more than 5 Ám apart. Process bases formed of coarse elongate fibers; process shafts striate to finely to coarsely fibrous. Processes taper distally to a bifid or minutely capitate distal tip. Apical process tuftlike, being of broad base, more or less parallel sided, up to 8 Ám wide, coarsely fibrous, distally branching into 2 to several tapering branchlets; each branchlet distally bifid to minutely pacitate. Process arrangement appears nontabular; tabulation unknown. Cingulum not observed, except along the posterior edge of the precingular archeopyle; indicated by a relatively smooth strip bordered beneath by a row of processes aligned in the direction of the cingulum. Sulcus not observed. Archeopyle precingular (Type P).
The most variable feature of this species is process number and shape. One extreme variant may display numerous, short, slender (up to 8 Ám) processes, while another extreme variant may display long (up to 29 Ám) relatively broad (up to 12 Ám wide), hollow to solid, proximally and distally flaring, fibrous Cordosphaeridium-like processes. Both extremes are relatively rare; most specimens being as described in the above paragraph. Intermediate forms bear a combination of the broad and slender processes.
Emended description: Marheinecke, 1992, p.51: Exochosphaeridium bifidum ssp. bifidum
Cyst sphaeroidal to subsphaeroidal. Wall thick, composed of pedium and spongious luxuria, developing a net-like tegillum. Luxuria forms c. 60-80 thin, solid processes. Base of processes broadened and striate, distal ends usually bifurcate or multifurcate. Processes intraareate, three to four processes per area. Cingulum marked by a row of processes, seldom connected by a weak ridge. Sulcal processes in generall thinner, but not always distinguishable. Apical process larger and branched. Antapical process consists of two fused processes. Archeopyle precingular 3"", operculum secate.
Affinities:
Clarke and Verdier, 1969, p. 73: Baltisphaeridium bifidum
It is evident that B. bifidum must be compared with B. striolatum (Defl. 1937) Downie and Sarjeant 1963. From an examination of the holotype of B. striolatum it is concluded that B. bifidum differs from it in the more constant form of the processes, the presence of bifid or expanded tops, and the absence of low sutures connecting the bases of processes.
Originally Baltisphaeridium, subsequently (and now) Exochosphaeridium.
Taxonomic senior synonym: Hystrichosphaeridium (now Exochosphaeridium) majus according to Peyrot (2011, p.284).
The emendation by Davey (1969b) was given under the heading for the species but probably more appropriately applies to the autonym. Davey (1969b, p.27,29) also proposed this combination, considering it to be not validly published in Clarke et al. (1968).
Holotype: Clarke and Verdier, 1967, pl. 17, fig. 5
Paratype: Clarke and Verdier, 1967
Locus typicus: Culver Cliff, Isle of Wight, S England
Stratum typicum: Cenomanian-Campanian
Translation Marheinecke, 1992: LPP
Original description: Clarke and Verdier, 1967, p. 72-73: Baltisphaeridium bifidum
Diagnosis: A species of Baltisphaeridium diagnosed by the thick wall and long processes which have slightly bifid or expanded tops. The base of the processes and the body generally exhibit a striate appearance.
Description (annotated): Main body circular, wall 2-3 µm thick, bearing long distinct processes. Processes generally discrete, only occasionally being joined at their bases. Each process widens at its base and possesses a short bifurcation or expansion distally. The sculpture of the body, which extends in some cases onto the base of the processes, consists of elongated perforations which imparts a striate appearance to the wall and especially to the proximal part of the processes. An apical opening is present on some specimens.
Dimensions: Holotype: diameter of body, 66 µm, length of processes, 22 µm. Range: diameter of body, 44-72 µm, length of processes, 13-34 µm.
Clarke et al., 1968, p. 182
Baltisphaeridium bifidum Clarke and Verdier, 1967 is now considered to have a precingular archaeopyle. Its transfer to Exochosphaeridium Davey et al., 1966, as Exochosphaeridium bifidum is therefore proposed.
Revised description: May, 1980, p.52
Cyst main body ovoidal. Bilayered; endophragm ca. 1.5 Ám thick, formed of vertical fibers or bacula; periphragm ca. 0.5 Ám thick, formed of short fibers matted or arranged into a fine reticulum (lacunae measuring ca. 0.4 Ám across). Processes formed of periphragm, generally spaced more than 5 Ám apart. Process bases formed of coarse elongate fibers; process shafts striate to finely to coarsely fibrous. Processes taper distally to a bifid or minutely capitate distal tip. Apical process tuftlike, being of broad base, more or less parallel sided, up to 8 Ám wide, coarsely fibrous, distally branching into 2 to several tapering branchlets; each branchlet distally bifid to minutely pacitate. Process arrangement appears nontabular; tabulation unknown. Cingulum not observed, except along the posterior edge of the precingular archeopyle; indicated by a relatively smooth strip bordered beneath by a row of processes aligned in the direction of the cingulum. Sulcus not observed. Archeopyle precingular (Type P).
The most variable feature of this species is process number and shape. One extreme variant may display numerous, short, slender (up to 8 Ám) processes, while another extreme variant may display long (up to 29 Ám) relatively broad (up to 12 Ám wide), hollow to solid, proximally and distally flaring, fibrous Cordosphaeridium-like processes. Both extremes are relatively rare; most specimens being as described in the above paragraph. Intermediate forms bear a combination of the broad and slender processes.
Emended description: Marheinecke, 1992, p.51: Exochosphaeridium bifidum ssp. bifidum
Cyst sphaeroidal to subsphaeroidal. Wall thick, composed of pedium and spongious luxuria, developing a net-like tegillum. Luxuria forms c. 60-80 thin, solid processes. Base of processes broadened and striate, distal ends usually bifurcate or multifurcate. Processes intraareate, three to four processes per area. Cingulum marked by a row of processes, seldom connected by a weak ridge. Sulcal processes in generall thinner, but not always distinguishable. Apical process larger and branched. Antapical process consists of two fused processes. Archeopyle precingular 3"", operculum secate.
Affinities:
Clarke and Verdier, 1969, p. 73: Baltisphaeridium bifidum
It is evident that B. bifidum must be compared with B. striolatum (Defl. 1937) Downie and Sarjeant 1963. From an examination of the holotype of B. striolatum it is concluded that B. bifidum differs from it in the more constant form of the processes, the presence of bifid or expanded tops, and the absence of low sutures connecting the bases of processes.