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Pervosphaeridium pseudhystrichodinium
Pervosphaeridium pseudohystrichodinium (Deflandre, 1937) Yun, 1981; Emendation: Davey, 1969a, p.163, as Exochosphaeridium pseudhystrichodinium.
Originally Hystrichosphaeridium, subsequently Baltisphaeridium (an acritarch genus), thirdly Exochosphaeridium, fourthly (and now) Pervosphaeridium.
Taxonomic junior synonym: Hystrichosphaeridium (al. Exochosphaeridium) palmatum, according to Yun Hyesu (1981, p.29). Ziaja (1989, p.214) considered Exochosphaeridium muelleri to be a possible taxonomic junior synonym of Pervosphaeridium pseudhystrichodinium. Yun Hyesu (1981, p.29) considered Xanthidium hirsutum of Ehrenberg, 1837b (name not validly published) to be a possible taxonomic junior synonym of this species.
Holotype: Deflandre, 1937, pl.15 [al. pl.12], fig.3
Age: Late Cretaceous
Description: Yun 1981, p. 29-30: Pervosphaeridium pseudhystrichodinium
The spherical CB consists of a ca. 1.2 µm thick, coarsely perforated (diameter of perforation = 1 µm) inner layer and a finely folded outer layer with interspersed rows of fine pores here and there. The spine base is oval in outline and here it is particularly evident how the fine folds, which extend from the distal spine end, widen radially and unite with those of the neighboring spine. Numerous (3-4 per paratabula), relatively uniformly structured, hollow spines arise from the periphragma and taper gradually and continuously toward the distal end. Their tips are closed, obtuse, punctiform, slightly thickened or rarely pointed. Occasionally they are forked medially or proximally, but never at the tip. The number of spines of such structure varies depending on the specimen, they are usually restricted to the polar or paracingular region. In some specimens the polar processes are slightly larger than the others. The precingular archaeopyle, ca. 36 µm in diameter, is formed by the removal of two paratabulae; it is trapezoidal with recessed upper marginal line.
Material: Ca. 120 specimens.
Measurements: Size of CB = 48 (52) 57 x 54 (57) 66 µm, max. length of processes = 21 (25.5) 30 µm, number of processes = 60-70.
Remarks: Yun 1981, p. 29-30
In the discussion on the taxonomy and nomenclature concerning the species "hirsutum" (EHRENBERG) and "striolatum" (DEFLANDRE), DAVEY, DOWNIE, SARJEANT & WILLIAMS did recognize the priority of the species "striolatum" after DEFLANDRE (1946, p. 111) under the assumption that the two represent the same species, as was claimed also by LEJEUNE-CARPENTIER 1941. Mrs. DEFLANDRE-RIGAUD kindly gave me permission to examine the holotypes as well as the paratypes of Hystrichosphaeridium striolatum and H. pseudhystrichodinium. It became evident that H. striolatum cannot be synonymous with Xanthidium hirsutum (?) EHRENBERG for the following reason. H.striolatum has partially very fine or wide, thin, probably solid, distally or medially multifurcate processes the free ends of which are never thickened, rounded or truncated, but are only acuminate. Moreover, the fine, small folds with perforations on the CB-surface, which widen and radiate evenly from the spines over the CB, are missing. In contrast to this form, the holotype of X. hirsutum and the same species O. WETZEL. 1933, which was reexamined and newly depicted by LEJEUNE-CARPENTIER 1941, have slurdier, probably hollow, either simple or proximally, medially or rarely distally bifurcate processes, the free ends of which invariably are rounded, truncated or slightly thickened. Furthermore, the radial ribs around the spine are well developed. What is more, on account of the same spine morphology, X. hirsutum (?) EHRENBERG is identical to H. pseudhystrichodinium. Although the surface structure on the holotype of the latter species was not clearly visible, it was well recognizable on the paratype (DEFLANDRE 1937, Pl. XV, Fig. 4). The forms, which were later described as H. striolatum, show a greater resemblance to X. hirsutum (?) or H. pseudhystrichodinium than to their holotype. It is my opinion,therefore, that since DEFLANDRE no further reliable description was carried out. H. palmatum (DEFLANDRE & COURTEVILLE 1939) shows insufficient differences to the present species. The spines in H. palmatum are not flattened, but slightly longer. This difference is within the range of variability however. My specimens most closely resemble the forms described by COOKSON & HUGHES 1964 and NORVICK 1976.
Comparison: This species has partially forked, shorter spines, while the spines in E. spinosum are longer, slenderer and only simple. Established so far: Albian-Danian, cosmopolitan.
Originally Hystrichosphaeridium, subsequently Baltisphaeridium (an acritarch genus), thirdly Exochosphaeridium, fourthly (and now) Pervosphaeridium.
Taxonomic junior synonym: Hystrichosphaeridium (al. Exochosphaeridium) palmatum, according to Yun Hyesu (1981, p.29). Ziaja (1989, p.214) considered Exochosphaeridium muelleri to be a possible taxonomic junior synonym of Pervosphaeridium pseudhystrichodinium. Yun Hyesu (1981, p.29) considered Xanthidium hirsutum of Ehrenberg, 1837b (name not validly published) to be a possible taxonomic junior synonym of this species.
Holotype: Deflandre, 1937, pl.15 [al. pl.12], fig.3
Age: Late Cretaceous
Description: Yun 1981, p. 29-30: Pervosphaeridium pseudhystrichodinium
The spherical CB consists of a ca. 1.2 µm thick, coarsely perforated (diameter of perforation = 1 µm) inner layer and a finely folded outer layer with interspersed rows of fine pores here and there. The spine base is oval in outline and here it is particularly evident how the fine folds, which extend from the distal spine end, widen radially and unite with those of the neighboring spine. Numerous (3-4 per paratabula), relatively uniformly structured, hollow spines arise from the periphragma and taper gradually and continuously toward the distal end. Their tips are closed, obtuse, punctiform, slightly thickened or rarely pointed. Occasionally they are forked medially or proximally, but never at the tip. The number of spines of such structure varies depending on the specimen, they are usually restricted to the polar or paracingular region. In some specimens the polar processes are slightly larger than the others. The precingular archaeopyle, ca. 36 µm in diameter, is formed by the removal of two paratabulae; it is trapezoidal with recessed upper marginal line.
Material: Ca. 120 specimens.
Measurements: Size of CB = 48 (52) 57 x 54 (57) 66 µm, max. length of processes = 21 (25.5) 30 µm, number of processes = 60-70.
Remarks: Yun 1981, p. 29-30
In the discussion on the taxonomy and nomenclature concerning the species "hirsutum" (EHRENBERG) and "striolatum" (DEFLANDRE), DAVEY, DOWNIE, SARJEANT & WILLIAMS did recognize the priority of the species "striolatum" after DEFLANDRE (1946, p. 111) under the assumption that the two represent the same species, as was claimed also by LEJEUNE-CARPENTIER 1941. Mrs. DEFLANDRE-RIGAUD kindly gave me permission to examine the holotypes as well as the paratypes of Hystrichosphaeridium striolatum and H. pseudhystrichodinium. It became evident that H. striolatum cannot be synonymous with Xanthidium hirsutum (?) EHRENBERG for the following reason. H.striolatum has partially very fine or wide, thin, probably solid, distally or medially multifurcate processes the free ends of which are never thickened, rounded or truncated, but are only acuminate. Moreover, the fine, small folds with perforations on the CB-surface, which widen and radiate evenly from the spines over the CB, are missing. In contrast to this form, the holotype of X. hirsutum and the same species O. WETZEL. 1933, which was reexamined and newly depicted by LEJEUNE-CARPENTIER 1941, have slurdier, probably hollow, either simple or proximally, medially or rarely distally bifurcate processes, the free ends of which invariably are rounded, truncated or slightly thickened. Furthermore, the radial ribs around the spine are well developed. What is more, on account of the same spine morphology, X. hirsutum (?) EHRENBERG is identical to H. pseudhystrichodinium. Although the surface structure on the holotype of the latter species was not clearly visible, it was well recognizable on the paratype (DEFLANDRE 1937, Pl. XV, Fig. 4). The forms, which were later described as H. striolatum, show a greater resemblance to X. hirsutum (?) or H. pseudhystrichodinium than to their holotype. It is my opinion,therefore, that since DEFLANDRE no further reliable description was carried out. H. palmatum (DEFLANDRE & COURTEVILLE 1939) shows insufficient differences to the present species. The spines in H. palmatum are not flattened, but slightly longer. This difference is within the range of variability however. My specimens most closely resemble the forms described by COOKSON & HUGHES 1964 and NORVICK 1976.
Comparison: This species has partially forked, shorter spines, while the spines in E. spinosum are longer, slenderer and only simple. Established so far: Albian-Danian, cosmopolitan.