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Oligosphaeridium complex
Oligosphaeridium *complex (White, 1842, p.39, pl.4, fig.11) Davey and Williams, 1966b, p.71–74.
Holotype: White, 1842, pl.4, fig.11, lost according to Davey and Williams (1966b, p.74).
Neotype: Davey and Williams, 1966b, pl.7, fig.1, designated by Davey and Williams (1966b, p.71).
Originally Xanthidium tubiferum var. complex (Appendix A), subsequently Xanthidium complex (Appendix A), thirdly Hystrichosphaeridium complex, fourthly (and now) Oligosphaeridium complex.
Taxonomic junior synonyms: Hystrichosphaeridium elegantulum, according to Deflandre (1946b, p.111); Hystrichosphaeridium himalayense, according to Jain and Garg (1986b, p.64);
Oligosphaeridium cephalum, according to Lejeune-Carpentier and Sarjeant (1981, p.9) and Jain (1982, p.52);
Geodia? irregularis, according to Harker and Sarjeant in Harker et al. (1990, p.59).
Srivastava (1995, p.316) indicated that the epithet should be rendered as "complexum". In Latin, "complexus" is an adjective derived from the verb "complector" (= to embrace, clasp). White (1842) may have been referring to the process endings in this species, which expand distally and may be imagined to reach out to "clasp", in which case the epithet would indeed be properly rendered as "complexum". However, he may have wished to imply the English meaning of the word "complex", believing, incorrectly, that the word also existed in Latin, parallel to Latin words such as "triplex" and "felix", which retain the same ending regardless of gender. Given the uncertainty of White's original intent, and the long-standing stability of the epithet as "complex", we prefer to retain the latter spelling, considering it a "fantasy" or "neo-latin name". (We acknowledge discussion with J. Jansonius, upon which the preceding sentences are based.)
Age: Senonian.
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Oligosphaeridium complex (White, 1842) Davey and Williams, 1969. Emended diagnosis from Davey and Williams (1966b, p.71) Central body subspherical to ovoidal. Wall composed of endophragm and periphragm, the latter giving rise to the processes. Processes simple or branched, cylindrical for most of their length, open and expanded distally with aculeate or secate margin. Reflected tabulation inferred 4', 6", 5-6"’, 1p, 1"”. Apical archeopyle usually present having zig-zag margin. Processes in complete specimen not exceeding 18. Their specimens, Size: central body 29-58 µm, process length 29-58 µm.
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Original description: White 1842, p. 39: Xanthidium tubiferum complex
Emended diagnosis: Davey and Williams 1966, p. 71-72
Central body subspherical to ovoidal. Wall composed of thin endophragm and periphragm, the latter giving rise to processes. Processes simple or branched, cylindrical for most of their length, open and expanded distally with aculeate or secate margin. Reflected tabulation inferred 4', 6'', 5-6''', 1p, 1''''. Apical archaeopyle usually present having a zigzag margin. Processes in complete specimens not exceeding 18.
Dimensions: Range: diameter of central body 34-55 µm, length of processes 22-43 µm.
Description: Davey and Williams 1966, p. 72
In the specimens from the Cenomanian, the periphragm of the central body is smooth or very slightly granular. The processes are cylindrical for most of their length, with an expanded opening distally, the margin of which is developed into aculei and secae can be simple or branched, erect or patulate, orthogonal or even recurved. Where the processes meet the central body there is often a clearly marked ring indicating the point of divergence of the endophragm and periphragm. The wall of the processes is smooth or faintly fibrous; their length usually measures between the radius and the diameter of the central body. The small number of processes and the apical archaeopyle, when present, enable one readily to determine the tabulation of O.complex as reflected by the position of the processes.
Examples from the Speeton Clay (Barremian) of Yorkshire are very similar to the forms illustrated by Eisenack, 1958. The periphragm of the central body is often slightly granular and some of the processes are more deeply divided and show more variation than is usual in this species. 11 specimens were measured, the diameter of the central body being 35-62 µm and the length of the processes 13-47 µm.
Specimens from the London Clay (Ypresian) strongly resemble the Cenomanian forms, the processes perhaps being a little stouteer. Diameter of central body 29-58 µm, length of processes 23-39 µm (6 specimans measured).
Holotype: White, 1842, pl.4, fig.11, lost according to Davey and Williams (1966b, p.74).
Neotype: Davey and Williams, 1966b, pl.7, fig.1, designated by Davey and Williams (1966b, p.71).
Originally Xanthidium tubiferum var. complex (Appendix A), subsequently Xanthidium complex (Appendix A), thirdly Hystrichosphaeridium complex, fourthly (and now) Oligosphaeridium complex.
Taxonomic junior synonyms: Hystrichosphaeridium elegantulum, according to Deflandre (1946b, p.111); Hystrichosphaeridium himalayense, according to Jain and Garg (1986b, p.64);
Oligosphaeridium cephalum, according to Lejeune-Carpentier and Sarjeant (1981, p.9) and Jain (1982, p.52);
Geodia? irregularis, according to Harker and Sarjeant in Harker et al. (1990, p.59).
Srivastava (1995, p.316) indicated that the epithet should be rendered as "complexum". In Latin, "complexus" is an adjective derived from the verb "complector" (= to embrace, clasp). White (1842) may have been referring to the process endings in this species, which expand distally and may be imagined to reach out to "clasp", in which case the epithet would indeed be properly rendered as "complexum". However, he may have wished to imply the English meaning of the word "complex", believing, incorrectly, that the word also existed in Latin, parallel to Latin words such as "triplex" and "felix", which retain the same ending regardless of gender. Given the uncertainty of White's original intent, and the long-standing stability of the epithet as "complex", we prefer to retain the latter spelling, considering it a "fantasy" or "neo-latin name". (We acknowledge discussion with J. Jansonius, upon which the preceding sentences are based.)
Age: Senonian.
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Oligosphaeridium complex (White, 1842) Davey and Williams, 1969. Emended diagnosis from Davey and Williams (1966b, p.71) Central body subspherical to ovoidal. Wall composed of endophragm and periphragm, the latter giving rise to the processes. Processes simple or branched, cylindrical for most of their length, open and expanded distally with aculeate or secate margin. Reflected tabulation inferred 4', 6", 5-6"’, 1p, 1"”. Apical archeopyle usually present having zig-zag margin. Processes in complete specimen not exceeding 18. Their specimens, Size: central body 29-58 µm, process length 29-58 µm.
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Original description: White 1842, p. 39: Xanthidium tubiferum complex
Emended diagnosis: Davey and Williams 1966, p. 71-72
Central body subspherical to ovoidal. Wall composed of thin endophragm and periphragm, the latter giving rise to processes. Processes simple or branched, cylindrical for most of their length, open and expanded distally with aculeate or secate margin. Reflected tabulation inferred 4', 6'', 5-6''', 1p, 1''''. Apical archaeopyle usually present having a zigzag margin. Processes in complete specimens not exceeding 18.
Dimensions: Range: diameter of central body 34-55 µm, length of processes 22-43 µm.
Description: Davey and Williams 1966, p. 72
In the specimens from the Cenomanian, the periphragm of the central body is smooth or very slightly granular. The processes are cylindrical for most of their length, with an expanded opening distally, the margin of which is developed into aculei and secae can be simple or branched, erect or patulate, orthogonal or even recurved. Where the processes meet the central body there is often a clearly marked ring indicating the point of divergence of the endophragm and periphragm. The wall of the processes is smooth or faintly fibrous; their length usually measures between the radius and the diameter of the central body. The small number of processes and the apical archaeopyle, when present, enable one readily to determine the tabulation of O.complex as reflected by the position of the processes.
Examples from the Speeton Clay (Barremian) of Yorkshire are very similar to the forms illustrated by Eisenack, 1958. The periphragm of the central body is often slightly granular and some of the processes are more deeply divided and show more variation than is usual in this species. 11 specimens were measured, the diameter of the central body being 35-62 µm and the length of the processes 13-47 µm.
Specimens from the London Clay (Ypresian) strongly resemble the Cenomanian forms, the processes perhaps being a little stouteer. Diameter of central body 29-58 µm, length of processes 23-39 µm (6 specimans measured).