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Cleistosphaeridium lumectum
Cleistosphaeridium lumectum, (Sarjeant, 1960) Davey et al., 1969
Originally Baltisphaeridium, subsequently (and now) Cleistosphaeridium.
Stover and Evitt, 1978, considered this to be a problematical species of Cleistosphaeridium.
This combination was not validly published in Davey et al., 1966, since these authors did not fully reference the basionym.
Holotype: Sarjeant, 1960, pl.6, fig.1, text-fig.2
Locus typicus: Ringstead Waxy Clay 1 foot below the base of the Ringstead Coral Bed at the top of the cliffs at Osmington Mills, Dorset (grid reference 817736)
Stratum typicum: Late Orxfordian
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Original description as Baltisphaeridium lumectum: [Sarjeant, 1960, p. 139]:
Diagnosis:
A species of Baltisphaeridium having an unornamented spheroidal shell, from which arise slender processes, simple, bifurcate or trifurcate, usually curved in some degree. The number of processes is such that 35 to 40 are seen around the shell periphery: their length is greater than two-thirds the shell diameter.
Description:
Shell dark yellowish brown in colour. The processes are of constant length. Near their tips they frequently bifurcate or trifurcate, the resultant branches not being of constant length on an individual process or between processes: equally frequently, however, they are simple.
Dimensions.
Type specimen: overall diameter 60 µm, diameter of shell 25 µm, spines c. 17 µm long. Range: overall diameters 45-65 µm.
Affinities: (p. 140):
In the combination of form, length, and number of the spines, Baltisphaeridium lumectum differs from all other species described. Baltiphaeridium multifurcatum (Deflandre, 1937), from the Cretaceous of France, has processes similar in form but much shorter (less than one-quarter the shell diameter): in addition, the shell surface of this species is covered by a "vermicular ornamentation" lacking in B. lumectum. The specimens attributed to B. polytrichum (Valensi, 1947) by Downie, 1957, from the Upper Kimmeridgian of Dorset, have simple or bifurcate processes less than half the shell diameter in length, but similar in number: their resemblance to B. Iumectum is such that they would perhaps be better named Baltisphaeridium sp. aff. Iumectum than referred to B. polytrichum a species having entirely simple spines in much greater density (Valensi, 1947, 1953).
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Courtinat, 1989, p.166: (Translation: LPP):
Remark:
SEM analysis indicates that this form possesses a (4AI(1a)) archaeopyle. The complete paratabulation formula could not be defined.
Originally Baltisphaeridium, subsequently (and now) Cleistosphaeridium.
Stover and Evitt, 1978, considered this to be a problematical species of Cleistosphaeridium.
This combination was not validly published in Davey et al., 1966, since these authors did not fully reference the basionym.
Holotype: Sarjeant, 1960, pl.6, fig.1, text-fig.2
Locus typicus: Ringstead Waxy Clay 1 foot below the base of the Ringstead Coral Bed at the top of the cliffs at Osmington Mills, Dorset (grid reference 817736)
Stratum typicum: Late Orxfordian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description as Baltisphaeridium lumectum: [Sarjeant, 1960, p. 139]:
Diagnosis:
A species of Baltisphaeridium having an unornamented spheroidal shell, from which arise slender processes, simple, bifurcate or trifurcate, usually curved in some degree. The number of processes is such that 35 to 40 are seen around the shell periphery: their length is greater than two-thirds the shell diameter.
Description:
Shell dark yellowish brown in colour. The processes are of constant length. Near their tips they frequently bifurcate or trifurcate, the resultant branches not being of constant length on an individual process or between processes: equally frequently, however, they are simple.
Dimensions.
Type specimen: overall diameter 60 µm, diameter of shell 25 µm, spines c. 17 µm long. Range: overall diameters 45-65 µm.
Affinities: (p. 140):
In the combination of form, length, and number of the spines, Baltisphaeridium lumectum differs from all other species described. Baltiphaeridium multifurcatum (Deflandre, 1937), from the Cretaceous of France, has processes similar in form but much shorter (less than one-quarter the shell diameter): in addition, the shell surface of this species is covered by a "vermicular ornamentation" lacking in B. lumectum. The specimens attributed to B. polytrichum (Valensi, 1947) by Downie, 1957, from the Upper Kimmeridgian of Dorset, have simple or bifurcate processes less than half the shell diameter in length, but similar in number: their resemblance to B. Iumectum is such that they would perhaps be better named Baltisphaeridium sp. aff. Iumectum than referred to B. polytrichum a species having entirely simple spines in much greater density (Valensi, 1947, 1953).
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Courtinat, 1989, p.166: (Translation: LPP):
Remark:
SEM analysis indicates that this form possesses a (4AI(1a)) archaeopyle. The complete paratabulation formula could not be defined.