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Exochosphaeridium rhopalophorum
From Fensome et al., 2019:
Exochosphaeridium rhopalophorum (Valensi, 1955a, p.36, fig.1C) Lentin and Williams, 1985, p.131. Holotype: Valensi, 1955a, fig.1C. Originally Hystrichosphaeridium, subsequently (and now) Exochosphaeridium. Age: Late Cretaceous.
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Original description (Valensi, 1955a) (translated from French):
Hystrichosphaeridium rhopalophorum n. sp.
Fig. 1 C.
HOLOTYPE: Cretaceous Slex from Venesmes. The shell, slightly ellipsoidal in outline, is bristling with a large number of processes about a third of its major axis in length. These club-shaped processes insert onto the shell through their swollen portion.
The base of these processes is very strongly enlarged, conical, or potbellied; their narrowed end generally originates at a third of their length; sometimes, it simply extends the base, gradually thinning, or, on the contrary, separates from it by a more or less pronounced constriction. The processes are hollow, and their cavity does not appear to communicate with that of the shell.
The surface of the shell is finely granular and dark yellow in color. The wingspan of Hystrichosphaeridium rhopalophorum is 47 to 50 μ, the major axis of the shell alone measures 32 μ and its minor axis 26 μ. The processes are about ten μ long.
Hystrichosphaeridium rhopalophorum is reminiscent of Micrhystridium lagynophorum from the Middle Jurassic of Normandy in the shape of its processes. However, it differs in its size (47 to 50 μ wingspan, instead of 30 to 33 μ), the greater density of its processes, which are circular or elliptical in section but never polygonal, and the absence of membranous ridges connecting them.
The same Venesmes flint provided me with two other specimens of this species.
Exochosphaeridium rhopalophorum (Valensi, 1955a, p.36, fig.1C) Lentin and Williams, 1985, p.131. Holotype: Valensi, 1955a, fig.1C. Originally Hystrichosphaeridium, subsequently (and now) Exochosphaeridium. Age: Late Cretaceous.
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Original description (Valensi, 1955a) (translated from French):
Hystrichosphaeridium rhopalophorum n. sp.
Fig. 1 C.
HOLOTYPE: Cretaceous Slex from Venesmes. The shell, slightly ellipsoidal in outline, is bristling with a large number of processes about a third of its major axis in length. These club-shaped processes insert onto the shell through their swollen portion.
The base of these processes is very strongly enlarged, conical, or potbellied; their narrowed end generally originates at a third of their length; sometimes, it simply extends the base, gradually thinning, or, on the contrary, separates from it by a more or less pronounced constriction. The processes are hollow, and their cavity does not appear to communicate with that of the shell.
The surface of the shell is finely granular and dark yellow in color. The wingspan of Hystrichosphaeridium rhopalophorum is 47 to 50 μ, the major axis of the shell alone measures 32 μ and its minor axis 26 μ. The processes are about ten μ long.
Hystrichosphaeridium rhopalophorum is reminiscent of Micrhystridium lagynophorum from the Middle Jurassic of Normandy in the shape of its processes. However, it differs in its size (47 to 50 μ wingspan, instead of 30 to 33 μ), the greater density of its processes, which are circular or elliptical in section but never polygonal, and the absence of membranous ridges connecting them.
The same Venesmes flint provided me with two other specimens of this species.