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Membranilarnacia glabra
From Fensome et al., 2019:
Membranilarnacia glabra Agelopoulos, 1967, p.47–49, pl.12, fig.5; pl.13, figs.2–9; text-fig.6. Holotype: Agelopoulos, 1967, pl.12,
fig.5; text-fig.6. Age: Late Eocene.
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Original description: [Agelopoulos, 1967] (translated from German):
Membranilarnacia glabra n. sp.
Pl. 12, Fig. 5, Pl. 13, Figs. 2, 9, Fig. 6
1935 Spiny ball in outer shell, Membranilarnax sp. indet. - O. WETZEL, Die Mikropalaeontologie ..... p. 62, Pl. 10, Fig. 3
Holotype: Prb. 23 No. 262, Pl. 12, Fig. 5, Fig. 6
Paratypoids: Prb. 23 No. 253 and Prb. 23 No. 253, Pl. 13, Fig. 2, 9
Locus typicus: Heiligenhafen (Hohes Ufer)
Stratum typicum: Upper Eocene
Derivatio nominis: Glabra = the smooth one.
Diagnosis: Central body spherical to oval, delicate, transparent, and thin-walled, concentrically surrounded by an equally transparent and delicate outer shell; this shell is supported by appendages. The surface of both shells is sculptured.
Description: This form is present in the examined specimens, some of which are very well preserved. The central shell is spherical to predominantly oval, transparent, and colorless. It sometimes shows fine sculpture. As mentioned above, it is very delicate and more brittle than usual. Its delicate structure results in its easy breakability. The base of the processes often causes polygonal pieces to break off. An appendage can sometimes be seen in the center of such pieces. The central shell is concentrically surrounded by an equally fine and transparent shell. Its shape is sometimes spherical, but occasionally it also shows slight deviations here and there. Like the inner shell, it is colorless and slightly sculptured. This is supported by long, narrow processes, occasionally short and broad ones, which stand perpendicular to the central shell. They consist of thin, closely spaced fibers that are clearly visible either at the base or at the end. At the end, the processes expand more or less into a funnel. All appendages sit on the inner shell, with broad bases. It is difficult to determine whether they are open at their ends. No escape holes were observed.
Additions: This form shows a certain similarity to Cordosphaeridium diktyoplokus KLUMPP 1953. The shape and fine structure of the inner shell, as well as the exposed pieces, emphasize this. There is also a similarity in the development of the processes. The differences between the two forms are that in Cordosphaeridium diktyoplokus the processes are open at the ends, whereas in the present species they are not. Another key difference is the presence of a second shell, which is absent in Cordosphaeridium diktyoplokus.
There appears to be another similarity with Membranilarnacia leptoderma (COOKSON & EISENACK 1958). However, the central shells of this species are quite thick-walled, and the widely spaced processes are very slender.
Number of specimens: 40
Dimensions: Holotype: Total diameter of the central shell 109 μ, measured longitudinally, 61 μ, measured transversely 54 μ. The length of the appendages varies between 26 and 32 μ.
Paratypoids: In the paratypoids, the total diameter varies between 86 and 102 μ. The diameter of the central shell, measured longitudinally, varies between 45 and 58 μ, and transversely between 38 and 54 μ. The length of the appendages varies between 18 and 32 μ.
The total diameter of the other specimens varies between 90 and 109 μ. The diameter of the central shell, measured longitudinally, varies between 48 and 58 μ, and transversely between 38 and 48 μ. The length of the appendages varies between 19 and 32 μ.
Occurrence: Upper Eocene.
Membranilarnacia glabra Agelopoulos, 1967, p.47–49, pl.12, fig.5; pl.13, figs.2–9; text-fig.6. Holotype: Agelopoulos, 1967, pl.12,
fig.5; text-fig.6. Age: Late Eocene.
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Original description: [Agelopoulos, 1967] (translated from German):
Membranilarnacia glabra n. sp.
Pl. 12, Fig. 5, Pl. 13, Figs. 2, 9, Fig. 6
1935 Spiny ball in outer shell, Membranilarnax sp. indet. - O. WETZEL, Die Mikropalaeontologie ..... p. 62, Pl. 10, Fig. 3
Holotype: Prb. 23 No. 262, Pl. 12, Fig. 5, Fig. 6
Paratypoids: Prb. 23 No. 253 and Prb. 23 No. 253, Pl. 13, Fig. 2, 9
Locus typicus: Heiligenhafen (Hohes Ufer)
Stratum typicum: Upper Eocene
Derivatio nominis: Glabra = the smooth one.
Diagnosis: Central body spherical to oval, delicate, transparent, and thin-walled, concentrically surrounded by an equally transparent and delicate outer shell; this shell is supported by appendages. The surface of both shells is sculptured.
Description: This form is present in the examined specimens, some of which are very well preserved. The central shell is spherical to predominantly oval, transparent, and colorless. It sometimes shows fine sculpture. As mentioned above, it is very delicate and more brittle than usual. Its delicate structure results in its easy breakability. The base of the processes often causes polygonal pieces to break off. An appendage can sometimes be seen in the center of such pieces. The central shell is concentrically surrounded by an equally fine and transparent shell. Its shape is sometimes spherical, but occasionally it also shows slight deviations here and there. Like the inner shell, it is colorless and slightly sculptured. This is supported by long, narrow processes, occasionally short and broad ones, which stand perpendicular to the central shell. They consist of thin, closely spaced fibers that are clearly visible either at the base or at the end. At the end, the processes expand more or less into a funnel. All appendages sit on the inner shell, with broad bases. It is difficult to determine whether they are open at their ends. No escape holes were observed.
Additions: This form shows a certain similarity to Cordosphaeridium diktyoplokus KLUMPP 1953. The shape and fine structure of the inner shell, as well as the exposed pieces, emphasize this. There is also a similarity in the development of the processes. The differences between the two forms are that in Cordosphaeridium diktyoplokus the processes are open at the ends, whereas in the present species they are not. Another key difference is the presence of a second shell, which is absent in Cordosphaeridium diktyoplokus.
There appears to be another similarity with Membranilarnacia leptoderma (COOKSON & EISENACK 1958). However, the central shells of this species are quite thick-walled, and the widely spaced processes are very slender.
Number of specimens: 40
Dimensions: Holotype: Total diameter of the central shell 109 μ, measured longitudinally, 61 μ, measured transversely 54 μ. The length of the appendages varies between 26 and 32 μ.
Paratypoids: In the paratypoids, the total diameter varies between 86 and 102 μ. The diameter of the central shell, measured longitudinally, varies between 45 and 58 μ, and transversely between 38 and 54 μ. The length of the appendages varies between 18 and 32 μ.
The total diameter of the other specimens varies between 90 and 109 μ. The diameter of the central shell, measured longitudinally, varies between 48 and 58 μ, and transversely between 38 and 48 μ. The length of the appendages varies between 19 and 32 μ.
Occurrence: Upper Eocene.