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Membranilarnacia tenella
From Fensome et al., 2019:
Membranilarnacia? tenella Morgenroth, 1968, p.554–555, pl.48, figs.2–4. Holotype: Morgenroth, 1968, pl.48, figs.2–3. Originally Membranilarnacia, subsequently (and now) Membranilarnacia?. Questionable assignment: Stover and Evitt (1978, p.64). Age: Danian.
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Original description: [Morgenroth, 1968] (translated from German):
Membranilarnacia tenella n. sp.
Pl. 48, Figs. 2-4
Derivation of the name: tenella lat.: The Delicate.
? 1933 Membranilarnax pterospermoides n. sp. WETZEL, O., Die in ökologischer..., p. 52, Pl. 6, Figs. 1, 2.
Holotype: The specimen preserved in prep. KG9 and illustrated on Pl. 48, Figs. 2, 3.
Paratypoide: KG4, KG5, KG6, KG10, KG12.
Locus typicus: Kjölby Gaard, Hunstrup (Jutland).
Typical stratum: Danien A.
Diagnosis: A species of the genus Membranilarnacia. Central shell thin-walled, usually distinctly ellipsoidal, but sometimes almost spherical. Shell surface smooth to weakly granulated. Approximately 30-40 slender, solid processes rise from the central shell, which may be perforated by tiny holes. Weak granulation is often visible on the cais of the processes on the theca wall. The length of the processes is less than the smallest radius of the central shell. The processes are connected distally to each other by a closed, structureless membrane that concentrically surrounds the central shell.
The central shell of all present specimens has a large opening with an irregularly serrated edge.
Dimensions:
Length of central shell: 43 μ (39 μ/ 47 μ)
Width of central shell: 36 μ (31 μ/43 μ)
Appendage length: 12 μ (8 μ/17 μ)
(100 measurements)
Number of specimens examined: 151.
Comparisons: The new species can be distinguished from Membranilarnacia leptoderma (Cooksos & EISENACK 1948) and Membranilarnacia polycladiata (Cooksos & EISENACK 1958) by the significantly greater number of appendages and by the thinness of the central shell.
Within the range of variation of the Eocene Cannosphaeropsis ursulae Morgenboth 1966, specimens also occur in which the outer shell, normally consisting of a fine, highly differentiated network, with all its transitions, mellows into a smooth membrane. Thus, Cannosphaeropsis ursulae apparently shows transitions from the Cannosphaeropsis cyst to the Melodilarnacia cyst. The latter varieties of ursulae are therefore very similar to Melodilarnacia tenella, but are distinguished from it by fewer and longer processes. In addition, Cannosphaeropsis ursulae has a spherical central shell with a somewhat thicker wall.
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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.
Membranilarnacia tenella Morgenroth, 1968, has a thin-walled, spherical to slightly ellipsoidal central body, with a smooth to granular surface. There are 30-40 slender, solid processes which may have tiny perforations. Process length is less than the lower radius of the central body. The processes are distally united through a structureless unbroken membrane. Size: length of central body 39-47 µm, width 31-43 µm, processes 8-17 µm.
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Membranilarnacia? tenella Morgenroth, 1968, p.554–555, pl.48, figs.2–4. Holotype: Morgenroth, 1968, pl.48, figs.2–3. Originally Membranilarnacia, subsequently (and now) Membranilarnacia?. Questionable assignment: Stover and Evitt (1978, p.64). Age: Danian.
---------------------------------------------------------------------------------------------------
Original description: [Morgenroth, 1968] (translated from German):
Membranilarnacia tenella n. sp.
Pl. 48, Figs. 2-4
Derivation of the name: tenella lat.: The Delicate.
? 1933 Membranilarnax pterospermoides n. sp. WETZEL, O., Die in ökologischer..., p. 52, Pl. 6, Figs. 1, 2.
Holotype: The specimen preserved in prep. KG9 and illustrated on Pl. 48, Figs. 2, 3.
Paratypoide: KG4, KG5, KG6, KG10, KG12.
Locus typicus: Kjölby Gaard, Hunstrup (Jutland).
Typical stratum: Danien A.
Diagnosis: A species of the genus Membranilarnacia. Central shell thin-walled, usually distinctly ellipsoidal, but sometimes almost spherical. Shell surface smooth to weakly granulated. Approximately 30-40 slender, solid processes rise from the central shell, which may be perforated by tiny holes. Weak granulation is often visible on the cais of the processes on the theca wall. The length of the processes is less than the smallest radius of the central shell. The processes are connected distally to each other by a closed, structureless membrane that concentrically surrounds the central shell.
The central shell of all present specimens has a large opening with an irregularly serrated edge.
Dimensions:
Length of central shell: 43 μ (39 μ/ 47 μ)
Width of central shell: 36 μ (31 μ/43 μ)
Appendage length: 12 μ (8 μ/17 μ)
(100 measurements)
Number of specimens examined: 151.
Comparisons: The new species can be distinguished from Membranilarnacia leptoderma (Cooksos & EISENACK 1948) and Membranilarnacia polycladiata (Cooksos & EISENACK 1958) by the significantly greater number of appendages and by the thinness of the central shell.
Within the range of variation of the Eocene Cannosphaeropsis ursulae Morgenboth 1966, specimens also occur in which the outer shell, normally consisting of a fine, highly differentiated network, with all its transitions, mellows into a smooth membrane. Thus, Cannosphaeropsis ursulae apparently shows transitions from the Cannosphaeropsis cyst to the Melodilarnacia cyst. The latter varieties of ursulae are therefore very similar to Melodilarnacia tenella, but are distinguished from it by fewer and longer processes. In addition, Cannosphaeropsis ursulae has a spherical central shell with a somewhat thicker wall.
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Membranilarnacia tenella Morgenroth, 1968, has a thin-walled, spherical to slightly ellipsoidal central body, with a smooth to granular surface. There are 30-40 slender, solid processes which may have tiny perforations. Process length is less than the lower radius of the central body. The processes are distally united through a structureless unbroken membrane. Size: length of central body 39-47 µm, width 31-43 µm, processes 8-17 µm.
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