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Membranilarnax liradiscoides
From Fensome et al., 2019:
Membranilarnax liradiscoides Wetzel, 1933b, p.52–53, pl.6, figs.3a–b. Emendation: Marheinecke, 1992, p.116, as Membranilarnax liradiscoides. Holotype: not designated. Lectotype: Wetzel, 1933b, pl.6, fig.3a (specimen to right), designated by Lentin and Williams (1989, p.239). Originally (and now) Membranilarnax, subsequently Membranilarnacia, thirdly Membranilarnacia?. Marheinecke (1992, p.116) retained this species in Membranilarnax. Age: Late Cretaceous.
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Original description [Wetzel, 1933b] (translated from German):
Membranilarnax liradiscoides n. sp.
Plate VI, Fig. 3a and b.
Type: Prep. 241 (Plate VI, Fig. 3).
Diagnosis: The spherical or lenticular central shell is covered by a network of filaments forming approximately six consistently large, irregularly shaped meshes. Short radial spines, ending in forked spines, emerge from the nodes. Longer, furcate processes, enclosed in a pale membrane (wing lamella? margin? floating girdle?), arise in the equatorial plane. The overall shape is round to polygonal. The color is brownish.
Comparable forms.
? (no date). Liradiscus barbadensis GREVILLE. WEISSFLOG, Diatom Plates, Plate 62, Fig. 14.
? 1896. Liradiscus barbadensis GREV. SCHÜTT, Bacillariaceae. In: ENGLER and PRANTL, Plant Families, 1st Part, 1st Section b, p. 68, Fig. 91.
? 1928. Aulosphaera sp. DOFLEIN-REICHENOW, Textbook of Protozoology, 2nd Part, p. 829, Fig. 796.
The similarity to Liradiscus barbadensis GREVILLE, which WEISSFLOG—rightly, perhaps?—classified as a diatom, is due to its spherical shape, its light-colored rim, and its irregular surface mesh. However, the present pair of flint fossils does not have such a smooth periphery, nor needle-like marginal ribs, but rather forked spines and less wavy mesh lines with radial spines at the nodes.
The similarity to Liradiscus barbadensis GREVILLE, which WEISSFLOG—whether correctly or not—classified as a diatom, is based on its spherical shape, its light-colored rim, and its irregular surface mesh. The surface structure of the shell bears a certain resemblance to the lattice-like sphere of the radiolary *Aulosphaera* sp., as illustrated, for example, by Doflein-Reichenow (see above). However, an exact match is not implied; the differences in size alone should raise concerns, although extant radiolarians of the same genus sometimes vary considerably in size, as V. Haecker has repeatedly demonstrated. In any case, classification within the Hystrichospherids seems to me the most appropriate initial classification. — See also the flint fossils *Cannosphaeropsis utinensis* (pp. 6 ff.), *Cenosphaera* cf. Doederleini (p. 4), and *Pleurozonaria globulus* n. g. n. sp. (p. 29).
Dimensions: Diameter of the inner shell 35–40 μm, of the whole 60–70 μm; Thickness 30 μm.
Two specimens observed that are fused together (?) by the "belt membrane"; the first fossilized specimen? Plate VI, Fig. 3a and b, from Preparation 241 of a glacial erratic flint.
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Original description [Wetzel, 1933b] in German:
Membranilarnax liradiscoides n. sp.
Taf. VI Fig. 3a u. b.
Typus: Präp. 241 (Taf. VI Fig. 3).
Diagnose: Die kugel- oder linsenförmige Zentralschale wird überdacht von einem Fadengerüst, das ca. 6 durchweg große, unregelmäßig geformte Maschen bildet und in den Knoten kurze Radialstacheln trägt, die in Gabeldörnchen enden. In der Äquatorebene entspringen längere, ebenfalls furcate Fortsätze, die in eine helle Haut eingeschlossen sind (Flügellamelle? Saum? Schwebegürtel?). Umriß des Ganzen rund bis vieleckig. Farbe bräunlich.
Vergleichbare Formen.
? (ohne Jahr). Liradiscus barbadensis GREVILLE. WEISSFLOG, Diatomeentafeln, Taf. 62 Fig. 14.
? 1896. Liradiscus barbadensis GREV. SCHÜTT, Bacillariaceae. In: ENGLER und PRANTL, Pflanzenfamilien, 1. Tl., 1. Abtlg. b, S. 68 Fig. 91.
? 1928. Aulosphaera sp. DOFLEIN-REICHENOW, Lehrb. d. Protozoenkunde, 2. Tl., S. 829 Fig. 796.
Die Ähnlichkeit mit dem von WEISSFLOG - ob mit Recht? - zu den Diatomeen gerechneten Liradiscus barbadensis GREVILLE beruht auf der kugelförmigen Gestalt, auf der hellen Saumbildung und auf dem un- regelmäßigen Maschennetz der Oberfläche. Allerdings besitzt das vorliegende Paar von Feuersteinfossilien nicht eine so glatte Peripherie, keine nadelförmigen Saumrippen, sondern gabelstachlige Hautstützen und weniger gewellte Maschenlinien mit Radialstacheln in den Knotenpunkten.
In der Oberflächenausstattung der Schale besteht eine gewisse Übereinstimmung mit der Gitterkugel der Radiolarie Aulosphaera sp., wie sie z. B. DOFLEIN-REICHENOW (s. o.) abbildet. Aber eine Gleichheit ist auch hier nicht gemeint; schon die Größenunterschiede dürften Bedenken erregen, obgleich die rezenten Radiolarien derselben Gattung manchmal sehr verschieden groß sind, wie z. B. V. HAECKER Wiederholt gezeigt hat. Jedenfalls ist die Einreihung bei den Hystrichosphäriden m. E. zunächst am besten. — - Vgl. außerdem die Feuersteinfossilien Cannosphaeropsis utinensis (S. 6 ff.), Cenosphaera? cf. Doederleini (S. 4) und Pleurozonaria globulus n. g. n. sp. (S. 29).
Maße: Durchmesser der Innenschale 35-40 μ, des Ganzen 60-70 μ; Dicke 30 μ.
2 Exemplare beobachtet, die mit der,,Gürtelmembran“ zusammengeklebt (?) sind; zum erstenmal fossil? Taf. VI Fig. 3 a u. b aus Präp. 241 eines Geschiebefeuersteines.
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Emendation Marheinecke, 1992, p. 116-117 (translated from German):
Emended description: Cyst chorate, spheroidal to ovaloidal. Wall composed of pedium and cancellous luxuria, forming a large number of irregularly distributed processes and septa. The septa form a pleural pattern on the cyst surface. The processes arise from the septa both at the points of contact and in between; they are bi- or trifurcate, trabeculate. A delicate supratectum is usually present. Areation: indicated by the polygonal archeopyle. Archeopyle: apical, ?(1+2+3+4), secant operculum.
Additional note: The well-developed fielding could not be interpreted as areation. Perhaps, however, this will be possible upon examination of many specimens under the SEM. Because of this uncertainty, the term "fielding" is used in the description. According to the emended descriptions of the genera Membranilanarcia and Membranilarnax by Williams & Downie (1966) and Sarjeant (1985b), respectively, the character inventory of M. liradiscoides clearly falls within the genus diagnosis of Membranilarnax. The morphological proximity to the holotype Membranilarnax pterospermoides is close. The present septa are difficult to recognize in the light microscope, as the presence of the supratectum, trabeculae, and septa complicates interpretation.
Specimens: >85.
Statistics: Diameter of the central capsule: 39(45)48; total diameter: 61(65)68.
Measured specimens: 12.
Known range: Late Cretaceous.
Membranilarnax liradiscoides Wetzel, 1933b, p.52–53, pl.6, figs.3a–b. Emendation: Marheinecke, 1992, p.116, as Membranilarnax liradiscoides. Holotype: not designated. Lectotype: Wetzel, 1933b, pl.6, fig.3a (specimen to right), designated by Lentin and Williams (1989, p.239). Originally (and now) Membranilarnax, subsequently Membranilarnacia, thirdly Membranilarnacia?. Marheinecke (1992, p.116) retained this species in Membranilarnax. Age: Late Cretaceous.
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Original description [Wetzel, 1933b] (translated from German):
Membranilarnax liradiscoides n. sp.
Plate VI, Fig. 3a and b.
Type: Prep. 241 (Plate VI, Fig. 3).
Diagnosis: The spherical or lenticular central shell is covered by a network of filaments forming approximately six consistently large, irregularly shaped meshes. Short radial spines, ending in forked spines, emerge from the nodes. Longer, furcate processes, enclosed in a pale membrane (wing lamella? margin? floating girdle?), arise in the equatorial plane. The overall shape is round to polygonal. The color is brownish.
Comparable forms.
? (no date). Liradiscus barbadensis GREVILLE. WEISSFLOG, Diatom Plates, Plate 62, Fig. 14.
? 1896. Liradiscus barbadensis GREV. SCHÜTT, Bacillariaceae. In: ENGLER and PRANTL, Plant Families, 1st Part, 1st Section b, p. 68, Fig. 91.
? 1928. Aulosphaera sp. DOFLEIN-REICHENOW, Textbook of Protozoology, 2nd Part, p. 829, Fig. 796.
The similarity to Liradiscus barbadensis GREVILLE, which WEISSFLOG—rightly, perhaps?—classified as a diatom, is due to its spherical shape, its light-colored rim, and its irregular surface mesh. However, the present pair of flint fossils does not have such a smooth periphery, nor needle-like marginal ribs, but rather forked spines and less wavy mesh lines with radial spines at the nodes.
The similarity to Liradiscus barbadensis GREVILLE, which WEISSFLOG—whether correctly or not—classified as a diatom, is based on its spherical shape, its light-colored rim, and its irregular surface mesh. The surface structure of the shell bears a certain resemblance to the lattice-like sphere of the radiolary *Aulosphaera* sp., as illustrated, for example, by Doflein-Reichenow (see above). However, an exact match is not implied; the differences in size alone should raise concerns, although extant radiolarians of the same genus sometimes vary considerably in size, as V. Haecker has repeatedly demonstrated. In any case, classification within the Hystrichospherids seems to me the most appropriate initial classification. — See also the flint fossils *Cannosphaeropsis utinensis* (pp. 6 ff.), *Cenosphaera* cf. Doederleini (p. 4), and *Pleurozonaria globulus* n. g. n. sp. (p. 29).
Dimensions: Diameter of the inner shell 35–40 μm, of the whole 60–70 μm; Thickness 30 μm.
Two specimens observed that are fused together (?) by the "belt membrane"; the first fossilized specimen? Plate VI, Fig. 3a and b, from Preparation 241 of a glacial erratic flint.
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Original description [Wetzel, 1933b] in German:
Membranilarnax liradiscoides n. sp.
Taf. VI Fig. 3a u. b.
Typus: Präp. 241 (Taf. VI Fig. 3).
Diagnose: Die kugel- oder linsenförmige Zentralschale wird überdacht von einem Fadengerüst, das ca. 6 durchweg große, unregelmäßig geformte Maschen bildet und in den Knoten kurze Radialstacheln trägt, die in Gabeldörnchen enden. In der Äquatorebene entspringen längere, ebenfalls furcate Fortsätze, die in eine helle Haut eingeschlossen sind (Flügellamelle? Saum? Schwebegürtel?). Umriß des Ganzen rund bis vieleckig. Farbe bräunlich.
Vergleichbare Formen.
? (ohne Jahr). Liradiscus barbadensis GREVILLE. WEISSFLOG, Diatomeentafeln, Taf. 62 Fig. 14.
? 1896. Liradiscus barbadensis GREV. SCHÜTT, Bacillariaceae. In: ENGLER und PRANTL, Pflanzenfamilien, 1. Tl., 1. Abtlg. b, S. 68 Fig. 91.
? 1928. Aulosphaera sp. DOFLEIN-REICHENOW, Lehrb. d. Protozoenkunde, 2. Tl., S. 829 Fig. 796.
Die Ähnlichkeit mit dem von WEISSFLOG - ob mit Recht? - zu den Diatomeen gerechneten Liradiscus barbadensis GREVILLE beruht auf der kugelförmigen Gestalt, auf der hellen Saumbildung und auf dem un- regelmäßigen Maschennetz der Oberfläche. Allerdings besitzt das vorliegende Paar von Feuersteinfossilien nicht eine so glatte Peripherie, keine nadelförmigen Saumrippen, sondern gabelstachlige Hautstützen und weniger gewellte Maschenlinien mit Radialstacheln in den Knotenpunkten.
In der Oberflächenausstattung der Schale besteht eine gewisse Übereinstimmung mit der Gitterkugel der Radiolarie Aulosphaera sp., wie sie z. B. DOFLEIN-REICHENOW (s. o.) abbildet. Aber eine Gleichheit ist auch hier nicht gemeint; schon die Größenunterschiede dürften Bedenken erregen, obgleich die rezenten Radiolarien derselben Gattung manchmal sehr verschieden groß sind, wie z. B. V. HAECKER Wiederholt gezeigt hat. Jedenfalls ist die Einreihung bei den Hystrichosphäriden m. E. zunächst am besten. — - Vgl. außerdem die Feuersteinfossilien Cannosphaeropsis utinensis (S. 6 ff.), Cenosphaera? cf. Doederleini (S. 4) und Pleurozonaria globulus n. g. n. sp. (S. 29).
Maße: Durchmesser der Innenschale 35-40 μ, des Ganzen 60-70 μ; Dicke 30 μ.
2 Exemplare beobachtet, die mit der,,Gürtelmembran“ zusammengeklebt (?) sind; zum erstenmal fossil? Taf. VI Fig. 3 a u. b aus Präp. 241 eines Geschiebefeuersteines.
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Emendation Marheinecke, 1992, p. 116-117 (translated from German):
Emended description: Cyst chorate, spheroidal to ovaloidal. Wall composed of pedium and cancellous luxuria, forming a large number of irregularly distributed processes and septa. The septa form a pleural pattern on the cyst surface. The processes arise from the septa both at the points of contact and in between; they are bi- or trifurcate, trabeculate. A delicate supratectum is usually present. Areation: indicated by the polygonal archeopyle. Archeopyle: apical, ?(1+2+3+4), secant operculum.
Additional note: The well-developed fielding could not be interpreted as areation. Perhaps, however, this will be possible upon examination of many specimens under the SEM. Because of this uncertainty, the term "fielding" is used in the description. According to the emended descriptions of the genera Membranilanarcia and Membranilarnax by Williams & Downie (1966) and Sarjeant (1985b), respectively, the character inventory of M. liradiscoides clearly falls within the genus diagnosis of Membranilarnax. The morphological proximity to the holotype Membranilarnax pterospermoides is close. The present septa are difficult to recognize in the light microscope, as the presence of the supratectum, trabeculae, and septa complicates interpretation.
Specimens: >85.
Statistics: Diameter of the central capsule: 39(45)48; total diameter: 61(65)68.
Measured specimens: 12.
Known range: Late Cretaceous.