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Manumiella druggii
From Fensome et al., 2019:
Manumiella druggii (Stover, 1974, p.171, pl.1, figs.3a–b,4; text-fig.3B) Bujak and Davies, 1983, p.161. Holotype: Stover, 1974, pl.1, figs.3a–b. Originally Deflandrea, subsequently Isabelia (combination illegitimate), thirdly Isabelidinium, fourthly (and now) Manumiella. Taxonomic senior synonym: Broomea (as and now Manumiella) seelandica, according to Firth (1987, p.213) — however, Thorn et al. (2009, p.443) retained Manumiella druggii. Taxonomic junior synonym: Isabelidinium tingitanense, according to Lentin and Williams (1985, p.201). Age: Early to Middle Paleocene.
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Original diagnosis: Stover, 1974, p.171: Deflandrea druggii
Outline of periphragm in dorso-ventral view is broadly elliptical, rarely elongate and with a shallow antapical concavity which separates poorly developed antapical horns. Apical margin may be evenly rounded or a short, broadly-based, blunt apical horn may be present. Periphragm is about 1 µm thick, and is smooth, scabrate or irregularly granulate with the sculptural features varying in diameter from ca. 0.5 µm to 2.0 µm. Usually the coarser sculpturing is concentrated on the areas beyond the limits of the endoblast. Surface of periphragm lacks traces of tabulation except for small intercalary archeopyle .
Endoblast outline circular or nearly so in dorso-ventral view, commonly modified by folding; endoblast occupies a major part of the pericoel, and is not in contact laterally with the inner surface of the periphragm. Endophragm is ca. 1 µm thick, smooth or faintly scabrate. No opening observed in the endophragm in a position corresponding to the archeopyle in the periphragm. Operculum is relatively small, usually with a narrow apical margin, oblique and slightly convex sides, rounded antapical corners and is hinged antapically.
Dimensions: Specimens vary in width (92-103 µm) and length (104-122 µm); length: width ratio lies between 1:0.83 and 1:0.93. In nearly all specimens in which folding of the endoblast is not severe, its width exceeds its height.
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Supplemental description: Hultberg, 1985, p. 137
Circumcavate cyst, composed of endophragm and periphragm, separated by a pericoel. The surface of both endophragm and periphragm is smooth. The shape of the endophragm is rounded rhomboidal. The shape of the periphragm is rhomboidal, with a very small dorsoapical protrusion, and a very slight antapical indentation. No trace of paratabulation is present, except the archeopyle.
The archeopyle is intercalary, type I, formed by the detachment of paraplate 2a. The archeopyle is lati-deltaform. Operculum free. Paracingulum is indicated by folds in the periphragm. The paracingulum is almost circular. Parasulcus is not indicated. 94-120 µm (length), 54-95 µm (breadth).
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Supplemental discussion Thorn et al., 2009:
Discussion: Stover (1973) originally described M. druggii as broadly elliptical in outline, rarely elongate, with very poorly-developed
antapical horns separated by an extremely shallow concavity. The antapical protuberances are barely discernible (Plate I, figs. 12, 16). The periphragmmay be smooth to finely granulate in texture and exhibits a relatively small archeopyle with an antapically-hinged operculum. The endocyst occupies a major part of the pericoel, is circumcavate, commonly folded and generally circular in outline. The apexmay be rounded (e.g. Plate I, fig. 12), or is conspicuously dimpled (e.g. Plate I, fig. 16). The forms with dimpled apical areas typically have a short, blunt apical protrusion. In the López de Bertodano Formation on Seymour
Island, M. druggii was observed in the 40 m below the KT boundary (Fig. 3).
Lange (1969, pl. I, figs. 1–5) illustrated five specimens of Deflandrea cretacea Cookson 1956 (now Isabelidinium cretaceum (Cookson 1956) Lentin & Williams 1977); this material is here considered to be Manumiella druggii. Furthermore, the size of the material of Lange (1969) (mean length and width 104 and 74 μmrespectively) is consistent with the type material of M. druggii. This is 104–122 μm long and 92–103 μm wide (Stover, 1973). Stover (1973) stated that M. druggii is distinguished from I. cretaceum by being circumcavate and twice the size (Wilson,1978). The overall length andwidth of I. cretaceum is 45–65 μm and 43–56 μm respectively (Cookson, 1956). Stover (1973) noted that a specimen of Drugg (1967, pl. 2, fig. 17), identified as I. cretaceum, is probably conspecific with M. druggii. Wilson (1978) discussed the differentiation of Deflandrea [Isabelidinium] cretacea from Isabelia [Manumiella] druggii in detail. The distinction of these two taxa is important because the bicavate I. cretaceum ranges from the mid Santonian to the early Maastrichtian (Helby et al., 1987, fig. 40). By contrast, the circumcavate M. druggii is confined to the late Maastrichtian to earliest Danian (Wilson, 1984, figs. 3, 4, Helby et al., 1987, fig. 40; Askin, 1988b, fig. 2). On Seymour Island, there is a significant stratigraphical gap (approximately 900 m of section) between the range top of I. cretaceum and the range base of M. druggii (Askin, 1988a, fig. 5).
Wilson (1978) also discussed variation in the apical region of Manumiella druggii, and separated those with an apical horn into
Manumiella seelandica. This restricted M. druggii to specimens with rounded or sub-rounded apices. Wilson (1978) conceded that the two species are ‘very closely related’ due to their ‘virtually identical’ dimensions and similar overall shape and morphology apart from the apex. An illustration of Manumiella sp. cf. M. druggii in Askin (1988a) was compared to the species due to its truncated apex, but this seems an unduly cautious assignment as it appears to fit well within the range of variation of this species. Eshet et al. (1992, pl. II, fig. 4) illustrated a specimen of Manumiella sp. from a KT section at Hor Hahar, Israel, which compares well with the holotype. Marenssi et al. (2004, figs. 6c,d) retained M. druggii as a separate species to M. seelandica, and illustrated two relatively granulate specimens from the Maastrichtian Calafate Formation of southern Patagonia. They also illustrated two specimens of Manumiella sp. (Marenssi et al., 2004, figs. 6a,b); these are assigned to M. druggii based on the new taxonomic key above. Marenssi et al. (2004, fig. 6a) has a dimpled apex with poorly-developed antapical horns. The other specimen (Marenssi et al., 2004, fig. 6b) closely resembles M. druggii, despite being relatively elongate in outline, with an incipient antapical horn in the form of a slight protrusion. Stover (1973) noted rare elongation in outline in his original description, which may be a result of lateral compression. The Manumiella sp. in Marenssi et al. (2004, fig. 6b) is slightly folded.
Manumiella druggii (Stover, 1974, p.171, pl.1, figs.3a–b,4; text-fig.3B) Bujak and Davies, 1983, p.161. Holotype: Stover, 1974, pl.1, figs.3a–b. Originally Deflandrea, subsequently Isabelia (combination illegitimate), thirdly Isabelidinium, fourthly (and now) Manumiella. Taxonomic senior synonym: Broomea (as and now Manumiella) seelandica, according to Firth (1987, p.213) — however, Thorn et al. (2009, p.443) retained Manumiella druggii. Taxonomic junior synonym: Isabelidinium tingitanense, according to Lentin and Williams (1985, p.201). Age: Early to Middle Paleocene.
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Original diagnosis: Stover, 1974, p.171: Deflandrea druggii
Outline of periphragm in dorso-ventral view is broadly elliptical, rarely elongate and with a shallow antapical concavity which separates poorly developed antapical horns. Apical margin may be evenly rounded or a short, broadly-based, blunt apical horn may be present. Periphragm is about 1 µm thick, and is smooth, scabrate or irregularly granulate with the sculptural features varying in diameter from ca. 0.5 µm to 2.0 µm. Usually the coarser sculpturing is concentrated on the areas beyond the limits of the endoblast. Surface of periphragm lacks traces of tabulation except for small intercalary archeopyle .
Endoblast outline circular or nearly so in dorso-ventral view, commonly modified by folding; endoblast occupies a major part of the pericoel, and is not in contact laterally with the inner surface of the periphragm. Endophragm is ca. 1 µm thick, smooth or faintly scabrate. No opening observed in the endophragm in a position corresponding to the archeopyle in the periphragm. Operculum is relatively small, usually with a narrow apical margin, oblique and slightly convex sides, rounded antapical corners and is hinged antapically.
Dimensions: Specimens vary in width (92-103 µm) and length (104-122 µm); length: width ratio lies between 1:0.83 and 1:0.93. In nearly all specimens in which folding of the endoblast is not severe, its width exceeds its height.
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Supplemental description: Hultberg, 1985, p. 137
Circumcavate cyst, composed of endophragm and periphragm, separated by a pericoel. The surface of both endophragm and periphragm is smooth. The shape of the endophragm is rounded rhomboidal. The shape of the periphragm is rhomboidal, with a very small dorsoapical protrusion, and a very slight antapical indentation. No trace of paratabulation is present, except the archeopyle.
The archeopyle is intercalary, type I, formed by the detachment of paraplate 2a. The archeopyle is lati-deltaform. Operculum free. Paracingulum is indicated by folds in the periphragm. The paracingulum is almost circular. Parasulcus is not indicated. 94-120 µm (length), 54-95 µm (breadth).
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Supplemental discussion Thorn et al., 2009:
Discussion: Stover (1973) originally described M. druggii as broadly elliptical in outline, rarely elongate, with very poorly-developed
antapical horns separated by an extremely shallow concavity. The antapical protuberances are barely discernible (Plate I, figs. 12, 16). The periphragmmay be smooth to finely granulate in texture and exhibits a relatively small archeopyle with an antapically-hinged operculum. The endocyst occupies a major part of the pericoel, is circumcavate, commonly folded and generally circular in outline. The apexmay be rounded (e.g. Plate I, fig. 12), or is conspicuously dimpled (e.g. Plate I, fig. 16). The forms with dimpled apical areas typically have a short, blunt apical protrusion. In the López de Bertodano Formation on Seymour
Island, M. druggii was observed in the 40 m below the KT boundary (Fig. 3).
Lange (1969, pl. I, figs. 1–5) illustrated five specimens of Deflandrea cretacea Cookson 1956 (now Isabelidinium cretaceum (Cookson 1956) Lentin & Williams 1977); this material is here considered to be Manumiella druggii. Furthermore, the size of the material of Lange (1969) (mean length and width 104 and 74 μmrespectively) is consistent with the type material of M. druggii. This is 104–122 μm long and 92–103 μm wide (Stover, 1973). Stover (1973) stated that M. druggii is distinguished from I. cretaceum by being circumcavate and twice the size (Wilson,1978). The overall length andwidth of I. cretaceum is 45–65 μm and 43–56 μm respectively (Cookson, 1956). Stover (1973) noted that a specimen of Drugg (1967, pl. 2, fig. 17), identified as I. cretaceum, is probably conspecific with M. druggii. Wilson (1978) discussed the differentiation of Deflandrea [Isabelidinium] cretacea from Isabelia [Manumiella] druggii in detail. The distinction of these two taxa is important because the bicavate I. cretaceum ranges from the mid Santonian to the early Maastrichtian (Helby et al., 1987, fig. 40). By contrast, the circumcavate M. druggii is confined to the late Maastrichtian to earliest Danian (Wilson, 1984, figs. 3, 4, Helby et al., 1987, fig. 40; Askin, 1988b, fig. 2). On Seymour Island, there is a significant stratigraphical gap (approximately 900 m of section) between the range top of I. cretaceum and the range base of M. druggii (Askin, 1988a, fig. 5).
Wilson (1978) also discussed variation in the apical region of Manumiella druggii, and separated those with an apical horn into
Manumiella seelandica. This restricted M. druggii to specimens with rounded or sub-rounded apices. Wilson (1978) conceded that the two species are ‘very closely related’ due to their ‘virtually identical’ dimensions and similar overall shape and morphology apart from the apex. An illustration of Manumiella sp. cf. M. druggii in Askin (1988a) was compared to the species due to its truncated apex, but this seems an unduly cautious assignment as it appears to fit well within the range of variation of this species. Eshet et al. (1992, pl. II, fig. 4) illustrated a specimen of Manumiella sp. from a KT section at Hor Hahar, Israel, which compares well with the holotype. Marenssi et al. (2004, figs. 6c,d) retained M. druggii as a separate species to M. seelandica, and illustrated two relatively granulate specimens from the Maastrichtian Calafate Formation of southern Patagonia. They also illustrated two specimens of Manumiella sp. (Marenssi et al., 2004, figs. 6a,b); these are assigned to M. druggii based on the new taxonomic key above. Marenssi et al. (2004, fig. 6a) has a dimpled apex with poorly-developed antapical horns. The other specimen (Marenssi et al., 2004, fig. 6b) closely resembles M. druggii, despite being relatively elongate in outline, with an incipient antapical horn in the form of a slight protrusion. Stover (1973) noted rare elongation in outline in his original description, which may be a result of lateral compression. The Manumiella sp. in Marenssi et al. (2004, fig. 6b) is slightly folded.