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Impagidinium caecopapillatum
From Fensome et al., 2019:
Impagidinium caecopapillatum Prössl, 1992b, p.104–106, pl.1, figs.6–7,9–10,12–13; pl.3, figs.2–3,5–6,8–11; text-fig.2. Holotype: Prössl, 1992b, pl.3, figs.3,6,9. Age: Middle Eocene.
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Original description: [Prössl, 1992b] (translated from German):
Impagidinium caecopapillatum sp. nov.
Plate 1, Figs. 6, 9, 12; 7, 10, 13; Plate 3, Figs. 55, 8; 3, 6, 9; 10, 11.
Derived from: caecus (Latin) = invisible, hidden: because of the papillae, which are difficult to see in transmitted light but clearly visible in SEM.
Holotype: Plate 3, Figs. 3, 6, 9 (SO-87-10-68lSM.B 14 259)
Paratype: Plate 1, Figs. 7, 10, 13 (SO-87-10-33lSM.B 14 260)
Locus typicus and stratum typicum: Karkar Formation in Garoe (Somalia), ? Middle Eocene.
Diagnosis: Suboval, two-layered cyst with a gonyulax tabulation and a 3" P-archaeopyle. Suturocavate septa, irregularly slightly serrated, with slightly perforated margins. Intratabular ornamentation consisting of myopic papillae. Irnpagidiniurn caecopapillatum sp. nov. differs from all other species of this genus by its intratabular ornamentation with papillae and loricate septa.
Description: The two-layered cyst is suboval, always longer than wide, and has a gonyulax tabulation with 4, 6", 6c, 6"', and 1"" paraplates. The length varies between 47.5-73 μm, the width between 36-68 μm. At the level of the lower edge of the 1c paraplate, the cyst has a suture that extends almost to the 6" paraplate (Plate 3, Fig. 1). 3). Below this lies the elongated 1" paraplate and the flagellar mark ("flagellar scar" by Helenes 1984). The sulcus is formed by the paraplates as, ras, rs, and ls, as well as the flagellar mark. Ideally, this is clearly separated from the surrounding sulcal plates by sutures. As a special feature, an additional paraplate may occur, enclosed by the plates ras, rs, and ls, and the flagellar mark (Fig. 2). However, this has only been observed in the well-preserved holotype and does not appear to be species-specific. The archaeopyle belongs to type P and is represented by the 3" paraplate. In some specimens, the archaeopyle may be somewhat reduced by a rim (Plate 3, Fig. 9). The operculum is free.
The suture ridges are formed by the periphragma, are sutorocavate, and have an irregularly serrated (loricate) margin, which may exhibit a slight perforation distally. The septa are most strongly developed antapically and reach a height of 2.5–9 μm. Apically, the junction of the septa forms a small, triangular process with a length of 3–8 μm.
The intratabular ornaments consist of irregularly distributed papillae, whose height and diameter are less than 0.5 μm. The papillae cover the entire surface of the paraplates, including the cingulate plates.
Discussion: The specimens of Impagidinium caecopapillatum sp. nov. appear to correspond to the cysts designated by MANUM 1976 in Plate 1, Figs. 16, 17 as Leptodinium sp. I (MANUM pers. comm. 1992). Although no description is available from MANUM (1976), the specimen in Fig. 17 clearly shows a sulcus typical of Impagidinium. The septa are usually somewhat more highly developed in individuals of the new species. The loricate septal margins and the papillae are not visible in MANUM's illustrations, so a precise identification is not possible without examining the original material.
Impagidinium caecopapillatum sp. nov. differs from the very similar species Impagidinium veccosum (BRIDEAUX & McINTYRE 1975) STOVER & EVI'lT 1978 in a denser and more frequent arrangement of ornaments. In the new species, the ornamentation also extends to the septa and is also developed in the cingulate region.
In terms of the arrangement of the sulcal paraplates, Impagidinium caecopapillatum sp. nov. of the Pleistocene species Impagidinium sphaericum WALL 1967. However, the species described by WALL has lower suture ridges, a smaller apical process, and no papillae on the paraplates.
WRENN & KOKINOS (1986) and WRENN & KOKINOS (1986) each mention a species similar to the new species. The cysts, designated Impagidinium sp. E by WRENN & KOKINOS (1986) but not further described, have densely verrucate surface ornamentation. WIGGINS (1986) describes a punctate surface with perforate septa.
Dimensions, measured on 12 specimens:
Total length: 47.5-(62-73 μm) (holotype: 72 μm)
Total width: 36-(54-68 μm) (holotype: 68 μm)
Septal height: 2.5-(5-9 μm) (holotype: 2.5-5 μm)
Apical process: 3-(5-9 μm) (holotype: 4 μm)
Papillae: < 0.5 μm
Impagidinium caecopapillatum Prössl, 1992b, p.104–106, pl.1, figs.6–7,9–10,12–13; pl.3, figs.2–3,5–6,8–11; text-fig.2. Holotype: Prössl, 1992b, pl.3, figs.3,6,9. Age: Middle Eocene.
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Original description: [Prössl, 1992b] (translated from German):
Impagidinium caecopapillatum sp. nov.
Plate 1, Figs. 6, 9, 12; 7, 10, 13; Plate 3, Figs. 55, 8; 3, 6, 9; 10, 11.
Derived from: caecus (Latin) = invisible, hidden: because of the papillae, which are difficult to see in transmitted light but clearly visible in SEM.
Holotype: Plate 3, Figs. 3, 6, 9 (SO-87-10-68lSM.B 14 259)
Paratype: Plate 1, Figs. 7, 10, 13 (SO-87-10-33lSM.B 14 260)
Locus typicus and stratum typicum: Karkar Formation in Garoe (Somalia), ? Middle Eocene.
Diagnosis: Suboval, two-layered cyst with a gonyulax tabulation and a 3" P-archaeopyle. Suturocavate septa, irregularly slightly serrated, with slightly perforated margins. Intratabular ornamentation consisting of myopic papillae. Irnpagidiniurn caecopapillatum sp. nov. differs from all other species of this genus by its intratabular ornamentation with papillae and loricate septa.
Description: The two-layered cyst is suboval, always longer than wide, and has a gonyulax tabulation with 4, 6", 6c, 6"', and 1"" paraplates. The length varies between 47.5-73 μm, the width between 36-68 μm. At the level of the lower edge of the 1c paraplate, the cyst has a suture that extends almost to the 6" paraplate (Plate 3, Fig. 1). 3). Below this lies the elongated 1" paraplate and the flagellar mark ("flagellar scar" by Helenes 1984). The sulcus is formed by the paraplates as, ras, rs, and ls, as well as the flagellar mark. Ideally, this is clearly separated from the surrounding sulcal plates by sutures. As a special feature, an additional paraplate may occur, enclosed by the plates ras, rs, and ls, and the flagellar mark (Fig. 2). However, this has only been observed in the well-preserved holotype and does not appear to be species-specific. The archaeopyle belongs to type P and is represented by the 3" paraplate. In some specimens, the archaeopyle may be somewhat reduced by a rim (Plate 3, Fig. 9). The operculum is free.
The suture ridges are formed by the periphragma, are sutorocavate, and have an irregularly serrated (loricate) margin, which may exhibit a slight perforation distally. The septa are most strongly developed antapically and reach a height of 2.5–9 μm. Apically, the junction of the septa forms a small, triangular process with a length of 3–8 μm.
The intratabular ornaments consist of irregularly distributed papillae, whose height and diameter are less than 0.5 μm. The papillae cover the entire surface of the paraplates, including the cingulate plates.
Discussion: The specimens of Impagidinium caecopapillatum sp. nov. appear to correspond to the cysts designated by MANUM 1976 in Plate 1, Figs. 16, 17 as Leptodinium sp. I (MANUM pers. comm. 1992). Although no description is available from MANUM (1976), the specimen in Fig. 17 clearly shows a sulcus typical of Impagidinium. The septa are usually somewhat more highly developed in individuals of the new species. The loricate septal margins and the papillae are not visible in MANUM's illustrations, so a precise identification is not possible without examining the original material.
Impagidinium caecopapillatum sp. nov. differs from the very similar species Impagidinium veccosum (BRIDEAUX & McINTYRE 1975) STOVER & EVI'lT 1978 in a denser and more frequent arrangement of ornaments. In the new species, the ornamentation also extends to the septa and is also developed in the cingulate region.
In terms of the arrangement of the sulcal paraplates, Impagidinium caecopapillatum sp. nov. of the Pleistocene species Impagidinium sphaericum WALL 1967. However, the species described by WALL has lower suture ridges, a smaller apical process, and no papillae on the paraplates.
WRENN & KOKINOS (1986) and WRENN & KOKINOS (1986) each mention a species similar to the new species. The cysts, designated Impagidinium sp. E by WRENN & KOKINOS (1986) but not further described, have densely verrucate surface ornamentation. WIGGINS (1986) describes a punctate surface with perforate septa.
Dimensions, measured on 12 specimens:
Total length: 47.5-(62-73 μm) (holotype: 72 μm)
Total width: 36-(54-68 μm) (holotype: 68 μm)
Septal height: 2.5-(5-9 μm) (holotype: 2.5-5 μm)
Apical process: 3-(5-9 μm) (holotype: 4 μm)
Papillae: < 0.5 μm