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Odontochitina elbeialyi
Etymology. In honor of Prof. Salah Y. El Beialy, a pioneer Egyptian
palynologist, Geology Department, Faculty of Science, Mansoura University,
Egypt.
Holotype. Plate 1, figs. 1–3, Borehole Bk-12, sample depth 2570, slide
B, England finder B29.
Type locality. B-12 Borehole, Bakr Oil Field, western bank to Gulf of Suez, Egypt (Fig. 1).
Type stratum. Matulla Formation, Santonian.
Repository. Department of Geology, Faculty of Science, Tanta University, Egypt.
Diagnosis. Cornucavate to slightly circumcavate species of Odontochitina, having a cyst with ceratoid outline and three large horns, which are often truncated distally; smooth endophragm and granulate periphragm; gonyaulacoid tabulation weakly expressed by the archeopyle sutures and by occasional sutural lines or low ridges on the pericyst; apical archeopyle type (tA), free polyplacoid operculum.
Dimensions. Holotype: Central body length (without operculum) 67 μm, central body width 79 μm, antapical horn length 35 μm, lateral horn length 28 μm. Range: Central body length (without operculum) 70(55) 43 μm, central body width 81(70)60 μm, antapical horn length 50(36) 20 μm, lateral horn length 33(28)17 μm. Specimens measured: 28.
Stratigraphic range. Santonian.
Description. Large-sized ceratioid cornucavate to slightly circumcavate dinoflagellate cyst. Central body subspherical or subrectangular in outline, compressed dorsoventrally and bears three large truncated horns. The central body wall consists of two thin layers (ca. 1 μm or less): endophragm and periphragm. Endophragm smooth, periphragm granulate, rarely scabrate, but free of perforations. Horns usually wide proximally, tapering gradually, blunt, but often truncated distally. The apical and antapical horns are longer than the right lateral one. Apical and antapical horns are generally straight. The antapical horn is often truncated distally and may possess an irregular outline distally. The lateral horn arising at the cingular area often bears a small outgrowth or elbow and is curved distally towards the antapex. In some specimens, the endocyst bears a nipple, within the antapical, apical or lateral horns (Plate 1, figs. 1–3). Specimens of this species usually exhibit a wide antapical concavity. Tabulation is weakly expressed on the pericyst by an occasional presence of sutural lines or low ridges, at the cingulum (two transverse ridges) or rarely at plate boundaries. The archeopyle is apical type (tA), archaeopyle sutures indicating four apical and six precingular plates. The operculum is free polyplacoid. Only one complete specimen with an operculum has been found in the examined material.
Comparison. Odontochitina elbeialyi sp. nov. is an easily recognizable species. It differs from all other previously described species of the genus by its large and truncated horns (Table 1). The horns are robust, devoid of striae and rarely folded. Odontochitina elbeialyi sp. nov. is similar to Odontochitina tabulata El-Mehdawi, 1998 in possessing low sutural ridges (even faint) and by the occasional presence of the apical and antapical nipples on the endocyst (Plate 1, figs. 1–2; El-Mehdawi, 1998, pl. 1. figs. 1, 6; pl. 2, fig. 6), but differs by its poor indication of tabulation and in lacking ridges and perforations on the horns. Moreover, the tabulation in Odontochitina tabulata is clear, and the horns are thinner, slender and pointed distally rather than wide and truncated in Odontochitina elbeialyi. The new species differs from Odontochitina porifera Cookson, 1956 in the general shape of the horns and in lacking perforations. A comparison with other species which are also close to the new species is also given here (Table 1). Odontochitina ancala Bint, 1986 also has, like Odontochitina elbeialyi sp. nov., a cingulum indicated by two transverse sutural lines or low ridges, but differs in being cornucavate (rather than cornucavate to circumcavate), by its horns which are finer and straighter, perforated (rather than unperforated) and pointed (rather than often truncated) distally and by its periphragm smooth or scabrate (rather than granulate). Odontochitina rhakodes Bint, 1986 also possesses sutural lines or low ridges indicating the cingulum, and horns that may be truncated distally, but differs in being perforated. Odontochitina elbeialyi sp. nov. resembles Odontochitina sp. II of Barreda et al. (1999), Muderongia sp. A, Boukhamsin et al. (2022) and probably the species recognized as Muderongia staurota by Mahmoud and Deaf (2007) and as?Xenascus ghanaensis by Niechwedowicz and Walaszczyk (2022), especially in the general shape of the cyst and that of the horns and also by the occasional presence or absence of sutural lines.
palynologist, Geology Department, Faculty of Science, Mansoura University,
Egypt.
Holotype. Plate 1, figs. 1–3, Borehole Bk-12, sample depth 2570, slide
B, England finder B29.
Type locality. B-12 Borehole, Bakr Oil Field, western bank to Gulf of Suez, Egypt (Fig. 1).
Type stratum. Matulla Formation, Santonian.
Repository. Department of Geology, Faculty of Science, Tanta University, Egypt.
Diagnosis. Cornucavate to slightly circumcavate species of Odontochitina, having a cyst with ceratoid outline and three large horns, which are often truncated distally; smooth endophragm and granulate periphragm; gonyaulacoid tabulation weakly expressed by the archeopyle sutures and by occasional sutural lines or low ridges on the pericyst; apical archeopyle type (tA), free polyplacoid operculum.
Dimensions. Holotype: Central body length (without operculum) 67 μm, central body width 79 μm, antapical horn length 35 μm, lateral horn length 28 μm. Range: Central body length (without operculum) 70(55) 43 μm, central body width 81(70)60 μm, antapical horn length 50(36) 20 μm, lateral horn length 33(28)17 μm. Specimens measured: 28.
Stratigraphic range. Santonian.
Description. Large-sized ceratioid cornucavate to slightly circumcavate dinoflagellate cyst. Central body subspherical or subrectangular in outline, compressed dorsoventrally and bears three large truncated horns. The central body wall consists of two thin layers (ca. 1 μm or less): endophragm and periphragm. Endophragm smooth, periphragm granulate, rarely scabrate, but free of perforations. Horns usually wide proximally, tapering gradually, blunt, but often truncated distally. The apical and antapical horns are longer than the right lateral one. Apical and antapical horns are generally straight. The antapical horn is often truncated distally and may possess an irregular outline distally. The lateral horn arising at the cingular area often bears a small outgrowth or elbow and is curved distally towards the antapex. In some specimens, the endocyst bears a nipple, within the antapical, apical or lateral horns (Plate 1, figs. 1–3). Specimens of this species usually exhibit a wide antapical concavity. Tabulation is weakly expressed on the pericyst by an occasional presence of sutural lines or low ridges, at the cingulum (two transverse ridges) or rarely at plate boundaries. The archeopyle is apical type (tA), archaeopyle sutures indicating four apical and six precingular plates. The operculum is free polyplacoid. Only one complete specimen with an operculum has been found in the examined material.
Comparison. Odontochitina elbeialyi sp. nov. is an easily recognizable species. It differs from all other previously described species of the genus by its large and truncated horns (Table 1). The horns are robust, devoid of striae and rarely folded. Odontochitina elbeialyi sp. nov. is similar to Odontochitina tabulata El-Mehdawi, 1998 in possessing low sutural ridges (even faint) and by the occasional presence of the apical and antapical nipples on the endocyst (Plate 1, figs. 1–2; El-Mehdawi, 1998, pl. 1. figs. 1, 6; pl. 2, fig. 6), but differs by its poor indication of tabulation and in lacking ridges and perforations on the horns. Moreover, the tabulation in Odontochitina tabulata is clear, and the horns are thinner, slender and pointed distally rather than wide and truncated in Odontochitina elbeialyi. The new species differs from Odontochitina porifera Cookson, 1956 in the general shape of the horns and in lacking perforations. A comparison with other species which are also close to the new species is also given here (Table 1). Odontochitina ancala Bint, 1986 also has, like Odontochitina elbeialyi sp. nov., a cingulum indicated by two transverse sutural lines or low ridges, but differs in being cornucavate (rather than cornucavate to circumcavate), by its horns which are finer and straighter, perforated (rather than unperforated) and pointed (rather than often truncated) distally and by its periphragm smooth or scabrate (rather than granulate). Odontochitina rhakodes Bint, 1986 also possesses sutural lines or low ridges indicating the cingulum, and horns that may be truncated distally, but differs in being perforated. Odontochitina elbeialyi sp. nov. resembles Odontochitina sp. II of Barreda et al. (1999), Muderongia sp. A, Boukhamsin et al. (2022) and probably the species recognized as Muderongia staurota by Mahmoud and Deaf (2007) and as?Xenascus ghanaensis by Niechwedowicz and Walaszczyk (2022), especially in the general shape of the cyst and that of the horns and also by the occasional presence or absence of sutural lines.