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Ampulladinium aiax
From Fensome et al., 2019:
Ampulladinium aiax, Mantle, 2009b, p.113–114, pl.5, figs.8–11; text-figs.5A–B.
Holotype: Mantle, 2009b, pl.5, fig.8.
Age: Callovian.
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Original description: [Mantle, 2009b, p. 113-114]:
Ampulladinium aiax sp. nov.
Plate 5, Figs 8-11; Text-fig. 5
Diagnosis: Cysts small, proximate-proximochorate, acavate. 2 morphotypes: a subcircular form with short, robust processes; and a rounded subtriangular form with finer processes. Cyst widest halfway up hypocyst (subtriangular form) or at paracingulum (subcircular form); up to twice width of apex. Sculpture consisting of closely spaced capitate processes and fine bacula; typically absent from a large portion of the ventral surface. Processes may be joined distally forming a partial ectophragm. Archeopyle apical; operculum free. Paratabulation indicated by accessory archeopyle sutures and paracingulum.
Description: A small, rounded dinoflagellate cyst densely sculptured with short, fine, nontabular processes that are commonly fused distally to form a narrow ectocoel. However, the ectophragm is typically ragged and incomplete, only developed over small localised patches of the cyst surface and possibly due to preservational factors. The processes (1-4 um long) vary form baculate to capitate to thin, membranous stalks with flared tips, and are absent from a large ovoidal portion of the ventral surface and along the paracingulum. Low grana may.be present on the narrow paracingulum (4-6 um wide). The only other indication of paratabulation is the angular archeopyle margin, the accessory tears along precingular parasutures, and the broad, shallow parasulcal notch.
Dimensions (7 specimens): Length of cyst (excluding operculum and processes) 31 (40) 45 um; maximum width of cyst 32 (38) 43 um; thickness of cyst wall 0.5-1 um.
Holotype: SGM H11, EF L37/4. CPC no. 39144; Pl. 5, Fig. B. Length of cyst (excluding operculum and processes) 43 um; maximum width of cyst 37 um; thickness of cyst wall 0.5-1 um.
Typ. locality: Timor Sea, Bayu-Undan Field, Challis-11 ST1, sidewall core at 1552.5 m.
Etymology: Aiax (the name shared by two Greek heroes who fought side by side at Troy); with reference to rhe two morphological varients of the new species. -
Comparison: Ampulladiniwm aiax sp. nov. differs from the type species, A. variabile RIDING, HELBY & PARKER in RIDING & HELBY 2001 (2001g: 183-184; figs 2A-P), in possessing a thin, distinct paracingulum, a rounded rather than lobate antapex, and a more prominent ventral area devoid of sculptural elements. Some specimens of A. aiax may superficially resemble species of Sentusidinium having short, slender processes; but the partial ectophragm, bare ventral patch, and thin paracingulum distinguish the new species from members of that genus.
Local occurrence: Elang Formation; Voodooia tabulata Interval Zone (Subzones VT2-5): rare.
Ampulladinium aiax, Mantle, 2009b, p.113–114, pl.5, figs.8–11; text-figs.5A–B.
Holotype: Mantle, 2009b, pl.5, fig.8.
Age: Callovian.
---------------------------------------------------------------------------------------------------
Original description: [Mantle, 2009b, p. 113-114]:
Ampulladinium aiax sp. nov.
Plate 5, Figs 8-11; Text-fig. 5
Diagnosis: Cysts small, proximate-proximochorate, acavate. 2 morphotypes: a subcircular form with short, robust processes; and a rounded subtriangular form with finer processes. Cyst widest halfway up hypocyst (subtriangular form) or at paracingulum (subcircular form); up to twice width of apex. Sculpture consisting of closely spaced capitate processes and fine bacula; typically absent from a large portion of the ventral surface. Processes may be joined distally forming a partial ectophragm. Archeopyle apical; operculum free. Paratabulation indicated by accessory archeopyle sutures and paracingulum.
Description: A small, rounded dinoflagellate cyst densely sculptured with short, fine, nontabular processes that are commonly fused distally to form a narrow ectocoel. However, the ectophragm is typically ragged and incomplete, only developed over small localised patches of the cyst surface and possibly due to preservational factors. The processes (1-4 um long) vary form baculate to capitate to thin, membranous stalks with flared tips, and are absent from a large ovoidal portion of the ventral surface and along the paracingulum. Low grana may.be present on the narrow paracingulum (4-6 um wide). The only other indication of paratabulation is the angular archeopyle margin, the accessory tears along precingular parasutures, and the broad, shallow parasulcal notch.
Dimensions (7 specimens): Length of cyst (excluding operculum and processes) 31 (40) 45 um; maximum width of cyst 32 (38) 43 um; thickness of cyst wall 0.5-1 um.
Holotype: SGM H11, EF L37/4. CPC no. 39144; Pl. 5, Fig. B. Length of cyst (excluding operculum and processes) 43 um; maximum width of cyst 37 um; thickness of cyst wall 0.5-1 um.
Typ. locality: Timor Sea, Bayu-Undan Field, Challis-11 ST1, sidewall core at 1552.5 m.
Etymology: Aiax (the name shared by two Greek heroes who fought side by side at Troy); with reference to rhe two morphological varients of the new species. -
Comparison: Ampulladiniwm aiax sp. nov. differs from the type species, A. variabile RIDING, HELBY & PARKER in RIDING & HELBY 2001 (2001g: 183-184; figs 2A-P), in possessing a thin, distinct paracingulum, a rounded rather than lobate antapex, and a more prominent ventral area devoid of sculptural elements. Some specimens of A. aiax may superficially resemble species of Sentusidinium having short, slender processes; but the partial ectophragm, bare ventral patch, and thin paracingulum distinguish the new species from members of that genus.
Local occurrence: Elang Formation; Voodooia tabulata Interval Zone (Subzones VT2-5): rare.