Back
Imbatodinium inflatum
Imbatodinium inflatum Harker and Sarjeant in Harker et al., 1990, ex Harker and Sarjeant, 1991
Questionable assignment: Harker and Sarjeant in Harker et al. (1990, p.36). In their remarks Harker and Sarjeant in Harker et al., 1990, stated that the "... generic placement is provisional."
This name was not validly published in Harker et al. (1990) since the lodgement of the holotype was not cited (I.C.N. Article 40.7).
Holotype: Harker et al., 1990, pl.2, fig.4, text-fig.17
Locus typicus: Mowbray, Manitoba, Canada
Stratum typicum: Campanian
Original diagnosis: Harker, Sarjeant and Caldwell, 1990, p. 36
Proximate cysts with a rounded rhomboidal ambitus, prolonged into three horns; a single long, narrow, tapering apical horn and two subequal, broadly conical antapical horns. Dorsal surface tends to be more strongly arched than the ventral surface. Overall length twice the breadth; greatest width in the equatorial region.
Phragma thin (0.5-1.0 µm) and apparently composed of a single layer; surface smooth to finely granular, with a relief of less than 1 µm. Cingulum represented by two narrow, subparallel rows of discontinuous ridge-like thickenings in the equatorial region; indications of paratabulation are otherwise lacking. Archaeopyle apical or combination apical-intercalary, with a deep sulcal notch and a simple, free operculum.
Original description: Harker, Sarjeant and Caldwell, 1990, p. 36
In all observed specimens, the breadth of this species is greatest in the equatorial region. The cingular ridges are frequently discontinuous, breaking down into a series of aligned granules (relief less than 1 Ám); in some specimens the position of the cingulum can be recognized only by an absence of surface ornament round the equatorial region, below and adjacent to the posterior termination of the sulcal notch. The narrow apical horn is subject to distortion or breakage because of the thinness of the autophragm (Pl. 2, Figs. 3, 4).
Dimensions: Holotype: overall length 70 µm, breadth 40 µm; length of apical horn 15 µm, left antapical horn 6 µm, right antapical horn 6 µm; cingulum width 5 µm. (Apical horn distorted, estimated true length c. 25 µm; estimated true overall length thus c. 80 µm). Range of 12 measurable specimens: overall length 64-110 µm, mean 82 µm; breadth 36-77 µm, mean 50 µm; length of apical horn 15-25 µm, mean 17 µm; antapical horns 5-9 µm, mean 6 µm; cingulum width 3-5 µm, mean 5 µm. 43 specimens were counted.
Affinities:
Harker, Sarjeant and Caldwell, 1990, p. 36: This species is thin-walled and subject to crumpling; though the holotype was the best and bestoriented specimen seen, it is recognizedly not ideal. Its generic placement is provisional. Apart from its lack of cavation, it is strikingly similar to Cepadinium Duxbury 1983 in general features: future studies may well indicate (as happened with Aptea Eisenack 1958 and Doidyx Sarjeant 1966: see Sarjeant and Stover, 1976) that this difference is not crucial, in which case a transfer to that genus may prove appropriate. For the moment, however, it is placed in Imbatodinium, even though less elongate than typical species of that genus, because of its general comparability in morphology and style of archaeopyle. The most similar species is I. jaegeri, from which (and from all other species of Imbatodinium) it differs in possessing maximum width in the equatorial region and having a weakly defined cingulum. Ovoidinium Davey 1970 emend. Lentin and Williams 1976 and Ascodinium Cookson and Eisenack 1960 are similar in the nature of the cingulum, archaeopyle and antapical horns, but differ in possessing a conspicuous endoblast and having a more rotund ambitus.
Questionable assignment: Harker and Sarjeant in Harker et al. (1990, p.36). In their remarks Harker and Sarjeant in Harker et al., 1990, stated that the "... generic placement is provisional."
This name was not validly published in Harker et al. (1990) since the lodgement of the holotype was not cited (I.C.N. Article 40.7).
Holotype: Harker et al., 1990, pl.2, fig.4, text-fig.17
Locus typicus: Mowbray, Manitoba, Canada
Stratum typicum: Campanian
Original diagnosis: Harker, Sarjeant and Caldwell, 1990, p. 36
Proximate cysts with a rounded rhomboidal ambitus, prolonged into three horns; a single long, narrow, tapering apical horn and two subequal, broadly conical antapical horns. Dorsal surface tends to be more strongly arched than the ventral surface. Overall length twice the breadth; greatest width in the equatorial region.
Phragma thin (0.5-1.0 µm) and apparently composed of a single layer; surface smooth to finely granular, with a relief of less than 1 µm. Cingulum represented by two narrow, subparallel rows of discontinuous ridge-like thickenings in the equatorial region; indications of paratabulation are otherwise lacking. Archaeopyle apical or combination apical-intercalary, with a deep sulcal notch and a simple, free operculum.
Original description: Harker, Sarjeant and Caldwell, 1990, p. 36
In all observed specimens, the breadth of this species is greatest in the equatorial region. The cingular ridges are frequently discontinuous, breaking down into a series of aligned granules (relief less than 1 Ám); in some specimens the position of the cingulum can be recognized only by an absence of surface ornament round the equatorial region, below and adjacent to the posterior termination of the sulcal notch. The narrow apical horn is subject to distortion or breakage because of the thinness of the autophragm (Pl. 2, Figs. 3, 4).
Dimensions: Holotype: overall length 70 µm, breadth 40 µm; length of apical horn 15 µm, left antapical horn 6 µm, right antapical horn 6 µm; cingulum width 5 µm. (Apical horn distorted, estimated true length c. 25 µm; estimated true overall length thus c. 80 µm). Range of 12 measurable specimens: overall length 64-110 µm, mean 82 µm; breadth 36-77 µm, mean 50 µm; length of apical horn 15-25 µm, mean 17 µm; antapical horns 5-9 µm, mean 6 µm; cingulum width 3-5 µm, mean 5 µm. 43 specimens were counted.
Affinities:
Harker, Sarjeant and Caldwell, 1990, p. 36: This species is thin-walled and subject to crumpling; though the holotype was the best and bestoriented specimen seen, it is recognizedly not ideal. Its generic placement is provisional. Apart from its lack of cavation, it is strikingly similar to Cepadinium Duxbury 1983 in general features: future studies may well indicate (as happened with Aptea Eisenack 1958 and Doidyx Sarjeant 1966: see Sarjeant and Stover, 1976) that this difference is not crucial, in which case a transfer to that genus may prove appropriate. For the moment, however, it is placed in Imbatodinium, even though less elongate than typical species of that genus, because of its general comparability in morphology and style of archaeopyle. The most similar species is I. jaegeri, from which (and from all other species of Imbatodinium) it differs in possessing maximum width in the equatorial region and having a weakly defined cingulum. Ovoidinium Davey 1970 emend. Lentin and Williams 1976 and Ascodinium Cookson and Eisenack 1960 are similar in the nature of the cingulum, archaeopyle and antapical horns, but differ in possessing a conspicuous endoblast and having a more rotund ambitus.