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Leptodinium pinnosum
Leptodinium pinnosum Davey, 1988
Holotype: Davey, 1987, pl.5, fig.1-3
Locus typicus: Papuan Basin, Papua New Guinea
Stratum typicum: Late Berriasian
Original diagnosis: Davey, 1987, p.39
Shape: Ellipsoidal, without an obvious apical protrusion.
Wall: The two wall layers are closely appressed except where they form the sutural crests. The endophragm is relatively stout rarely deformed and is not developed into an apical horn. Intratabular areas are mainly smooth, but rare, isolated granules or spines can occur.
Wall features: The crests are mainly suturocavate and are well developed on the dorsal and lateral surfaces, but are lower on the ventral surface. The latter is not noticeably suturocavate. Th"e crests are mainly smooth distally and are often perforate. Gonal cavations are particularlywell developed around the antapical plate and at the apex where a low horn is usually developed only by an extension of the periphragm.
Paratabulation: The sutural crests indicate a gonyaulacacean formula of 3"-4", 6", 6c, 5"""-6""", 1"""". Crests between 1" and 4, and 6" and the sulcus are poorly developed; the latter plate is narrow and subtriangular in shape.
Archaeopyle: Precingular, Type P (3" only); operculum free.
Size: Small to moderate.
Dimensions: Range: Body length (without crests) 43-53 µm, body width (without crests) 31-36 µm; maximum height of crests 8 µm.
Original description: Davey, 1987, p. 39
The rare, intratabular surface granules or small spines may be present on the pre- and postcingular plates. The outer margins of the crests run approximately parallel to the cyst surface except in the gonal regions where they are slightly higher. Here the cavation is most noticeable, particularly where the postcingular plates border onto the antapical plate. The apical horn, when developed, is formed as an extension of the crests in the apical region, is relatively low and may possess a terminal mamelon. The distal margins of the crests may occasionally have small, subconical spines.
Affinities:
Davey, 1987, p. 40: The combination of ellipsoidal body and high sutural crests distinguishes Leptodinium pinnosum from previously described forms. Perhaps the most similar form is L. freakei (Sarjeant 1963) Sarjeant 1969, from the Oxfordian of England. This latter form differs from L pinnosum primarily in having lower crests which are not not!iceably suturocavate and in the ventral surface tabulation. The type species, L. subtile Klement 1960, is also similar, but is less elongate and has lower crests; the tabulation illustrated by Klement 19G0 is very similar to that of L. pinnosum.
Holotype: Davey, 1987, pl.5, fig.1-3
Locus typicus: Papuan Basin, Papua New Guinea
Stratum typicum: Late Berriasian
Original diagnosis: Davey, 1987, p.39
Shape: Ellipsoidal, without an obvious apical protrusion.
Wall: The two wall layers are closely appressed except where they form the sutural crests. The endophragm is relatively stout rarely deformed and is not developed into an apical horn. Intratabular areas are mainly smooth, but rare, isolated granules or spines can occur.
Wall features: The crests are mainly suturocavate and are well developed on the dorsal and lateral surfaces, but are lower on the ventral surface. The latter is not noticeably suturocavate. Th"e crests are mainly smooth distally and are often perforate. Gonal cavations are particularlywell developed around the antapical plate and at the apex where a low horn is usually developed only by an extension of the periphragm.
Paratabulation: The sutural crests indicate a gonyaulacacean formula of 3"-4", 6", 6c, 5"""-6""", 1"""". Crests between 1" and 4, and 6" and the sulcus are poorly developed; the latter plate is narrow and subtriangular in shape.
Archaeopyle: Precingular, Type P (3" only); operculum free.
Size: Small to moderate.
Dimensions: Range: Body length (without crests) 43-53 µm, body width (without crests) 31-36 µm; maximum height of crests 8 µm.
Original description: Davey, 1987, p. 39
The rare, intratabular surface granules or small spines may be present on the pre- and postcingular plates. The outer margins of the crests run approximately parallel to the cyst surface except in the gonal regions where they are slightly higher. Here the cavation is most noticeable, particularly where the postcingular plates border onto the antapical plate. The apical horn, when developed, is formed as an extension of the crests in the apical region, is relatively low and may possess a terminal mamelon. The distal margins of the crests may occasionally have small, subconical spines.
Affinities:
Davey, 1987, p. 40: The combination of ellipsoidal body and high sutural crests distinguishes Leptodinium pinnosum from previously described forms. Perhaps the most similar form is L. freakei (Sarjeant 1963) Sarjeant 1969, from the Oxfordian of England. This latter form differs from L pinnosum primarily in having lower crests which are not not!iceably suturocavate and in the ventral surface tabulation. The type species, L. subtile Klement 1960, is also similar, but is less elongate and has lower crests; the tabulation illustrated by Klement 19G0 is very similar to that of L. pinnosum.