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Phthanoperidinium flebile
Phthanoperidinium flebile Liengjarern et al., 1980
Holotype: Liengjarern et al., 1980, pl.54, fig.6
Locus typicus: Hamstead, Isle oI Wight, England
Stratum typicum: Early Oligocene
Original diagnosis: Liengjarern et al., 1980, p.488
Phthanoperidinium with ?partial (not continuous) endophragm occasionally developed beneath the horns. Ornament intratabular of small echinae or setae, laevigate sutural bands may be observable. Cingulum indicated by a relatively broad equatorial band free of ornament.
Original description: Liengjarern et al., 1980, p.488-489
The autocyst ambitus is subcircular to oval, but is frequently folded and the ambitus may appear somewhat fusiform; the ambital outline is little affected by the horns. The apical horn is very short, subtriangular to rectangular in outline; its apical margin may be smooth or may bear a tuft of short spines, to which sometimes the entire horn is reduced. The hypocyst is posteriorly rounded, and may bear a very short, sharp, antapical horn slightly to the left of the median line.
The autophragm is thin and bears a variable number of small setae or echinae, sometimes reduced to granules, atabular to intratabular in distribution; on some specimens the number of spines is reduced. and these may adopt a penitabular arrangement. Sutural bands, when observable, are smooth and of variable width
The cingulum, observable on some specimens, appears as a relatively wide and free of ornament; it is not indented. The sulcus has only been seen on one specimen, appearing as a very broad, slightly depressed area with ornament more sparse than on the rest of the ventral autocyst face.
The archeopyle, rarely observable, is intercalary and formed by the loss of paraplate 2a, additional splitting may sometimes develop along the lateral sutures of paraplate 3", but only very rarely; along the sutures of the remaining paraplates in the intercalary series.
Dimensions. Holotype, autocyst length 39 µm, breadth 28 µm, apical horn 5 µm, antapical horn 1 µm.
Range. Autocyst length 31(35)42 µm, breadth 22(27)31 µm, apical horn 1(3)5 µm, antapical horn 0(1)2 µm. Specimens measured 20.
Affinities:
Liengjarern et al., 1980, p.489: P. echinatum most closely resembles P. flebile in its ornament of spines, but in P. echinatum these are sutural to penitabular (distribution as a single simulate ring); whereas they are intratabular to atabular in P. flebile.
Holotype: Liengjarern et al., 1980, pl.54, fig.6
Locus typicus: Hamstead, Isle oI Wight, England
Stratum typicum: Early Oligocene
Original diagnosis: Liengjarern et al., 1980, p.488
Phthanoperidinium with ?partial (not continuous) endophragm occasionally developed beneath the horns. Ornament intratabular of small echinae or setae, laevigate sutural bands may be observable. Cingulum indicated by a relatively broad equatorial band free of ornament.
Original description: Liengjarern et al., 1980, p.488-489
The autocyst ambitus is subcircular to oval, but is frequently folded and the ambitus may appear somewhat fusiform; the ambital outline is little affected by the horns. The apical horn is very short, subtriangular to rectangular in outline; its apical margin may be smooth or may bear a tuft of short spines, to which sometimes the entire horn is reduced. The hypocyst is posteriorly rounded, and may bear a very short, sharp, antapical horn slightly to the left of the median line.
The autophragm is thin and bears a variable number of small setae or echinae, sometimes reduced to granules, atabular to intratabular in distribution; on some specimens the number of spines is reduced. and these may adopt a penitabular arrangement. Sutural bands, when observable, are smooth and of variable width
The cingulum, observable on some specimens, appears as a relatively wide and free of ornament; it is not indented. The sulcus has only been seen on one specimen, appearing as a very broad, slightly depressed area with ornament more sparse than on the rest of the ventral autocyst face.
The archeopyle, rarely observable, is intercalary and formed by the loss of paraplate 2a, additional splitting may sometimes develop along the lateral sutures of paraplate 3", but only very rarely; along the sutures of the remaining paraplates in the intercalary series.
Dimensions. Holotype, autocyst length 39 µm, breadth 28 µm, apical horn 5 µm, antapical horn 1 µm.
Range. Autocyst length 31(35)42 µm, breadth 22(27)31 µm, apical horn 1(3)5 µm, antapical horn 0(1)2 µm. Specimens measured 20.
Affinities:
Liengjarern et al., 1980, p.489: P. echinatum most closely resembles P. flebile in its ornament of spines, but in P. echinatum these are sutural to penitabular (distribution as a single simulate ring); whereas they are intratabular to atabular in P. flebile.