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Phelodinium pachyceras
Phelodinium pachyceras Liengjarern et al., 1980, p.486–487, pl.54, fig.4.
Holotype: Liengjarern et al., 1980, pl.54, fig.4.
Williams et al. (1998, p.481) were incorrect in rendering the epithet as "pachycerum". As a Greek compound noun, it should be cited as pachyceras, as in Liengjarern et al. (1980). N.I.A.
Age: late Eocene–early Oligocene.
Original diagnosis: Liengjarern et al., 1980, p.486
Phelodinium characterized by apical and antapical horns, triangular in outline, proximally broad, and distally rounded. Thin-walled cysts moderately compressed dorso-ventrally. Endocyst sub-circular, with low apical and antapical lobes. Apical and antapical pericoels well developed; a narrow ambital pericoel may occur between the horns.Pericyst ornament atabular of reduced spinules. Pericingulum margins indicated by folds on the periphragm. Perisulcus broad and shallow.
Original description: Liengjarern et al., 1980, p.486-487
The cyst is thin-walled and usually compressed dorso-ventrally. The ambitus has convex sides and is projected into three prominent horns; these are triangular, with a broad base and a blunt distal ending, and are subequal in size. The epipericyst is more or less conical and somewhat larger than the hypopericyst; the posterior margin of the hypopericyst is straight or slightly concave. The endocyst is rounded, only weakly bilobed posteriorly; a rounded, low projection into the base of the apical horn may occur. The pericoels are well developed beneath the horns, a narrow pericoel is commonly present between the antapical horns. The ornament is reduced to small spinules or granules, apparently atabular in distribution. Cingulum relatively wide, not indented; its margins are marked by two parallel folds on the periphragm. The sulcus is very broad posteriorly but narrows markedly towards the cingular zone. The archeopyle is difficult to observe due to the opercula remaining nearly always in place, but the wide posterior archeopyle suture (H4), Iying very close to the cingular margin, is evident on most specimens observed. Dimensions. Holotype, pericyst length 75 µm. breadth 53 µm, endocyst length 46 µm, breadth 53 µm, apical horn 12 µm, left antapical horn 15 µm, right antapical horn 13 µm.
Range. Pericyst length 57(65)77 µm, breadth 45(51.6)56 µm, apical horn 6(9)12 µm, left antapical horn 9(12)14 µm, right antapical horn 8(10)13 µm. Specimens measured--12.
Affinities:
Liengjarern et al., 1980, p.487: The prominent broad horns and reduced ornament, as well as a strong dorso-ventral compression, distinguish P. pachyceras from the other species allocated to this genus.
Holotype: Liengjarern et al., 1980, pl.54, fig.4.
Williams et al. (1998, p.481) were incorrect in rendering the epithet as "pachycerum". As a Greek compound noun, it should be cited as pachyceras, as in Liengjarern et al. (1980). N.I.A.
Age: late Eocene–early Oligocene.
Original diagnosis: Liengjarern et al., 1980, p.486
Phelodinium characterized by apical and antapical horns, triangular in outline, proximally broad, and distally rounded. Thin-walled cysts moderately compressed dorso-ventrally. Endocyst sub-circular, with low apical and antapical lobes. Apical and antapical pericoels well developed; a narrow ambital pericoel may occur between the horns.Pericyst ornament atabular of reduced spinules. Pericingulum margins indicated by folds on the periphragm. Perisulcus broad and shallow.
Original description: Liengjarern et al., 1980, p.486-487
The cyst is thin-walled and usually compressed dorso-ventrally. The ambitus has convex sides and is projected into three prominent horns; these are triangular, with a broad base and a blunt distal ending, and are subequal in size. The epipericyst is more or less conical and somewhat larger than the hypopericyst; the posterior margin of the hypopericyst is straight or slightly concave. The endocyst is rounded, only weakly bilobed posteriorly; a rounded, low projection into the base of the apical horn may occur. The pericoels are well developed beneath the horns, a narrow pericoel is commonly present between the antapical horns. The ornament is reduced to small spinules or granules, apparently atabular in distribution. Cingulum relatively wide, not indented; its margins are marked by two parallel folds on the periphragm. The sulcus is very broad posteriorly but narrows markedly towards the cingular zone. The archeopyle is difficult to observe due to the opercula remaining nearly always in place, but the wide posterior archeopyle suture (H4), Iying very close to the cingular margin, is evident on most specimens observed. Dimensions. Holotype, pericyst length 75 µm. breadth 53 µm, endocyst length 46 µm, breadth 53 µm, apical horn 12 µm, left antapical horn 15 µm, right antapical horn 13 µm.
Range. Pericyst length 57(65)77 µm, breadth 45(51.6)56 µm, apical horn 6(9)12 µm, left antapical horn 9(12)14 µm, right antapical horn 8(10)13 µm. Specimens measured--12.
Affinities:
Liengjarern et al., 1980, p.487: The prominent broad horns and reduced ornament, as well as a strong dorso-ventral compression, distinguish P. pachyceras from the other species allocated to this genus.