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Hystrichokolpoma petasatum
From Fensome et al., 2019:
Hystrichokolpoma petasatum Islam, 1983b, p.340–341, pl.3, figs.4–5. Holotype: Islam, 1983b, pl.3, fig.5. Questionable assignment: Islam (1983b, p.340). Age: Early to Middle Eocene.
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Paratype: Islam, 1983
Locus typicus: Hampshire Basin, S England
Stratum typicum: Early-Middle Eocene
Original diagnosis: Islam, 1983, p. 340-341
Cyst ellipsoidal, skolochorate and biphragmal; endophragm chagrinate or weakly reticulate; periphragm chagrinate; intratabular hollow processes, epi- and hypocystal processes broad with subquadrangular bases, generally tapering rapidly to narrow tubes and continuing to entire or wider serrate distal extremities; paracingular processes tubular and distally open; all processes proximally closed; four apical processes proximally joined together like a crown bearing distal tubules; antapical process longest, distally suddenly tapering to open tubule bearing spinules; paratabulation 4', 6'', 6c, 6''', ?1p, 1'''', xs; archeopyle apicaltype 4A.
Dimensions. Holotype: cyst body 42x33 µm, length of processes 15-20 µm, length of antapical process 25 µm. Range: cyst length 50(45)42 µm, breadth 40(38)33 µm, length of processes 15-22 µm, length of antapical process 30(27)25 µm. Specimens measured: 4.
Affinities:
Islam, 1983, p. 341: The generic allocation of the species is made on the basis of general morphology including two types of processes and apical archeopyle, but is tentative because of the peculiarity involving the apical series of processes which are proximally joined to look like a crown, and this is how it differs from other species of the genus. However, in process morphology, it resembles Hystrichokolpoma rigaudiae Deflandre and Cookson 1955 for which the processes of the operculum have not been described. Other species of this genus with operculum known do not, however, show the peculiar proximal joining of apical processes as in this species.
Hystrichokolpoma petasatum Islam, 1983b, p.340–341, pl.3, figs.4–5. Holotype: Islam, 1983b, pl.3, fig.5. Questionable assignment: Islam (1983b, p.340). Age: Early to Middle Eocene.
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Paratype: Islam, 1983
Locus typicus: Hampshire Basin, S England
Stratum typicum: Early-Middle Eocene
Original diagnosis: Islam, 1983, p. 340-341
Cyst ellipsoidal, skolochorate and biphragmal; endophragm chagrinate or weakly reticulate; periphragm chagrinate; intratabular hollow processes, epi- and hypocystal processes broad with subquadrangular bases, generally tapering rapidly to narrow tubes and continuing to entire or wider serrate distal extremities; paracingular processes tubular and distally open; all processes proximally closed; four apical processes proximally joined together like a crown bearing distal tubules; antapical process longest, distally suddenly tapering to open tubule bearing spinules; paratabulation 4', 6'', 6c, 6''', ?1p, 1'''', xs; archeopyle apicaltype 4A.
Dimensions. Holotype: cyst body 42x33 µm, length of processes 15-20 µm, length of antapical process 25 µm. Range: cyst length 50(45)42 µm, breadth 40(38)33 µm, length of processes 15-22 µm, length of antapical process 30(27)25 µm. Specimens measured: 4.
Affinities:
Islam, 1983, p. 341: The generic allocation of the species is made on the basis of general morphology including two types of processes and apical archeopyle, but is tentative because of the peculiarity involving the apical series of processes which are proximally joined to look like a crown, and this is how it differs from other species of the genus. However, in process morphology, it resembles Hystrichokolpoma rigaudiae Deflandre and Cookson 1955 for which the processes of the operculum have not been described. Other species of this genus with operculum known do not, however, show the peculiar proximal joining of apical processes as in this species.