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Oligosphaeridium inordinatum
Plate 7, Figs. 1, 2, 4, 5
Holotype: Plate 7, Figure 2, 5
Type Locality: Speeton Bed LB6, early Barremian, variabilis ammonite Zone. Holotype: Slide LB6(5), E.F. M41.0.
Derivation of Name: From the Latin inordinatus, not arranged, disorderly, irregular - in reference to the processes of this species.
Diagnosis: A large, robust, fairly thick-walled species with a spheroidal cyst, bearing a dense ornament of fine granules to very short, fine spines. There is no expression of tabulation. Hollow, smooth, mesotabular processes indicate a tabulation scheme of 4', 6'', 0c, 6''', 1p, 1''''. Processes flare proximally and are distally flared and raggedly complex. The archeopyle involves the loss of four apical plates and significant splitting along precingular sutures often occurs, resulting in a very broad archeopyle margin.
Dimensions: Holotype: Central body 51x43 μm. Overall 116x101 μm
All specimens measured (9): Central body 63 (53) 43 μm × 66 (56) 51 μm.
Overall: 139 (113) 91 μm × 122 (113) 101 μm
Remarks: The combination of dense granular to spinose ornament and distally raggedly complex processes distinguishes this species from all others. The ornament can be similar to the Aptian species Oligosphaeridium verrucosum Davey 1979b, although in the latter species, “the granules tend to be aligned on either side of the pre-and postcingular paraplate boundaries” (Davey 1979b, p. 558). No such alignment was noted in Oligosphaeridium inordinatum.
Also, the very short, fine spines observed in O. inordinatum were not described for O. verrucosum. Davey described the processes of O. verrucosum as having, “a rather irregular secate-aculeate margin”, his illustrations of the holotype (op. cit., Plate 5, Figs. 1, 2) show none of the ragged distal complexity of O. inordinatum.
The very fine, spinose ornament sometimes displayed by O. inordinatum is similar to that of Oligosphaeridium pulcherrimum (Deflandre and Cookson 1955) Davey and Williams 1966b subsp. hirsutum n. subsp., although the latter is much smaller and has fenestrate distal process terminations typical of the species.
The recorded range of Oligosphaeridium inordinatum at Speeton is between Beds LB6 and LB4D (early Barremian, variabilis to rarocinctum ammonite Zones). This species was also observed in conventional core in well 14/19-19, restricted to the early Barremian, palynofloral Zone LKP17, although there is some evidence from other Central North Sea wells that this species ranges as young as palynofloral Zone LKP18.
Holotype: Plate 7, Figure 2, 5
Type Locality: Speeton Bed LB6, early Barremian, variabilis ammonite Zone. Holotype: Slide LB6(5), E.F. M41.0.
Derivation of Name: From the Latin inordinatus, not arranged, disorderly, irregular - in reference to the processes of this species.
Diagnosis: A large, robust, fairly thick-walled species with a spheroidal cyst, bearing a dense ornament of fine granules to very short, fine spines. There is no expression of tabulation. Hollow, smooth, mesotabular processes indicate a tabulation scheme of 4', 6'', 0c, 6''', 1p, 1''''. Processes flare proximally and are distally flared and raggedly complex. The archeopyle involves the loss of four apical plates and significant splitting along precingular sutures often occurs, resulting in a very broad archeopyle margin.
Dimensions: Holotype: Central body 51x43 μm. Overall 116x101 μm
All specimens measured (9): Central body 63 (53) 43 μm × 66 (56) 51 μm.
Overall: 139 (113) 91 μm × 122 (113) 101 μm
Remarks: The combination of dense granular to spinose ornament and distally raggedly complex processes distinguishes this species from all others. The ornament can be similar to the Aptian species Oligosphaeridium verrucosum Davey 1979b, although in the latter species, “the granules tend to be aligned on either side of the pre-and postcingular paraplate boundaries” (Davey 1979b, p. 558). No such alignment was noted in Oligosphaeridium inordinatum.
Also, the very short, fine spines observed in O. inordinatum were not described for O. verrucosum. Davey described the processes of O. verrucosum as having, “a rather irregular secate-aculeate margin”, his illustrations of the holotype (op. cit., Plate 5, Figs. 1, 2) show none of the ragged distal complexity of O. inordinatum.
The very fine, spinose ornament sometimes displayed by O. inordinatum is similar to that of Oligosphaeridium pulcherrimum (Deflandre and Cookson 1955) Davey and Williams 1966b subsp. hirsutum n. subsp., although the latter is much smaller and has fenestrate distal process terminations typical of the species.
The recorded range of Oligosphaeridium inordinatum at Speeton is between Beds LB6 and LB4D (early Barremian, variabilis to rarocinctum ammonite Zones). This species was also observed in conventional core in well 14/19-19, restricted to the early Barremian, palynofloral Zone LKP17, although there is some evidence from other Central North Sea wells that this species ranges as young as palynofloral Zone LKP18.