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Orobodinium changii
Orobodinium changii Tykoezinski et al., 2001, p.89, pl.4, figs.1a–b,2a–b,3a–b,4a–b,5a–b,6a–b,7a–b,8–9. Tykoezinski et al., 2001, pl.4, figs.1a–b,9.
Taxonomic junior synonym: Orobodinium cunstonense (name not validly published), according to Tykoezinski et al. (2001, p.89).
Age: early Callovian.
Original description (Tykoezinski et al., 2001):
Orobodinium changii sp. nov. Plate 4, figs. 1-9
Cymatiosphaera Sp .A Tykoezinski (written communication, 1982), p. 106, pi. 21, figure 7.
Orobodinium sp. C Gocht & Wille, 1990, p. 705, fig. 25.
Orobodinium cunstonense Smith (written communication, 1995), p. 305-307 Vol. II, Plate 90, figs. K-W; Plate 91, figs. A-I, text-fig. 2.2.20D.
Derivation of Name. Proposed in honour of James Chang, consultant haematologist at The Christie Hospital, Manchester.
Type Locality. Cunstone Nab coastal section, South of Scarborough, Yorkshire (TA099830).
Type Horizon. Abbotsbury Cornbrash Formation, Fleet member, unit oc2 of Wright 1977a, early Callovian, M. herveyi Zone, M. terebratus Subzone.
Holotype. Slide 89008/19, Reference M27/1 (Plate 4, figures la-b, 9).
Diagnosis. A small, almost, spherical cyst with an autophragm. Differentiation of the autophragm into an inner pedium layer and an outer luxurium is not clearly discernible. The cyst is covered by a continuous, regular reticulum of ridges that are vacuolate in section. No reflection of paratabulation is present other than the archeopyle margin. The archeopyle is apical, with a free operculum.
Description. Shape: The cyst is almost perfectly spherical when complete. Wall relationships: The cyst appears to have a simple undifferentiated autophragm only, although from observations made on other members of the genus it is possible that there may be two wall layers closely appressed, an inner pedium layer, and an outer luxurium which bears the surface ornament of the cyst, in the terminology of Below 1987a, b. Wall features: Low relatively broad continuous ridges that interconnect to form a regular reticulum cover the surface of the cyst. These are ca. 0.5-1 jim wide enclosing sub-polygonal lumina, normally measuring ca. 2.5-5 jam in width. All the lumina present on one specimen are of relatively equal sizes. The ridges are low (ca. 1 |jm) and rounded in section and appear to have a vacuolate structure. Occasionally specimens possess some ridges that fade out (although the reticulation remains complete), and some may have faint, very poorly developed "ghost-like" ridges that occur within lumina. Paratabulation and parasutural features: No paratabulation is evident. The principal archeopyle margin indicates the presence of seven precingular paraplates. Archeopyle: The archeopyle is apical and the operculum is free, only occasionally being found within the cyst. Cyst Size: Diameter min. 22(23)25 µm max. 15 specimens measured.
Remarks and Comparisons. This species of Orobodinium differs from all others by the possession of a complete, regular reticulum on the surface of the cyst. Orobodinium rete Gocht and Wille 1990 from the early Bathonian is most morphologically similar to O. changii. This species possesses a vermiculate to reticulate surface ornament, but any reticulation is composed of undulose rugulae and is incomplete. The lumina are not of equal size and there is a tendency toward bireticulation. Gocht and Wille (1990) recorded O. changii as an informal species distinct from O. rete. Although the cyst is described as not showing any paratabulation, it may be possible that some of the ridges on the cyst are approximately parasutural but are masked by the reticulation. Even so, specimens observed displayed no positive proof of paratabulation other than the principal archeopyle suture. Occurrence. Late Bathonian, C. discus Zone, Abbotsbury Cornbrash Formation, Berry Member, Shipton-onCherwell, Oxfordshire, Tykoezinski (written commun., 1982) [as Cymatiosphaera sp.A]: Early Callovian, M. herveyi Zone, south-west Germany, Gocht and Wille (1990): Early Callovian to Early Oxfordian, M. herveyi to Q. mariae Zones, M. terebratus to scarburgense Subzones, Abbotsbury Cornbrash Formation (unit al)-Oxford Clay Formation, Smith (written commun., 1995) [as O. cunstonense].
Taxonomic junior synonym: Orobodinium cunstonense (name not validly published), according to Tykoezinski et al. (2001, p.89).
Age: early Callovian.
Original description (Tykoezinski et al., 2001):
Orobodinium changii sp. nov. Plate 4, figs. 1-9
Cymatiosphaera Sp .A Tykoezinski (written communication, 1982), p. 106, pi. 21, figure 7.
Orobodinium sp. C Gocht & Wille, 1990, p. 705, fig. 25.
Orobodinium cunstonense Smith (written communication, 1995), p. 305-307 Vol. II, Plate 90, figs. K-W; Plate 91, figs. A-I, text-fig. 2.2.20D.
Derivation of Name. Proposed in honour of James Chang, consultant haematologist at The Christie Hospital, Manchester.
Type Locality. Cunstone Nab coastal section, South of Scarborough, Yorkshire (TA099830).
Type Horizon. Abbotsbury Cornbrash Formation, Fleet member, unit oc2 of Wright 1977a, early Callovian, M. herveyi Zone, M. terebratus Subzone.
Holotype. Slide 89008/19, Reference M27/1 (Plate 4, figures la-b, 9).
Diagnosis. A small, almost, spherical cyst with an autophragm. Differentiation of the autophragm into an inner pedium layer and an outer luxurium is not clearly discernible. The cyst is covered by a continuous, regular reticulum of ridges that are vacuolate in section. No reflection of paratabulation is present other than the archeopyle margin. The archeopyle is apical, with a free operculum.
Description. Shape: The cyst is almost perfectly spherical when complete. Wall relationships: The cyst appears to have a simple undifferentiated autophragm only, although from observations made on other members of the genus it is possible that there may be two wall layers closely appressed, an inner pedium layer, and an outer luxurium which bears the surface ornament of the cyst, in the terminology of Below 1987a, b. Wall features: Low relatively broad continuous ridges that interconnect to form a regular reticulum cover the surface of the cyst. These are ca. 0.5-1 jim wide enclosing sub-polygonal lumina, normally measuring ca. 2.5-5 jam in width. All the lumina present on one specimen are of relatively equal sizes. The ridges are low (ca. 1 |jm) and rounded in section and appear to have a vacuolate structure. Occasionally specimens possess some ridges that fade out (although the reticulation remains complete), and some may have faint, very poorly developed "ghost-like" ridges that occur within lumina. Paratabulation and parasutural features: No paratabulation is evident. The principal archeopyle margin indicates the presence of seven precingular paraplates. Archeopyle: The archeopyle is apical and the operculum is free, only occasionally being found within the cyst. Cyst Size: Diameter min. 22(23)25 µm max. 15 specimens measured.
Remarks and Comparisons. This species of Orobodinium differs from all others by the possession of a complete, regular reticulum on the surface of the cyst. Orobodinium rete Gocht and Wille 1990 from the early Bathonian is most morphologically similar to O. changii. This species possesses a vermiculate to reticulate surface ornament, but any reticulation is composed of undulose rugulae and is incomplete. The lumina are not of equal size and there is a tendency toward bireticulation. Gocht and Wille (1990) recorded O. changii as an informal species distinct from O. rete. Although the cyst is described as not showing any paratabulation, it may be possible that some of the ridges on the cyst are approximately parasutural but are masked by the reticulation. Even so, specimens observed displayed no positive proof of paratabulation other than the principal archeopyle suture. Occurrence. Late Bathonian, C. discus Zone, Abbotsbury Cornbrash Formation, Berry Member, Shipton-onCherwell, Oxfordshire, Tykoezinski (written commun., 1982) [as Cymatiosphaera sp.A]: Early Callovian, M. herveyi Zone, south-west Germany, Gocht and Wille (1990): Early Callovian to Early Oxfordian, M. herveyi to Q. mariae Zones, M. terebratus to scarburgense Subzones, Abbotsbury Cornbrash Formation (unit al)-Oxford Clay Formation, Smith (written commun., 1995) [as O. cunstonense].