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Rhiptocorys veligera
Rhiptocorys *veligera (Deflandre, 1937b, p.81, pl.12 [al. pl.9], fig.9) Lejeune-Carpentier and Sarjeant, 1983, p.5. Emendations: Lejeune-Carpentier, 1943, p.B24–B25, as Ceratocorys veligera; Lejeune-Carpentier and Sarjeant, 1983, p.5–6, as Rhiptocorys veligera.
Holotype: Deflandre, 1937b, pl.12 (al. pl.9), fig.9; Fensome et al., 1995, fig.1 — p.1885.
Originally Micrhystridium (Appendix A), subsequently Ceratocorys (Appendix B), thirdly Microdinium, fourthly Microdinium?, fifthly (and now) Rhiptocorys, sixthly Phanerodinium, seventhly Phanerodinium?. Lentin and Williams (1993, p.560) retained this species in Rhiptocorys. Taxonomic junior synonyms: Microdinium irregulare and Ceratocorys (as Microdinium, now Rhiptocorys) smolenskiensis, both according to Below (1987b, p.56) — however, Lentin and Vozzhennikova (1990, p.112) retained Ceratocorys (as Rhiptocorys) smolenskiensis.
Age: Senonian.
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Emended diagnosis: Lejeune-Carpentier and Sarjeant 1983, p. 5-8
Cyst spheroidal, with hypotract almost twice as large as epitract. Proximochorate, with high suturocavate crests (c. one quarter of the cyst diameter) bounding the paraplates of the hypotract. The cingulum is marked by a single suturocavate structure on its anterior margin and by low ridges, or not at all, on its posterior margin. Epitractal paraplates feebly marked by low ridges or not demarcated at all. Sulcus extending from posterior end of epitract to the antapex, fairly narrow but widening somewhat in its posterior portion. Paratabulation: ?", ?5", 6c, 6"", 1p, 1"". Posterior intercalary paraplate (1p) relatively large. Phragma scabrate to granulate overall; some paraplates show a variable development of areolae, each areola typically having a pustule at its centre. Archaeopyle epitractal; operculum either thrown off as a unit or formed by the partial or complete loss of a series of opercular pieces.
Holotype: Deflandre, 1937, Pl. 12: 9.
Locus typicus: Flint, collected in Paris, France (probably from a path in the Jardin des Plantes):
Stratum typicum: Upper Cretaceous (?Senonian) .
Description: Lejeune-Carpentier and Sarjeant 1983, p. 5-8
The epitract is low-arched, having the form of a longitudinal hemiellipsoid; the hypotract, in contrast, is much larger and has the form of two-thirds of a spheroid. The cingulum between is always visible but is variably marked. In some specimens (for example specimen CX11-170; fig. 4) there is a high suturocavate crest on its anterior margin, surrounding the epitract, and only a low ridge on the posterior margin, while in others (e.g. CX11-419: fig. 7) the posterior margin is scarcely perceptible at all. In contrast, yet other specimens (e.g. CX111-133: fig. 5) have a crest on the posterior margin that is quite well marked, albeit lower and less inflated than the anterior cingular crest. Though the divisions between them are not always well marked, six cingular paraplates may be distinguished, of which the sixth is less longitudinally elongate than the others.
The paraplates of the epitract are so very poorly marked in the specimens examined that our remarks concerning them must be in the highest degree tentative. On some specimens (e.g. CX11-173: fig. 6) the entire epitract has been lost in archaeopyle formation; in others (e.g. CX11-170; fig. 4) it is present but shows no indication of any separation into paraplates. However, in a few favourable specimens (e.g. CX11-419: Pl. 11: 3; Fig. 7), the paraplates of the epitract, though they have begun to separate into opercular pieces, are still attached. The apical paraplate or paraplates - the latter seems more likely, though we could not be confident - appear to be thrown off as a single opercular piece, the precingular paraplates as separate opercular pieces. Four precingular paraplates were distinguished with confidence (Fig. 7) but their total number probably is five or possibly six.
The paratabulation of the hypotract is, in contrast, readily determinable because of the high, suturocavate crests that bound them. Six postcingular paraplates are developed; paraplate 1" " is smallest and separated from the antaPeX by a large, subquadrate posterior intercalary paraplate (fig. 7 and 8); paraplate 6" " is somewhat narrower than the remaining postcingulars, which are of closely similar size. The antapical paraplate is moderately large and of rounded-hexagonal outline (Fig. 8).
The suturocavate crests have entire to undulate or scalloped distal edges.
The surficial ornament is highly variable, not only between specimens but even on individual cysts (see in particular Figs 5 and 7). There is an overall cover of granules, sometimes fine to medium, sometimes coarse and becoming enlarged, on parts or the whole of some paraplates, into scabrae, even (rarely) into tubercles or echinae (Fig. 5). Many specimens exhibit, on some but never (in the material seen) on all paraplates, a pattern of areolae, usually of rather regular shape and typically centred on a papilla (Pl. 2: 4-5 and Figs 4, 6). Other specimens, however, lack this ornament entirely (e.g. CXI1-291; Fig. 8). The cysts vary in colour from amber to mid-brown.
Dimensions Holotype: overall diameter 25µm, diameter of central body 18µm. Figured specimens: overall diameter 27 to 31µm, diameter of central body 21-26µm.
Remarks: Lejeune-Carpentier and Sarjeant 1983, p. 5-8
The holotype was examined briefly by the second author during a visit to Paris in 1980, through the courtesy of Mme. Marthe Deflandre-Rigaud, and seen to be a specimen in oblique lateral view, corresponding in all essential particulars with those from Belgium.
When Davey described specimens of this species from the Cenomanian of England (1969), he perceived most major features of its morphology. However, in the forms he observed, the epitractal archaeopyle appears not to have been fully developed: one of the specimens he illustrated lacks the apical paraplate(s) but retains the precingulars, though they appear to be separated by sutures and to have flapped open (ibid., Pl. 4: 4). Under these circumstances, his attribution of the species to Microdinium becomes perfectly comprehensible. The second specimen he illustrated shows the antapical paratabulation especially well (ibid., Pl. 3: 4). The only other acceptable record of this species - though no illustration is furnished - is from an offshore borehole on the Grand Banks off Newfoundland, eastern Canada (Barss et a/., 1979), in sediments to which a Maastrichtian date was assigned. The known range of Rhiptocorys veligera is thus Upper Cretaceous (Cenomanian-Maastrichtian).
The specimen illustrated by Wilson (1971), from the Maastrichtian of Denmark, certainly is not attributable to this species, having too markedly ovoidal an ambitus and too large an epitract; and the forms from a borehole on the Grand Banks, offshore eastern Canada, compared by Barss et al. ( 1979) to Wilson"s form must be presumed likewise to be of different taxonomic affinity.
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Holotype: Deflandre, 1937b, pl.12 (al. pl.9), fig.9; Fensome et al., 1995, fig.1 — p.1885.
Originally Micrhystridium (Appendix A), subsequently Ceratocorys (Appendix B), thirdly Microdinium, fourthly Microdinium?, fifthly (and now) Rhiptocorys, sixthly Phanerodinium, seventhly Phanerodinium?. Lentin and Williams (1993, p.560) retained this species in Rhiptocorys. Taxonomic junior synonyms: Microdinium irregulare and Ceratocorys (as Microdinium, now Rhiptocorys) smolenskiensis, both according to Below (1987b, p.56) — however, Lentin and Vozzhennikova (1990, p.112) retained Ceratocorys (as Rhiptocorys) smolenskiensis.
Age: Senonian.
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Emended diagnosis: Lejeune-Carpentier and Sarjeant 1983, p. 5-8
Cyst spheroidal, with hypotract almost twice as large as epitract. Proximochorate, with high suturocavate crests (c. one quarter of the cyst diameter) bounding the paraplates of the hypotract. The cingulum is marked by a single suturocavate structure on its anterior margin and by low ridges, or not at all, on its posterior margin. Epitractal paraplates feebly marked by low ridges or not demarcated at all. Sulcus extending from posterior end of epitract to the antapex, fairly narrow but widening somewhat in its posterior portion. Paratabulation: ?", ?5", 6c, 6"", 1p, 1"". Posterior intercalary paraplate (1p) relatively large. Phragma scabrate to granulate overall; some paraplates show a variable development of areolae, each areola typically having a pustule at its centre. Archaeopyle epitractal; operculum either thrown off as a unit or formed by the partial or complete loss of a series of opercular pieces.
Holotype: Deflandre, 1937, Pl. 12: 9.
Locus typicus: Flint, collected in Paris, France (probably from a path in the Jardin des Plantes):
Stratum typicum: Upper Cretaceous (?Senonian) .
Description: Lejeune-Carpentier and Sarjeant 1983, p. 5-8
The epitract is low-arched, having the form of a longitudinal hemiellipsoid; the hypotract, in contrast, is much larger and has the form of two-thirds of a spheroid. The cingulum between is always visible but is variably marked. In some specimens (for example specimen CX11-170; fig. 4) there is a high suturocavate crest on its anterior margin, surrounding the epitract, and only a low ridge on the posterior margin, while in others (e.g. CX11-419: fig. 7) the posterior margin is scarcely perceptible at all. In contrast, yet other specimens (e.g. CX111-133: fig. 5) have a crest on the posterior margin that is quite well marked, albeit lower and less inflated than the anterior cingular crest. Though the divisions between them are not always well marked, six cingular paraplates may be distinguished, of which the sixth is less longitudinally elongate than the others.
The paraplates of the epitract are so very poorly marked in the specimens examined that our remarks concerning them must be in the highest degree tentative. On some specimens (e.g. CX11-173: fig. 6) the entire epitract has been lost in archaeopyle formation; in others (e.g. CX11-170; fig. 4) it is present but shows no indication of any separation into paraplates. However, in a few favourable specimens (e.g. CX11-419: Pl. 11: 3; Fig. 7), the paraplates of the epitract, though they have begun to separate into opercular pieces, are still attached. The apical paraplate or paraplates - the latter seems more likely, though we could not be confident - appear to be thrown off as a single opercular piece, the precingular paraplates as separate opercular pieces. Four precingular paraplates were distinguished with confidence (Fig. 7) but their total number probably is five or possibly six.
The paratabulation of the hypotract is, in contrast, readily determinable because of the high, suturocavate crests that bound them. Six postcingular paraplates are developed; paraplate 1" " is smallest and separated from the antaPeX by a large, subquadrate posterior intercalary paraplate (fig. 7 and 8); paraplate 6" " is somewhat narrower than the remaining postcingulars, which are of closely similar size. The antapical paraplate is moderately large and of rounded-hexagonal outline (Fig. 8).
The suturocavate crests have entire to undulate or scalloped distal edges.
The surficial ornament is highly variable, not only between specimens but even on individual cysts (see in particular Figs 5 and 7). There is an overall cover of granules, sometimes fine to medium, sometimes coarse and becoming enlarged, on parts or the whole of some paraplates, into scabrae, even (rarely) into tubercles or echinae (Fig. 5). Many specimens exhibit, on some but never (in the material seen) on all paraplates, a pattern of areolae, usually of rather regular shape and typically centred on a papilla (Pl. 2: 4-5 and Figs 4, 6). Other specimens, however, lack this ornament entirely (e.g. CXI1-291; Fig. 8). The cysts vary in colour from amber to mid-brown.
Dimensions Holotype: overall diameter 25µm, diameter of central body 18µm. Figured specimens: overall diameter 27 to 31µm, diameter of central body 21-26µm.
Remarks: Lejeune-Carpentier and Sarjeant 1983, p. 5-8
The holotype was examined briefly by the second author during a visit to Paris in 1980, through the courtesy of Mme. Marthe Deflandre-Rigaud, and seen to be a specimen in oblique lateral view, corresponding in all essential particulars with those from Belgium.
When Davey described specimens of this species from the Cenomanian of England (1969), he perceived most major features of its morphology. However, in the forms he observed, the epitractal archaeopyle appears not to have been fully developed: one of the specimens he illustrated lacks the apical paraplate(s) but retains the precingulars, though they appear to be separated by sutures and to have flapped open (ibid., Pl. 4: 4). Under these circumstances, his attribution of the species to Microdinium becomes perfectly comprehensible. The second specimen he illustrated shows the antapical paratabulation especially well (ibid., Pl. 3: 4). The only other acceptable record of this species - though no illustration is furnished - is from an offshore borehole on the Grand Banks off Newfoundland, eastern Canada (Barss et a/., 1979), in sediments to which a Maastrichtian date was assigned. The known range of Rhiptocorys veligera is thus Upper Cretaceous (Cenomanian-Maastrichtian).
The specimen illustrated by Wilson (1971), from the Maastrichtian of Denmark, certainly is not attributable to this species, having too markedly ovoidal an ambitus and too large an epitract; and the forms from a borehole on the Grand Banks, offshore eastern Canada, compared by Barss et al. ( 1979) to Wilson"s form must be presumed likewise to be of different taxonomic affinity.
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