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Xenascus perforatus
Xenascus perforatus (Vozzhennikova, 1967, p.188–189, pl.112, figs.1a–b,3; pl.113, fig.1) Yun Hyesu, 1981, p.62. Emendation: Yun Hyesu, 1981, p.62, as Xenascus perforatus — however, see Lentin and Vozzhennikova (1990, p.119).
Originally Endoceratium, subsequently (and now) Xenascus.
Taxonomic senior synonym: Hystrichosphaera (as Phoberocysta, now Xenascus) ceratioides, according to Davey and Verdier (1971, p.27) — however, Yun Hyesu (1981, p.62) retained Xenascus perforatus.
Lentin and Vozzhennikova (1990, p.118–119) provided an "expanded description" for this species.
Holotype: Vozzhennikova, 1967, pl.112, fig.1a, Lentin and Vozzhennikova, 1990, pl.16, fig.5, text-fig.69
Locus typicus: Smolensk region, Russia
Stratum typicum: Late Cretaceous
Translation Vozzhennikova, 1967: Lees in Sarjeant, 1971
Translation Yun, 1981: LPP
Original description: Vozzhennikova, 1967, p. 188: Endoceratium perforatum
Hypotheca with two, widely seperated, divergent antapical horns of unequal size. The narrower part of the horns have pores. The smaller horn lies below the transverse furrow. The latter is well-developed and its edges, together with the lateral walls of the horns and theca bear a few pointed spines. Internal body oval, its surface covered with small rosettes coloured yellow. The thecal surface smooth. The epitheca is not preserveed in our material.
Dimensions: holotype - length of crushed theca 156 µm, length of antapical horns 95.5 µm and 62.1µm, breadth 97.2 µm, breadth of internal body 67.5 µm.
Emended diagnosis: Yun, 1981, p. 62
The central body is divided by the narrow paracingulum into a larger epicyst and a smaller hypocyst. A characteristic feature is the large, blunted, in outline triangular antapical horn, which surrounds as a large pericoel the complete hypocyst . It is connected to a simple lateral horn and a hollow, distally open spine on the opposite side of the central body.
Description: Yun, 1981, p. 62 - 63
The cyst consists of a thick, partly granulate endophragm and a smooth, thin periphragm. The periphragm developes thorns, low, solid or hollow, somtimes distally closed spines, apical and antapical as well as lateral horns. Usually the spines are oval in cross-section and distally widened or splitted into two to four acuminate or capitate branchs of unequal size. These appear in opposite to the thorns, which are restricted to the horns, on the central body and are arranged in ca. 5 parallel rows. Between the spines on some specimens plate boundaries are indicated, the paracingulum usually most obviuos. The 6-7 Ám wide cingulum runs from a prominent, lateral paracingular spine along the base of the lateral horn. The blunted, in outline elongated triangular apical horn is surrounded by four small spines and consists always of two vertical ridges, which flatten distally. These ridges may exsist on the antapical horn, too. The in outline triangular, blunted antapical horn reaches on the lateral side of the central body up to thr margin of the archaeopyle an on the other side to the upper paracingulum margin, where a open, prominent spine is developed. The antapical horn tapers rapidly in the proximal 2/3 and slower in the distal 1/3. On the side, where the antapical horn reaches the archaeopyle margin, a simple lateral horn is developed on which"s distal margin a hollow spine or/and a small bulge may appear. This bulge is of variable size and developes thorns on the distal part.
Expanded description: Lentin and Vozzhennikova, 1990, p.118-119
Cyst shape ceratioid, with a single apical and broadly triangular antapical horn and one well developed postcingular horn which extends outward laterally then bends at a distinct angle towards the antapex; distal extremities of horns are perforate; endocyst broadly oval; circumcavate. Periphragm smooth with irregularly arranged spines and broad blade-like ridges; endophragm finely granulose. Paratabulation expressed by the archeopyle only. Archeopyle apical, operculum free. Paracingulum and parasulcus are not indicated.
Size: Holotype, length 156 µm - without operculum, width 97 µm; length of antapical horn 96 µm; endocyst, width 68 µm.
Affinities:
Vozzhennikova, 1967, p. 188: This species differs from E. ludbrooki in the different shape of its theca, the lager antapical horns and the presence on them of apertures. It should be noted that the species is very similar to Hystrichosphaera ceratoides Deflandre, which is very similar to members of the genus Endoceratium.
Yun, 1981, p. 63: This species differs from X. ceratoides in having a large, triangular, by thorns covered antapical horn, which reaches from the archaeopyle to the precingulum. Further by the relatively small lateral horn, which rises from the antapical horn, whereas on X. ceratoides the lateral horn is larger and rises directly from the central body.
Originally Endoceratium, subsequently (and now) Xenascus.
Taxonomic senior synonym: Hystrichosphaera (as Phoberocysta, now Xenascus) ceratioides, according to Davey and Verdier (1971, p.27) — however, Yun Hyesu (1981, p.62) retained Xenascus perforatus.
Lentin and Vozzhennikova (1990, p.118–119) provided an "expanded description" for this species.
Holotype: Vozzhennikova, 1967, pl.112, fig.1a, Lentin and Vozzhennikova, 1990, pl.16, fig.5, text-fig.69
Locus typicus: Smolensk region, Russia
Stratum typicum: Late Cretaceous
Translation Vozzhennikova, 1967: Lees in Sarjeant, 1971
Translation Yun, 1981: LPP
Original description: Vozzhennikova, 1967, p. 188: Endoceratium perforatum
Hypotheca with two, widely seperated, divergent antapical horns of unequal size. The narrower part of the horns have pores. The smaller horn lies below the transverse furrow. The latter is well-developed and its edges, together with the lateral walls of the horns and theca bear a few pointed spines. Internal body oval, its surface covered with small rosettes coloured yellow. The thecal surface smooth. The epitheca is not preserveed in our material.
Dimensions: holotype - length of crushed theca 156 µm, length of antapical horns 95.5 µm and 62.1µm, breadth 97.2 µm, breadth of internal body 67.5 µm.
Emended diagnosis: Yun, 1981, p. 62
The central body is divided by the narrow paracingulum into a larger epicyst and a smaller hypocyst. A characteristic feature is the large, blunted, in outline triangular antapical horn, which surrounds as a large pericoel the complete hypocyst . It is connected to a simple lateral horn and a hollow, distally open spine on the opposite side of the central body.
Description: Yun, 1981, p. 62 - 63
The cyst consists of a thick, partly granulate endophragm and a smooth, thin periphragm. The periphragm developes thorns, low, solid or hollow, somtimes distally closed spines, apical and antapical as well as lateral horns. Usually the spines are oval in cross-section and distally widened or splitted into two to four acuminate or capitate branchs of unequal size. These appear in opposite to the thorns, which are restricted to the horns, on the central body and are arranged in ca. 5 parallel rows. Between the spines on some specimens plate boundaries are indicated, the paracingulum usually most obviuos. The 6-7 Ám wide cingulum runs from a prominent, lateral paracingular spine along the base of the lateral horn. The blunted, in outline elongated triangular apical horn is surrounded by four small spines and consists always of two vertical ridges, which flatten distally. These ridges may exsist on the antapical horn, too. The in outline triangular, blunted antapical horn reaches on the lateral side of the central body up to thr margin of the archaeopyle an on the other side to the upper paracingulum margin, where a open, prominent spine is developed. The antapical horn tapers rapidly in the proximal 2/3 and slower in the distal 1/3. On the side, where the antapical horn reaches the archaeopyle margin, a simple lateral horn is developed on which"s distal margin a hollow spine or/and a small bulge may appear. This bulge is of variable size and developes thorns on the distal part.
Expanded description: Lentin and Vozzhennikova, 1990, p.118-119
Cyst shape ceratioid, with a single apical and broadly triangular antapical horn and one well developed postcingular horn which extends outward laterally then bends at a distinct angle towards the antapex; distal extremities of horns are perforate; endocyst broadly oval; circumcavate. Periphragm smooth with irregularly arranged spines and broad blade-like ridges; endophragm finely granulose. Paratabulation expressed by the archeopyle only. Archeopyle apical, operculum free. Paracingulum and parasulcus are not indicated.
Size: Holotype, length 156 µm - without operculum, width 97 µm; length of antapical horn 96 µm; endocyst, width 68 µm.
Affinities:
Vozzhennikova, 1967, p. 188: This species differs from E. ludbrooki in the different shape of its theca, the lager antapical horns and the presence on them of apertures. It should be noted that the species is very similar to Hystrichosphaera ceratoides Deflandre, which is very similar to members of the genus Endoceratium.
Yun, 1981, p. 63: This species differs from X. ceratoides in having a large, triangular, by thorns covered antapical horn, which reaches from the archaeopyle to the precingulum. Further by the relatively small lateral horn, which rises from the antapical horn, whereas on X. ceratoides the lateral horn is larger and rises directly from the central body.