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Odontochitina blastema
Odontochitina blastema Davey, 1970
Now Xenascus. Originally Odontochitina, subsequently (and now) Xenascus.
Tax. jr. synonym of Xenascus ceratioides (Deflandre, 1937) Lentin and Williams, 1973, according to Davey and Verdier, 1971. Stover and Helby, 1987, retained Odontochitina (as Xenascus) blastema as a separate species.
Holotype: Davey, 1970, pl.5, fig.4
Locus typicus: Minieres Borehole, Escalles, Pas de Calais, France
Stratum typicum: Cenomanian
Original diagnosis: Davey, 1970, p. 356
Central body ovoidal; outer membrane forming long tapering apical horn and two shorter tapering antapical horns. Periphragm smooth or slightly punctate; in region of central body gives rise to small number of branched precingular and postcingular processes. Apical region commonly lost in archaeopyle formation.
Dimensions: Holotype: width of central body 48 Ám, length of antapical horns 54 and 61 Ám, length of subsidiary processes 8-20 Ám. Range: length of apical horn 78 Ám (one specimen); length of antapical horns 50 (55.7) 61 Ám, width of central body 41 (44.4) 51 Ám, length of subsidiary processes 4-23 Ám. Number of specimens measured, 5.
Original description: Davey, 1970, p. 356
O. blastema is of the typical Odontochitina shape but possesses a numbcr of subsidiary processes. These processes vary considerably in size and shape. They may be finely acuminate or more usually they branch, either distally or proximally, and terminate with a small bifurcation. When well developed they are seen to be in two series encircling the central body. One series (precingular) lies just posterior to the archeopyle margin, while the other series (postcingular) is situated towards the posterior end of the central body. Between the two series, corresponding approximately to the widest part of the central body there is an area devoid of processes marking the position of the cingulum. In one specimen (pl. 5, fig. 5) two processes are present also on the proximal part of the larger antipical horn.
Affinities:
Davey, 1970, p. 356: The prescnce of well developed subsidiary processes easily differentiates O. blastema from all previous described species in this genus. Since the overall form of the shell is identical to that of other members of Odontochitina, it was considered proper that this species should be placed in this genus. Hystrichosphaera ceratioides Deflandre is similar in size, overall form and possesses precingular and postcingular proccsses. However, this species possesses a distinct tabulation.
Now Xenascus. Originally Odontochitina, subsequently (and now) Xenascus.
Tax. jr. synonym of Xenascus ceratioides (Deflandre, 1937) Lentin and Williams, 1973, according to Davey and Verdier, 1971. Stover and Helby, 1987, retained Odontochitina (as Xenascus) blastema as a separate species.
Holotype: Davey, 1970, pl.5, fig.4
Locus typicus: Minieres Borehole, Escalles, Pas de Calais, France
Stratum typicum: Cenomanian
Original diagnosis: Davey, 1970, p. 356
Central body ovoidal; outer membrane forming long tapering apical horn and two shorter tapering antapical horns. Periphragm smooth or slightly punctate; in region of central body gives rise to small number of branched precingular and postcingular processes. Apical region commonly lost in archaeopyle formation.
Dimensions: Holotype: width of central body 48 Ám, length of antapical horns 54 and 61 Ám, length of subsidiary processes 8-20 Ám. Range: length of apical horn 78 Ám (one specimen); length of antapical horns 50 (55.7) 61 Ám, width of central body 41 (44.4) 51 Ám, length of subsidiary processes 4-23 Ám. Number of specimens measured, 5.
Original description: Davey, 1970, p. 356
O. blastema is of the typical Odontochitina shape but possesses a numbcr of subsidiary processes. These processes vary considerably in size and shape. They may be finely acuminate or more usually they branch, either distally or proximally, and terminate with a small bifurcation. When well developed they are seen to be in two series encircling the central body. One series (precingular) lies just posterior to the archeopyle margin, while the other series (postcingular) is situated towards the posterior end of the central body. Between the two series, corresponding approximately to the widest part of the central body there is an area devoid of processes marking the position of the cingulum. In one specimen (pl. 5, fig. 5) two processes are present also on the proximal part of the larger antipical horn.
Affinities:
Davey, 1970, p. 356: The prescnce of well developed subsidiary processes easily differentiates O. blastema from all previous described species in this genus. Since the overall form of the shell is identical to that of other members of Odontochitina, it was considered proper that this species should be placed in this genus. Hystrichosphaera ceratioides Deflandre is similar in size, overall form and possesses precingular and postcingular proccsses. However, this species possesses a distinct tabulation.