Back
Diconodinium vitricorne
Diconodinium vitricorne Roncaglia et al., 1999, p.303,305, fig.16, nos.1-5.
Roncaglia et al. cited the epithet as "vitricornu", a compound of two Latin nouns, "vitrum" and "cornu". Since, in botanical tradition (Nicolson, 1986), compound epithets generally are made to agree with the gender of the generic name, we cite the specific epithet as "vitricorne".
Holotype: Roncaglia et al., 1999, fig.16, nos.1-2.
Age: Campanian.
Original Diagnosis (Roncaglia et al., 1999)
Holotype. Single specimen mount no. IGNS SM 4720 (Figure 16.1, 2); from Fossil Record Sample no. O32/f168/CR20.
Paratypes. Single specimen mount no. IGNS SM 4719 (Figure 16.3); from Fossil Record Sample no. O32/f217/HBN23. Single specimen mount no. IGNS SM 4721 (Figure 16.5); from Fossil Record Sample no. O32/f217/HBN23.
Type locality. Conway River railway cutting, southern Marlborough, New Zealand.
Stratigraphic occurrence. 120–195 m in the Haumuri Bluff section; 106–128 m in the Conway River section. From the Vozzhennikovia spinulosa Subzone of Roncaglia & Schiøler (1997) to the Isabelidinium korojonense Zone (new definition), lower Haumurian, lower to upper Campanian (Upper Cretaceous), in the Conway Siltstone, southern Marlborough, New Zealand.
Etymology. Latin, vitrum-i = glass; cornu-us = horn.
Diagnosis. Large, acavate, oval to almost biconical cyst, with one sharp apical horn ending in a solid, hyaline tip, and one sharp, left antapical horn located close to the long axis. The autophragm is smooth, mostly thin, but thickened at the apex, and occasionally at the antapex, to form the solid tip of the horn. Two continuous parallel, equatorial ridges indicate the paracingulum. The parasulcus is marked by a deep midventral depression. The archeopyle, type I(2a), is rarely discernible and the operculum is usually attached. The paratabulation is indicated by paracingulum, parasulcus and archeopyle only.
Description. Cyst large, acavate, elongate, oval to nearly biconical, with one apical and one left antapical horn located close to the long axis. The apical horn is subconical, with an acuminate, solid, hyaline tip; occasionally, fine, hair-like elements are present on the solid part of the horn. The antapical horn is subconical, sharp and usually hollow; however, an antapical horn with a solid tip was observed in a few specimens. A small bulge on the phragm, on the right side of the antapical horn, indicates the location of a second, undeveloped antapical horn. The autophragm is smooth and thin (0.5 ìm), but becomes distinctively thickened at the apex and, occasionally, at the antapex, to form a horn with a solid tip. The paracingulum is indicated by continuous, parallel, equatorial ridges on the autophragm. The parasulcus is marked by a deep depression in the midventral area. The archeopyle is intercalary, type I(2a), rarely discernible. The paratabulation is indicated by paracingulum, parasulcus and, rarely, by the archeopyle.
Dimensions (11 specimens measured). Overall length: 113(142)186 µm (holotype 148 µm). Overall width: 48(72)90 µm (holotype 72 µm).
Discussion. Diconodinium vitricornu differs from D. cristatum in having an acuminate apical horn and a parasulcus marked by a deep, midventral depression, and in being much bigger. It differs from all other species of Diconodinium by having a smooth autophragm that is distinctly thickened at the apex, and occasionally at the antapex, to form a horn with a solid tip. Since D. vitricornu occurs within a narrow stratigraphic interval in the Haumuri Bluff and Conway River sections, it may be of stratigraphic importance.
Roncaglia et al. cited the epithet as "vitricornu", a compound of two Latin nouns, "vitrum" and "cornu". Since, in botanical tradition (Nicolson, 1986), compound epithets generally are made to agree with the gender of the generic name, we cite the specific epithet as "vitricorne".
Holotype: Roncaglia et al., 1999, fig.16, nos.1-2.
Age: Campanian.
Original Diagnosis (Roncaglia et al., 1999)
Holotype. Single specimen mount no. IGNS SM 4720 (Figure 16.1, 2); from Fossil Record Sample no. O32/f168/CR20.
Paratypes. Single specimen mount no. IGNS SM 4719 (Figure 16.3); from Fossil Record Sample no. O32/f217/HBN23. Single specimen mount no. IGNS SM 4721 (Figure 16.5); from Fossil Record Sample no. O32/f217/HBN23.
Type locality. Conway River railway cutting, southern Marlborough, New Zealand.
Stratigraphic occurrence. 120–195 m in the Haumuri Bluff section; 106–128 m in the Conway River section. From the Vozzhennikovia spinulosa Subzone of Roncaglia & Schiøler (1997) to the Isabelidinium korojonense Zone (new definition), lower Haumurian, lower to upper Campanian (Upper Cretaceous), in the Conway Siltstone, southern Marlborough, New Zealand.
Etymology. Latin, vitrum-i = glass; cornu-us = horn.
Diagnosis. Large, acavate, oval to almost biconical cyst, with one sharp apical horn ending in a solid, hyaline tip, and one sharp, left antapical horn located close to the long axis. The autophragm is smooth, mostly thin, but thickened at the apex, and occasionally at the antapex, to form the solid tip of the horn. Two continuous parallel, equatorial ridges indicate the paracingulum. The parasulcus is marked by a deep midventral depression. The archeopyle, type I(2a), is rarely discernible and the operculum is usually attached. The paratabulation is indicated by paracingulum, parasulcus and archeopyle only.
Description. Cyst large, acavate, elongate, oval to nearly biconical, with one apical and one left antapical horn located close to the long axis. The apical horn is subconical, with an acuminate, solid, hyaline tip; occasionally, fine, hair-like elements are present on the solid part of the horn. The antapical horn is subconical, sharp and usually hollow; however, an antapical horn with a solid tip was observed in a few specimens. A small bulge on the phragm, on the right side of the antapical horn, indicates the location of a second, undeveloped antapical horn. The autophragm is smooth and thin (0.5 ìm), but becomes distinctively thickened at the apex and, occasionally, at the antapex, to form a horn with a solid tip. The paracingulum is indicated by continuous, parallel, equatorial ridges on the autophragm. The parasulcus is marked by a deep depression in the midventral area. The archeopyle is intercalary, type I(2a), rarely discernible. The paratabulation is indicated by paracingulum, parasulcus and, rarely, by the archeopyle.
Dimensions (11 specimens measured). Overall length: 113(142)186 µm (holotype 148 µm). Overall width: 48(72)90 µm (holotype 72 µm).
Discussion. Diconodinium vitricornu differs from D. cristatum in having an acuminate apical horn and a parasulcus marked by a deep, midventral depression, and in being much bigger. It differs from all other species of Diconodinium by having a smooth autophragm that is distinctly thickened at the apex, and occasionally at the antapex, to form a horn with a solid tip. Since D. vitricornu occurs within a narrow stratigraphic interval in the Haumuri Bluff and Conway River sections, it may be of stratigraphic importance.