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Laciniadinium aquiloniforme
Laciniadinium? aquiloniforme Schioler et al.1997
Holotype: Schioler et al.1997: GEUS Catalogue No. 1996-PS-1 (Plate II, 9).
Paratypes: Schioler et al.1997: GEUS Catalogue nos 1996-PS-3 (Plate II, 10), 1996-PS-2 (Plate II, 11, 12), 1996-PS-4 (Plate II, 13), 1996-PS-5 (Plate II, 15) .
Locus typicus: ENCI Quarry, Maastricht, The Netherlands.
Stratum typicum: ENCI Quarry section 3.66 m, Lixhe 2 Member, upper Maastrichtian, Upper Cretaceous.
Diagnosis: Schioler et al. 1997, p. 83, 85
Small rhombic two-layered dorsoventrally compressed cornucavate cyst with a prominent apical horn bearing a short acuminate solid process. The peri- and endophragm are closely appressed except below the apical horn and in the extreme antapical and lateral parts of the cyst. The periphragm is smooth and flat on the dorsal and ventral sides. The endophragm is ellipsoidal to rhomboidal in ambital view with length approximately equal to the width, thin and smooth. The paracingulum is always expressed by parallel septate ridges connecting the dorsal and ventral surfaces on the lateral margins. The archeopyle type is uncertain.
Description: Schioler et al. 1997, p. 83, 85
The periphragm is smooth and has the shape of a rhombic box, formed by two flat surfaces connected by lateral sides. The dorsal and ventral side of the periphragm are bounded marginally by low ridges, and meet at the poles of the cyst. An acuminate process arises from the apex of the cyst (length of apical process: 3-5 ,um). The apical process is solid, but often contains 2-5 small vacuoli. Laterally, two pairs of low parallel ridges connect the dorsal and the ventral surface of the periphragm in the equatorial part of the cyst thereby indicating the paracingulum (distance between ridges: 4-5 Ám, Plate II, 10, 13, 16). The ridges bear low septa (height of septa: 2 Ám, Plate II, 9). At the junctions with the dorsal and ventral sides of the cyst each ridge form a spine-like and apparently solid projection. The antapical part of the periphragm is acute and sometimes pulled out to a small horn, but lacks a terminal process. The endophragm is ellipsoidal to rhomboidal in ambital view with length approximately equal to the width, smooth and closely appressed to the periphragm except below the apical horn and in the extreme antapical and lateral parts of the cyst where small pericoels are developed. A large delta-shaped opening sometimes occurs in the epicyst (Plate II, 10) but the archeopyle type is uncertain. The paracingulum is indicated by two parallel low ridges on the lateral sides of the cyst, and on some specimens by two very faint equatorial lines on the dorsal side (Plate II, 10). The parasulcus is not indicated. The paratabulation is indeterminate, indicated by paracingular ridges and possibly marginal ridges.
Dimensions [in Ám, 6 specimens measured, dimensions given as holotype, minimum (mean) maximum]: length of peri-cyst, 45, 36 (45) 50; width of pericyst, 33, 33 (37) 44; length of endocyst, 26, 26 (32) 38; width of endocyst, 25, 25 (30) 36.
Discussion: Schioler et al. 1997, p. 83, 85
As the archeopyle type has not been determined, it is with some hesitation that the new taxon is placed in Laciniadinium. The new species resembles Laciniadinium rhombiforme (Vozzennikova, 1967) Lentin & Vozzennikova, 1990, but differs in being considerably broader and in lacking paratabulation other than indications of paracingulum and in having septa in marginal position on the paracingular ridges. Laciniadinium? aquiloniforme differs from all other species of Laciniadinium in having a regular rhombic shape with wide and flat dorsal and ventral surfaces, and in having lateral spines.
Stratigraphic occurrence: Upper Maastrichtian, Upper Cretaceous in the ENCI Quarry, Maastricht, The Netherlands. Frequent to rare in the Lixhe and Groensveld members, absent elsewhere.
Holotype: Schioler et al.1997: GEUS Catalogue No. 1996-PS-1 (Plate II, 9).
Paratypes: Schioler et al.1997: GEUS Catalogue nos 1996-PS-3 (Plate II, 10), 1996-PS-2 (Plate II, 11, 12), 1996-PS-4 (Plate II, 13), 1996-PS-5 (Plate II, 15) .
Locus typicus: ENCI Quarry, Maastricht, The Netherlands.
Stratum typicum: ENCI Quarry section 3.66 m, Lixhe 2 Member, upper Maastrichtian, Upper Cretaceous.
Diagnosis: Schioler et al. 1997, p. 83, 85
Small rhombic two-layered dorsoventrally compressed cornucavate cyst with a prominent apical horn bearing a short acuminate solid process. The peri- and endophragm are closely appressed except below the apical horn and in the extreme antapical and lateral parts of the cyst. The periphragm is smooth and flat on the dorsal and ventral sides. The endophragm is ellipsoidal to rhomboidal in ambital view with length approximately equal to the width, thin and smooth. The paracingulum is always expressed by parallel septate ridges connecting the dorsal and ventral surfaces on the lateral margins. The archeopyle type is uncertain.
Description: Schioler et al. 1997, p. 83, 85
The periphragm is smooth and has the shape of a rhombic box, formed by two flat surfaces connected by lateral sides. The dorsal and ventral side of the periphragm are bounded marginally by low ridges, and meet at the poles of the cyst. An acuminate process arises from the apex of the cyst (length of apical process: 3-5 ,um). The apical process is solid, but often contains 2-5 small vacuoli. Laterally, two pairs of low parallel ridges connect the dorsal and the ventral surface of the periphragm in the equatorial part of the cyst thereby indicating the paracingulum (distance between ridges: 4-5 Ám, Plate II, 10, 13, 16). The ridges bear low septa (height of septa: 2 Ám, Plate II, 9). At the junctions with the dorsal and ventral sides of the cyst each ridge form a spine-like and apparently solid projection. The antapical part of the periphragm is acute and sometimes pulled out to a small horn, but lacks a terminal process. The endophragm is ellipsoidal to rhomboidal in ambital view with length approximately equal to the width, smooth and closely appressed to the periphragm except below the apical horn and in the extreme antapical and lateral parts of the cyst where small pericoels are developed. A large delta-shaped opening sometimes occurs in the epicyst (Plate II, 10) but the archeopyle type is uncertain. The paracingulum is indicated by two parallel low ridges on the lateral sides of the cyst, and on some specimens by two very faint equatorial lines on the dorsal side (Plate II, 10). The parasulcus is not indicated. The paratabulation is indeterminate, indicated by paracingular ridges and possibly marginal ridges.
Dimensions [in Ám, 6 specimens measured, dimensions given as holotype, minimum (mean) maximum]: length of peri-cyst, 45, 36 (45) 50; width of pericyst, 33, 33 (37) 44; length of endocyst, 26, 26 (32) 38; width of endocyst, 25, 25 (30) 36.
Discussion: Schioler et al. 1997, p. 83, 85
As the archeopyle type has not been determined, it is with some hesitation that the new taxon is placed in Laciniadinium. The new species resembles Laciniadinium rhombiforme (Vozzennikova, 1967) Lentin & Vozzennikova, 1990, but differs in being considerably broader and in lacking paratabulation other than indications of paracingulum and in having septa in marginal position on the paracingular ridges. Laciniadinium? aquiloniforme differs from all other species of Laciniadinium in having a regular rhombic shape with wide and flat dorsal and ventral surfaces, and in having lateral spines.
Stratigraphic occurrence: Upper Maastrichtian, Upper Cretaceous in the ENCI Quarry, Maastricht, The Netherlands. Frequent to rare in the Lixhe and Groensveld members, absent elsewhere.