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Moorodinium peregrinum
Moorodinium peregrinum Backhouse, 1988
Holotype: Backhouse, 1988, pl.33, fig.1a-b; text-fig.30A
Locus typicus: Perth Basin, W Australia
Stratum typicum: Late Thithonian-?earliest Valanginian
Original description: Backhouse, 1988, p.99
Medium-sized proximochorate cysts, subovoid to lobate; epicyst an inflated cone with a rounded apex; hypocyst with two multibranched lobes: in a left antapical position, and in a lateral position, slightly right of the parasulcal zone. Autophragm finely folded, and on rare specimens appears to bear low parasutural septa. Paratabulation otherwise not indicated. Paracingulum indicated by raised ridges and numerous fine cross striae, approximately 5 Ám wide, offset only 2 or 3 Ám. Position of parasulcus indicated at paracingulum, otherwise not expressed. Two sub-parallel, non-tabular septa, up to 6 Ám high, pass dorso-ventrally over apex of cyst. Archeopyle combination epicystal, type [tA, tP]: operculum attached for a considerable part of cyst circumference, only at parasulcus, or free. Primary archeopyle suture formed immediately above anterior paracingular transverse septum.
Dimensions: Length of holotype 77 Ám, width 56 Ám. Range of length (23 specimens) 58(69)85 Ám, width 42(50)63 Ám.
Affinities:
Backhouse, 1988, p.99: As in other species of Moorodinium the apical ventro-dorsal septa of M. peregrinum confer a strong preferred lateral orientation to the epicyst. The lobes of the hypocyst confer a preferred dorsoventral orientation to the lower half of the cyst. In most cases detached epicysts and hypocysts are found in lateral and dorso-ventral orientations respectively. When the epicyst is still attached to the hypocyst at the parasulcus the cyst is usually twisted so that the epicyst is laterally oriented and the hypocyst dorso-ventrally oriented. Whole specimens may be oriented either way, or twisted across the centre (Pl. 33, fig. 4). Moorodinium peregrinum is distinguished from other species of Moorodinium by its lobate hypocyst, large epicyst, and high apical septa. It is the largest species of Moorodinium encountered in this study.
Holotype: Backhouse, 1988, pl.33, fig.1a-b; text-fig.30A
Locus typicus: Perth Basin, W Australia
Stratum typicum: Late Thithonian-?earliest Valanginian
Original description: Backhouse, 1988, p.99
Medium-sized proximochorate cysts, subovoid to lobate; epicyst an inflated cone with a rounded apex; hypocyst with two multibranched lobes: in a left antapical position, and in a lateral position, slightly right of the parasulcal zone. Autophragm finely folded, and on rare specimens appears to bear low parasutural septa. Paratabulation otherwise not indicated. Paracingulum indicated by raised ridges and numerous fine cross striae, approximately 5 Ám wide, offset only 2 or 3 Ám. Position of parasulcus indicated at paracingulum, otherwise not expressed. Two sub-parallel, non-tabular septa, up to 6 Ám high, pass dorso-ventrally over apex of cyst. Archeopyle combination epicystal, type [tA, tP]: operculum attached for a considerable part of cyst circumference, only at parasulcus, or free. Primary archeopyle suture formed immediately above anterior paracingular transverse septum.
Dimensions: Length of holotype 77 Ám, width 56 Ám. Range of length (23 specimens) 58(69)85 Ám, width 42(50)63 Ám.
Affinities:
Backhouse, 1988, p.99: As in other species of Moorodinium the apical ventro-dorsal septa of M. peregrinum confer a strong preferred lateral orientation to the epicyst. The lobes of the hypocyst confer a preferred dorsoventral orientation to the lower half of the cyst. In most cases detached epicysts and hypocysts are found in lateral and dorso-ventral orientations respectively. When the epicyst is still attached to the hypocyst at the parasulcus the cyst is usually twisted so that the epicyst is laterally oriented and the hypocyst dorso-ventrally oriented. Whole specimens may be oriented either way, or twisted across the centre (Pl. 33, fig. 4). Moorodinium peregrinum is distinguished from other species of Moorodinium by its lobate hypocyst, large epicyst, and high apical septa. It is the largest species of Moorodinium encountered in this study.