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Hystrichogonyaulax italica
Hystrichogonyaulax italica (Corradani, 1973) Helenes, 1984
Now Rhynchodiniopsis?. Originally Gonyaulacysta, subsequently Millioudodinium?, thirdly Hystrichogonyaulax, fourthly (and now) Rhynchodiniopsis?.
Holotype: Corradini, 1973, pl.19, figs.8a-b, text-figs.3a-d; Jan du Chêne et al., 1986, pl.98, fig.11c
Paratype: Corradini, 1973
Locus typicus: Castel di Casio, Bologna, Italy
Stratum typicum: Late Cretaceous-Palaeocene
Original diagnosis: Corradini, 1973, p. 132: Gonyaulacysta italica
Test subspherical. Apical horn absent. Surface bearing crests and spines often capitate. Tabulation 3", 1a, 6", 6c, 6""", 1p, 1"""". Plate bounderies marked bv low, poorly c!efined crests, wllich normally bear thin spines. Cingulum wealily laevo-rotatory; cingular plates poorly marked by extremely minute crests. Sulcus reduced to a small triangular area on the epitract; rectangular and a little more developed on the hypotract. Plate 1""" extremely reduced and seldom well defined. Archeopyle precingular formed by loss of 3".
Dimensions: holotype: overall length 90 Ám, breadth 82 Ám, breadth of the cingulum 51 Ám, length of the spines 4-8 Ám. Range: diameter of the test 60-(80)-90 Ám, breadth of the cingulum 4-7 Ám, length of the spines 2-14 Ám.
Original description: Corradini, 1973, p. 132: Gonyaulacysta italica
Cyst almost spherical ]acking of apical horn. Test wall moderately thick. Surface of the periphragm smooth, finely granular or rough, scattered with granules and simple spines, distally capitate, varying in length from 2 to 14 Ám. Low crests, of about 1 Ám thick. border the plates and reflect the following tabulation 3", 1a, 6", 6c, 6""", 1p, 1"""". The number of apical plates is alwavs three. Plate 1" is triangular, narrow and elongate occupving the epitractal prolongation of the sulcus. It is related with the plate through a very narrow groove. The plates 2" and 3" are polygonal in shape. The anterior intercalary plate la is rectangular and displaced between 3" and 6". Among the six precingular plates only the trapezoidal 6" is reduced. Cingulum weakly helicoid, well defined and subdivided into six cingular plates by poorly marked crests. Plate 1""" very reduced and not clearly defined. Plates 2""" and 6""" larger than plate 1""", but markedly smaller than other postcingular plates. Reduced, elongated posteric!r intercalary plate below plate 2""". The sulcus is formed by a little triangular area on the epitract and by a relatively more wide area on the hypotract. The last area is subdivided in small, not well defined areas by imperceptible crests. Antapical plate 1"""" rectangular in shape and extending mainly to the ventral surface of the cyst. Archeopyle precingular formed by loss of plate 3".
Affinities:
Corradini, 1973, p. 132: Gonyaulacysta italica
The lack of an apical horn and the peculiar situation of antapical plate, always excentric, differentiate G. italica from all previously described species. This form has only recovered from Castel di Casio assemblage.
Now Rhynchodiniopsis?. Originally Gonyaulacysta, subsequently Millioudodinium?, thirdly Hystrichogonyaulax, fourthly (and now) Rhynchodiniopsis?.
Holotype: Corradini, 1973, pl.19, figs.8a-b, text-figs.3a-d; Jan du Chêne et al., 1986, pl.98, fig.11c
Paratype: Corradini, 1973
Locus typicus: Castel di Casio, Bologna, Italy
Stratum typicum: Late Cretaceous-Palaeocene
Original diagnosis: Corradini, 1973, p. 132: Gonyaulacysta italica
Test subspherical. Apical horn absent. Surface bearing crests and spines often capitate. Tabulation 3", 1a, 6", 6c, 6""", 1p, 1"""". Plate bounderies marked bv low, poorly c!efined crests, wllich normally bear thin spines. Cingulum wealily laevo-rotatory; cingular plates poorly marked by extremely minute crests. Sulcus reduced to a small triangular area on the epitract; rectangular and a little more developed on the hypotract. Plate 1""" extremely reduced and seldom well defined. Archeopyle precingular formed by loss of 3".
Dimensions: holotype: overall length 90 Ám, breadth 82 Ám, breadth of the cingulum 51 Ám, length of the spines 4-8 Ám. Range: diameter of the test 60-(80)-90 Ám, breadth of the cingulum 4-7 Ám, length of the spines 2-14 Ám.
Original description: Corradini, 1973, p. 132: Gonyaulacysta italica
Cyst almost spherical ]acking of apical horn. Test wall moderately thick. Surface of the periphragm smooth, finely granular or rough, scattered with granules and simple spines, distally capitate, varying in length from 2 to 14 Ám. Low crests, of about 1 Ám thick. border the plates and reflect the following tabulation 3", 1a, 6", 6c, 6""", 1p, 1"""". The number of apical plates is alwavs three. Plate 1" is triangular, narrow and elongate occupving the epitractal prolongation of the sulcus. It is related with the plate through a very narrow groove. The plates 2" and 3" are polygonal in shape. The anterior intercalary plate la is rectangular and displaced between 3" and 6". Among the six precingular plates only the trapezoidal 6" is reduced. Cingulum weakly helicoid, well defined and subdivided into six cingular plates by poorly marked crests. Plate 1""" very reduced and not clearly defined. Plates 2""" and 6""" larger than plate 1""", but markedly smaller than other postcingular plates. Reduced, elongated posteric!r intercalary plate below plate 2""". The sulcus is formed by a little triangular area on the epitract and by a relatively more wide area on the hypotract. The last area is subdivided in small, not well defined areas by imperceptible crests. Antapical plate 1"""" rectangular in shape and extending mainly to the ventral surface of the cyst. Archeopyle precingular formed by loss of plate 3".
Affinities:
Corradini, 1973, p. 132: Gonyaulacysta italica
The lack of an apical horn and the peculiar situation of antapical plate, always excentric, differentiate G. italica from all previously described species. This form has only recovered from Castel di Casio assemblage.