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Muderongia australis
Muderongia australis Helby, 1987; emend. Monteil, 1991
Holotype: Helby, 1987, fig.2; Monteil, 1991, pl.5, fig.2
Locus typicus: Australia
Stratum typicum: Barremian
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Muderongia australis Helby, 1987, emend. Monteil, 1991b. This species has spinules and granules delineating the tabulation. It differs from Muderongia simplex in the nature of the cingular horns. In M.simplex, they are robust with relatively blunt extremities. M.australis has notched cingular horns and lateral edges slope in towards the anterior of the cyst; the posterior lateral extremities of the horns are usually pointed and often inclined posteriorly. M.macwhaei has long posterior extensions of the cingular horns. Muderongia tomaszowensis has relatively blunt and stocky cingular horns and no right posterior pericoel bulge. Muderongia tetracantha does not have a right antapical horn and has spindly cingular horns. Size: cingular width (less horns) 78-126 µm, maximum width of endocyst 43-80 µm, length loisthocyst 83-107 µm, length endocyst 50-67 µm.
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Original description: Helby, 1987, p. 300-302
Proximate cyst, showing rhomboidal body with apical horn when flattened dorsoventrally, essentially symmetrical cingular horns, a left antapical horn and a periphragm bulge of variable size constituting a reduced right antapical horn although in rare specimens there appears to be only one antapical horn. Cingular horns projecting laterally from paracingulum as stout lateral bosses. Each cingular horn consisting of parts of 2 modified paraplates from the precingular and postcingular series, and a single elongate cingular paraplate on the left horn and 2 cingular paraplates on the right horn (Fig.3A,B). Postcingular paraplates extending further from the cyst body, occasionally having a slight antapical inclination of the lower surface of the distal tip (Fig.3D). Distal edge of cingular horns sloping with an anterior inclination towards the cyst, ridging of the parasutures giving a distinctive notched appearance, with a gentle concavity marking the position of the cingular paraplates. Right horn may be slightly longer than the left, with more distal inclination. The term 'boss' refers to that part of the horn that projects laterally in line with the paracingulum but not including the anteriorly inclined portions of the precingular paraplates or the posteriorly inclined portions of the postcingular paraplates. Cyst 2-layered, cornucavate, wall layers close together or appressed over most of the dorsal and ventral surfaces. Endocyst rhomboidal with small endoparacingulum. Periphragm varying among distinctive protrusions at horn locations except for populations from smooth, scabrate, granulate to right antapical horn (Fig.3I). Edges of lateral occasionally perforate. Periphragm commonly protrusions on endocyst rarely with slight notching differentiated in the vicinity of the parasutures suggesting someparasutural differentiation on the from slightly raised scabration or granulation to paratabular spinules. In some populations coarse grana and spinules (0.5-1 Ám in height and width at the base) scattered on paraplate surfaces. Commonly extremities of horns bearing scattered spinules. On other specimens the periphragm finely perforate particularly on the horns and along lines on dorsal and ventral surfaces where wall layers separate. Endophragm scabrate to coarsely granulate. Paratabulation indicated by archeopyle, paracingulum and parasutural ridges or granulation. Tabulation formula interpreted as ?pr, 4', 6'', 6c, 6''', 1p, 1'''' (Fig.5). There is a suggestion of a very small preapical paraplate at the anterior end of the apical horn on some specimens. Archeopyle apical, type [tA], principal archeopyle suture zigzag with parasulcal notch set off to left side. Paracingulum expressed as transverse feature across dorsal surface and onto cingular horns where it is evident as a concave area between the notches at the lateral edge of the horns. Paracingulum offset against the parasulcus. Parasulcus slightly sinuous offsetting from midventral position on hypocyst to left ventral position on the epicyst. Sulcal paraplates not well defined.
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Emended description: Monteil 1991b, p. 472
Cysts proximate to proximochorate, compressed dorsoventrally. two-layered, cornucavate to delphicavate or circumcavate Pericyst ceratioid, asymmetrical, with 5 prominent horns: 1 apical (axial, type AP l); 2 subequal lateral (bent, type L ll), indented; 2 inequal antapical (joined, type ATP ll). Postcingular extension short, horizontal to subhorizontal, longer (up to two times) than the precingular one. Right antapical horn reduced or expressed by a small, rounded or angular bulge. Horns normal to tapered with distal extremities closed and rounded to pointed; proximal extremities narrow to wide. Endocyst oval to rhombic, sometimes with eccentric antapex extending in the left antapical horn. Periphragm thin. psilate to scabrate; periphragm may be ornamented by verrucae, spines or
processes (stages I to IV) Spines usually densely distributed on the distal half of the horns, with decreasing density towards the central body. Endophragm thin, psilate to granulate. Archeopyle apical, type (4A), with angular margin.
Parasulcal notch marked. Operculum free. Paratabulation indicated by archeopyle, by low parasutural ridges or septa, and more or less clearly expressed by distribution and type of processes (stages I to IV), when those are present Periphragm showing occasionally penitabular verrucae Formula :?pr, 4', Oa, 6", 6c, 6"', 1p, 1"", 3s (with rs, Is and ps fused), fm (DE CRUZ & MONTEIL, in progress) Pericingulum marked by indentation of lateral horns and by parallel transverse structures. Perisulcus sinuous, marked by parasulcal notch offset Perisulcal area exceptionally clearly subdivided.
Dimensions of the holotype (without operculum): 120 Ám x 100 Ám (overall L x 1, estimated from fig. 2 in HELBY, 1987).
Comparisons: Muderongia australis emend differs from M. macwhaei emend. nov in having a short postcingular ex-tension~ horizontal to subhorizontal, rather than a long one, always distinctly oblique. In both species, the postcingularextension is longer than the precingular one: M. australis up to two times and M. macwachaei emend. up to four to six times.
Holotype: Helby, 1987, fig.2; Monteil, 1991, pl.5, fig.2
Locus typicus: Australia
Stratum typicum: Barremian
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Muderongia australis Helby, 1987, emend. Monteil, 1991b. This species has spinules and granules delineating the tabulation. It differs from Muderongia simplex in the nature of the cingular horns. In M.simplex, they are robust with relatively blunt extremities. M.australis has notched cingular horns and lateral edges slope in towards the anterior of the cyst; the posterior lateral extremities of the horns are usually pointed and often inclined posteriorly. M.macwhaei has long posterior extensions of the cingular horns. Muderongia tomaszowensis has relatively blunt and stocky cingular horns and no right posterior pericoel bulge. Muderongia tetracantha does not have a right antapical horn and has spindly cingular horns. Size: cingular width (less horns) 78-126 µm, maximum width of endocyst 43-80 µm, length loisthocyst 83-107 µm, length endocyst 50-67 µm.
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Original description: Helby, 1987, p. 300-302
Proximate cyst, showing rhomboidal body with apical horn when flattened dorsoventrally, essentially symmetrical cingular horns, a left antapical horn and a periphragm bulge of variable size constituting a reduced right antapical horn although in rare specimens there appears to be only one antapical horn. Cingular horns projecting laterally from paracingulum as stout lateral bosses. Each cingular horn consisting of parts of 2 modified paraplates from the precingular and postcingular series, and a single elongate cingular paraplate on the left horn and 2 cingular paraplates on the right horn (Fig.3A,B). Postcingular paraplates extending further from the cyst body, occasionally having a slight antapical inclination of the lower surface of the distal tip (Fig.3D). Distal edge of cingular horns sloping with an anterior inclination towards the cyst, ridging of the parasutures giving a distinctive notched appearance, with a gentle concavity marking the position of the cingular paraplates. Right horn may be slightly longer than the left, with more distal inclination. The term 'boss' refers to that part of the horn that projects laterally in line with the paracingulum but not including the anteriorly inclined portions of the precingular paraplates or the posteriorly inclined portions of the postcingular paraplates. Cyst 2-layered, cornucavate, wall layers close together or appressed over most of the dorsal and ventral surfaces. Endocyst rhomboidal with small endoparacingulum. Periphragm varying among distinctive protrusions at horn locations except for populations from smooth, scabrate, granulate to right antapical horn (Fig.3I). Edges of lateral occasionally perforate. Periphragm commonly protrusions on endocyst rarely with slight notching differentiated in the vicinity of the parasutures suggesting someparasutural differentiation on the from slightly raised scabration or granulation to paratabular spinules. In some populations coarse grana and spinules (0.5-1 Ám in height and width at the base) scattered on paraplate surfaces. Commonly extremities of horns bearing scattered spinules. On other specimens the periphragm finely perforate particularly on the horns and along lines on dorsal and ventral surfaces where wall layers separate. Endophragm scabrate to coarsely granulate. Paratabulation indicated by archeopyle, paracingulum and parasutural ridges or granulation. Tabulation formula interpreted as ?pr, 4', 6'', 6c, 6''', 1p, 1'''' (Fig.5). There is a suggestion of a very small preapical paraplate at the anterior end of the apical horn on some specimens. Archeopyle apical, type [tA], principal archeopyle suture zigzag with parasulcal notch set off to left side. Paracingulum expressed as transverse feature across dorsal surface and onto cingular horns where it is evident as a concave area between the notches at the lateral edge of the horns. Paracingulum offset against the parasulcus. Parasulcus slightly sinuous offsetting from midventral position on hypocyst to left ventral position on the epicyst. Sulcal paraplates not well defined.
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Emended description: Monteil 1991b, p. 472
Cysts proximate to proximochorate, compressed dorsoventrally. two-layered, cornucavate to delphicavate or circumcavate Pericyst ceratioid, asymmetrical, with 5 prominent horns: 1 apical (axial, type AP l); 2 subequal lateral (bent, type L ll), indented; 2 inequal antapical (joined, type ATP ll). Postcingular extension short, horizontal to subhorizontal, longer (up to two times) than the precingular one. Right antapical horn reduced or expressed by a small, rounded or angular bulge. Horns normal to tapered with distal extremities closed and rounded to pointed; proximal extremities narrow to wide. Endocyst oval to rhombic, sometimes with eccentric antapex extending in the left antapical horn. Periphragm thin. psilate to scabrate; periphragm may be ornamented by verrucae, spines or
processes (stages I to IV) Spines usually densely distributed on the distal half of the horns, with decreasing density towards the central body. Endophragm thin, psilate to granulate. Archeopyle apical, type (4A), with angular margin.
Parasulcal notch marked. Operculum free. Paratabulation indicated by archeopyle, by low parasutural ridges or septa, and more or less clearly expressed by distribution and type of processes (stages I to IV), when those are present Periphragm showing occasionally penitabular verrucae Formula :?pr, 4', Oa, 6", 6c, 6"', 1p, 1"", 3s (with rs, Is and ps fused), fm (DE CRUZ & MONTEIL, in progress) Pericingulum marked by indentation of lateral horns and by parallel transverse structures. Perisulcus sinuous, marked by parasulcal notch offset Perisulcal area exceptionally clearly subdivided.
Dimensions of the holotype (without operculum): 120 Ám x 100 Ám (overall L x 1, estimated from fig. 2 in HELBY, 1987).
Comparisons: Muderongia australis emend differs from M. macwhaei emend. nov in having a short postcingular ex-tension~ horizontal to subhorizontal, rather than a long one, always distinctly oblique. In both species, the postcingularextension is longer than the precingular one: M. australis up to two times and M. macwachaei emend. up to four to six times.