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Muderongia macwhaei
Muderongia macwhaei Cookson and Eisenack, 1958; emend. Helby, 1987; emend. Monteil, 1991
Tax. sr. synonym of Muderongia extensiva Duxbury, 1977, according to Monteil, 1991.
Tax. sr. synonym of Phoberocysta rariornata Prössl, 1990, according to Monteil, 1991.
Helby, 1987, considered that the specimens illustrated in pl.6, figs. 1,4-5 of Cookson and Eisenack, 1958, are not Muderongia macwhaei.
Holotype: Cookson and Eisenack, 1958, pl. 6, fig.2; Monteil, 1991, pl.4, fig.4
Paratypes: Cookson and Eisenack, 1958
Locus typicus: Cootabarlow, S Australia
Stratum typicum: Aptian
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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 macwhaei Cookson and Eisenack, 1958, emend. Helby, 1987, emend. Monteil, 1991b. According to Monteil (1991, p.473-474), Muderongia macwhaei is proximate to proximochorate, compressed dorsoventrally, two-layered, cornucavate to delphicavate. Pericyst ceratioid, asymmetrical with 5 prominent horns: 1 apical (axial type AP 1), 2 subequal lateral (bent, type L 11), indented, 2 unequal antapical(joined type ATP 11) . Postcingular extension long, always distinctly oblique, longer (up to 4 to 6 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 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. Exceptionally, spines may be aligned on faintly marked ribs. 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. Formula ?pr, 4', 0a, 6", 6c, 6"’, 1p, 1"”. Pericingulum marked by indentation of lateral horns and by parallel transverse structures. Perisulcus marked by parasulcal notch offset. Perisulcal area not observed. Size: overall length 142-166 µm, width 52-54 µm, apical horn length 23-52 µm. Dimension of holotype with operculum 161 x 74 µm, apical horn 47 µm, endocyst 62 x 57 µm.
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Original description: Cookson and Eisenack, 1958, p. 41
The test is roughly rhomboidal in outline and prolonged into two straight median horns (apical and antapical respectively) and two curved and downwardly directed lateral horns of varying length; near the points of origin of the horns, smaller more irregular outgrouth may develop. The capule has a smooth, moderate thick wall and entirely fills the central cavity of the test, sometimes even extending into the proximal ends of the horns. The girdle is represented by two fine, closely-opposed, straight lines which completely cross the equator of the test. Frequently the extreme distal region of the test becomes detached by a split which develops beneath the base of the apical horn.
Dimensions: Range - 142-166 Ám overall; apical horn 23-52 Ám.
Emended description: Helby, 1987, p. 303-305
Proximate cyst, dorsoventrally flattened to give rhomboidal body with apical horn, 2 unequal antapical horns and 2 essentially symmetrical cingular horns. All horns prominent, with the exception of the right antapical horn which in rare specimens may be difficult to discern. Cingular horns distinctive, each projecting laterally from the paracingulum, as stout lateral bosses. Junctions of the paraplate series bounding the paracingulum slightly raised, particularly at the lateral edge of the horns, giving rise to their characteristic notched appearance which is accentuated by gentle concavity of the cingular paraplates. Postcingular paraplates further modified by extension into a long, hollow, rounded, antapically inclined horn. Endocyst rhomboidal with protuberances at bases of horns but otherwise without horn modification. Cyst wall 2-layered, cornucavate. Periphragm smooth to scabrate, except at extremities of horns where small spinules (0.5 Ám in length) occasionally develop. Perforations of the periphragm, where present, usually at the extremities of the horns, but may occur at the point of separation of the wall layers. Endophragm scabrate to granulate. Paratabulation indicated by archeopyle, sutures, slightly raised parasutures bounding paracingulum on cingular horns and parasutural ridges on left antapical horn and apical horn. Archeopyle apical, type [tA], principal archeopyle suture zigzag with offset parasulcal notch. Operculum free. Paracingulum not usually distinct, except on the cingular horns. Parasulcus not easily identified, except at the parasulcal notch.
Emended description: Monteil, 1991, p. 472
Cysts proximate to proximochorate, compressed dorsoventrally, two-layered, cornucavate to delphicavate. 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 11). Postcingular extension long, always distinctly oblique, longer (up to four to six 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 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. Exceptionally, spines may be aligned on faintly marked ribs. 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. Formula :?pr, 4', Oa, 6", 6c, 6''', 1p, 1''''. Pericingulum marked by indentation of lateral horns and by parallel transverse structures. Perisulcus marked by parasulcal notch offset. Perisulcal area not observed.
The species Muderongia macwhaei (O) Cookson and Eisenack 1958, has been subdivided into three formae: A, B and C. Their distinction is very useful for the biostratigraphic subdivision of the Early Valanginian in south-east France.
--forma A: short and slightly tapered horns, with rounded tip. Right antapical horn expressed by a rounded bulge. Periphragm not spinous. Length of the postcingular extension: 12,5 to 17,5 Ám (ranging from the Upper Otopeta Zone to the Upper Pertransiens Zone);
--forma B: tapered horns of intermediate length, with rounded tip. Right antapical horn expressed by a rounded bulge. Periphragm not spinous. Length of the postcingular extension: 25 to 37,5 Ám (appearance coinciding with the base of the Pertransiens Zone);
--forma C: long and tapered horns, with typically pointed tip. Right antapical horn expressed by an angular bulge. Periphragm often spinous. Length of the postcingular extension: 37,5 to 50 Ám (appearing in the Upper Pertransiens Zone).
Tax. sr. synonym of Muderongia extensiva Duxbury, 1977, according to Monteil, 1991.
Tax. sr. synonym of Phoberocysta rariornata Prössl, 1990, according to Monteil, 1991.
Helby, 1987, considered that the specimens illustrated in pl.6, figs. 1,4-5 of Cookson and Eisenack, 1958, are not Muderongia macwhaei.
Holotype: Cookson and Eisenack, 1958, pl. 6, fig.2; Monteil, 1991, pl.4, fig.4
Paratypes: Cookson and Eisenack, 1958
Locus typicus: Cootabarlow, S Australia
Stratum typicum: Aptian
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Muderongia macwhaei Cookson and Eisenack, 1958, emend. Helby, 1987, emend. Monteil, 1991b. According to Monteil (1991, p.473-474), Muderongia macwhaei is proximate to proximochorate, compressed dorsoventrally, two-layered, cornucavate to delphicavate. Pericyst ceratioid, asymmetrical with 5 prominent horns: 1 apical (axial type AP 1), 2 subequal lateral (bent, type L 11), indented, 2 unequal antapical(joined type ATP 11) . Postcingular extension long, always distinctly oblique, longer (up to 4 to 6 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 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. Exceptionally, spines may be aligned on faintly marked ribs. 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. Formula ?pr, 4', 0a, 6", 6c, 6"’, 1p, 1"”. Pericingulum marked by indentation of lateral horns and by parallel transverse structures. Perisulcus marked by parasulcal notch offset. Perisulcal area not observed. Size: overall length 142-166 µm, width 52-54 µm, apical horn length 23-52 µm. Dimension of holotype with operculum 161 x 74 µm, apical horn 47 µm, endocyst 62 x 57 µm.
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Original description: Cookson and Eisenack, 1958, p. 41
The test is roughly rhomboidal in outline and prolonged into two straight median horns (apical and antapical respectively) and two curved and downwardly directed lateral horns of varying length; near the points of origin of the horns, smaller more irregular outgrouth may develop. The capule has a smooth, moderate thick wall and entirely fills the central cavity of the test, sometimes even extending into the proximal ends of the horns. The girdle is represented by two fine, closely-opposed, straight lines which completely cross the equator of the test. Frequently the extreme distal region of the test becomes detached by a split which develops beneath the base of the apical horn.
Dimensions: Range - 142-166 Ám overall; apical horn 23-52 Ám.
Emended description: Helby, 1987, p. 303-305
Proximate cyst, dorsoventrally flattened to give rhomboidal body with apical horn, 2 unequal antapical horns and 2 essentially symmetrical cingular horns. All horns prominent, with the exception of the right antapical horn which in rare specimens may be difficult to discern. Cingular horns distinctive, each projecting laterally from the paracingulum, as stout lateral bosses. Junctions of the paraplate series bounding the paracingulum slightly raised, particularly at the lateral edge of the horns, giving rise to their characteristic notched appearance which is accentuated by gentle concavity of the cingular paraplates. Postcingular paraplates further modified by extension into a long, hollow, rounded, antapically inclined horn. Endocyst rhomboidal with protuberances at bases of horns but otherwise without horn modification. Cyst wall 2-layered, cornucavate. Periphragm smooth to scabrate, except at extremities of horns where small spinules (0.5 Ám in length) occasionally develop. Perforations of the periphragm, where present, usually at the extremities of the horns, but may occur at the point of separation of the wall layers. Endophragm scabrate to granulate. Paratabulation indicated by archeopyle, sutures, slightly raised parasutures bounding paracingulum on cingular horns and parasutural ridges on left antapical horn and apical horn. Archeopyle apical, type [tA], principal archeopyle suture zigzag with offset parasulcal notch. Operculum free. Paracingulum not usually distinct, except on the cingular horns. Parasulcus not easily identified, except at the parasulcal notch.
Emended description: Monteil, 1991, p. 472
Cysts proximate to proximochorate, compressed dorsoventrally, two-layered, cornucavate to delphicavate. 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 11). Postcingular extension long, always distinctly oblique, longer (up to four to six 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 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. Exceptionally, spines may be aligned on faintly marked ribs. 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. Formula :?pr, 4', Oa, 6", 6c, 6''', 1p, 1''''. Pericingulum marked by indentation of lateral horns and by parallel transverse structures. Perisulcus marked by parasulcal notch offset. Perisulcal area not observed.
The species Muderongia macwhaei (O) Cookson and Eisenack 1958, has been subdivided into three formae: A, B and C. Their distinction is very useful for the biostratigraphic subdivision of the Early Valanginian in south-east France.
--forma A: short and slightly tapered horns, with rounded tip. Right antapical horn expressed by a rounded bulge. Periphragm not spinous. Length of the postcingular extension: 12,5 to 17,5 Ám (ranging from the Upper Otopeta Zone to the Upper Pertransiens Zone);
--forma B: tapered horns of intermediate length, with rounded tip. Right antapical horn expressed by a rounded bulge. Periphragm not spinous. Length of the postcingular extension: 25 to 37,5 Ám (appearance coinciding with the base of the Pertransiens Zone);
--forma C: long and tapered horns, with typically pointed tip. Right antapical horn expressed by an angular bulge. Periphragm often spinous. Length of the postcingular extension: 37,5 to 50 Ám (appearing in the Upper Pertransiens Zone).