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Muderongia staurota
Muderongia staurota Sarjeant, 1966; Emendation: Monteil, 1991b, p.475–476.
Holotype: Sarjeant, 1966, pl.21, fig.6; text-fig.53a
Locus typicus: Speeton Clay, Shell West Heslerton, Yorkshire
Stratum typicum: Lower Cretaceous (Lower 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 staurota Sarjeant, 1966c, emend. Monteil, 1991b. Muderongia staurota is emended by Monteil (1991b) as follows: Cysts proximate to proximochorate, compressed dorsoventrally, two-layered, cornucavate to delphicavate or circumcavate. Pericyst ceratioid, symmetrical with 4 prominent tapered horns: 1 apical (axial type AP 1), 2 subequal lateral (bent, type L 11), not indented, 1 antapical (axial, type ATP 1). Left lateral horn slightly more reduced than the right one. Postcingular extension short. Distal extremities closed and pointed or open and perforated-ragged; proximal extremities narrow to wide, particularly the antapical horn always wider than the others. A small rounded bulge may be present in right antapical position. Endocyst oval to rhombic. Periphragm thin, psilate to scabrate, sometimes finely perforated in the distal two-thirds of the horns; small perforations not organized or arranged in few rows; periphragm may be ornamented by processes. Endophragm thin, psilate to granulate. Archeopyle apical type (4A), with angular margin. Parasulcal notch marked. Operculum free. Paratabulation only indicated by archeopyle and more or less clearly expressed by distribution and type of processes, when those are present. Formula ?pr, 4', 6", 6c, 6"’, 1p, 1"”. Pericingulum suggested by lateral horns. Perisulcus marked by parasulcal notch offset. Perisulcal area not observed. Size: holotype, overall length 170 µm, width 93 µm, length of apical horn (tip missing) 55 µm, length of antapical horn 34.5 µm, length of longer lateral horns 26 µm, endocyst length 70 µm, width 55 µm. Paratype, overall length 145 µm, width 80 µm, length of apical horn 47 µm, length of antapical horn 44 µm, length of longer lateral horns 31 µm, endocyst length 56 µm, width 51 µm.
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Original diagnosis: Sarjeant 1966, p. 203-204: Muderongia staurota
A Muderongia having an ovoidal to ellipsoidal enclosing body, prolonged into four strong horns. Apical horn strong and tapering, length slightly less than length of shell alone. Lateral horns quite short, less than shell breadth, at first almost parallel sided, but at about one-third length, anterior margin tapering backward to form an angle with posterior margin. Antapical horn basically conical, with slight out-bulge at one side; length also less than length of shell alone. Inner body ovoidal to ellipsoidal. Periphragm smooth or finely pitted; endophragm varying from smooth to densely granular. Shell showing neither trace of tabulation nor of cingulum or sulcus. An apical archaeopyle is formed.
Dimensions: Holotype: overall length 170Ám, breadth 93Ám; length of apical horn (tip missing) 55Ám, of antapical horn 34.5Ám, of longer lateral horns 26Ám, length of inner body, 70Ám, breadth 55Ám. Paratype: overall length I45Ám, breadth 80Ám; length of apical horn, 47Ám, of antapical horn, c.44Ám, of longer lateral horns c.31Ám; length of inner body c.56Ám, breadth c.51Ám. These two specimens represent opposite extremes of the observed range of variation.
Original description: Sarjeant 1966, p. 203-204: Muderongia staurota
The enclosing body has a basically cruciform outline, with a distinctly oval shell enclosing, more or less tightly, an inner body of similar shape. The lateral horns show no distinct notch, nor is a second, shorter antapical horn developed; however, the backward curve of the lateral horns and the lateral bump on the antapical horn suggest affinity to species showing these features. The periphragm shows some degree of pitting, variable in degree and location but usually especially dense on the apical horn. The inner body varies from smooth to granular; where it is smooth, the inner body becomes hard to distinguish and may only be confirmed under phase contrast. (The holotype and paratype illustrate this variation.) This species is relatively common in the Lower Barremian of the West Heslerton Borehole: over 20 specimens were noted, of which the majority comprised either detached apices or shells lacking an apex, complete shells being relatively infrequent. Both holotype and paratype show incipient development of an archaeopyle.
Remarks: Sarjeant 1966, p. 203-204
Muderongia staurota sp. nov. is characterized by the morphology of its shell processes. In contrast M. mcwhaei has a pronouncedly rhombic shell outline; proportionately longer and slimmer horns; notched lateral horns and a second, short antapical horn. M. simplex Alberti I96I, from the Lower Cretaceous Hauterivian to Valanginian) of Germany and Bulgaria, has short horns of almost equivalent relative length, the lateral horns being blunt and notched, and a second antapical horn being again developed. M. perforata Alberti I96I, from the Upper Cretaceous (Turonian) of Germany, has very strong, thick horns, the second antapical horn being especially pronounced. M. tetracantha (Gocht I957), from the Lower Cretaceous (Hauterivian) of Germany, has in contrast extremely long and delicate horns; a second antapical horn is lacking, but the notching of the lateral horns is so deep as to approach bifurcation into unequal branches. M. tomaszowensis Alberti I96I, from the Lower Cretaceous (Valanginian) of Germany and Poland, has stubby apical and antapical horns and blunt notched lateral horns. M. crucis Neale & Sarjeant 1962, from the Lower Cretaceous (Hauterivian) of England, is extremely large (overall length 250-325Ám), with long axial horns and long lateral horns, the latter backswept and not notched.
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Emended diagnosis: Monteil, 1991, p. 475
Cysts proximate to proximochorate, compressed dorsoventrally, two-layered, cornucavate to delphicavate or circumcavate. Pericyst ceratioid, symmetrical, with 4 prominent tapered horns: 1 apical (axial, type AP l); 2 subequal lateral (bent, type L ll), not indented; 1 antapical (axial, type ATP I). Left lateral horn may be slightly more reduced than the right one. Postcingular extension short. Distal extremities closed and pointed or open and perforated-ragged (Pl. 5, fig. 7; pl. 11, fig. 3); proximal extremities narrow to wide, particularly the antapical horn always wider than the others. A small rounded bulge may be present in right antapical position. Endocyst oval to rhombic. Periphragm thin, psilate to scabrate, sometimes finely perforated in the distal two-thirds of the horns (Pl. 6, fig 2); small perforations not organized or arranged in few rows; periphragm may be ornamented by processes (stages I to IV). Endophragm thin, psilate to granulate. Archeopyle apical, type (4A), with angular margin. Parasulcal notch marked. Operculum free. Paratabulation only indicated by archeopyle, 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 suggested by the lateral horns. Perisulcus marked by parasulcal notch offset. Perisulcal area not observed. Dimensions of the holotype (with operculum): 170 Ám x 93 Ám (overall L x I).
Holotype: Sarjeant, 1966, pl.21, fig.6; text-fig.53a
Locus typicus: Speeton Clay, Shell West Heslerton, Yorkshire
Stratum typicum: Lower Cretaceous (Lower 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 staurota Sarjeant, 1966c, emend. Monteil, 1991b. Muderongia staurota is emended by Monteil (1991b) as follows: Cysts proximate to proximochorate, compressed dorsoventrally, two-layered, cornucavate to delphicavate or circumcavate. Pericyst ceratioid, symmetrical with 4 prominent tapered horns: 1 apical (axial type AP 1), 2 subequal lateral (bent, type L 11), not indented, 1 antapical (axial, type ATP 1). Left lateral horn slightly more reduced than the right one. Postcingular extension short. Distal extremities closed and pointed or open and perforated-ragged; proximal extremities narrow to wide, particularly the antapical horn always wider than the others. A small rounded bulge may be present in right antapical position. Endocyst oval to rhombic. Periphragm thin, psilate to scabrate, sometimes finely perforated in the distal two-thirds of the horns; small perforations not organized or arranged in few rows; periphragm may be ornamented by processes. Endophragm thin, psilate to granulate. Archeopyle apical type (4A), with angular margin. Parasulcal notch marked. Operculum free. Paratabulation only indicated by archeopyle and more or less clearly expressed by distribution and type of processes, when those are present. Formula ?pr, 4', 6", 6c, 6"’, 1p, 1"”. Pericingulum suggested by lateral horns. Perisulcus marked by parasulcal notch offset. Perisulcal area not observed. Size: holotype, overall length 170 µm, width 93 µm, length of apical horn (tip missing) 55 µm, length of antapical horn 34.5 µm, length of longer lateral horns 26 µm, endocyst length 70 µm, width 55 µm. Paratype, overall length 145 µm, width 80 µm, length of apical horn 47 µm, length of antapical horn 44 µm, length of longer lateral horns 31 µm, endocyst length 56 µm, width 51 µm.
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Original diagnosis: Sarjeant 1966, p. 203-204: Muderongia staurota
A Muderongia having an ovoidal to ellipsoidal enclosing body, prolonged into four strong horns. Apical horn strong and tapering, length slightly less than length of shell alone. Lateral horns quite short, less than shell breadth, at first almost parallel sided, but at about one-third length, anterior margin tapering backward to form an angle with posterior margin. Antapical horn basically conical, with slight out-bulge at one side; length also less than length of shell alone. Inner body ovoidal to ellipsoidal. Periphragm smooth or finely pitted; endophragm varying from smooth to densely granular. Shell showing neither trace of tabulation nor of cingulum or sulcus. An apical archaeopyle is formed.
Dimensions: Holotype: overall length 170Ám, breadth 93Ám; length of apical horn (tip missing) 55Ám, of antapical horn 34.5Ám, of longer lateral horns 26Ám, length of inner body, 70Ám, breadth 55Ám. Paratype: overall length I45Ám, breadth 80Ám; length of apical horn, 47Ám, of antapical horn, c.44Ám, of longer lateral horns c.31Ám; length of inner body c.56Ám, breadth c.51Ám. These two specimens represent opposite extremes of the observed range of variation.
Original description: Sarjeant 1966, p. 203-204: Muderongia staurota
The enclosing body has a basically cruciform outline, with a distinctly oval shell enclosing, more or less tightly, an inner body of similar shape. The lateral horns show no distinct notch, nor is a second, shorter antapical horn developed; however, the backward curve of the lateral horns and the lateral bump on the antapical horn suggest affinity to species showing these features. The periphragm shows some degree of pitting, variable in degree and location but usually especially dense on the apical horn. The inner body varies from smooth to granular; where it is smooth, the inner body becomes hard to distinguish and may only be confirmed under phase contrast. (The holotype and paratype illustrate this variation.) This species is relatively common in the Lower Barremian of the West Heslerton Borehole: over 20 specimens were noted, of which the majority comprised either detached apices or shells lacking an apex, complete shells being relatively infrequent. Both holotype and paratype show incipient development of an archaeopyle.
Remarks: Sarjeant 1966, p. 203-204
Muderongia staurota sp. nov. is characterized by the morphology of its shell processes. In contrast M. mcwhaei has a pronouncedly rhombic shell outline; proportionately longer and slimmer horns; notched lateral horns and a second, short antapical horn. M. simplex Alberti I96I, from the Lower Cretaceous Hauterivian to Valanginian) of Germany and Bulgaria, has short horns of almost equivalent relative length, the lateral horns being blunt and notched, and a second antapical horn being again developed. M. perforata Alberti I96I, from the Upper Cretaceous (Turonian) of Germany, has very strong, thick horns, the second antapical horn being especially pronounced. M. tetracantha (Gocht I957), from the Lower Cretaceous (Hauterivian) of Germany, has in contrast extremely long and delicate horns; a second antapical horn is lacking, but the notching of the lateral horns is so deep as to approach bifurcation into unequal branches. M. tomaszowensis Alberti I96I, from the Lower Cretaceous (Valanginian) of Germany and Poland, has stubby apical and antapical horns and blunt notched lateral horns. M. crucis Neale & Sarjeant 1962, from the Lower Cretaceous (Hauterivian) of England, is extremely large (overall length 250-325Ám), with long axial horns and long lateral horns, the latter backswept and not notched.
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Emended diagnosis: Monteil, 1991, p. 475
Cysts proximate to proximochorate, compressed dorsoventrally, two-layered, cornucavate to delphicavate or circumcavate. Pericyst ceratioid, symmetrical, with 4 prominent tapered horns: 1 apical (axial, type AP l); 2 subequal lateral (bent, type L ll), not indented; 1 antapical (axial, type ATP I). Left lateral horn may be slightly more reduced than the right one. Postcingular extension short. Distal extremities closed and pointed or open and perforated-ragged (Pl. 5, fig. 7; pl. 11, fig. 3); proximal extremities narrow to wide, particularly the antapical horn always wider than the others. A small rounded bulge may be present in right antapical position. Endocyst oval to rhombic. Periphragm thin, psilate to scabrate, sometimes finely perforated in the distal two-thirds of the horns (Pl. 6, fig 2); small perforations not organized or arranged in few rows; periphragm may be ornamented by processes (stages I to IV). Endophragm thin, psilate to granulate. Archeopyle apical, type (4A), with angular margin. Parasulcal notch marked. Operculum free. Paratabulation only indicated by archeopyle, 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 suggested by the lateral horns. Perisulcus marked by parasulcal notch offset. Perisulcal area not observed. Dimensions of the holotype (with operculum): 170 Ám x 93 Ám (overall L x I).