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Muderongia brachialis
Muderongia brachialis Ottone and Pérez-Loinaze, 2002, p.117–118,120, figs.2A–D.
Holotype: Ottone and Pérez-Loinaze, 2002, fig.2D.
Age: Hauterivian.
Original description (Ottone and Pérez-Loinaze, 2002):
Muderongia brachialis sp. nov. Figures 2.A-D
Synonyms. Muderongia staurota Sarjeant, in Aguirre-Urreta et al., 1999, pl. II, 1, 4.
Holotype. BAFC-Pl 926(5) T31/1; figure 2.D.
Repository. The Palynological Collection, Geological Sciences Department, University of Buenos Aires, Argentina.
Type locality. Paraje El Rincon (Rio Agrio), Neuquen Province, Argentina.
Type stratum. The sample yielding the holotype is a shale horizon of the Upper Member of the Agrio Formation, Mendoza Group, about 7 m above the top of Avile Member, in beds containing ammonites of the Spitidiscus riccardii Biozone (Aguirre-Urreta and Rawson, 1977).
Occurrence. The Agrio Formation, base of the Upper Member at Par* El Rincon (Rio Agrio) and Agua de la Mula, in levels with ammonites of the Spitidiscus riccardii and basal Crioceratites sclilagintweiti Biozones (Aguirre-Urreta and Rawson, 1977).
Derivation of name. In reference to the characteristic lateral horns (etymology: latin, brachialis, of the arm).
Diagnosis. A species of Mucterongia with wide an¬tapical pericoel, one antapical horn and two prominent, bent, lateral horns. Left and right lateral horns are usually of different length, the longer being about the same length as the long axis of the endocyst.
Description. Cyst proximate, compressed dorsoventrally. The wall is two-layered, producing a cornucavate to delphicavate form. Pericyst ceratioicl, usually slightly asymmetrical, but rarely symmetrical, dis¬playing four prominent tapered horns with pointed tips. Endocyst oval or, rarely, almost equidimensional and rhombic in outline. Apical horn longer than, or approximately of equivalent length to, the longitudinal axis of the endocyst, Lateral horns bent. They are almost perpendicular to the longitudinal axis of the cyst and, at about one-third length, they bend posteriorly at an angle of about 55 ", then taper steeply to their tips. Left and right lateral horns of different length or, rarely, almost identical. In cysts with lateral horns of differing length, one is about three-quarters the length of the other; the length of the longer lateral horn is about the same as the length of the longitudinal axis of the endocyst, whereas the length of the shorter lateral horn is about the same length as the transverse axis. In cysts with lateral horns of almost equal length, horn length is about the same as endocyst length. Antapical horn is parallel with the longitudinal axis of the endocyst but slightly off set of it. The length of the antapical horn is about the same as that of the longitudinal axis of the endocyst. Antapical pericoel wide. Archeopyle apical, free (type (4A) of Evitt, 1985]. Periphragm and endophragm both thin, psi-late to scabrate. Faint evidence of paracingular notching on lateral horns and some apparent para¬sutural lineation between cingular, pericingular and postcingular paraplates, particularly on the lateral horns. Parasulcus evident at the parasulcal notch. Paratabulation indicated by archeopyle suture and paracingular sutures.
Dimensions (18 complete specimens with apical horn in place). Pericyst length: 133(184)209 µm, width: 93(126)157 µm; endocyst length: 55(64)75 µm, width: 42(53)62 µm. Holotype, pericyst length: 197 µm, width: 105 µm, apical horn: 92 µm, antapical horn: 51 µm, longer lateral horn: 52 µm, shorter lateral horn: 39 µm, endocyst length: 58 µm, width: 42 µm.
Comparison. The lateral horns of Muderongia stauro¬ta Sarjeant emend. Monteil 1991 are short, less than the width of the endocyst breadth (see also: Millioud, 1969; de Reneville and Raynaud, 1981; Costa and Davey, 1999). The specimen figured as M. stattrota by Sarjeant (1966, pl. 23, fig. 4 only) is somewhat com-parable to M. braclualis, however, Sarjeant's form has a relatively narrow antapical pericoel. Muderongia crucis Neale and Sarjeant emend. Monteil 1991 has a narrow antapical pericoel. Muderongia tetracantha (Gocht) Alberti emend. Monteil 1991 has curved lateral horns and also lacks a wide antapical pericoel, Muderongia pariata Duxbury emend. Monteil 1991 and M. tomaszowensis Alberti emend. Monteil 1991 have axial lateral horns (horns aligned with the paracingulum from their base to their end).
Holotype: Ottone and Pérez-Loinaze, 2002, fig.2D.
Age: Hauterivian.
Original description (Ottone and Pérez-Loinaze, 2002):
Muderongia brachialis sp. nov. Figures 2.A-D
Synonyms. Muderongia staurota Sarjeant, in Aguirre-Urreta et al., 1999, pl. II, 1, 4.
Holotype. BAFC-Pl 926(5) T31/1; figure 2.D.
Repository. The Palynological Collection, Geological Sciences Department, University of Buenos Aires, Argentina.
Type locality. Paraje El Rincon (Rio Agrio), Neuquen Province, Argentina.
Type stratum. The sample yielding the holotype is a shale horizon of the Upper Member of the Agrio Formation, Mendoza Group, about 7 m above the top of Avile Member, in beds containing ammonites of the Spitidiscus riccardii Biozone (Aguirre-Urreta and Rawson, 1977).
Occurrence. The Agrio Formation, base of the Upper Member at Par* El Rincon (Rio Agrio) and Agua de la Mula, in levels with ammonites of the Spitidiscus riccardii and basal Crioceratites sclilagintweiti Biozones (Aguirre-Urreta and Rawson, 1977).
Derivation of name. In reference to the characteristic lateral horns (etymology: latin, brachialis, of the arm).
Diagnosis. A species of Mucterongia with wide an¬tapical pericoel, one antapical horn and two prominent, bent, lateral horns. Left and right lateral horns are usually of different length, the longer being about the same length as the long axis of the endocyst.
Description. Cyst proximate, compressed dorsoventrally. The wall is two-layered, producing a cornucavate to delphicavate form. Pericyst ceratioicl, usually slightly asymmetrical, but rarely symmetrical, dis¬playing four prominent tapered horns with pointed tips. Endocyst oval or, rarely, almost equidimensional and rhombic in outline. Apical horn longer than, or approximately of equivalent length to, the longitudinal axis of the endocyst, Lateral horns bent. They are almost perpendicular to the longitudinal axis of the cyst and, at about one-third length, they bend posteriorly at an angle of about 55 ", then taper steeply to their tips. Left and right lateral horns of different length or, rarely, almost identical. In cysts with lateral horns of differing length, one is about three-quarters the length of the other; the length of the longer lateral horn is about the same as the length of the longitudinal axis of the endocyst, whereas the length of the shorter lateral horn is about the same length as the transverse axis. In cysts with lateral horns of almost equal length, horn length is about the same as endocyst length. Antapical horn is parallel with the longitudinal axis of the endocyst but slightly off set of it. The length of the antapical horn is about the same as that of the longitudinal axis of the endocyst. Antapical pericoel wide. Archeopyle apical, free (type (4A) of Evitt, 1985]. Periphragm and endophragm both thin, psi-late to scabrate. Faint evidence of paracingular notching on lateral horns and some apparent para¬sutural lineation between cingular, pericingular and postcingular paraplates, particularly on the lateral horns. Parasulcus evident at the parasulcal notch. Paratabulation indicated by archeopyle suture and paracingular sutures.
Dimensions (18 complete specimens with apical horn in place). Pericyst length: 133(184)209 µm, width: 93(126)157 µm; endocyst length: 55(64)75 µm, width: 42(53)62 µm. Holotype, pericyst length: 197 µm, width: 105 µm, apical horn: 92 µm, antapical horn: 51 µm, longer lateral horn: 52 µm, shorter lateral horn: 39 µm, endocyst length: 58 µm, width: 42 µm.
Comparison. The lateral horns of Muderongia stauro¬ta Sarjeant emend. Monteil 1991 are short, less than the width of the endocyst breadth (see also: Millioud, 1969; de Reneville and Raynaud, 1981; Costa and Davey, 1999). The specimen figured as M. stattrota by Sarjeant (1966, pl. 23, fig. 4 only) is somewhat com-parable to M. braclualis, however, Sarjeant's form has a relatively narrow antapical pericoel. Muderongia crucis Neale and Sarjeant emend. Monteil 1991 has a narrow antapical pericoel. Muderongia tetracantha (Gocht) Alberti emend. Monteil 1991 has curved lateral horns and also lacks a wide antapical pericoel, Muderongia pariata Duxbury emend. Monteil 1991 and M. tomaszowensis Alberti emend. Monteil 1991 have axial lateral horns (horns aligned with the paracingulum from their base to their end).