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Muderongia pariata
Muderongia pariata Duxbury, 1983; emend. Monteil, 1991
Tax. jr. synonym of Muderongia perforata Alberti, 1961, according to Arhus in Arhus et al., 1990. Monteil, 1991, retained Muderongia pariata as a separate species.
Holotype: Duxbury, 1983, pl.2, figs.5, 8, text-fig.16; Monteil, 1991, pl.7, figs.3a-c
Locus typicus: Atherfield section, Isle of Wight, England
Stratum typicum: Early Aptian-Early Albian
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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 pariata Duxbury, 1983, emend. Monteil, 1991b. Diagnosis from Duxbury (1983, p.36-37).. A thin-walled, obviously cavate Muderongia with a smooth endophragm and a generally smooth to finely perforate periphragm. The periphragm forms one apical, two lateral and one centrally located antapical horn. The apical and antapical horns are distally open and are of similar length, as are the laterals, which are short, distally blunt and notched. The cyst is dorso-ventrally flattened and the body layers are in contact over much of the dorsal and ventral surfaces, but are noticeably separate around much of the periphery. Distinctly perforate areas may be observed at the horn tips and in the mid-dorsal and mid-ventral areas. The archeopyle is apical, formed by detachment of the entire apical series. Paratabulation is absent except where expressed by the archeopyle margin, by linear, finely perforate areas on the ventral surface and by the paracingulum. Size: complete specimens 136 x 73 µm, operculum detached 73-107 x 64-110 µm.
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Original diagnosis: Duxbury, 1983, p.36
A thin-walled, obviously cavate Muderongia with a smooth endophragm and a generally smooth to finely perforate periphragm. The periphragm forms one apical, two lateral and one centrally positioned antapical horn. The apical and antapical horns are distally open and are of similar length, as are the laterals, which
are short, distally blunt and notched. The cyst is dorso-ventrally flattened and the body layers are in contact over much of the dorsal and ventral surfaces, but are noticeably separate around much of the periphery. Distinctly perforate areas may be observed at the horn tips and in the mid-dorsal and mid-ventral areas. The archeopyle is apical, formed by detachment of the entire apical series. Paratabulation is absent except where expressed by the archeopyle margin, by linear, finely perforate areas on the ventral surface and by the paracingulum.
Observed Dimensions: Holotype - 81 x 81 Ám Complete specimens - 136 x 73 Ám
Operculum detached - 107 (90) 73 x 110 (84) 64 Ám
Emended diagnosis: Monteil, 1991, p. 474
Cysts proximate, compressed dorso-ventrally, two-layered, cornucavate to delphicavate. Pericyst ceratioid, symmetrical, with 4 or 2 prominent horns; both
lateral horns may be considerably reduced: 1 apical (axial, type AP l); 2 subequal lateral (axial, type L I), indented; 1 antapical (axial, type ATP I). Lateral horns, sometimes stout, normal with distal extremities closed and rounded. Antapical
horn tapered with distal extremity closed and rounded. Horns may be open and perforated-scalloped (Pl. 2, fig. 12); proximal extremities wide, particularly the antapical one. Endocyst oval to rhombic. Periphragm thin, psilate to scabrate, finely perforated in the distal half of the horns and in the mid-dorsal and mid-ventral areas. Endophragm thin, psilate to granulate. Archeopyle apical, type (4A), with anular margin. Parasulcal notch marked. Operculum free. Paratabulation only indicated by archeopyle, or expressed by folds of periphragm and linear finely perforated areas and/or by low septa. Formula :?pr, 4', 0a, 6", 6c, 6''', 1p, 1'''', ?xs.
Pericingulum marked by indentation of lateral horns and by parallel transverse structures. Perisulcus marked by parasulcal notch offset. Perisulcal area may be marked by sinuous folds of periphragm and finely perforated fields (Pl. 7, fig. 3a-c).
Dimensions of the holotype (without operculum): 81 Ám x 81 Ám (overall L x I).
Affinities:
Duxbury, 1983, p. 36-37: Below (1981) described this species as Muderongia perforata Alberti, 1961, but he noted that it differs from that species as described in Alberti, 1961 in having only a single antapical horn. The distinctly cavate
hypocyst terminating in a single, broad-based, antapical horn distinguishes this species from all but two others, Muderongia staurota Sarjeant, 1966 and M. imparilis Duxbury, 1980. M. pariata most resembles M. staurota in its overall shape and in the relative disposition of the body layers, but it differs in the character of the lateral horns. In M. staurota, the lateral horns are usually of unequal length with the right lateral usually distinctly longer than the left. Also, the distal portions of these horns are backwardly-tapering at approximately one-third their length and no notching is observed. The lateral horns of M. pariata are short, distally blunt and notched. In his diagnosis of M. staurota, Sarjeant (1966b, p. 203) stated, "shell showing neither trace of tabulation nor of cingulum or sulcus". M. pariata, however, often displays some indication of the paracingulum, particularly on the dorsal surface, and may exhibit hints of paratabulation on the ventral surface, marked by linear, finely perforate areas. M. pariata also differs from M. staurota in having a distally open antapical horn as opposed to the sharply tapering, distally closed horn of the latter. Muderongia imparilis, as was discussed in Duxbury, 1980 (p. 128), appears to be morphologically intermediate between Muderongia and Odontochitina Dedlandre, 1935 emend. Davey, 1970. As such, its length to breadth ratio is considerably greater than that of M. pariata. Also, the lateral horns are very unequal with the left being blunt and unnotched whilst the right is considerably longer and tapers to a point.
Monteil, 1991, p. 475: Muderongia pariata differs from M tomaszowensis emend. in possessing a finely perforated periphragm in the distal half of the horns.
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Tax. jr. synonym of Muderongia perforata Alberti, 1961, according to Arhus in Arhus et al., 1990. Monteil, 1991, retained Muderongia pariata as a separate species.
Holotype: Duxbury, 1983, pl.2, figs.5, 8, text-fig.16; Monteil, 1991, pl.7, figs.3a-c
Locus typicus: Atherfield section, Isle of Wight, England
Stratum typicum: Early Aptian-Early Albian
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Muderongia pariata Duxbury, 1983, emend. Monteil, 1991b. Diagnosis from Duxbury (1983, p.36-37).. A thin-walled, obviously cavate Muderongia with a smooth endophragm and a generally smooth to finely perforate periphragm. The periphragm forms one apical, two lateral and one centrally located antapical horn. The apical and antapical horns are distally open and are of similar length, as are the laterals, which are short, distally blunt and notched. The cyst is dorso-ventrally flattened and the body layers are in contact over much of the dorsal and ventral surfaces, but are noticeably separate around much of the periphery. Distinctly perforate areas may be observed at the horn tips and in the mid-dorsal and mid-ventral areas. The archeopyle is apical, formed by detachment of the entire apical series. Paratabulation is absent except where expressed by the archeopyle margin, by linear, finely perforate areas on the ventral surface and by the paracingulum. Size: complete specimens 136 x 73 µm, operculum detached 73-107 x 64-110 µm.
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Original diagnosis: Duxbury, 1983, p.36
A thin-walled, obviously cavate Muderongia with a smooth endophragm and a generally smooth to finely perforate periphragm. The periphragm forms one apical, two lateral and one centrally positioned antapical horn. The apical and antapical horns are distally open and are of similar length, as are the laterals, which
are short, distally blunt and notched. The cyst is dorso-ventrally flattened and the body layers are in contact over much of the dorsal and ventral surfaces, but are noticeably separate around much of the periphery. Distinctly perforate areas may be observed at the horn tips and in the mid-dorsal and mid-ventral areas. The archeopyle is apical, formed by detachment of the entire apical series. Paratabulation is absent except where expressed by the archeopyle margin, by linear, finely perforate areas on the ventral surface and by the paracingulum.
Observed Dimensions: Holotype - 81 x 81 Ám Complete specimens - 136 x 73 Ám
Operculum detached - 107 (90) 73 x 110 (84) 64 Ám
Emended diagnosis: Monteil, 1991, p. 474
Cysts proximate, compressed dorso-ventrally, two-layered, cornucavate to delphicavate. Pericyst ceratioid, symmetrical, with 4 or 2 prominent horns; both
lateral horns may be considerably reduced: 1 apical (axial, type AP l); 2 subequal lateral (axial, type L I), indented; 1 antapical (axial, type ATP I). Lateral horns, sometimes stout, normal with distal extremities closed and rounded. Antapical
horn tapered with distal extremity closed and rounded. Horns may be open and perforated-scalloped (Pl. 2, fig. 12); proximal extremities wide, particularly the antapical one. Endocyst oval to rhombic. Periphragm thin, psilate to scabrate, finely perforated in the distal half of the horns and in the mid-dorsal and mid-ventral areas. Endophragm thin, psilate to granulate. Archeopyle apical, type (4A), with anular margin. Parasulcal notch marked. Operculum free. Paratabulation only indicated by archeopyle, or expressed by folds of periphragm and linear finely perforated areas and/or by low septa. Formula :?pr, 4', 0a, 6", 6c, 6''', 1p, 1'''', ?xs.
Pericingulum marked by indentation of lateral horns and by parallel transverse structures. Perisulcus marked by parasulcal notch offset. Perisulcal area may be marked by sinuous folds of periphragm and finely perforated fields (Pl. 7, fig. 3a-c).
Dimensions of the holotype (without operculum): 81 Ám x 81 Ám (overall L x I).
Affinities:
Duxbury, 1983, p. 36-37: Below (1981) described this species as Muderongia perforata Alberti, 1961, but he noted that it differs from that species as described in Alberti, 1961 in having only a single antapical horn. The distinctly cavate
hypocyst terminating in a single, broad-based, antapical horn distinguishes this species from all but two others, Muderongia staurota Sarjeant, 1966 and M. imparilis Duxbury, 1980. M. pariata most resembles M. staurota in its overall shape and in the relative disposition of the body layers, but it differs in the character of the lateral horns. In M. staurota, the lateral horns are usually of unequal length with the right lateral usually distinctly longer than the left. Also, the distal portions of these horns are backwardly-tapering at approximately one-third their length and no notching is observed. The lateral horns of M. pariata are short, distally blunt and notched. In his diagnosis of M. staurota, Sarjeant (1966b, p. 203) stated, "shell showing neither trace of tabulation nor of cingulum or sulcus". M. pariata, however, often displays some indication of the paracingulum, particularly on the dorsal surface, and may exhibit hints of paratabulation on the ventral surface, marked by linear, finely perforate areas. M. pariata also differs from M. staurota in having a distally open antapical horn as opposed to the sharply tapering, distally closed horn of the latter. Muderongia imparilis, as was discussed in Duxbury, 1980 (p. 128), appears to be morphologically intermediate between Muderongia and Odontochitina Dedlandre, 1935 emend. Davey, 1970. As such, its length to breadth ratio is considerably greater than that of M. pariata. Also, the lateral horns are very unequal with the left being blunt and unnotched whilst the right is considerably longer and tapers to a point.
Monteil, 1991, p. 475: Muderongia pariata differs from M tomaszowensis emend. in possessing a finely perforated periphragm in the distal half of the horns.
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