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Cannosphaeropsis quattrocchiae
Cannosphaeropsis quattrocchiae, Guerstein et al. 2001, p.158–160, pl.1, figs.1–12, pl.2, figs.1–8, text-figs.4a–b.
Holotype: Guerstein et al., 2001, pl.1, figs.4–8, text-figs.4a–b (not 4e–f as indicated by Guerstein et al., 2001, p.158).
Type locality: Cx-1 well, 1045-1050m depth 39˚11’S, 60˚11’W, Colorado Basin, Argentina.
Age: youngest occurrence probably early Miocene.
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Original description: [Guerstein et al., 2001]:
Diagnosis:
A species of Cannosphaeropsis with a smooth-walled central body surrounded by a complete ectophragmal trabecular network. Trabeculae ribbon-like, bearing a thin fibrous crest, supported by only two robust processes, one on the dorsal anterior part of the epicyst, the other on the dorsal posterior part of the hypocyst.
Description:
Shape: Cyst proximochorate to chorate. Central body subspherical to slightly elongate with complex dorsal anterior and posterior processes towards the poles that support the surrounding trabeculate network. Paracingulum delineated in the ectophragm by two, more or less parallel, but widely spaced trabecula.
Wall relationships: Autophragm smooth, bearing two thick, membranous processes, one on the dorsal epicyst and the other on the dorsal hypocyst. These processes connect the autophragm that froms the central body with the ectophragmal trabecula. The epicystal process is located anterior to paraplate 3”; and the hypocystal process is located at the 3”’/4”’/1”” triple junction. The epicystal process may be branched. Autophragm 1 µm thick. Ectophragm consisting of a complete, ribbon-like trabeculate network, with trabecula up to 4µm wide and bearing a thin crest that gives a fibrous appearance. Thickness of the trabecula increases toward gonal intersections, where platforms and trifurcate projections occur; these are formed from each of the three distal bifurcation of the processes. Tips of trifurcation bifurcate. Platform-like structures have one or two circular perforations up to 3µm in diameter. Platform surface is usually microperforate.
Paratabulation: Since the paratabulation can only be inferred from the trabeculate network, which is usually collapsed, it is difficult to determine. The study of the holotype and a few well-preserved specimens reflects a gonyaulacacean sexiform tabulation. Apical series arranged around a small preapical paraplate. In some cases 1’ and 4’ are fused. Paraplate 6” generally reduced and triangular in shape, reminiscent of its configuration in Spiniferites.
Paracingulum: Six cingular paraplates, with 3c, 4c and 5c being broad.
Parasulcus: Sulcal region elongate and clearly defined, with a large area defined by trabecula posterior to anterior sulcal paraplate. This large sulcal area presumably incorporates the right, left and posterior sulcal paraplates.
Archeopyle: Precingular, type P (3”); operculum simple, free.
Dimensions:
Holotype maximum diameter of the central body: 30 µm: overall diameter: 67-80µm.
Range of 22 specimens: diameter of the central body: 28-40 µm; overall diameter: 50-85 µm.
Affinities:
Cannosphaeropsis quattrocchiae is very similar to the type of Cannosphaeropsis, Cannosphaeropsis utinensis O. Wetzel, 1933. Both species have a smooth central body , a complete trabeculate ectophragm and robust polar processes that connect the autophragm to the ectophragm. Cnanosphaeropsis quattrocchiae differs from the type species, however, in having the following characteristics: a) ribbon-like trabecula with a thin sinuous crest rather that simple, solid, circular trabecula; b) perforate gonal platforms with several projections instead of simple gonal trifurcations and intergonal bifurcations; and c) the epicystal process that supports the ectophragmal trabecula is dorsally rather than ventrally offset. As noted by the Verteuil and Norris (1996), Cannospharopsis utinensis is characterized by: an autophragm and or trabecula that are never alveolate; one of the processes supporting the trabecular network is situated on the anterior sulcal area (near as/I’), and the other process, when present, is situated on paraplate 4”’and intergonal bifurcations. According to Sarjeant (1985), in Cannosphaeropsis utinensis the processes branch secondarily into three spines with bifurcate tips. In addition, the trabecula commonly have a pair of spines (trabecular spines) that lie usually midway between gonal positions. Cannosphaeropsis quattrocchiae shows a very different style of branching with no trabecular spines.
Cannosphareopsis passio de Vertueuil and Norris 1996 differs from Cannosphaeropsis quattrocchiae in having an apical boss on the central body and in having trabecula supported by cingular processes only. Canosphaeropsis passio also has an alveolate trabeculate ectophragm, with gonal trifurcations rotationally offset with respect to triple junction boundaries. The trabecula are solid and cylindrical. The central body and the ectophragm are connected by thin cylindrical cingular appendages only.
Cannosphaeropsis franciscana Damassa 1979 differs from Cannosphaeropsis quattrocchiae by having regular gonal processes connecting the central body to the trabeculate ectophragm. The ectophragmal network, formed by cylindrical to flattened trabecula in Cannosphaeropsis franciscana, is not complete on the dorsal surface and forms a single long projection at the apex.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999
Cannosphaeropsis quattrocchiae Guerstein et al., in press, has a smooth-walled central body surrounded by a complete trabecular network. The ectophragm is supported only by robust dorsally offset apical and antapical processes. Ectophragm is composed of ribbon-like trabecula bearing a thin fibrous crest. The two processes are dorsally offset, the apical process connecting the autophragm with trabecular network anterior to paraplate 3" and the antapical process at the 3"'/1"" and 4""/1"" boundaries. C.quattrocchiae differs from C.utinensis in: having ribbon-like trabecula with a thin sinuous crest rather than simple, solid circular trabecula, having perforate gonal platforms with several projections, and in having the polar anterior process that supports the ectophragmal trabecula located dorsally rather than ventrally.
Size: overall diameter 50-85 µm, central body 28-40 µm.
Holotype: Guerstein et al., 2001, pl.1, figs.4–8, text-figs.4a–b (not 4e–f as indicated by Guerstein et al., 2001, p.158).
Type locality: Cx-1 well, 1045-1050m depth 39˚11’S, 60˚11’W, Colorado Basin, Argentina.
Age: youngest occurrence probably early Miocene.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Guerstein et al., 2001]:
Diagnosis:
A species of Cannosphaeropsis with a smooth-walled central body surrounded by a complete ectophragmal trabecular network. Trabeculae ribbon-like, bearing a thin fibrous crest, supported by only two robust processes, one on the dorsal anterior part of the epicyst, the other on the dorsal posterior part of the hypocyst.
Description:
Shape: Cyst proximochorate to chorate. Central body subspherical to slightly elongate with complex dorsal anterior and posterior processes towards the poles that support the surrounding trabeculate network. Paracingulum delineated in the ectophragm by two, more or less parallel, but widely spaced trabecula.
Wall relationships: Autophragm smooth, bearing two thick, membranous processes, one on the dorsal epicyst and the other on the dorsal hypocyst. These processes connect the autophragm that froms the central body with the ectophragmal trabecula. The epicystal process is located anterior to paraplate 3”; and the hypocystal process is located at the 3”’/4”’/1”” triple junction. The epicystal process may be branched. Autophragm 1 µm thick. Ectophragm consisting of a complete, ribbon-like trabeculate network, with trabecula up to 4µm wide and bearing a thin crest that gives a fibrous appearance. Thickness of the trabecula increases toward gonal intersections, where platforms and trifurcate projections occur; these are formed from each of the three distal bifurcation of the processes. Tips of trifurcation bifurcate. Platform-like structures have one or two circular perforations up to 3µm in diameter. Platform surface is usually microperforate.
Paratabulation: Since the paratabulation can only be inferred from the trabeculate network, which is usually collapsed, it is difficult to determine. The study of the holotype and a few well-preserved specimens reflects a gonyaulacacean sexiform tabulation. Apical series arranged around a small preapical paraplate. In some cases 1’ and 4’ are fused. Paraplate 6” generally reduced and triangular in shape, reminiscent of its configuration in Spiniferites.
Paracingulum: Six cingular paraplates, with 3c, 4c and 5c being broad.
Parasulcus: Sulcal region elongate and clearly defined, with a large area defined by trabecula posterior to anterior sulcal paraplate. This large sulcal area presumably incorporates the right, left and posterior sulcal paraplates.
Archeopyle: Precingular, type P (3”); operculum simple, free.
Dimensions:
Holotype maximum diameter of the central body: 30 µm: overall diameter: 67-80µm.
Range of 22 specimens: diameter of the central body: 28-40 µm; overall diameter: 50-85 µm.
Affinities:
Cannosphaeropsis quattrocchiae is very similar to the type of Cannosphaeropsis, Cannosphaeropsis utinensis O. Wetzel, 1933. Both species have a smooth central body , a complete trabeculate ectophragm and robust polar processes that connect the autophragm to the ectophragm. Cnanosphaeropsis quattrocchiae differs from the type species, however, in having the following characteristics: a) ribbon-like trabecula with a thin sinuous crest rather that simple, solid, circular trabecula; b) perforate gonal platforms with several projections instead of simple gonal trifurcations and intergonal bifurcations; and c) the epicystal process that supports the ectophragmal trabecula is dorsally rather than ventrally offset. As noted by the Verteuil and Norris (1996), Cannospharopsis utinensis is characterized by: an autophragm and or trabecula that are never alveolate; one of the processes supporting the trabecular network is situated on the anterior sulcal area (near as/I’), and the other process, when present, is situated on paraplate 4”’and intergonal bifurcations. According to Sarjeant (1985), in Cannosphaeropsis utinensis the processes branch secondarily into three spines with bifurcate tips. In addition, the trabecula commonly have a pair of spines (trabecular spines) that lie usually midway between gonal positions. Cannosphaeropsis quattrocchiae shows a very different style of branching with no trabecular spines.
Cannosphareopsis passio de Vertueuil and Norris 1996 differs from Cannosphaeropsis quattrocchiae in having an apical boss on the central body and in having trabecula supported by cingular processes only. Canosphaeropsis passio also has an alveolate trabeculate ectophragm, with gonal trifurcations rotationally offset with respect to triple junction boundaries. The trabecula are solid and cylindrical. The central body and the ectophragm are connected by thin cylindrical cingular appendages only.
Cannosphaeropsis franciscana Damassa 1979 differs from Cannosphaeropsis quattrocchiae by having regular gonal processes connecting the central body to the trabeculate ectophragm. The ectophragmal network, formed by cylindrical to flattened trabecula in Cannosphaeropsis franciscana, is not complete on the dorsal surface and forms a single long projection at the apex.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999
Cannosphaeropsis quattrocchiae Guerstein et al., in press, has a smooth-walled central body surrounded by a complete trabecular network. The ectophragm is supported only by robust dorsally offset apical and antapical processes. Ectophragm is composed of ribbon-like trabecula bearing a thin fibrous crest. The two processes are dorsally offset, the apical process connecting the autophragm with trabecular network anterior to paraplate 3" and the antapical process at the 3"'/1"" and 4""/1"" boundaries. C.quattrocchiae differs from C.utinensis in: having ribbon-like trabecula with a thin sinuous crest rather than simple, solid circular trabecula, having perforate gonal platforms with several projections, and in having the polar anterior process that supports the ectophragmal trabecula located dorsally rather than ventrally.
Size: overall diameter 50-85 µm, central body 28-40 µm.