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Caligodinium pychnum
Caligodinium pychnum, Biffi and Manum, 1988
Holotype: Biffi and Manum, 1988, pl.2, figs.1,4,7,15
Locality: Montebello d'Urbino, Italy
Age: Early Miocene
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Original description: [Biffi and Manum, 1988, p. 178, 180]:
Diagnosis:
Proximate cyst of ovoid shape with some dorsoventral compression. Autophragm rigid, c. 2 µm thick; a flocculent outer covering may or may not be preserved. Ornamentation of low ridges producing a retirugulate surface pattern, more or less prominent.
Paratabulation expressed only by the apical archeopyle. Operculum composed of three pieces of which two (paraplates 1' and 3' respectively in present interpretation, Text-fig. 10A) frequently are dislodged, whereas the third piece (paraplate 2') is more commonly attached and often lacking expression of parasutures in the area of attachment. Anterior suture of paraplate 6'' is short and nearly equal to as.
Description:
The specimens usually show a dorsoventral aspect with the sulcal archeopyle suture somewhat off the mid-line. The rigid wall with its rugged profile and retirugulate appearance in surface view make these cysts easy to recognize. Internal wall surface appear pitted.
The archeopyle in its most complete development is trioperculate. In approximately half of the observed specimens all operculum pieces are more or less in place with varying degrees of sutural separation (Pl. 2 and 3). When the operculum has been lost the archeopyle at first glance seems to involve the entire apical series. However, on closer analysis the archeopyle suture can only been interpreted by inferring the attachment of apical paraplate 2' (Pl. 2, figs. 3, 6, 9, 12). Only rarely, in approximately one out of ten specimen, 2' is also lost (Pl. 2, figs. 16-18), thereby producing a tA archeopyle. Paraplate 1' usually extends with a characteristic flap over the apex so that the apical junction appears located somewhat towards the dorsal side. Operculum attachment is usually best developed along the parasutures 2'', 3'' and 2', which are rarely expressed and can therefore only be inferred from the analysis of accessory archeopyle sutures.
Dimensions:
Holotype: cyst breadth 48 µm; cyst length 56 µm; cyst length with operculum 62 µm. Mean values (bracketed) and extremes (n = 20); cyst breadth 45(50)54 µm, cyst length 49(57)62 µm; cyst length with operculum 57(65)70 µm.
Affinities:
Expression of paratabulation other than the archeopyle and operculum pieces is lacking. The operculum pieces have complex shapes and, when partly dislocated and superimposed, they present a bewildering view; the complexity is further increased by variation in the degree of suture development and mode of attachment. The interpretation proposed here (shown diagrammatically in Text-fig. 10A with Kofoidean notation) is based on detailed study and camera lucida drawings of 18 well preserved specimens which also document the kind of variety mentioned above.
Seven of the more representative specimens are shown in Plate 2 and 3. Our interpretation implies a sequence of geniculate and straight anterior sutures of six precingular plates which is consistent with a gonyaulacacean pattern. We think this provides an overwhelming argument for an apical archeopyle. Paraplate 2' shows varying degrees of attachment to precingulars and development of parasutures. The geniculate suture of 2' and 3' may best be accounted for by inferring intercalaries, but we have found it problematic to indicate this in our diagram. In Text-fig. 10B Drugg's schematic diagram (1970, Fig. 9B) of apical paraplates of C. amiculum has been reproduced with the addition of dotted lines to indicate sutures of the precingular series. The proposed annotation accounts for a precingular paraplate topology which is homomorphic with that for C. pychnum. A camera lucida drawing of the holotype of C. amiculum is shown in Text-fig. 11D, and in Text-figs. 11A-C we have reproduced Drugg's SEM photographs (1970, Figs. 8A, B and 9E) with our interpretation. In Drugg's diagram and our drawing of his holotype, the geniculate suture of 2' and 3' is inverted with respect of its homologue in C. pychnum; however, the SEM photograph in Text-fig. 11A appears to show the joint pointing the same direction as in our species. On available evidence this uncertainty cannot be settled. Caligodinium pychnum differs from C. amiculum Drugg in having a distinct retirugulate ornamentation. The frequent attachment of the paraplate 2' and the absence of parasutures between 2', 2'' and 3'' appear to be other distinctive features of C. pychnum.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.b
Caligodinium pychnum Biffi and Manum, 1988, differs from C.amiculum in having a distinctly retirugulate ornamentation. Paraplate 2' is also distinctive. Biffi and Manum (1988) interpreted the archeopyle as formed from three apical plates.
Size: cyst length 49-62 µm, width 45-54 µm, cyst length with operculum 57-70 µm.
Holotype: Biffi and Manum, 1988, pl.2, figs.1,4,7,15
Locality: Montebello d'Urbino, Italy
Age: Early Miocene
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Biffi and Manum, 1988, p. 178, 180]:
Diagnosis:
Proximate cyst of ovoid shape with some dorsoventral compression. Autophragm rigid, c. 2 µm thick; a flocculent outer covering may or may not be preserved. Ornamentation of low ridges producing a retirugulate surface pattern, more or less prominent.
Paratabulation expressed only by the apical archeopyle. Operculum composed of three pieces of which two (paraplates 1' and 3' respectively in present interpretation, Text-fig. 10A) frequently are dislodged, whereas the third piece (paraplate 2') is more commonly attached and often lacking expression of parasutures in the area of attachment. Anterior suture of paraplate 6'' is short and nearly equal to as.
Description:
The specimens usually show a dorsoventral aspect with the sulcal archeopyle suture somewhat off the mid-line. The rigid wall with its rugged profile and retirugulate appearance in surface view make these cysts easy to recognize. Internal wall surface appear pitted.
The archeopyle in its most complete development is trioperculate. In approximately half of the observed specimens all operculum pieces are more or less in place with varying degrees of sutural separation (Pl. 2 and 3). When the operculum has been lost the archeopyle at first glance seems to involve the entire apical series. However, on closer analysis the archeopyle suture can only been interpreted by inferring the attachment of apical paraplate 2' (Pl. 2, figs. 3, 6, 9, 12). Only rarely, in approximately one out of ten specimen, 2' is also lost (Pl. 2, figs. 16-18), thereby producing a tA archeopyle. Paraplate 1' usually extends with a characteristic flap over the apex so that the apical junction appears located somewhat towards the dorsal side. Operculum attachment is usually best developed along the parasutures 2'', 3'' and 2', which are rarely expressed and can therefore only be inferred from the analysis of accessory archeopyle sutures.
Dimensions:
Holotype: cyst breadth 48 µm; cyst length 56 µm; cyst length with operculum 62 µm. Mean values (bracketed) and extremes (n = 20); cyst breadth 45(50)54 µm, cyst length 49(57)62 µm; cyst length with operculum 57(65)70 µm.
Affinities:
Expression of paratabulation other than the archeopyle and operculum pieces is lacking. The operculum pieces have complex shapes and, when partly dislocated and superimposed, they present a bewildering view; the complexity is further increased by variation in the degree of suture development and mode of attachment. The interpretation proposed here (shown diagrammatically in Text-fig. 10A with Kofoidean notation) is based on detailed study and camera lucida drawings of 18 well preserved specimens which also document the kind of variety mentioned above.
Seven of the more representative specimens are shown in Plate 2 and 3. Our interpretation implies a sequence of geniculate and straight anterior sutures of six precingular plates which is consistent with a gonyaulacacean pattern. We think this provides an overwhelming argument for an apical archeopyle. Paraplate 2' shows varying degrees of attachment to precingulars and development of parasutures. The geniculate suture of 2' and 3' may best be accounted for by inferring intercalaries, but we have found it problematic to indicate this in our diagram. In Text-fig. 10B Drugg's schematic diagram (1970, Fig. 9B) of apical paraplates of C. amiculum has been reproduced with the addition of dotted lines to indicate sutures of the precingular series. The proposed annotation accounts for a precingular paraplate topology which is homomorphic with that for C. pychnum. A camera lucida drawing of the holotype of C. amiculum is shown in Text-fig. 11D, and in Text-figs. 11A-C we have reproduced Drugg's SEM photographs (1970, Figs. 8A, B and 9E) with our interpretation. In Drugg's diagram and our drawing of his holotype, the geniculate suture of 2' and 3' is inverted with respect of its homologue in C. pychnum; however, the SEM photograph in Text-fig. 11A appears to show the joint pointing the same direction as in our species. On available evidence this uncertainty cannot be settled. Caligodinium pychnum differs from C. amiculum Drugg in having a distinct retirugulate ornamentation. The frequent attachment of the paraplate 2' and the absence of parasutures between 2', 2'' and 3'' appear to be other distinctive features of C. pychnum.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.b
Caligodinium pychnum Biffi and Manum, 1988, differs from C.amiculum in having a distinctly retirugulate ornamentation. Paraplate 2' is also distinctive. Biffi and Manum (1988) interpreted the archeopyle as formed from three apical plates.
Size: cyst length 49-62 µm, width 45-54 µm, cyst length with operculum 57-70 µm.