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Canningia reticulata
From Fensome et al., 2019:
Canningia reticulata Cookson and Eisenack, 1960b, p.251, pl.38, figs.1–2.
Emendations: Below, 1981a, p.32; Helby, 1987, p.322–323. Holotype: Cookson and Eisenack, 1960b, pl.38, fig.1; Helby, 1987, fig.27J; Fensome et al., 2019a, figs.13K–L.
Taxonomic junior synonyms: Canningia palliata, according to Helby (1987, p.322–323); Canningia senonica, according to Santos et al. (2018, p.165); Cyclonephelium areolatum, Hashenia reticulata (subsequently Canningia xinjiangensis), and Cyclonephelium chabaca, all according to Fensome et al. (2019a, p.29).
Locus typicus: Jarlemai Siltstone, West Australia
Stratum typicum: Tithonian
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Original description: [Cookson and Eisenack, 1960, p. 251]:
Description:
Shell with straight or rounded sides; apical projection not prominent, basal indention clearly marked; a girdle is usually present slightly above the equator. Shell-membrane densely and irregular reticulate, the reticulum low, small-meshed and thick-walled.
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Emendations:
Below, 1981, p. 32:
Diagnosis:
Two-layered cyst. The smooth endophragma forms the sphaeroidal, lenticular inner body. Periphragm smooth, forming the in outline sphaeriodal to pentagonal outer body. ?Endophragmal, spongious, matted lattice structure fills pericoel.
Paratabulation weakly indicated, seemingly gonyaulaciodal.
Paracingulum spiral, indented into outer body, parasulcus just as thick, undifferentiated dent recognisable.
Archaeopyle apical, Type "Aa", operculum enlarged.
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Helby, 1987, p. 322:
Description:
Cyst lenticular with obtuse, low apical horn, 2 low rounded antapical horns, with that on the left larger and much further from the paracingulum. Ectophragm usually protrusive at the paracingulum. Autophragm and ectophragm relatively close to each other, and ectocoel wider below horns and paracingulum than elsewhere.
Supporting structures within the ectocoel varying in length and distribution and longest and most closely packed in parasutural areas (up to 6 µm long). Ectophragm finely reticulate to rugoreticulate, although some specimens may have granulate or smooth areas.
Paratabulation indicated by principal and accessory archeopyle sutures. However, on some specimens paraplate boundaries marked by low external ridges underlain by longer ectophragm supports. Paratabulation formula 4', 6'', 6c, 6''' ,1 p, 1'''' (Fig.28).
Archeopyle apical, type [tA], principal archeopyle suture zigzag with offset parasulcal notch and operculum free.
Parasulcus often marked by a reduction in the extent, or even absence, of ectocoel development and characteristically sinuous.
Paracingulum indicated laterally by equatorial protrusion of wall layers and transversely by slight parasutural ridges. Paracingulum markedly offset adjacent to the parasulcus (Fig.28).
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Comments Fensome et al., 2019a:
Canningia reticulata is distinguished by its finely reticulate periphragm and dense system of supports. We follow Helby (Citation1987) in synonymising Canningia palliata with Canningia reticulata, and add the following taxonomic junior synonyms: Cyclonephelium areolatum, Cyclonephelium chabaca, Cyclonephelium inconspicuum and Canningia xinjiangensis (formerly Hashenia reticulata).
Cookson and Eisenack (Citation1960, p. 253) described Cyclonephelium areolatum as comprising cysts that are circular to slightly oval in outline (i.e. ambitus), flat, and with ‘a peripheral sculptured zone … in the form of a thin, finely vermiculate or areolate membrane …’ with an ‘unsculptured portion’, presumably mid-ventrally and/or mid-dorsally. Cookson and Eisenack’s illustration of the holotype (their pl. 38, fig. 8) appears to show a form very similar to Canningia reticulata (the type of which is illustrated on the same plate) with a dark mid-dorsoventral area that these authors interpreted as unsculptured, and which presumably led them to assign this form to Cyclonephelium rather than Canningia. To us, the ‘areolation’ described by Cookson and Eisenack (Citation1960) reflects a holocavate wall very similar (if not identical) to that of Canningia reticulata, except for a dark, central ‘unsculptured’ area. The latter feature we consider not sufficiently distinctive to justify retaining Cyclonephelium areolatum separately from Canningia reticulata, and hence propose the synonymy.
Below (Citation1981a, p. 12) provided the following diagnosis for Cyclonephelium chabaca:
Proximate, nontabulate, lenticular central body of almost rounded outline, apically rounded or with a very low bulge. Low, broad apical horn frame-like, formed of periphragmal processes. Hypocyst asymmetrical with left antapical horn and marginally displaced bulge [?], or rarely rounded. Ornamentation of numerous thin, process-bearing, delicate, fine-meshed reticulum covering the whole cyst with the exception of a broad ventrally located surface corresponding to the parasulcal zone. Archaeopyle of type (A). The angular archaeopyle outline indicates six precingular paraplates and [paraplate] as [anterior sulcal]. Pandasutural bands are rarely partially developed. [Translation]
Below (Citation1981a, p.13) appeared to suggest that Cyclonephelium chabaca differs from Canningia reticulata in that the periphragm in the former is mesh-like, whereas that of the latter is complete. However, in our view this difference does not accord with the original description and illustrations of Canningia reticulata (even with regard to the parasulcal hiatus in the outer wall layer), and so we consider Cyclonephelium chabaca to be a taxonomic junior synonym of Canningia reticulata. Canningia xinjiangensis (originally Hashenia reticulata) appears identical to Canningia reticulata.
Stratigraphical occurrence. Canningia reticulata was originally described from the Tithonian of Australasia. The type material of Canningia areolata is also from the Tithonian of Australia. Brideaux (Citation1977) recorded Canningia palliata from the Barremian of north-western Canada. Canningia xinjiangensis was originally described from the Turonian to Maastrichtian of China. Below (Citation1981a) recorded Cyclonephelium chabaca from the Aptian to Cenomanian of south-western Morocco.
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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.
Canningia reticulata Cookson and Eisenack, 1960b, emend. Below, 1981a, emend. Helby, 1987, is holocavate but over most of the surface the ectophragm is closely appressed to the autophragm. Ectocoel wider below horns and paracingulum than elsewhere. Supporting structures with ectocoel of varying length, up to 6 µm. Ectophragm finely reticulate to rugoreticulate. Paratabulation indicated by principal and accessory archeopyle sutures. Below (1981) said that the operculum was attached. He thought this significant and included similar forms with free opercula in Cyclonephelium. Helby (1987) in his emendation states that the operculum is free. Size according to Helby (1987), overall length 100-115 µm, overall width 70-97 µm.
Canningia reticulata Cookson and Eisenack, 1960b, p.251, pl.38, figs.1–2.
Emendations: Below, 1981a, p.32; Helby, 1987, p.322–323. Holotype: Cookson and Eisenack, 1960b, pl.38, fig.1; Helby, 1987, fig.27J; Fensome et al., 2019a, figs.13K–L.
Taxonomic junior synonyms: Canningia palliata, according to Helby (1987, p.322–323); Canningia senonica, according to Santos et al. (2018, p.165); Cyclonephelium areolatum, Hashenia reticulata (subsequently Canningia xinjiangensis), and Cyclonephelium chabaca, all according to Fensome et al. (2019a, p.29).
Locus typicus: Jarlemai Siltstone, West Australia
Stratum typicum: Tithonian
-------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Cookson and Eisenack, 1960, p. 251]:
Description:
Shell with straight or rounded sides; apical projection not prominent, basal indention clearly marked; a girdle is usually present slightly above the equator. Shell-membrane densely and irregular reticulate, the reticulum low, small-meshed and thick-walled.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emendations:
Below, 1981, p. 32:
Diagnosis:
Two-layered cyst. The smooth endophragma forms the sphaeroidal, lenticular inner body. Periphragm smooth, forming the in outline sphaeriodal to pentagonal outer body. ?Endophragmal, spongious, matted lattice structure fills pericoel.
Paratabulation weakly indicated, seemingly gonyaulaciodal.
Paracingulum spiral, indented into outer body, parasulcus just as thick, undifferentiated dent recognisable.
Archaeopyle apical, Type "Aa", operculum enlarged.
-----------------------------------------------------
Helby, 1987, p. 322:
Description:
Cyst lenticular with obtuse, low apical horn, 2 low rounded antapical horns, with that on the left larger and much further from the paracingulum. Ectophragm usually protrusive at the paracingulum. Autophragm and ectophragm relatively close to each other, and ectocoel wider below horns and paracingulum than elsewhere.
Supporting structures within the ectocoel varying in length and distribution and longest and most closely packed in parasutural areas (up to 6 µm long). Ectophragm finely reticulate to rugoreticulate, although some specimens may have granulate or smooth areas.
Paratabulation indicated by principal and accessory archeopyle sutures. However, on some specimens paraplate boundaries marked by low external ridges underlain by longer ectophragm supports. Paratabulation formula 4', 6'', 6c, 6''' ,1 p, 1'''' (Fig.28).
Archeopyle apical, type [tA], principal archeopyle suture zigzag with offset parasulcal notch and operculum free.
Parasulcus often marked by a reduction in the extent, or even absence, of ectocoel development and characteristically sinuous.
Paracingulum indicated laterally by equatorial protrusion of wall layers and transversely by slight parasutural ridges. Paracingulum markedly offset adjacent to the parasulcus (Fig.28).
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Comments Fensome et al., 2019a:
Canningia reticulata is distinguished by its finely reticulate periphragm and dense system of supports. We follow Helby (Citation1987) in synonymising Canningia palliata with Canningia reticulata, and add the following taxonomic junior synonyms: Cyclonephelium areolatum, Cyclonephelium chabaca, Cyclonephelium inconspicuum and Canningia xinjiangensis (formerly Hashenia reticulata).
Cookson and Eisenack (Citation1960, p. 253) described Cyclonephelium areolatum as comprising cysts that are circular to slightly oval in outline (i.e. ambitus), flat, and with ‘a peripheral sculptured zone … in the form of a thin, finely vermiculate or areolate membrane …’ with an ‘unsculptured portion’, presumably mid-ventrally and/or mid-dorsally. Cookson and Eisenack’s illustration of the holotype (their pl. 38, fig. 8) appears to show a form very similar to Canningia reticulata (the type of which is illustrated on the same plate) with a dark mid-dorsoventral area that these authors interpreted as unsculptured, and which presumably led them to assign this form to Cyclonephelium rather than Canningia. To us, the ‘areolation’ described by Cookson and Eisenack (Citation1960) reflects a holocavate wall very similar (if not identical) to that of Canningia reticulata, except for a dark, central ‘unsculptured’ area. The latter feature we consider not sufficiently distinctive to justify retaining Cyclonephelium areolatum separately from Canningia reticulata, and hence propose the synonymy.
Below (Citation1981a, p. 12) provided the following diagnosis for Cyclonephelium chabaca:
Proximate, nontabulate, lenticular central body of almost rounded outline, apically rounded or with a very low bulge. Low, broad apical horn frame-like, formed of periphragmal processes. Hypocyst asymmetrical with left antapical horn and marginally displaced bulge [?], or rarely rounded. Ornamentation of numerous thin, process-bearing, delicate, fine-meshed reticulum covering the whole cyst with the exception of a broad ventrally located surface corresponding to the parasulcal zone. Archaeopyle of type (A). The angular archaeopyle outline indicates six precingular paraplates and [paraplate] as [anterior sulcal]. Pandasutural bands are rarely partially developed. [Translation]
Below (Citation1981a, p.13) appeared to suggest that Cyclonephelium chabaca differs from Canningia reticulata in that the periphragm in the former is mesh-like, whereas that of the latter is complete. However, in our view this difference does not accord with the original description and illustrations of Canningia reticulata (even with regard to the parasulcal hiatus in the outer wall layer), and so we consider Cyclonephelium chabaca to be a taxonomic junior synonym of Canningia reticulata. Canningia xinjiangensis (originally Hashenia reticulata) appears identical to Canningia reticulata.
Stratigraphical occurrence. Canningia reticulata was originally described from the Tithonian of Australasia. The type material of Canningia areolata is also from the Tithonian of Australia. Brideaux (Citation1977) recorded Canningia palliata from the Barremian of north-western Canada. Canningia xinjiangensis was originally described from the Turonian to Maastrichtian of China. Below (Citation1981a) recorded Cyclonephelium chabaca from the Aptian to Cenomanian of south-western Morocco.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Canningia reticulata Cookson and Eisenack, 1960b, emend. Below, 1981a, emend. Helby, 1987, is holocavate but over most of the surface the ectophragm is closely appressed to the autophragm. Ectocoel wider below horns and paracingulum than elsewhere. Supporting structures with ectocoel of varying length, up to 6 µm. Ectophragm finely reticulate to rugoreticulate. Paratabulation indicated by principal and accessory archeopyle sutures. Below (1981) said that the operculum was attached. He thought this significant and included similar forms with free opercula in Cyclonephelium. Helby (1987) in his emendation states that the operculum is free. Size according to Helby (1987), overall length 100-115 µm, overall width 70-97 µm.