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Aptea vannophora
From Fensome et al., 2019:
Aptea? vannophora, (Davey, 1969a, p.168,170, pl.9, fig.3; pl.11, figs.11–12; text-fig.16E) Fensome et al., 2019a, p.19.
Holotype: Davey, 1969a, pl.9, fig.3; pl.11, fig.11; Fauconnier and Masure, 2004, pl.17, fig.12; Fensome et al., 2019a, fig.12G.
Originally Cyclonephelium, subsequently (and now) Aptea?.
Questionable assignment: Fensome et al. (2019a, p.19).
Age: Cenomanian.
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Original diagnosis: Davey, 1969, p. 168
Shell subcircular in outline, with slight apical prominence and one or two reduced antapical horns. Shell wall coarsely granular with areas devoid of processes of moderate size. Processes numerous, short, solid, of irregular shape and often confluent distally. Apical archaeopyle with zigzag margin.
Dimensions: length of shell (without operculum) 47(57.8)70 µm, width 56(65.5)78 µm, maximum length of processes 3(5.3)8 µm.
Original description: Davey, 1969, p.168
When two antapical horns are present the portion of the shell between them is concave and from this region a broad furrow passes towards the apex. The furrow or sulcus decreases in width and depth in this direction and disappears just posterior to the archaeopyle margin. The processes vary greatly in size from mere enlarged granules (0.5µm) to 8 µm in length. In the larger processes the stem is quite narrow, the distal third widening rapidly and is sometimes bifurcate. The processes are often joined to form a short line on the shell surface. Rarely the cingulum is just discernible by a concentration of small processes along its borders.
Affinities:
Davey, 1969, p. 168: C. vannophorum sp. nov. is most closely comparable to ?C. attadalicum Cookson & Eisenack (1962) from the AptianlAlbian of Australia. The processes are similar in form but the shell of ?C. attadalicum is more polygonal and the cingulum is always well defined.
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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.
Cyclonephelium compactum Deflandre and Cookson, 1955, has processes which are generally short and joined to one another, forming lamella like projections arranged either parallel to the margin, or in the form of an irregular network. Sometimes a series of processes are joined by short trabeculae. Size: shell 61-72 µm, processes 5-10 µm, overall 72-87 µm.
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Comments Fensome et al., 2019a:
This species, which has been used as a stratigraphical marker, was described by Davey (Citation1969, p. 168) as follows:
The processes vary greatly in size from mere enlarged granules (0.5 μ) to 8 μ in length. In the larger processes the stem is quite narrow, the distal third widening rapidly … and is sometimes bifurcate. The processes are often joined to form a short line on the shell surface. Rarely the cingulum is just discernible by a concentration of small processes along its borders.
The close-up of the holotype (Davey Citation1969, pl. 9, fig. 3) shows very fine hairs that may join, splay or thicken distally, forming a kind of filigree pattern, and in plan view commonly form linear clumps. However, subsequent photographs of the holotype by Iain Prince show that this ‘filigree’ development is localised and the ornament over areas of the cysts appears free standing (Martin Pearce, personal communication 2018). Thus, this species is intermediate between Aptea and Tenua, and hence we question its assignment to the former. Aptea? vannophora closely resembles Tenua hystrix, the difference (at least in theory) being that the former has predominantly interconnected (i.e. linear) ornament and the latter has predominantly free-standing ornament. However, it may be difficult in future to retain both species separately.
Although Davey (Citation1969) did not specifically mention whether ornament is present or absent dorsoventrally, from the full illustration of the holotype of Aptea? vannophora (Davey, Citation1969, pl. 11, fig. 11) the mid-ventral area appears to bear a less intense ornament cover than peripheral areas do. Nevertheless, the dorsoventral areas do appear to bear ornament, which accords with an assignment to Aptea.
Davey (Citation1969, p. 168) noted that Cyclonephelium vannophorum ‘is most closely comparable to ?C. attadalicum …. The processes are similar in form but the shell of ?C. attadalicum is more polygonal and the cingulum is always well defined’. For us, the main difference between these two species is that Cyclonephelium (now Tenua) attadalicum appears to have isolated processes whereas Aptea vannophora (as represented in the holotype) has hair-like processes that tend to join and clump. However, the processes of the former are quite hair-like, so a re-examination of the type material of both species may reveal a closer resemblance.
Stratigraphical occurrence. Davey (Citation1969) recorded Aptea vannophora (as Cyclonephelium vannophorum) from the Cenomanian of southern England.
Aptea? vannophora, (Davey, 1969a, p.168,170, pl.9, fig.3; pl.11, figs.11–12; text-fig.16E) Fensome et al., 2019a, p.19.
Holotype: Davey, 1969a, pl.9, fig.3; pl.11, fig.11; Fauconnier and Masure, 2004, pl.17, fig.12; Fensome et al., 2019a, fig.12G.
Originally Cyclonephelium, subsequently (and now) Aptea?.
Questionable assignment: Fensome et al. (2019a, p.19).
Age: Cenomanian.
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Original diagnosis: Davey, 1969, p. 168
Shell subcircular in outline, with slight apical prominence and one or two reduced antapical horns. Shell wall coarsely granular with areas devoid of processes of moderate size. Processes numerous, short, solid, of irregular shape and often confluent distally. Apical archaeopyle with zigzag margin.
Dimensions: length of shell (without operculum) 47(57.8)70 µm, width 56(65.5)78 µm, maximum length of processes 3(5.3)8 µm.
Original description: Davey, 1969, p.168
When two antapical horns are present the portion of the shell between them is concave and from this region a broad furrow passes towards the apex. The furrow or sulcus decreases in width and depth in this direction and disappears just posterior to the archaeopyle margin. The processes vary greatly in size from mere enlarged granules (0.5µm) to 8 µm in length. In the larger processes the stem is quite narrow, the distal third widening rapidly and is sometimes bifurcate. The processes are often joined to form a short line on the shell surface. Rarely the cingulum is just discernible by a concentration of small processes along its borders.
Affinities:
Davey, 1969, p. 168: C. vannophorum sp. nov. is most closely comparable to ?C. attadalicum Cookson & Eisenack (1962) from the AptianlAlbian of Australia. The processes are similar in form but the shell of ?C. attadalicum is more polygonal and the cingulum is always well defined.
---------------------------------------------------------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Cyclonephelium compactum Deflandre and Cookson, 1955, has processes which are generally short and joined to one another, forming lamella like projections arranged either parallel to the margin, or in the form of an irregular network. Sometimes a series of processes are joined by short trabeculae. Size: shell 61-72 µm, processes 5-10 µm, overall 72-87 µm.
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Comments Fensome et al., 2019a:
This species, which has been used as a stratigraphical marker, was described by Davey (Citation1969, p. 168) as follows:
The processes vary greatly in size from mere enlarged granules (0.5 μ) to 8 μ in length. In the larger processes the stem is quite narrow, the distal third widening rapidly … and is sometimes bifurcate. The processes are often joined to form a short line on the shell surface. Rarely the cingulum is just discernible by a concentration of small processes along its borders.
The close-up of the holotype (Davey Citation1969, pl. 9, fig. 3) shows very fine hairs that may join, splay or thicken distally, forming a kind of filigree pattern, and in plan view commonly form linear clumps. However, subsequent photographs of the holotype by Iain Prince show that this ‘filigree’ development is localised and the ornament over areas of the cysts appears free standing (Martin Pearce, personal communication 2018). Thus, this species is intermediate between Aptea and Tenua, and hence we question its assignment to the former. Aptea? vannophora closely resembles Tenua hystrix, the difference (at least in theory) being that the former has predominantly interconnected (i.e. linear) ornament and the latter has predominantly free-standing ornament. However, it may be difficult in future to retain both species separately.
Although Davey (Citation1969) did not specifically mention whether ornament is present or absent dorsoventrally, from the full illustration of the holotype of Aptea? vannophora (Davey, Citation1969, pl. 11, fig. 11) the mid-ventral area appears to bear a less intense ornament cover than peripheral areas do. Nevertheless, the dorsoventral areas do appear to bear ornament, which accords with an assignment to Aptea.
Davey (Citation1969, p. 168) noted that Cyclonephelium vannophorum ‘is most closely comparable to ?C. attadalicum …. The processes are similar in form but the shell of ?C. attadalicum is more polygonal and the cingulum is always well defined’. For us, the main difference between these two species is that Cyclonephelium (now Tenua) attadalicum appears to have isolated processes whereas Aptea vannophora (as represented in the holotype) has hair-like processes that tend to join and clump. However, the processes of the former are quite hair-like, so a re-examination of the type material of both species may reveal a closer resemblance.
Stratigraphical occurrence. Davey (Citation1969) recorded Aptea vannophora (as Cyclonephelium vannophorum) from the Cenomanian of southern England.