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Aptea retirugosa
From Fensome et al., 2019:
Aptea? retirugosa, (He Chengquan, 1991, p.56, pl.8, fig.11) Fensome et al., 2019a, p.17.
Holotype: He Chengquan, 1991, pl.8, fig.11; Fensome et al., 2019a, fig.12C.
Originally Canningia; subsequently Kallosphaeridium, thirdly Canningia?, fourthly (and now) Aptea?.
Questionable assignment; Fensome et al. (2019a, p.17). Fensome et al. (2019a, p.17) recommended that this species be restricted to the holotype.
Age: Late Cretaceous.
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Original description: [He Chengquan, 1991] (translated from Chinese with Google):
Canningia retirugosa (sp. nov.)
(Plate 8, Figure 11)
Description: The shell is nearly round, slightly wider than long. The top is slightly convex, the tail is round, and the tail convex is lacking. The belt is fuzzy, about 6µm wide, and its edges are marked by thin ridges that are longer but not continuous enough. The shell wall is thin, and the surface is densely covered with short wrinkle-like patterns; the wrinkles are straight or curved, thin but high, and are serrated on the outline. They are interconnected to form an incomplete fine mesh. The ancient mouth is obvious, top-shaped, (tA)-shaped, and its edge is obviously angular. The mouth cover is separated and stored in situ.
The holotype specimen is 55µm long, 62.5µm wide, and has a wrinkle length of 1-2µm.
Comparison: This new species is distinguished from Canningia rotundata by its small size, thin wall, clear wrinkles that can be connected to each other into incomplete fine mesh, and fuzzy belt display. The latter has a more obvious apex angle, or has a tail convex, and the shell wall is thicker. This new species is also different from C. reticulata and C. rugulosa (Clarke et Verdier) in that it lacks a tail convex and only slightly displays apex convexity.
Origin and horizon: West Bashbulak, Wuqia County, at the bottom of Wuyitak Formation.
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Comment Fensome et al., 2019a:
1991 Canningia retirugosa He Chengquan, p. 56; pl. 8, fig. 11.2009 Kallosphaeridium retirugosum (He Chengquan) He Chengquan et al., p. 164.2016 Canningia? retirugosa He Chengquan; Wood et al., p. 69–71.
Comments. This species was originally described in Chinese with a single illustration, which appears to show an areoligeracean with linear ornament. Thus, it does not belong in Kallosphaeridium, which is a gonyaulacacean with five climactal paraplates (Jan du Chêne and Adediran Citation1985, Wood et al. Citation2016). Wood et al. (Citation2016) tentatively retained this species in Canningia, but as a cyst with a single wall layer and probably linear ornament (although possibly affected by corrosion) this species better fits the definition of Aptea. Hence, we questionably transfer it to Aptea, but recommend that the name be restricted to the holotype, pending further study.
Aptea? retirugosa, (He Chengquan, 1991, p.56, pl.8, fig.11) Fensome et al., 2019a, p.17.
Holotype: He Chengquan, 1991, pl.8, fig.11; Fensome et al., 2019a, fig.12C.
Originally Canningia; subsequently Kallosphaeridium, thirdly Canningia?, fourthly (and now) Aptea?.
Questionable assignment; Fensome et al. (2019a, p.17). Fensome et al. (2019a, p.17) recommended that this species be restricted to the holotype.
Age: Late Cretaceous.
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Original description: [He Chengquan, 1991] (translated from Chinese with Google):
Canningia retirugosa (sp. nov.)
(Plate 8, Figure 11)
Description: The shell is nearly round, slightly wider than long. The top is slightly convex, the tail is round, and the tail convex is lacking. The belt is fuzzy, about 6µm wide, and its edges are marked by thin ridges that are longer but not continuous enough. The shell wall is thin, and the surface is densely covered with short wrinkle-like patterns; the wrinkles are straight or curved, thin but high, and are serrated on the outline. They are interconnected to form an incomplete fine mesh. The ancient mouth is obvious, top-shaped, (tA)-shaped, and its edge is obviously angular. The mouth cover is separated and stored in situ.
The holotype specimen is 55µm long, 62.5µm wide, and has a wrinkle length of 1-2µm.
Comparison: This new species is distinguished from Canningia rotundata by its small size, thin wall, clear wrinkles that can be connected to each other into incomplete fine mesh, and fuzzy belt display. The latter has a more obvious apex angle, or has a tail convex, and the shell wall is thicker. This new species is also different from C. reticulata and C. rugulosa (Clarke et Verdier) in that it lacks a tail convex and only slightly displays apex convexity.
Origin and horizon: West Bashbulak, Wuqia County, at the bottom of Wuyitak Formation.
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Comment Fensome et al., 2019a:
1991 Canningia retirugosa He Chengquan, p. 56; pl. 8, fig. 11.2009 Kallosphaeridium retirugosum (He Chengquan) He Chengquan et al., p. 164.2016 Canningia? retirugosa He Chengquan; Wood et al., p. 69–71.
Comments. This species was originally described in Chinese with a single illustration, which appears to show an areoligeracean with linear ornament. Thus, it does not belong in Kallosphaeridium, which is a gonyaulacacean with five climactal paraplates (Jan du Chêne and Adediran Citation1985, Wood et al. Citation2016). Wood et al. (Citation2016) tentatively retained this species in Canningia, but as a cyst with a single wall layer and probably linear ornament (although possibly affected by corrosion) this species better fits the definition of Aptea. Hence, we questionably transfer it to Aptea, but recommend that the name be restricted to the holotype, pending further study.