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Acrosphaera pseudarktios Caulet, 1986

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Description:
Shell surface smooth, spherical, with randomly arranged irregular pores of varying sizes (4--5 on a half-circumference). Two or more poreless spines up to one-third the length of the shell-diameter project outward from all pore margins. Spines forked and joined by very thin siliceous threads building an extra-cortical shell.

Dimensions: Shell diameter 80--110 μm (based on 20 specimens); maximum length of spines 20 μm.

Name: similar to arktios.

Holotype: (Plate 1,8), Sample MD 75072-I; 110 cm, slide 1.

Remarks: This species is probably a southern form of Acrosphaera arktios described by Nigrini (1970, p. 166, pl.1, figs.4--5). It differs by the shell dimensions, the number of spines arising from the pore margin, and the siliceous threads of the extra-cortical shell. Moreover, the spines are not strongly curved.
Caulet 1986


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