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Sphaeropyle robusta Kling, 1973

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Four concentric shells. Innermost shell robust, spherical, with circular pores of uniform size, irregularly arranged, 3-4 per half-circumference. Second shell (outward) robust, spherical, with circular pores of fairly uniform size, quincuncially arranged, 6-7 per half-circumference, weakly framed. Third shell, usually relatively thin-walled (particularly in later representatives), spherical to subspherical, with circular pores of variable size but conspicuously large relative to other shells, 7-9 per half-circumference, with tiny by-spines at most bar intersections. Cortical shell robust, subspherical to elongate, protruding at one end, bearing a pylome which is surrounded with a corona of stout teeth; pores circular, irregularly arranged, usually with well developed frames, about 20 per half-circumference; bar intersections ooften developed into short by-spines.
Approximately 6 rdial bars connect the inner three shells, many times this number between cortical and next inner shell. Stout radial main-spines are usually short in Leg 18 material, but appear broken and could be better developed (preserved) elsewhere.
Earlier populations are smaller with peristomal teeth fused into a rim. They are otherwise similar although it may eventually be possible to separate these forms as a new species.
Dimensions:
Based on 10 specimens from 177A-6-4 (70-72cm) and 173-9-4 (85-57cm): diameter of innermost shell 16-18, second shell 40-46, third 100-110, cortical (small diameter) 146-200.
Based on 10 specimens from 173-24-2 (57-59cm) and 173-27-2 (57-59cm): innermost shell 10-20, second 30-44, third 62-100, cortical 98-156.
Remarks:
This species differs from S. langii, its apparent descendent, primarily in its more robust cortical shell with framed pores. S. langii is generally smaller with a thin cortical shell bearing simple, cylindrical pores. Ancestry of this species is unknown.
Kling 1973


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