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Actinomma sol Cleve, 1901

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Actinomma sol:
Radial proportion of the three shells 1:2.5:9. Cortical shell thick-walled, with circular, regular, six-lobed pores, as broad as the bars. At each nodal-point is a bristle like spine, half as long as the radius, thus every pore surrounding by a corona of six bristles.

Owing to the thickness of the cortical shell, the interior shells were visible merely as faint shadows, so I am not quite convinced whether the shells are 3 or 2. If the latter be the case, the species belongs to Haliomma and is then nearest akin to H. horrida.

Diameter of the outer shell 0.09 mm, of the cellules 0.001 mm.
Cleve 1901
Benson, 1966, p. 132-134; pl. 2, figs. 12-13, not fig. 11
Thecosphaera sp.

Fully developed forms consisting of three concentric, latticed, spherical shells (two inner medullary shells and an outer cortical shell) joined by numerous (10-30 or more) thin, delicate, radial beams. Surface of cortical shell without main spines but with short thorns or thin conical spines located at the nodes of the intervening bars; a few tests with short thorns continuous inward as radial beams; cortical shell with relatively small, subequal, circular to subpolygonal, hexagonally-arranged pores, 10-17 on half the circumference; pores surrounded by polygonal frames; intervening bars of variable thickness but generally heavy; thickness of shell wall variable (as thick as 18 µm, generally 5-8 µm). Medullary shells widely separated from cortical shell. Inner medullary shell polyhedral with thin intervening bars separating large polygonal pores, 2-3 on half its circumference; inner joined to the outer medullary shell by 10-20 thin radial beams which arise from its surface. Outer medullary shell spherical to subspherical, with small, subequal, regularly arranged, polygonal to subcircular pores (8-14 on half the circumference) separated by thin intervening bars, with or without polygonal frames; joined to the cortical shell by 10-30 thin, cylindrical, radial beams arising from its surface; numerous thin, conical spines also arise from its surface.

Measurements; based on 39 specimens from stations 27 and 71: diameter of cortical shell 87-144 µm [diameters >100 µm probably are of Cenosphaera sp from the Gulf of California], of outer medullary shell 37-46 µm, of inner medullary shell 15-20 µm.
Benson 1966
Actinomma sol:
Three concentric shells. Outermost with regular, circular pores with well developed polygonal frames, usually bearing short bristle-shaped spines on the nodes (broken off in the specimen photographed); no primary (conspicuously larger) radial. Outermost shell diameter: 70-100 µm.
Boltovskoy 1998











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