Catalog entries: Stylodictya inaequalispina
Original description: Shell circular, interradii rounded, with five unequal margin spines, in two pairs 180° apart, and one odd, shorter spine between one pair in the center of the quadrant forming the axis of the trivium, spines well-developed, more than the radius of the disc in length, stout, conical, tips pointed, bases somewhat expanded, with two opposite pairs of backwardly directed hooklets somewhat above the base, these the points of attachment of protoplasmic musclelike threads; all six rings of sieve-plate concentric, annular, following the contour of the margin of the plate, gradually increasing in breadth from the center to the periphery, the earlier rings a little less than half the breadth of the penultimates ones, periradial constrictions hardly marked, but the rings are divided into segments by radial beams which project to form the spines; the pores rather large, mostly subcircular with the distalmost ones tending to become subhexagonal, pores more or less regular increasing in diameter from the center to the edge, two or three on the breadth of a ring; margin of the sieve-plate not regularly denticulate.
Diameter of sieve plate, 150µm; of pores, 2.2-6.6µm; breadths of rings, 8.8-14.4µm; length of longer spines, 69.4µm; of the short one, 38.6µm; position of the hooklets above base of spines, 12.2µm. Distinguishing characters (rw): Stylodictya inaequalispina n. sp. differs from others of the genus in the inequality of the five spines, four of them are equal and much like those of species of Staurodictya, as indeed the disc resembles species of that genus, but the odd, small spine with its hooklets in the axis of the trivium removes the species from that genus. It is not at all related to S. sexispinata n. sp., a species which in many ways is unique and may later be assigned to a new genus.
Remarks on original description: [The authors here list this species under the subgeneric name Stylodictyon and include the subgeneric name in the species name.
Last occurrence (top): within Paleogene Period (23.03-66.04Ma, top in Chattian stage). Data source: Lazarus et al. 2015 - "P age group"
First occurrence (base): within Paleogene Period (23.03-66.04Ma, base in Danian stage). Data source: Lazarus et al. 2015 - "P age group"
Plot of occurrence data:
Stylodictya inaequalispina compiled by the radiolaria@mikrotax project team viewed: 25-10-2020
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