16. Radiolaria - Deep Sea Drilling Project

M. G. PETRUSHEVSKAYA, G. E. KOZLOVA
Stylodictya inaequalispina Clark and Campbell
(Plate 18, Figure 8)
Stylodictya inaequalispina Clark and Campbell, 1942, p. 45, pi. 3,
fig. 5.
Disc diameter 150-190µ; width of rings 12µ, pore diameter 4-6µ
(in center 2µ), length of spines up to 50µ.
Eocene-Oligocene.
Stylodictya rosella, Kozlova sp. n.
(Plate 18, Figure 9)
Stylodictya sp. Clark and Campbell, 1945, p. 24, pi. 3, fig. 19.
Central chamber is surrounded by 9-11 slightly curved (scalloped)
annular systems, each system doubling in size beginning in
the center to the edge of the disc; pores are found, 2 or 3 on each
ring, approximately of the same size; there are up to twenty-four
inner spines of uniform thickness; at the rim of the disc they appear
either as thin spicules or as massive flat teeth.
Disc is very thin in its central part and becomes very thick at the
rim (the last 5 to 6 rings).
Disc diameter 250-270µ, width of rings 7-16µ, pore diameter
3-4µ; diameter of the first system 24µ.
It differs from S. targaeformis (see below) by larger dimensions,
the thickness along its rim, and by a greater number of spines.
Eocene-Oligocene.
Stylodictya targaeformis (Clark and Campbell)
(Plate 18, Figure 10)
Staurodictya targaeformis Clark and Campbell, 1942, p. 43, pi. 3,
fig. 6.
Specimens from Atlantic have eight external spines.
Disc diameter 170-200µ; width of rings 5-10µ; pore diameter
2-5µ, length of spines 40µ; diameter of the first system 30µ.
Eocene-Oligocene.
Stylodictya orbiculata (Haeckel)
(Plate 18, Figure 7)
Trematodiscus orbiculatus Haeckel, 1862, pi. 28, fig. 2.
Porodiscus orbiculatus Haeckel, 1887, p. 492.
Disc diameter 125-140µ, width of rings 7-15µ;pore diameter 5µ.
Eocene-Oligocene.
Stylodictya aculeata (Jörgensen)
(Plate 18, Figure 6)
Stylodictya aculeata Jörgensen, 1905, p. 119, pi. 10, fig. 41;
Petrushevskaya, 1967, p. 35, pi. 11, figs. 1-3.
Quaternary.
CIRCODISCUS Kozlova, new genus
Porodiscus Haeckel, 1881, p. 491, (part.); Ommatodiscus Stöhr,
1880, p. 115 (part.); Flustrella Campbell, 1954, p. 89 (part.)
Type species Trematodiscus microporus Stöhr, 1880, p. 108, pi.
4, fig. 17.
Slightly convex skeleton with round or oval outline. Consists of
frontal, sagittal and equatorial girdles, their wings connected to
form regular round or oval rings.
First system is of the Trizonium type {in sensu Haeckel), its
dimension 30-40µ, with fully developed girdles; in the rest of
them, only the equatorial girdle is fully developed; saggital and
frontal girdles terminate at the point of the junction with the ring of
the previous system; distance between (width of rings) is considerably
larger than the diameter of the central chamber. Spines (four
main and four secondary) pass inside of the skeleton. Rim is
smooth.
It differs from Plectodiscus gen. nov., by the character of the
connection of its wings and accordingly by the structure of the first
system.
The name is derived from Greek "Circos" (circle) and "Discos"
(disk), masculine.
Eocene-Recent.
Circodiscus microporus (Stöhr)
(Plate 19, Figure 1-7)
Trematodiscus microporus Stöhr, 1880, p. 108, pi. 4, fig. 17.
Porodiscus microporus Stöhr, Haeckel, 1887, p. 493.
526
Skeleton is oval, flat, consisting of 3 or 4 comparatively wide,
oval, annular girdles; pores are even, circular, 5 or 6 on each ring.
Inner spines (8?) do not extend outside; rim of the disc seldom has a
smooth, clearly outlined tapered edge; more often it is "torn" and
disconnected.
Disc diameter with four systems 180-200µ width of rings
25-35µ, pore diameter 5-8µ.
Miocene-Quaternary.
Circodiscus sp.
(Plate 19, Figure 8)
From C. microporus it differs by having wider rings and smaller
pores.
Disc diameter (with three systems) 160µ, width of rings 3040µ,
pore diameter 3-4µ.
Miocene.
Genus PLECTODISCUS Kozlova, new genus
Discospira Haeckel, 1862 (part.); Porodiscus Haeckel, 1882, p. 492
(part.); Flustrella Campbell 1954, p. 89 (part.). Type species
Porodiscus circularis Clark and Campbell, 1945, p. 42, pi. 11,
figs. 2, 6, 10.
Thin, biconvex skeleton, with oval, less frequently circular
outline, consisting of frontal, equatorial and sagittal girdles. The
closed-spiral structure of girdles is of the Spironium type: wings of
the same type of girdle form a one-half turn of the spiral, and at the
point of their juncture overlap each other. First system has fully
developed girdles, its dimensions are 40 × 50µ; in the rest of the
girdles, only the equatorial girdle is fully developed, both saggital
and frontal girdles terminating at the point of their junction with
the previous system. Distance between rings is greater than is the
diameter of the central chamber. Inner spines are indistinct; rim of
the disc is smooth or is covered by numerous short spines.
Depending on the degree of inclination of the plane of the
girdles in relation to the main axes of the skeleton, the equatorial
girdles appear from the surface (rest of girdles in corresponding
cross-section) in the form of rings, as a single or double spiral, or in
the form of rings connected by zigzag radial lines.
The name is derived from Greek "plecta" (interlacing) and
"Discos" (disk), masculine.
Paleocene-Oligocene.
Plectodiscus circularis (Clark and Campbell)
(Plate 19, Figures 9-12)
Porodiscus circularis Clark and Campbell, 1942, p. 42, pi. 11, figs. 2,
6, 10.
Porodiscus uralicus Lipman, 1960, p. 86, pi. XI, figs. 9-11;
Porodiscus durus Moksyakova, p. 146, pi. 2, fig. 8.
Skeleton is oval, less frequently circular in outline, consisting of
4 to 6 systems, the width of which increases slightly from the center
toward the rim of the disc; all possible varieties of the outer forms
of the girdle are represented here: the enclosed-spiral (Plate-Figure
12), annular (Plate-Figures 9, 10) and spiral; pores are round and of
uniform size, four or five on the width of each system; disc rim is
tapered; main and secondary radial spines are of uniform thickness
and appear at the rim of the disc in the form of (16?) tiny spicules.
Disc diameter 120-25Oµ, distance between systems 20-35µ, pore
diameter 6-9µ.
Paleocene?-Eocene. Paleocene forms have a coarser and larger
skeleton.
Plectodiscus bergontianus (Carnevale)
(Plate 19, Figure 13)
Porodiscus bergontianus Carnevale, 1908, p. 23, pi. 4, fig. 2.
Porodiscus squinaboli Carnevale, 1908, p. 23, pi. 4, fig. 3.
Disc diameter 230-240µ, width of rings 15-20µ, pore diameter
5-7µ.
This form differs from P. circularis by the greater number of
systems and their smaller width.
Eocene.
Genus OMMATOCAMPE Ehrenberg
Ommatocampe Ehrenberg, 1860, p. 852; Haeckel, 1887, p. 392;
Campbell, 1954 p. 76. Type species Ommatocampe polyarthra
Ehrenberg, 1872b, pi. 6, fig. 9.