Cenozoic Spumellarian Radiolaria With Eccentric Microsphere
Author
Dumitrica, Paulian
Institute of Earth Sciences, Université de Lausanne, Géopolis, 1015 Lausanne, Switzerland; mailing address: Dennigkofenweg 33, 3073 Gümligen, Switzerland
Paulian.Dumitrica@unil.ch
text
Acta Palaeontologica Romaniae
2019
2019-04-25
15
1
39
60
http://dx.doi.org/10.35463/j.apr.2019.01.04
journal article
10.35463/j.apr.2019.01.04
1842-371x
10520604
57C54916-CC13-4BA1-BA82-2A99A822D9D1
Helioferrusa hollandei
nov. sp.
Figures 9b, c, h, i
Description
. Shell thin disc-shaped consisting of 4 shells: a double medullary shell with an eccentric microsphere, a large main cortical shell, and a peripheral equatorial ring. Microsphere very small, eccentric in the outer medullary shell. Outer medullary shell prunoid or subspherical, with large circular or polygonal pores and included in the cavity of the cortical shell with whom it is connected to the two faces of the latter by a bunch of oblique radial beams. These beams do not cross this shell. Cortical shell large, disc-shaped or lenticular and a little thicker than the diameter of the outer medullary shell. It has numerous very small circular to oval pores of various sizes and irregularly or, partly, radially disposed. This shell is surrounded by a peripheral ring with similar pores but usually smaller. Inside this ring there are radial costae that divide its circumference in unequal segments. Periphery of ring with tiny thorns.
Material
.
Four specimens
, from the late middle Miocene sample
PROA
96P.
Holotype
. The illustrated specimen, coll.
MGL 103561
.
Dimensions
. Diameter of microsphere 17-19 μm, of outer medullary shell 49-54 μm, of cortical shell 173-232 μm, of peripheral ring 232-330 μm.
Etymology
. The species is dedicated to André
Hollande
, co-author of the valuable monograph on living
Radiolaria
from the Gulf of
Alger
.
Remarks
. In this species I included two morphotypes: one found in sample
PROA
96P (
Fig. 9b
), represented by
7 specimens
, the other one in sample
DSDP
21-205-7-1,
70-72 cm
from South
Fiji
Basin, which is late Miocene (NN10 Zone) in age (
Fig. 9c
). These two morphotypes are practically contemporaneous but morphologically rather different. The morphotype from the sample
PROA
96P has the cortical shell flat, very thin similar to that of
Heliodiscus riedeli
nov. sp.
, and the peripheral ring has thin intervening bars between pores. The morphotype from the sample
DSDP
21-205-7-1, 70-72 has the lenticular cortical shell, with rather convex faces and larger pores, and the peripheral ring has much smaller pores, separated by larger intervals, approximately as large as diameter of pores. These differences seem to be rather important, at least at subspecies level, but because I found a single specimen with such characters in that sample I do not know what signification they could have.
Range and occurrence
. Late middle Miocene from tropical and subtropical Pacific.