105
Wall structure and test morphology in three large deep-sea agglutinated
foraminifera, Rhabdammina parabyssorum Stschedrina 1952, R. abyssorum
Sars 1869 and Astrorhiza granulosa (Brady 1879)
(Foraminiferida, Textulariina)
ANDREW J. GOODAyl and CHRISTOPHER W. SMARr
1.
2.
Southampton Oceanography Centre, Empress Dock, European Way, Southampton, S014 3ZH, United Kingdom
Department of Geological Sciences, University of Plymouth, Drake Circus, Plymouth, PIA BAA, United Kingdom
ABSTRACT
We describe novel test-wall features in two species, Rhabdammina parabyssorum from the
Arabian Sea and Astroriziza granulosa from the NE Atlantic Ocean. These large agglutinated
foraminifera have tests which consist of a central inflated region giving rise to a variable number
of radiating arms. Both species include two- and three-rayed morphotypes and both have a twolayered wall structure in which a thin inner layer is overlain by a thicker, outer, friable layer.
This wall structure has never been clearly described or illustrated before, despite the fact that one
of the species, A. granulosa, has been known for well over a century. At least in R. parabyssorum,
the outer layer is virtually devoid of cement while the inner layer contains well-developed
'undifferentiated' cement (sensu Bender, 1995). The well-known species Rhabdammina abyssorum
differs from R. parabyssorum only in having a much simpler, unlayered wall structure. This raises
questions about the taxonomic significance of wall structure versus test morphology in large
agglutinated foraminifera. If these two forms are distinct species (the interpretation adopted
here), then it indicates that morphologically identical sibling species exist among agglutinated
foraminifera. The alternative interpretation, that these forms are variants of one species, implies
that agglutinated wall structure may exhibit substantial intraspecific variability.
The function of the weakly cemented, friable outer test layer is not known. We offer the
suggestion that in R. parabyssorum, it could possibly be a dynamic, ephemeral feature involved in
some way with the trophic biology of the foraminifer.
INTRODUCTION
Large agglutinated foraminifera are an important
component of deep-sea biological communities,
particularly in bathyal continental margins regions
which receive a fairly substantial food supply
(Gooday, 1990; Levin, 1991; Gooday et ai., 1997).
Many of these taxa have fairly robust, albeit often
brittle, tests and are easily collected, sometimes in
large quantities, by dredges and other towed
sampling gears. For this reason, they attracted the
attention of pioneer deep-sea biologists such as W.B.
Carpenter and M. and G.O. Sars and include some of
the most familiar of deep-sea foraminifera.
One such species is Rhabdammina abyssorum
which has a distinctive radiate, tubular test and
has been recorded from a wide bathymetric range in
many parts of the world. Much of the early material
was collected using towed gears.
More recently, this species has been observed in
life position in cores and has been the subject of some
pioneering physiological observations (Linke, 1992).
Here we describe a species, closely resembling R.
abyssorum, obtained in core samples from a 3400 mdeep site in the NW Arabian Sea, off the coast of
Oman (Gooday et al., 1997). This form has a twolayered wall structure which is quite different from
the relatively simple, single-layered wall typical
of R. abyssorum, but very close to the description
given by Stschedrina (1952b) of R. parabyssorum.
The third species considered in this paper,
Astrorhiza granulosa, occurs in epibenthic sledge
material obtained by the Institute of Oceanographic
Sciences (lOS, nowpart of SOc, the Southampton
Oceanography Centre) on the continental slope off
NW Africa.
We chose to examine Rhabdammina
parabyssorum and A. granulosa because they both
have an agglutinated wall consisting of two layers
which differ in their composition, texture and
degree of cementation. They also display a similar
range of morphological variation. We describe these
features and discuss their possible taxonomic and
ecological significance.
In: Hart, M.B., Kaminski, M.A., & Smart, C.W. (eds) 2000. Proceedings of the Fifth International Workshop on Agglutinated
Foraminifera. Grzybowski Foundation Special Publication, 7, 105-115.
106
A.J. Gooday & C.W. Smart
Table 1. Positions of stations mentioned in text and figure captions.
Station and
series numbers
Date
Discovery 8973
Challenger
50606#1
Discovery 12719#1
Discovery 12671#3
Discovery 12671#4
Discovery 12687
Lat. (ON)
Long.
(OW)
Depth
(m)
Gear
4th Oct. '76
6th July '79
32° 1.9'
50° 10.4'
11°19.4'
50° 40.1'
3003-3008
1110-1120
Epibenthic sledge
Epibenthic sledge
1st Nov. '94
11 th Oct. '94
11 th Oct. '94
18-20 Oct. '94
19° 07'
19° 00.03'
19° 00.29'
-19°
58° 39'
59° 00.00'
59° 00.22'
-59°
3000
3393
3392
-3350m
Agassiz Trawl
Multiple corer
Vegematic box corer
Multiple and box cores
MATERIALS AND METHODS
Station details are summarised in Table 1. The
Rhabdammina parabyssorum sampling site on the
Oman margin is situated below the Arabian Sea
oxygen minimum zone and is characterised by bottom
water oxygen concentrations around 3.0 ml.rl.
Specimens of R. abyssorum were collected at this site
in 1994 using an USNEL-type box corer, a BarnettWatson multiple corer (Barnett et al., 1984), and an
Agassiz trawl. They were picked from core surfaces
or trawl catches and preserved immediately in 10%
formalin buffered using sodium borate. Specimens of
R. abyssorum from the Porcupine Seabight (NE
Atlantic) and Astrorhiza granulosa from the NW
African margin were collected in 1979 and 1976,
respectively, using various versions of the lOS
epibenthic sledge (Aldred et al., 1976). Residues
from the sledge catches were fixed in buffered 10%
formalin and later transferred to 80% alcohol for
storage. Specimens were subsequently picked out
from the >500 J1.m residue.
Light photographs were taken using a WILD
M400 photomicroscope. For scanning electron microscopy, specimens were air dried, fixed to stubs using
silver dag, coated with gold and examined either in
a JEOL model 5300 or a JEOL model 6100 SEM at 20 or
25 Kv.
OBSERV AnONS
Rhabdammina parabyssorum Stschedrina, 1952
Plates 1 and 2
Rhabdammina parabyssorum Stschedrina 1952b, pp. 25-30,
pI. 1, figs 1-3.
The original description was based on material from
the North Pacific (Bering and Okhotsk Seas). The
new Arabian Sea record therefore extends the
geographical range of this species considerably.
Phenotypic variation. This species includes morphotypes which are radiate, tubular (biradiate) and
branched (Le., with a single dichotomous fork). Out
of 43 specimens individually picked from core surfaces at Station 12687, 26 were three-rayed, 12 were
two-rayed, 1 was one-rayed, 1 was five-rayed and 1
was branched. Three-rayed tests also dominated 277
more or less broken specimens from an Agassiz trawl
sample (12719#1) taken at the same site. More than
70% (194 specimens) were three-rayed, 27 (9.7%)
were four-rayed, 3 (1.1%) were branched, 2 (0.72%)
were five-rayed, and 2 (0.072%) were irregular in
shape. The remaining 44 (15.9%) specimens, simple
tubes longer than lcm, were regarded as two-rayed
forms; this designation was somewhat arbitrary
since some of these tubes could have been the broken
arms of specimens with more than two arms. The
branched morphotype resembles Rhabdammina
major de Folin, 1887, a form considered by Gooday
(1986) to be a variant of R. abyssorum on the basis of
its identical wall structure.
Wall structure. The test consists of an inner layer
overlain, at least in places, by a variably developed
outer layer (PI. I, Figs 1-3). Where the ends of the
arms are undamaged, the inner layer may expand
into a bell-shaped termination. The inner layer is
composed of fairly well-cemented quartz particles
and a variable proportion of sponge spicules, some of
which protrude from its outer surface (PI. I, Figs I, 2,
6, 7). In some specimens it is composed almost
entirely of spicules. On the inner surface of the test,
the spicules lie flat within an organiC matrix to give
a moderately smooth finish (PI. 2, Fig. 3), but
otherwise they are not arranged in any particular
pattern. Fractured test surfaces reveal the presence
of organic cement which forms an extensive but
rather featureless coating on spicules and other particles (PI. 2, Figs 7,8). Places where particles have
become detached are visible as rounded scars on
cement covered surfaces. Strands and columns of
cement are generally not developed.
The outer layer is more coarsely and loosely
agglutinated (friable) than the inner layer. It has a
somewhat irregular outer surface and is greyishbrown, in contrast to the lighter, more yellowish
colour of the inner wall. It is generally thicker than
the inner layer although the thickness varies considerably. The outer layer is best developed towards
the centre of the radiate test and becomes discontinuous towards the ends of the arms. Typically, the
arms are characterised by wider sections where the
outer layer is developed and narrower sections
where it is missing and the inner layer of the wall
exposed (PI. I, Figs 1-3). Sometimes, there is a
rather abrupt step between these sections. In a few
Wall structure and morphology of three large tubular foraminifera
specimens, the outer layer is hardly developed on
the radiating arms.
The outer layer is composed almost entirely of
mineral grains, most of which appear to be quartz.
The grains are subangular to sub rounded, a few lOs of
microns to about 100 /lm in size, and jumbled together
with no intervening matrix (PI. I, Figs 4,5). It therefore incorporates an extensive system of intergrain
voids (Pi. 2, Figs 5,6). Sponge spicules are generally
absent but scattered spicules, juvenile globigerinacean tests, and small amounts of fine-grained
material, are sometimes visible on undamaged outer
surfaces. Very little cement is present; a careful
examination of broken test surfaces revealed only
very occasional, short columnar strands between
adjacent grains.
Rltabdammina abyssorum M. Sars, 1869
Plate 3
Rhabdammina abyssorum M. Sars in Carpenter 1869 pp.
60-61.
"
,
Rhabdammina discreta Brady, 1881, p. 48.
Rhabdammina major de Folin, 1887, fig. 12a.
Phenotypic variation. Following Gooday (1986),
Thies (1991) and Bender (1995), we regard
Rhabdammina discreta and R. major as, respectively, two-rayed and branched morphotypes of R.
abyssorum. Out of 373 specimens from the epibenthic
sledge sample taken at Station 50606, 328 (87.9%)
were three rayed, 36 (9.7%) were four rayed, 7
(1.9%) were two-rayed (i.e., tubes >lcm length);
five-rayed and branched forms were each represented by a single specimen (0.27%).
Wall structure. The wall structure agrees well with
the description given by Mendelson (1982) of specimens from the Scottish margin (NE Atlantic). It is
relatively simple and homogenous without the inner
and outer layers seen in R. parabyssorum (PI. 3, Figs
1-5). On fractured surfaces, the wall structure
appears open with numerous irregular interconnecting voids (PI. 3, Fig. 6). It consists of large, subrounded to subangular quartz grains with the interstices filled by a jumble of much smaller, often
somewhat angular particles. The large grains are
generally 100-200 /lm in size, sometimes rather
larger. Most matrix particles are <10 /lm and there
are also some particles of intermediate size. Sponge
spicules were not observed. The outer surface is distinctly knobbly with many large, protruding quartz
grains. Coccoliths are fairly numerous on the surfaces between the large grains and form a kind of
outer veneer (PI. 3, Fig. 5). Open voids are also
exposed in these areas.
The wall is firmly cemented. The cement coats
the grain surfaces (PI. 3, Fig. 7) and resembles that
associated with the inner layer of Rhabdammina
parabyssoru m.
Asfrorhiza granulosa (Brady, 1879)
Plate 4
107
Marsipella granulosa Brady, 1879, pp. 86-87, pI. 3, figs 8-9.
Astrorhiza angulosa Brady, 1881, p. 48.
Phenotypic variation. Brady's two species have an
identical wall structure and we agree with Jones
(1994, p. 32) that they represent two- and threerayed variants of one species (PI. 4, Figs 1,2). In our
material from Station 8973, the two rayed form
varies from tubular to cigar-shaped and the threerayed form from triangular or sub triangular to more
rounded or elongate in shape, typically with sides
which are more or less curved. The two- and threerayed forms each account for about half of the 47
specimens in this sample.
Wall structure. The wall consists of distinct inner
and outer layers of completely different composition
(PI. 4, Figs 3, 5). The inner layer is yellowishorange, thin and composed of fairly well cemented
mineral grains of varying sizes. The outer layer is
white, much thicker than the inner layer, loosely
agglutinated, very friable and composed almost
entirely of small juvenile globigerinacean tests (PI.
4, Figs 4,6,7). At the ends and comers of the test, the
inner layer emerges to form a short projecting tube
terminating in an aperture.
DISCUSSION
Phenotypic variation in deep-sea foraminifera
Phenotypic variation is well-known among shallow-water foraminifera where it is associated with
environmental variability, both natural and
anthropogenic (Poag, 1978; Jorissen, 1987; Alve,
1995). In the deep sea, where conditions are generally more uniform, such plasticity is less common,
although many widely distributed calcareous
species do show some degree of morphological variability across their geographical and temporal
ranges (Boltovskoy et al., 1991). Morphological
variation is apparent among agglutinated taxa such
as Reophax and some other hormosinaceans in
which test morphology varies, sometimes considerably, according to the particles used in its construction (Schroder, 1986). There is also obvious variation in the number of tubular extensions (apertures)
in species of Rhabdammina, Astrorhiza and
Vanhoeffenella. All of these taxa contain more or
less linear (biradiate) morphotypes, in addition to
the more typical radiate forms. Both types are
represented in R. parabyssorum, R. abyssorum and A.
granulosa.
The number of rays developed in R.
parabyssorum, R. abyssorum and A. granulosa is not
obviously related to test size and may simply reflect
random variation. A more interesting form of variability seems to occur in Rhabdammina abyssorum.
Gooday (1986) pOinted out that Rhabdammina major
(=R. irregularis of some authors) has a wall structure which is identical to that of R. abyssorum and
R. discreta (now generally regarded as conspecific)
and often co-occurs with these two forms.
Stschedrina (1952a) also illustrated a branched
108
A.J. Gooday & C.W. Smart
Table 2. Some species of agglutinated foraminifera (and one xenophyophore) described as having a layered
wall structure.
Species
Astrorhiza
granulosa
Test morphology
Tubular, either
straight or radiate
BathysipllOn
capillare
B. major
Tubular, no proloculus
B. rufescens
Tubular, no proloculus
B. rufus
Tubular, no proloculus
Critlzionina
delacai
Irregular sphere, no
aperture
C. granum
Irregular sphere, no
aperture
Pelosina
arborescens
Tubular with
branched distal part
Pilulina argentea
Spherical with
aperture
Rhabdammina
parabyssorum
Tubular, either
straight or radiate
Occultammina
profunda
(xenophyophore)
Tubular, occasionally
branching
Tubular, no proloculus
Test structure
Thin, friable outer layer,
thinner, more strongly
cemented inner layer
Very thin outer veneer of
plate-like particles
Thin, loose, outer layer of
black apatite particles
Very thin outer veneer of
plate-like particles
Very thin outer veneer of
plate-like particles
Wall composed of fine siliceous
particles lined by a single
layer of /Lm-sized grains bound
by an organic sheet
Wall composed of siliceous
particles lined by a thin,
finely-grained, chalky-white
inner layer
Wall composed of mud but
with a thin inner layer of
quartz grains
Thin outer layer of minute,
flat-lying plate-like particles;
inner layer of small rod-like
particles embedded in a fine
matrix
Thin, friable outer layer,
thinner, more strongly
cemented inner layer
Outer layer mainly clay
particles; inner layer of siltsized mineral grains and
radiolarian fragments
morphotype among her specimens of R. abyssorum
from various Arctic regions and the NE Pacific. The
R. major form, in which the test branches dichotomously rather than being radiate, is represented in
the Arabian Sea material of R. parabyssomm,
albeit by only a few individuals. The significance of
the branched R. major form is unclear, but it could
possibly represent a stage in the life-cycle of these
species.
Wall structures in agglutinated foraminifera
Layered walls. In many morphologically simple
agglutinated foraminifera, the test wall is either
one grain thick, or more than one grain thick with
the grains arranged homogeneously throughout the
wall (Hofker, 1972; Bender, 1995). Some species,
however, have heterogeneous walls consisting of
two clearly defined agglutinated layers which
differ in the composition and/or arrangement of the
Reference
This study
Gooday & Claugher
(1989)
Gooday et al. (1995b)
Gooday & Claugher
(1989)
Gooday & Claugher
(1989)
Gooday et al.
(1995a)
Hoglund (1947)
Cartwright (1988)
Hoglund (1947)
This study
Tendal et al., (1981)
constituent particles (Table 2). The layering often
takes the form of a thin outer veneer which provides
a smooth finish to the wall (e.g., a number of
Bathysiphon species, Pilulina argentea), or a thin
agglutinated lining to the test lumen (e.g.,
Crithionina delacai, C. granum, Pelosina
arborescens). The tubular test of the xenophyophore
Occultammina profunda has a 15-30 /Lm thick outer
layer composed of fine clay particles and 50-90 /Lm
thick inner layer composed of silt-sized mineral
grains and radiolarian fragments (Tendal et al.,
1981). Less well-defined test wall heterogeneity is
encountered in other agglutinated foraminifera
(Lindenberg & Auras, 1984, p. 98).
Our observations indicate that a distinctive kind
of wall layering is developed in Rhabdammina
parabyssorum and Astrorlziza angulosa. In both
cases there is a friable outer layer (variably
developed in R. parabyssorum) overlying a thinner
Wall structure and morphology of three large tubular foraminifera
but more firmly cemented inner layer. This structure
is most similar to that of Pelosina arborescens, as
described by Cartwright (1988), and completely different from the thin surface veneer of particles
which occur in some Bathysiphon species. Published
accounts of A. angulosa, while not specifically
describing the wall structure, do suggest that the
inner and outer layers are a consistent feature of this
species; the exposure of the inner layer at the test
extremities is suggested by Brady's (1884, pI. 20, figs
10-22) illustrations and by Cushman's (1918, p. 11)
description. Examination of Brady's original material in the Challenger collection (Natural History
Museum, London) confirms that the test is two
layered. The outer layer present in our material of
Rhabdammina parabyssorum compares well with
Stschedrina's (1952b) original description.
Cement microstructures. Bender (Bender &
Hemleben, 1988; Bender, 1989, 1995) described the
nature and morphology of organic and calcareous
cements in a wide range of agglutinated
foraminifera. The fairly well-developed cement in
Rizabdammina parabyssorum (Arabian Sea) and R.
abyssorum (NE Atlantic) resembles the
'undifferentiated' cement present in more than half
of the species examined by Bender (1995). In both
species, the attachment areas of detached particles
are clearly visible on cement coated surfaces (PI. 2,
Figs 7,8; PI. 3, Fig. 7). In contrast, Bender's (1995)
Rizabdammina abyssorum from 400m depth in the
Greenland Sea had foam-like cement. There is
almost no trace of an organic matrix within the outer
test layer of Rhabdammina parabyssorum which is
similar to the friable tests of Astrorhiza arenaria
(Tendal & Thomsen, 1988; Bender, 1995, pI. 8, fig. I)
and Crith ion ina delacai (Gooday et al., 1995a).
Taxonomic implications
Cement. Loeblich & Tappan (1989) divided agglutinated foraminifera with organic cement into three
suborders according to the cement microstructure; a
fourth suborder was established to accommodate
taxa with secreted calcitic cement. However, Bender
(1989, 1995) observed that cement microstructure is
not a consistent, well-defined feature and may vary
within a genus. She therefore downgraded its taxonomic significance and recognised only two suborders
of agglutinated foraminifera, one characterised by
organic cement (this includes all morphologically
simple agglutinated foraminifera so far studied),
the other by calcitic cement. At the species level,
however, Bender (1995, p. 36) regarded the different
types of organic cement microstructure as being consistent and therefore 'an important tool for the
species concept and recognition of morphospecies'.
The present study suggests that this may not always
be the case since, as discussed above, both undifferentiated and foam-like microstructures occur in
Rlzabdammina abyssorum. In fact Bender (1995, p.
30) herself seems to allude to this issue when she
109
remarks that foam-like cement is not uniformly
developed throughout the test of R. abyssorum,
'hampering the classification of the cement type as
'foamy' or 'undifferentiated".
Test wall composition and structure. Rhabdammina
parabyssorum and R. abyssorum have identical test
morphologies and display the same range of variation, including three-, four-, five-rayed and
branched (R. major-like) morphotypes. The two
forms could be variants of one species. However, we
agree with Stschedrina (1952b) that the striking
and consistently different wall structures justify the
recognition of two distinct species. If this is correct,
then it suggests that sibling species with identical
test morphologies exist among foraminifera. The
alternative interpretation, that the two forms are
conspecific, also has important consequences because
it implies that wall structure can vary substantially
within a single species. A molecular approach
(Pawlowski et al., 1994) may be the only way to
establish whether or not R. abyssorum and R.
parabyssorum are really genetically distinct
entities.
The wall structure in R h a b dam min a
parabyssorum also raises important issues at the
generic level, as discussed by Stschedrina (1952b). In
his definition of the genus Astrorhiza, Hofker (1972,
p. 21; see also Loeblich & Tappan, 1987, p. 20)
emphasised the thick, sometimes friable test wall
composed of many layers of agglutinated particles,
so that the external volume of the test is much
greater than the internal volume. Astrorhiza
granulosa conforms well with this definition.
According to Hofker (1972, p. 26), the wall in
Rhabdammina is not as thick as in Astrorhiza, is
firmly cemented (not friable), and consists of one or
more layers of sand grains. This definition fits
Rhabdammina abyssorum well but is inconsistent
with the nature of the outer test layer developed in
R. parabyssorum. The wall structure in this species
is closer to that of Astrorhiza species, particularly
A. granulosa. Clearly, the diagnosis of
Rhabdammina, and the relation between this genus
and Astrorhiza, needs to be reconsidered.
Ecological implications
There are some striking similarities between the
organisation of the outer test layer in Arabian Sea
specimens of Rhabdammina parabyssorum and the
spherical test of Crithionina delacai from Explorers
Cove, Antarctica, as illustrated by Gooday et al.
(1995a; PI. 3). In both cases the wall is extremely
friable, contains very little cement and is made up of
a jumble of quartz grains with a loose, open texture
and a large proportion of empty, intergrain space.
One difference is that pseudopodia have been
observed within the wall of C. delacai but are not
obviously present in R. parabyssorum. This could
simply reflect the fact that the outer layer in R.
parabyssorum is situated away from the apertures
A.J. Gooday & C.W. Smart
110
and therefore relatively inaccessible to
pseudopodia.
Gooday et al. (1995a) suggest that the test wall
in Crithionina delacai is an ephemeral structure in a
constant state of flux. Similar arguments may apply
to the outer layer in R. parabyssorum. The fact that
it is variably developed within individual specimens, being thick in some areas of the test and absent
in others (sometimes with an abrupt junction between
the two areas), also suggest that it is a dynamic
rather than a static feature. It is possible that these
poorly cemented test structures are involved in
trophic mechanisms and perhaps represent a
response to fluctuating food supply (Gooday et al.,
1995a, p. 297). For example, their loose agglutinated
construction resembles that of the 'feeding cysts'
which are sometimes developed by calcareous and
other foraminifera (Arnold, 1979; Linke & Lutze,
1993; Bowser et al., 1995).
We have not examined the outer test layer in
Astrorhiza granulosa in such detail. However, the
fact that it is consistently developed in all available specimens suggests that, despite being loosely
agglutinated, it may be a more permanent structure
than the outer layer in Rhabdammina abyssorum.
QUESTIONS FOR THE FUTURE
There clearly remains much to be learnt about the
biology and taxonomic relationships of apparently
simple agglutinated foraminifera (Bowser et al.,
1995; Gooday et al., 1997). The present study raises a
number of questions.
1) What is the geographical distribution of the
two-layered form of Rhabdammina parabyssorum?
Do some records of R. abyssorum refer to this species
which prior to our study had only been reported from
the Sea of Okhotsk and Bering Sea?
2) What is the taxonomic relation between the
three species considered in this paper? Is overall
test morphology (which would group together
Rhabdammina parabyssorum and R. abyssorum)
more important than wall structure (which would
group together R. parabyssorum and A. granulosa)?
Are R. parabyssorum and R. abyssorum really
distinct species?
3) What is Rhabdammina
major? Is this
branched form a variant of R. abyssorum, as suggested by Gooday (1986). If so, what is its significance; for example, is it an ecological variant or a
stage in the life cycle?
4) How variable is the cement microstructure
within individual agglutinated species?
5) What is the biological function of the twolayered wall structure? Is it related in any way to
secondary agglutinated structures such as feeding
cysts? Is it involved in the trophic biology of the
foraminifer?
A number of approaches might be helpful in
addressing such issues. For example, long term
culture studies could help to resolve some of the
ecological questions while molecular methods might
illuminate the taxonomic problems.
ACKNOWLEDGEMENTS
We thank Mrs Jane Green, Dr. Roy Moate and the
late Dr. Derek Sargeant of the Plymouth University
Electron Microscope Unit for their help with SEM.
We are particularly grateful to Dr Andrey Gebruk
for obtaining copies of the Stschedrina papers and
translating important sections of them. This is SOC
DEEPSEAS contribution no. 37.
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112
A.J. Gooday & C.W. Smart
Plate 1. Rlwbdnmmina parillly~sor1/l1J Stschedrina from the Arilbi.111 Seil (lJiSCOI'l'rY Stillion 12671#4). 1\11
are SEM photogr<lphs unless otherwise stated.
1. Light photogmph of complete specimen; 2-3. details of Men where inner and outer layers are exposed
(arrows point out equivalent positions); 4-5. det,1ils of outer, frinb1e I,'yer composed of very wC'nkly cemented
quartz grnins; 6-7. det<li!s of inner layer composed of more firmly cemented quartz grains and sponge spicules.
Scale bars == 2 mm (1),500 Jlm (2), 100 Jlm (3,5,6), 50 Jlm (4,7)
Wall structure and morphology of three large tubular foraminifera
113
Plate 2. RJwbdammil1a par(1!'yssona1J Stschedrina from the Arabian Sea (Discovery Station 12671#4).
1-2. Fr(lctured surface of test showing inner layer composed largely of sponge spicules and outer layer
composed largely of quartz grains; 3. inner surface showing flat-lying sponge spicules embedded in organic
matrix; 4. fractured surface showing inner and outer layers; 5-6. details of outer layer showing virtual absence
of organic cement; 7-8. details of inner layer showing well-developed undifferentiated cement; note the scars
left on cement covered surfaces by detached grains. Scale bars: 100 tLm (1,2,4,5); lOtL!n (3,6,7); 1 pm (8).
A.J. Gooday & C.W. Smart
Plate 3. RJI(l/ldammillrl Ilbyssontm Sars from the Porcupine Seabight, NE Atlantic (Challenger Station
50606#1). All photographs taken llsing SEM.
1. Complete specimen; 2·3. Details of broken end of tube showing single layered constmction from large quartz
grains and fine-grained matrix; 4-5. Outer surface of test showing large quartz grains; 6-7. Broken surface
showing matrix particles and undifferentiated cement; note scars left on cement covered surfaces by detached
grains. Scale bars: 1 mm {ll, 200 J-tm (2), 100 11m (3-5), 10 Jlm (6,7)
Wall structure and morphology of three large tubular foraminifera
115
Plate 4. Aslrorhiz.(l gmnrllosn Brady from the NE Atlantic (Discovery Station 8973). AI! photographs tilken
SEM unless othen,,'ise stated.
t. Ught photograph of specimen with three ,'pertures; 2. Light photograph of specimen with I'\.\'o apertures;
3,5. Detail of aperturaJ end showing inner layer composed of mineral grains emerging from beneath outer
layer composed of juvenile globigerinacean shells; 4,6-7. Details of aliter Jayer. Scale bars: 1 mm (1,2), 100 pm
(3,4,6), 50 Jim (5,7).
l1~ing