Polar Biol (1990) 10:451 - 479
9 Springer-Verlag 1990
Some Nitzschia and Related Diatom Species
from Fast Ice Samples in the Arctic and Antarctic
Linda K. Medlin 1 and Grethe R. Hasle 2.
1University of Bristol, Botany Department, Bristol BS8 lUG, UK
2University of Oslo, Department of Biology, Marine Botany, P.O. Box 1069, Blindern, N-0316 Oslo 3, Norway
Received 28 August 1989, accepted 23 November 1989
Summary. Some Nitzschia and closely related species have
been examined in the light and electron microscopes from
fast ice samples in the Arctic and Antarctic. Nitzschia
neofrigida, forming arborescent colonies, and Nitzschia
promare, forming loose ribbon colonies, are described as
new species, both probably included in the distribution of
other similar species. A new combination, Auricula compacta, represents the first report of this genus from ice
samples. Colony formation is reported for the first time in
Nitzschia arctica and Nitzschia taeniiformis. No biopolar
species were found and several reports of Arctic species in
Antarctic ice samples have been refuted.
Introduction
The history of ice algal investigations in the polar regions
goes back to the middle of the 19th century (for review, see
Horner 1985). As early as 1909 (his Appendix II) Van
Heurck recognised that in both the Arctic and Antarctic
most ice-associated as well as littoral diatoms differed
from those in the plankton. There are now, however,
reports from the pack ice region and the ice edge zone in
the Weddell Sea documenting the similarity of ice and
planktonic assemblages (Garrison and Buck 1985; Garrison et al. 1987). But, there are also recent reports supporting Van Heurck's statement (e.g. McConville and Wetherbee 1983; Grossi and Sullivan 1985) showing the existence
of distinct algal assemblages in land-fast ice in Antarctic
nearshore waters. The situation in the Arctic may be.
simpler in the way that one or two of the sea ice algal
assemblages defined by Horner et al. (1988) are missing.
There is, however, evidence that ice-associated diatoms
play an unimportant role in the Arctic plankton (for
review, see Horner 1984).
Taxonomic and floristic work with the plankton and
the pack ice appears to be ahead of that with the fast ice
and the benthos in the Antarctic (Hasle 1964, 1965a,b;
Johansen and Fryxell 1985; Garrison et al. 1987), while the
*To whom correspondence should be addressed
reverse may be true in the Arctic (Horner and Schrader
1982; Hsiao 1983; Poulin in Medlin and Priddle, in press).
This perhaps only reflects the research efforts of the last
10-15 years in both polar regions. More emphasis is now
being placed on sea-ice communities and their contribution to the polar ecosystem. Moreover, it appears that the
diatoms present in each of the sea-ice assemblages defined
by Horner et al. (1988), can be used to describe a particular
type and age of ice (Hasle and Syvertsen 1985), and thus,
the need for correct species identification becomes essential as the assemblage delineation becomes more precise.
From some of the earliest reports of ice-associated and
littoral diatoms (Cleve 1883; Peragallo 1921), pennate
diatoms were noted to far outnumber centric ones. One
such pennate genus, Nitzschia, is particularly well represented in the ice and littoral community (Cleve and
Grunow 1880) and its species are difficult to identify
because they have few characters that can be used with
light microscopy (LM). In this paper we have studied
species of that genus along with some closely related forms
from both Arctic and Antarctic ice samples with light and
electron microscopy (EM). Several of these species have
been cited from both polar regions and we have tried to
establish the accuracy of some of these reports. Colony
formation or the absence of it has proven to be a very
reliable character and we have illustrated it where
applicable.
Materials and Methods
While most of our Antarctic samples came from nearshore waters,
most of the Arctic material was sampled at a greater distance from
land (Table 1). Each location is recorded where a particular species
has been found as that species is described. For some species we have
examined permanent mounts from the slide collections from the
British Museum (Natural History), London (= BM), the Swedish
Museum of Natural History, Stockholm (= S, P.T. Cleve slides), the
University of Copenhagen, Botanical Museum (= C, Ostrup and
Grontved slides), the Naturhistorisches Museum, Vienna (= W, the
Grunow collection), the Friedrich-Hustedt-Arbeitsplatz for Diatomeenkunde, Bremerhaven, (= BRM, Heiden slides and the Hustedt types), the Musrum National d'Histoire Naturelle, Laboratoire
452
Table 1. Locations of preserved samples examined from both polar regions
Number
Date
Arctic Samples
Eurasian Sector
IMBB 568
11/8/73
IMBB
1015/16
24/6/74
IMBB 1615 24/8/77
IMBB 2453
St.721
8/6/84
IMBB 2548
2/5/85
IMBB 2706 30/5/86
St.33
IMBB 2675 12/7/88
IMBB 2472 1878
North American Sector
IMBB 1012 16/4/74
Ice Core 1
15/5/79
Ice Core 2
18/5/79
Location
Collector
80~18'N
28~30'E
Svalbard
Under 1 m ice
T. Benjaminsen
IMR, Norway
66~26'N
32~
Denmark Strait
Ice
79~
27~
Svalbard
Lump in ice pond
T. Oritsland
IMR, Norway
76~
33~
Barents Sea
76~
24~
Barents Sea
under 60 cm ice
76~
34~15'E
Barents Sea
Under 70 cm ice
ca. 79~
12~
Kings Bay
Svalbard
ca. 68~
176~
S. Kristiansen
PRO MARE
51~
54~16'W
Newfoundland
Ice
Prudhoe Bay
Alaska
70~
t27 ~31. I'W
Narwhal Island
Beaufort Sea
M. Schaanning
Univ. of Oslo
E.E. Syvertsen
PRO MARE
E.E. Syvertsen
PRO MARE
G.R. Hasle
B.R. Heimdal
M.M. Kjellman
Vega Exped.
Number
Date
Antarctic Samples
Weddell Sea
IMBB 1592
Feb. 1977
Ant I1/4
Core 5
15/1/84
Ant III/3
Core 6c
Core 7
4/2/85
6/2/85
IMBB 2486
12/2/86
IMBB 2596
St.11
12/3/86
IMBB 2707
St.20
21/3/86
Ross Sea
Quad 1
Quad 1-7
Site L
18/11/81
12/11 to
12/21/84
IMBB 58(10) 23/11/76
T. Oritsland
IMR, Norway
East Antarctica
IMBB 2589
28/10/81
Rita Horner
OCSEAP
~
de Cryptogamie, Paris (= PC, Manguin slides), and the Department
of Biology, Marine Botany, Oslo (= IMBB). The geographical origin
of the particular mount is recorded the first time it is mentioned in
the text.
Holotypes were not encircled by most of these earlier workers
and we have had to search slides in these collections to find single
specimens corresponding to published drawings. It seems that Cleve
and Grunow split many of their samples because slides from the same
location and expedition can be found in each collection. We were
able to trace unprepared material of many of these slides in Stockholm and have used this unprepared material to make new permanent mounts and for electron microscopic examination. Where
appropriate, lectotypes have been designated from this dried material.
Rinsed and cleaned preparations (Simonsen 1974) from over 250
Arctic samples as well selected samples from the Antarctic were
examined with a Zeiss Standard 16 microscope equipped with bright
field (BF), phase contrast (PC), and Nomarski interference contrast
(NIC) optics at the University of Bristol and with a Leitz Orthoplan
and a Nikon Optiphot microscope equipped with the same type of
IMBB 2590
12/11/83
Location
Collector
77~
41~
Broken shelf-ice
77~
39~35.5'W
S. Fevolden
NARE 1976/77
77~
36~58.2'W
77~
44~54'W
75~
26~
Halley Bay
Under-surface
of pack-ice
65~
48~1 2 . 3 ' W
Brown lump in ice
65~
50~38.3'W
Infiltration layer
ca 78~
166~
Cape Armitage
E. McMurdo
Sound Sediment
Trap, 37 m
77~
166~36'E
60~
45~36'W
Signy Island
Iceberg shelf
69~00'S
39~
Bottom of 60 cm
sea-ice
500 m west of
Ongulkalven
Sea-ice
A. Bartsch
AWl,
W. Germany
S.Z. E1-Sayed
TAMU
E.E. Syvertsen
AMERIEZ
C.W. Sullivan
USARP
A. Leventer
USGS
T.A. Whitaker
BAS
K. Watanabe
NIPR, Japan
Syowa Station
optics at the University of Oslo. Preparations for electron microscopy were made following Medlin and Fryxell (1984) and Hasle
(1978) and examined on a Philips 501 scanning electron microscope
(SEM) or a Jeol 1200 EX transmission electron microscope (TEM) at
the University of Bristol, on a Jeol JFM 35C SEM or a Jeol JEM
100C TEM at the Electron Microscopical Unit for Biological
Sciences, University of Oslo, or on a Jeol JSM 25 at Texas A&M
University. Morphometric measurements for each species are presented in Table 2. Terminology follows that of Anonymous (1975),
Mann (1981, 1986), and Ross et al. (1979).
Observations from Arctic Material
Nitzschia frigida
G r u n o w in Cleve a n d G r u n o w 1880, p.
94, pl. 5, fig. 101, n o n N. frigida in P o u l i n a n d C a r d i n a l
1983, p. 111, fig. 11.
Type Locality: K a r a Sea.
453
Table 2. Morphometric measurements of species examined in this study
Nitzschiafrigida Grun.
Nitzschia neofrigida Medl.
Nitzschia polaris Grun.
Nitzschia stellata Mang.
Nitzschia taeniiformis Sim.
Nitzschia promare Medl.
Nitzschia scabra Cleve
Nitzschia arctica Cleve
Nitzschia brebissonii var.
borealis Cleve
Nitzschia laevissima Grun.
Nitzschia neglecta Hust.
Nitzschia lecointei V.H.
Hantzschia weyprechtii Grun.
Auricula compacta
(Hust.) Medl.
Apical
Axis
in ktm
Transapical
Axis
Fibula
in #m
in 10 #m
Striae
in 10 pm
CN
45 75
60 109
50-169
60-134
110-150
31-45
108-220
90 155
120-170
4.5-7.5
6-7
5-7
6.5-10
5
4-5.5
7-10
7-8
6-8
7-9
6-8
5-8
4-8
6 10
8-12
2-3
8-10
7-8
45-50N
40 R
40 P
40 R
24
45-50 N
mottled
24-26
12-18
+
+
+
+
+
+
+
-
115-170
44-98
27 112
55 75
85 134
6 6.5
4 6
2.5-5
6-7
12
6 8
3 6
5-14
9-11
6-9
40 V
35 40R
51-55 N
33-35
22-24
+
+
+
+
+
CN =central nodule
N = not resolvable with LM
R =just barely resolvable with LM, ~40 in 10/~m
P = not present on valve face, face appears hyaline
V=striae appearance varies from hyaline to isolated puncta to ~40 in 10 pm
Lectotype: G r u n o w slide 1933d W.
Material Examined: P.T. Cleve slides VI:I 7, K a r a Sea,
and V:4-76, Discovery Bay, Nares Exp.; Grunow slide
1933d, K a r a Sea; Ostrup slide 1475, N E Greenland; 14
Grontved slides, Katling-Vig, Denmark, glow ( = incinerated on a hot plate) and cleaned prep., 5 - 3 - 4 7 ; Cleve and
M611er slides 314, Franz Josef Land, Barents Sea, and
315-318, Mys Vankarem ( = C a p e Wankarema), East
Siberian Sea, BM Coll.; IMBB samples 568, 1014, 1015,
1016, 1615, 2453 and 2706; Ice core samples 1 and 2.
Frustules are united at their poles into arborescent colonies. (Fig. 1A). Several cells can be joined at one "branching
point". Mucilage adhering the cells to form this distinctive
colony shape is secreted through the girdle bands at the
poles. Within a single colony, cells can be oriented in either
valve or girdle view. The colonies appear to preserve well
because intact colonies were found in material 10 years
old. The cells often lie in girdle view in rinsed or mildly
cleaned preparations and the two valves are easily dislodged from their bands to give a distinct elliptic appearance to the frustule (Fig. 1B-E), such as that seen in the
original drawings of N. frigida by Grunow (Cleve and
Grunow 1880). Single valves are linear-lanceolate with
tapered, rounded apices (Fig. 1F L). The striae, composed of poroid areolae (puncta), run parallel across the
valve and perforate the outer canal wall (Fig. 1J, K).
The raphe system is more or less eccentric (Fig. 1F, J,
K). However, if the proximal mantle (that closest to the
raphe) is flattened beside the valve face in cleaned preparations, then the appearance of a more central raphe
system is given (Fig. 1F, J, K). One method we have used to
determine the position of the raphe is to compare the
width of the valve distally and proximally to the raphe at
the valve centre or at the central nodule (if resolvable
externally) on complete frustules seen in the SEM. F r o m
Fig. 1N, these two widths (v) are unequal and thus the
raphe must be eccentric. Fracture of this critical-pointdried frustule shows the cell to be quite rounded with the
raphe systems of the two valves lying under one another
and not offset to opposite corners of a rhomboid frustule.
Grontved (1950) noted that in colonies, the keels (raphe) of
the cells are not rarely seen centrally. This is possibly
because the cell is more rounded than rhomboid in cross
section and possibly because the cells can be in various
orientations in the colony.
This difficulty in determining the position of the raphe
in N. frigida has lead to conflicting interpretations of its
position in the literature. Cleve and Grunow (1880) listed
N. frigida under the Section Lineares implying that there
was an eccentric raphe. We have examined a slide of this
material from the K a r a Sea in the Cleve collection
(Fig. 1B) and in the Grunow collection and could only find
complete frustules in girdle view and were unable to
confirm the position of the raphe from the type material.
Ostrup (1895) drew a series of figures of N. frigida and
decided that N. frigida possessed a central raphe. One of
us (LKM) has examined his slides from northeast Greenland and found cells primarily with an eccentric raphe but
also with a broad proximal mantle, which would lend
interpretation of the raphe position as being central.
Grontved (1950) was convinced that the raphe position
was eccentric and he did not believe that Ostrups' figures
b - d were of N. frigida.
454
455
The raphe slit is interrupted by a central nodule, which
is easily seen with light microscopy (Fig. 1B-I). The polar
raphe endings extend externally into terminal fissures,
which are slightly curved around each valve apex (Fig. 1J,
K). Internally a simple helictoglossa is formed. The raphe
system is not elevated into a prominent keel (Fig. 1N) and
is spanned internally by small irregularly spaced fibulae.
These are joined to the valve at their bases by a thin ridge
of silica (Fig. 1J-L). The central two fibulae are quite
widely separated (up to 4/tm). The fibulae also stop some
distance from the valve apex. These two characters are
quite useful for identifying N. frigida in cleaned strewn
mounts where the colonies have been disrupted.
The cingulum is composed of three to four open bands
perforated with two to four rows of puncta (Fig. 1M, N).
On the valvocopula, the first row of puncta is separated
from the remaining irregular rows by a non-perforated
space (Fig. 1M). The number of irregular rows beneath the
non-perforate space is reduced in each subsequent band
and on the fourth band there are only two rows of puncta.
Nitzschia neofrigida Medlin sp. nov.
Type Locality: Prudhoe Bay, Alaska.
Type Slides: BM 81531 - Holotype rinsed preparation and
BM 81532 - Isotype cleaned preparation.
Material Examined: Ice core samples 1 and 2; IMBB
sample 1014.
Diagnosis: Cellulae lineares, in coloniis arborescentibus ex
minus quam 15 cellulis constantibus. Valvae lineares,
apicibus rotundate obtusis, 60-190/~m longae, 6/~m latae.
Striae punctatae, inaequaliter longae, 40 in 10/~m. Raphe
centralis. Fibulae 6 - 8 in 10 #m. Cingulum ex 3 taeniis
apertis constans, latitudine harem in directione abvalvari
decrescenti, omnibus serie una pororum prope partem
interiorem munitis.
arrows) can be seen to be equal. The keel appears to have a
ridge running alongside the raphe slit (Fig. 2H). The
fibulae are more robust and more regularly spaced than
those of N.frigida (Fig. 2B, C). A distinct central nodule is
present (Fig. 2B, D).
The cingulum is composed of three open bands with
each bearing a row of puncta along their advalvar margin
adjacent to the pars interior (Fig. 2F, G). The bands
decrease in width abvalvarly.
This species has probably been included in the distribution of N. frigida, although it could easily be distinguished from that species in the samples from Prudhoe
Bay by its greater cell size and by its colonies, which have
fewer but distinctly more robust cells. Identification of N.
neofrigida in cleaned preparations is more of a problem
because morphometric measurements of this species overlap with smaller specimens of N. polaris and with larger
specimens of N. frigida. However, valves of N. polaris are
always hyaline with LM (see discussion below), whereas
the irregular, but numerous striae of N. neofrigida can be
resolved under optimum conditions. Nitzschiafrigida, by
comparison, appears more fragile than N. neofrigida, is
linear-lanceolate with an eccentric raphe. With EM, distinctions between N.frigida and N. neofrigida can be made
on the structure of the valve and girdle bands. In N.frigida,
the valve striae completely reach the eccentric raphe, while
in N. neofrigida, the striae are irregular in length, occasionally meeting the centrally positioned raphe. The bands
of N.frigida contain several rows of puncta, while those of
N. neofrigida possess only a single row along their advalvar margin.
Nitzschia polaris Grunow in Cleve and M611er 1882, p. 4;
Cleve 1883, p. 480, pl. 38, fig. 72 as N. (recta var.?) polaris
Grun.
Frustules are united into arborescent colonies by mucilage
secreted through the girdle bands at the apices (Fig. 2A).
The number of cells per colony is usually less than 15 with
each individual having a pervalvar axis greater than
10 #m.
Valves are linear with rounded obtuse apices (Fig. 2B,
C, E). The punctate striae are somewhat irregular in
length, occasionally reaching the raphe canal (Fig. 2D, E).
A single punctum (sometimes two) perforates the outer
canal wall on each side of the raphe slit (one row of puncta
arrowed on adjacent cell in Fig. 2E).
The raphe is centrally or slightly subcentrally placed
on the valve on a low raised keel (Fig. 2G, H). Again, we
used the same method mentioned above to determine the
raphe position. The two widths of the valve in Fig. 2G (see
Frustules are linear in girdle view and slightly indented at
valve centre (Fig. 3D, E). As far as we are aware it does not
form colonies. In valve view, the linear valve tapers
gradually to rounded, slightly rostrate apices (Fig. 3A).
The valve face curves up from a shallow but distinct
mantle towards a central raphe lying atop a prominent
keel (Fig. 3E, G - K ) . The cells tend to lie on one valve face
(i.e. in girdle view) giving the impression that the raphe is
Fig. 1. Nitzschia frigida. A Arborescent colony, BF, IMBB 1012,
• 300. B Lectotype specimen, girdle view, DIC, Grunow slide 1933d
W, Kara Sea, • 3000. C Girdle view, NIC, Cleve slide V:4-76,
Discovery Bay, Nares Exp., • 2000. D Girdle view,NIC, IMBB 1012,
• 2000. E Girdle view, PC, IMBB 1015/16 • 2000. F Valve view
showing collapsed proximal mantle, PC, culture isolated from IMBB
2453, Pro Mare Exp. • 2000. G Valve view, but proximal mantle is
not collapsed, as for F, x 2000. H Valve view, PC, as for F, • 2000. I
Valve view, NIC, as for F, • 2000. J Valve view showing wide
proximal mantle, TEM, as for F, x 3200. K Valve view with narrow
proximal mantle, which is not collapsed at the apices, TEM, IMBB
560, • 4000. L Valve view of two specimens showing various degrees
of mantle exposure, TEM, as for F, x 2000. M Detail of four bands
associated with the epivalve (e),SEM, IMBB 2706, ProMare, • 5600.
N Fracture of critical point dried cell, note position of raphe (r) and
bands (b) on the two valves (v), SEM, IMBB 1012, • 8000
Type Locality: Mys Vankarem.
Lectotype: BM 81563 made from dried material in the
Cleve collection from Mys Vankarem.
Material Examined: P.T. Cleve collection, dried material,
Mys Vankarem; Cleve and M611er slides 315-318 not on
314, BM Coll.; Ice core samples 1 and 2.
456
Fig. 2. Nitzschia neofrigida all figures type material from Prudhoe
Bay. A Arborescent colony, NIC, x 500. B Cleaned girdle view, PC,
x 1000. C Valves dislodged showing internal and external views,
SEM, x 2300. D Detail of central nodule of C, SEM, x 9400. E Detail
of apex of C, note row ofpuncta (arrow) along one side of raphe slit of
adjacent cell, SEM, x 13300. F External view of valve apex with
girdle bands, note ligulae of third band (l) and central position of the
raphe, SEM, x 6300. G Detail of bands at mid valve, epivalve (e) with
three bands to the left and hypovalve (h) with two bands to the right,
note equal width of valve face (shown by arrows), SEM, x 8200. H
Detail of valve apex and ribs (r) beside raphe, SEM, x 7700
457
Fig. 3. Nitzschia polaris. A Valve view, NIC, type material, Vega
Expedition, Mys Vankarem, x I000. B Girdle view, note thickened
valve edge, as for A, x 1000. C Girdle view, as for A, x 1000. D Girdle
view, as for A, x 1000. E External valve view, SEM, as for A, x 1950.
F Internal view of valve apex, note areolae curving around apex and
into outer canal raphe wall, SEM, Prudhoe Bay, x 4000. G Internal
valve view, SEM, as for A, x 1200. H Detail of central nodule, SEM,
as for A, • 4500. I External view of valve apex and bands, note
prominent keel (k), SEM; as for F, x 8600. J Internal view of apex,
SEM, as for F, x 4100. K Detail of bands, epivalve (e) and three
bands to the left, SEM, as for F, • 5000
458
eccentric (Fig. 3B-D). Positive determination of raphe
position can be established by rolling the cells in fluid
mounts (compare Fig. 3A with B and D).
The valve appears hyaline with light microscopy
(Fig. 3A-D), but with SEM short but regular punctate
striae can be found along both valve margins (Fig. 3F, H,
J). The face itself is non-perforate and the marginal striae
continue around the apices and into the outer raphe canal
wall (Fig. 3F, I). The valves of this species are so robust
that the thickened margin of the valve can easily be seen
with LM as can the concavity of the valve (Fig. 3A).
The raphe system is interrupted by a central nodule
with central raphe endings meeting coaxially. The raphe
fissure lies within a ridged groove of the keel (Fig. 3K). The
fibulae spanning the raphe system are robust, more or less
flush with the internal valve surface and unequally spaced
along its length (Fig. 3F).
The cingulum is composed of three (four?) bands
decreasing in width abvalvarly. Each band has a single
row of puncta adjacent to the pars interior of the band
(Fig. 31, K).
Cleaned valves lying on one face can easily be confused
with N. neofrigida; however N. polaris is more heavily
silicified with more robust fibulae than N. neofrigida. The
close morphological relationship between these two species can easily be seen when the two are compared in the
SEM with the main difference being the more regular
striae and the more convex and arched valve in N. polaris.
The first published description and illustration of N.
polaris is that of Cleve (1883). Although both Franz Josef
Land and Mys Vankarem are listed as sites where Cleve
(1883) and Grunow (1884) had found N. polaris, the
illustration of N. polaris in Cleve (1883) is from Mys
Vankarem. We have examined some of this material from
the Cleve collection in the SEM and it has formed the basis
of our description of N. polaris. The later Latin description
of N. polaris published by Grunow (1884) appears to be
based primarily on the material seen in Cleve and M611er
slide 314 from Franz Josef Land, although specimens from
Mys Vankarem are included in the published illustrations.
Grunow gives a striae measurement of 40 in 10 #m. From
our SEM observations and also from our examination of
Cleve and M611er slides 314-318, it appears that two taxa
are present. The specimens on Cleve and M611er slide 314,
which could be assigned to N. polaris, have resolvable
striae, while those in slides 315-318 do not. LangeBertalot and Krammer (1987) have also illustrated this
same discrepancy between N. polaris from these two
locations. Their fig. 7 and 7A (Plate 7) from Cleve and
M611er slide 314 clearly depicts a specimen with resolvable
striae, while a more robust and hyaline specimen is shown
in their fig. 4 on the same plate from Cleve and M611er
slide 315. Our SEM observations indicate that the striae in
Fig. 4. Nitzschiapromareall figuresfrom type material, IMBB 2706,
Pro Mare Exp. A Valve view, note waisted cell, PC, • 1000. B
Portion of long ribbon colony, note cell apices free, PC, x 500. C
Internal valve view, SEM, • 3500. D External valve view, SEM,
• 3500. E detail of internal valve apex and fibulae, note distal valve
mantle weakly developed, SEM, x 9300. F Detail of external valve
the specimens from Mys Vankarem are restricted to the
mantle edge and would therefore not be resolved in the
light microscope. Thus, it would appear that those specimens resembling N. polaris in Cleve and M611er slide 314
belong to a different taxon. As the Mys Vankarem material was described and illustrated first, it must take priority
over the later publication by Grunow in which the Latin
description and the designation of Cleve and M611er slide
314 as a reference slide appear (R. Ross and P. Sims,
personal communication). We have also considered the
possibility that specimens on slide 314 are of N. neofrigida
but cannot confirm this without SEM observations. Peragallo (1921) described N. polaris var. antarctica associated
with green algae from the Argentine Islands, but we cannot
tell, without EM observations, if this variety is related to
N. polaris. Undoubtedly it is a littoral rather than iceassociated form.
Nitzschia promare Medlin sp. nov.
Type Locality: 76~
34~
Barents Sea.
Type Slides: BM 81533 - Holotype rinsed preparation and
BM 81534 - Isotype cleaned preparation.
Material Examined: IMBB samples 2706, 2548.
Origin of Name: PRO MARE (Norwegian Research Program for Marine Arctic Research), to be used as an
indeclinable word.
Diagnosis: Cellulae lineares, in coloniis longis, laxe affixis
et ad instar taeniae, cellulae ad apices liberae. Valvae
lineari-lanceolatae, ad centrum constrictae, apicibus
paullo rostratis, 31-45 #m longae, 4-5.5/~m latae. Striae
punctatae, parallelae, 45-50 in 10 pro. Fibulae irregulares,
8-12 in 10 #m. Cingulum ex taeniis numerosis, omnibus
seriebus 1-2 pororum munitis, constans.
Cells occur in long ribbon colonies attached along the
mid-region of the frustule with the apices remaining free
(Fig. 4B). The cells appear to be loosely held in this type of
formation because the colonies can easily be disrupted by
rinsing.
The frustules are narrow and linear in girdle view.
Valves are linear-lanceolate, slightly waisted at the centre
and taper more sharply towards slightly rostrate apices
(Fig. 4A, C, D). The proximal mantle (that adjacent to the
raphe system) is well developed, while no clear distinction
between face and mantle occurs on the other side of the
valve (Fig. 4E, F).
The striae are composed of small poroid areolae
(puncta), which are closed at the external valve surface
(Fig. 4F). Externally, the interstriae are narrow but distinct
ridges. Internally the areolae have small rounded openings
with some vertical development of the interstriae separating them (Fig. 4E, G, H).
The eccentric raphe system lies at the junction of the
valve face and mantle where it is elevated into a distinct
surface near centre, note distinct proximal valve mantle, SEM,
• 12100. G Detail of internal valve surface at central nodule, SEM,
• 8700. H Detail of central nodule and proximal valve mantle, note
thin fibulae SEM, x 11300. I Rinsed colony, detail of bands (arrows
show bands with one or two rows of puncta), SEM, • 11300
M~
460
keel (Fig. 4D). The central nodule, interrupting the raphe
slit, is easily seen with LM (Fig. 4A) and the middle two
fibulae are quite widely spaced. The striae continue into
the outer raphe canal wall (Fig. 4H).
The cingulum is composed of several bands, each
perforated with one or two rows of puncta (Fig. 4I).
We suspect that the distribution of this species has
probably been included with reports of species of the
Fragilariopsis group, such as Nitzschia grunowii Hasle and
N. cylindrus (Grun.) Hasle as well as with chains of
Achnanthes taeniata Grun. As the chains are easily disrupted by rinsing, these would probably be missed in
permanent mounts of rinsed material. Cleaned valves are
easily confused with smaller cells of N. frigida but can be
distinguished from that taxon by its waisted centre,
slightly greater width near the cell apices, more numerous
fibulae, and rostrate apices.
Nitzschia arctica Cleve 1896, p. 21, pl. 1, figs. 21, 22.
Synonym: Nitzschia vitrea var. Cleve 1883, p. 316.
Type Locality: N. vitrea var. from Bessels Bay.
Neotype: BM 81532 Prudhoe Bay, Ice Core i.
Material Examined: Cleve and M611er slides 315 and 318
BM Coll., BM 23350 of Nitzschia tenuis, Lewes, England;
Ice core samples 1 and 2.
Cells occur solitary or in short ribbon chains of up to five
cells unattached at their apices (Fig. 5A-C). The frustules
are linear and broad in girdle view (Fig. 5B). The valves are
lanceolate and taper to small rostrate apices (Fig. 5A, D).
The striae, composed of small rounded poroid areolae
(puncta), are separated by interstriae that are slightly more
developed externally than internally (Fig. 5F, H, I).
The eccentric raphe (Fig. 5H) is interrupted by a
central nodule (Fig 5D-F). The number of fibulae in
10 #m is much smaller than that seen in the other species
discussed here (Fig. 5A). Towards the apices the last two
fibulae span the valve from margin to margin (Fig. 5G).
This arrangement causes the raphe canal to twist at the
apex. At this position the apex lies in girdle view while the
remainder of the valve lies in valve view (Fig. 5A, D). There
are no flanges external to the raphe to facilitate colony
formation and we presume that mucilage secreted from
adjacent valve faces must be involved in forming the short
ribbon colonies.
There are two to four open bands in the cingulum.
Each is perforated by a single row of puncta at the
advalvar edge of the band. Scattered puncta also occur
beneath this row on each band (Fig. 5G-I).
We were unable to locate any slides from Cape Eglinton in the Cleve collection (the site from which Cleve
(1896) described Nitzschia arctica) but specimens matching our taxon are present in the Cleve and M611er slides
Fig. 5. Nitzschiaarctica all figures lectotype material from Prudhoe
Bay. A Lectotype specimen, Valve view, note the small densely
located fibulae, PC, x 500. B Girdle view of recently divided cell,
NIC, x 500. C Ribbon colony of three cells, SEM, x 1100. D Girdle
view, cleaned frustules, NIC, • 1000. E Internal valve view, SEM,
• 2000. F Detail of central nodule, SEM, x 7300. G Detail of valve
apex and girdle bands of E, note last fibula spans both margins such
315 and 318 from Mys Vankarem, which is also listed by
Cleve as a site where N. arctica can be found. The only
other taxon that might be confused with this species is
Nitzschia linearis var. tenuis, which Cleve (1896) cites as
also being present in his material from the Davis Strait as
well as being present in material from Greenland, Mys
Vankarem, and outside polar seas.
Nitzschia tenuis was considered to be a variety of N.
linearis by Grunow in Cleve and Grunow (1880). However,
Kobayashi and Kobori (1988) have convincingly shown
that these two taxa are distinct and should be kept as
separate entities. One of us (LKM) has examined the type
slide of N. tenuis Wm. Smith from Lewes, England and has
found that our specimens from sea-ice samples bear only a
superficial resemblance to that taxon. Nitzschia tenuis, a
later synonym of N. tergestina Kiitz. according to VanLandingham (1973), is linear for most of its length and
then just before the end of the cell, the valve tapers to small
rostrate apices. This abrupt tapering can be seen in
fig. 222 of the type material illustrated by Lange-Bertalot
and Simonsen (1978). Our specimens are lanceolate
throughout. They are wider and have fewer striae (25-26)
and fibulae (8-10) in 10 #m than N. tenuis and must be
regarded as N. arctica.
Jorgensen (1905) has reported this species as a frequent
member of the coastal plankton or northern Norwegian
fjords. He includes five figures of N. arctica, the first three
of which seem to fit well with the specimens we have,
although he was unable to see the striae on any of his
specimens. His figs. 15e, f are of a more sigmoid form and
he considered the possibility that these two figures were
straighter forms of N. laevissima. They may instead be very
large specimens of N. hybrida.
Nitzschia arctica might also be confused with N.
hudsonii Poulin and Cardinal but that species is narrower
and has finely punctate striae visible with LM.
Nitzschia promare and N. arctica both form loose
ribbon colonies, apparently attached by the juxtaposition
of sister valves. What role the eccentric raphe may play in
colony formation is not known. Specimens closely resembling N. arctica also form arborescent colonies (unpublished observation). We must be certain that two
different taxa are not involved before we can safely report
two different types of colony formation for the same
species. Long, thin, aciculate cells forming arborescent
colonies in samples from the Barents and Kara Sea were
described by Meunier (1910) as Nitzschia divaricata, but
we have not, as yet, examined this material.
Nitzschia laevissima Grunow in Cleve and M611er 1882,
p. 4; Grunow 1884, p. 106, pl. 1, figs. 65, 66.
Type Localities: Franz Josef Land, Mys Vankarem.
Leetotype: BM 81563 made from the dried material in the
that the apex twists on itself, SEM, x 12000. H Detail of external
valve surface, girdle view, raphe (r) to the left on the epivalve(e) with
two bands, raphe (r) to the right on the hypovalve (h), note unequal
width of proximal and distal mantles, SEM, x 4500. I Detail of bands
at valve apex, note perforation pattern of raphe canal (arrow),SEM,
• 7400
461
462
Fig. 6. Nitzschia laevissima. A Fragment of valve, lectotype material,
NIC, Mys Vankarem, • 1000. B Valve view, note isolated areolae,
PC, IMBB 1615, • 1000. C Girdle view, note cell swollen in middle
but not sigmoid, PC, IMBB 1615, • 850. D Valve view, note distinct
striae, PC, IMBB 1615, x 2000. E Fragment of valve, PC, Franz Josef
Land, Cleve and M611er Slide 312, • 1000. F Detail of valve with
perforate striae, TEM, IMBB 1615, •
G Detail of central
nodule, note occasionally perforated striae on valve face and wide
mantle, TEM, IMBB 1615, • 3800. H Detail of valve with non-
perforated striae, TEM, IMBB 1615, x 4000. I Detail of valve at
central nodule, external view, note proximal mantle below the
eccentric raphe, SEM, IMBB 1615, • 10800. J Detail of internal view
of central nodule, SEM, IMBB 1615, • 9100. K Detail of one apex of
specimen shown in I, note central position of raphe and curved
terminal fissures, epivalve with 2 bands, SEM, IMBB 1615, x 10800.
L Detail of inteinal valve apex showing slightly curved helictoglossa
and central position of raphe, SEM, IMBB 1615, • 7200
463
Cleve collection from Mys Vankarem.
Material Examined: Cleve and M611er slide 314 BM Coll.;
P.T. Cleve collection, dried material, Mys Vankarem;
IMBB samples 1615 and 2706.
Frustules are sigmoid in valve but not girdle view
(Fig. 6A-C) and occur as single cells. A displacement of
the raphe system from an eccentric position near the
middle of the frustule to an almost central position at the
apices is related to the curvature of the valve (Fig. 6J, K).
The valves are sigmoid-lanceolate with slender drawn
out rostrate apices (Fig. 6A, B, D, E). The proximal mantle
decreases in depth from its widest point near the central
nodule (Fig. 6I) to the apices (Fig. 6L). The striae are
composed of poroid areolae (puncta); however some striae
may be incompletely perforated, i.e. composed only of
isolated puncta (Fig. 6B, E, G). The variability in perforation can change the appearance of the valve when seen
with LM from completely hyaline (Fig. 6A) to isolated
puncta (Fig. 6B) to complete striae (Fig. 6D). Those specimens on the Cleve and M611er slide 314 possess only
isolated puncta randomly scattered over the valve face
(Fig. 6E).
The raphe lies atop a prominent keel. A conopeum or
canopy is not present (Fig. 6I). A central nodule, interrupting the raphe slit is easily seen with light microscopy
(Fig. 6A-E), but the central raphe endings terminate
coaxially, without any deflection to the ventral margin of
the valve. The terminal fissures are slightly curved around
the valve apex (Fig. 6K). Internally the helictoglossa is also
slightly deflected (Fig. 6L). The outer canal raphe wall is
perforated by a row of puncta on either side of the raphe
slit (Fig. 6 F - H , J). These puncta, which can be continuous
with the completely perforated valve striae, lie close to a
junction line where the fibulae join the valve. The fibulae
vary in thickness (Fig. 6F) and also in their spacing along
the raphe system (Fig. 6H). Towards the apices, they span
both valve margins (Fig. 6L).
The cingulum contains four open bands, each perforated with a single row of puncta lying along the advalvar
margin of the band. Occasionally a few puncta beneath
this row are present (Fig. 6K).
Nitzschia brebissonii vat. borealis Grunow in Cleve and
M611er 1882, p. 4; Cleve 1896, p. 21, pl. 1, figs. 28-32.
Type Locality: Mys Vankarem.
Lectotype: BM 81564 made from dried material in the
Cleve collection from Mys Vankarem.
Material Examined: P.T. Cleve collection, dried material,
Mys Vankarem; Cleve and M611er slides 315-318 BM
Coll.; Ice core samples 1 and 2.
These ceils, which do not form colonies, are linear in girdle
view with slightly flared tips (Fig. 7C, E, F). The lanceolate
valves are somewhat waisted at the middle, with drawnout rostrate apices (Fig. 7A, B, D, G).
The external valve surface slightly curves up to the
raphe, which is distinctly raised onto a prominent keel
(Fig. 7H, J). It is the prominence of the keel and the
narrowing of the valve that causes the flaring of the tips
seen in cells lying in girdle view (Fig. 7B, F). The interstriae
are very strongly developed externally above the rows of
poroid areolae (puncta) and curve slightly downwards to
form a shallow mantle (Fig. 7H, J). Internally the interstriae are more or less flush with the striae (Fig. 7G, H).
The raphe, centrally located on the valve, is uninterrupted by a central nodule (Fig. 7B) and ends in a
simple helictoglossa (Fig. 7G). A rib accompanies the
raphe along its length (Fig. 7J). The outer raphe canal wall
does not seem to be perforated. Fibulae are unevenly
spaced along the length of the raphe system. At each apex
the last fibula spans both valve margins, leaving a distinct
circular interspace (Fig. 7G).
The cingulum is composed of three open bands, each
with a different structure (Fig. 71). The valvocopula has
two rows of puncta separated by a non-perforate space.
The second band is slightly wider but with additional
scattered puncta beneath the second abvalvar row. The
third and narrowest band is completely different with
puncta closely packed into vertical rows.
Nitzschia brebissonii var. borealis, when lying on one
face, might be confused with N. taeniiformis Simonsen
(found in the Antarctic) but can be distinguished from that
species by the absence of a central nodule and the lack of
colony formation. It is more likely that N. brebissonii var.
borealis will be confused with N. scabra Cleve and varieties
of N. distans Greg., which also have a raphe without a
central nodule. The tips of cells of these species are also
flared in girdle view. Varieties of N. distans sometimes
form small ribbon colonies but in raw and cleaned material can be distinguished from N. brebissonii vat. borealis by
the hyaline appearance of the valves. Nitzschia scabra has
a mottled appearance to the valve surface due to incompletely perforated striae and also has a sub-eccentric raphe
system. The absence of a central nodule will distinguish
N. brebissonii var. borealis from N. arctica.
Nitzschia scabra Cleve 1883, p. 480, pl. 38, fig. 73a, b as
N. (Sigma var.?) scabra.
Type Locality: Mys Vankarem.
Neotype: BM 81561 prudhoe Bay Alaska, Ice Core 1.
Material Examined: Ice core samples t and 2; Cleve and
M611er slide 316, BM Coll; IMBB 2675.
These solitary cells are sigmoid in girdle view with slightly
flared tips (Fig. 8A, D), Valves are linear-lanceolate
(Fig. 8B-D), tapering to rostrate apices (Fig. 8E, G). The
rounded valve face curves up towards the keeled raphe.
Just before the raphe, the face folds downward to the cell's
interior and then back onto itself to form a longitudinal
channel with an overlying conopeum (canopy) (Fig. 8E, F),
which is free along its entire length. Thus, this channel,
which is formed along each side of the raphe, is "open" and
can be visualised as a shadow area along the raphe with
LM as it protrudes into the cell interior (Fig. 8B, D). The
channel is quite large at the valve apex and with the
prominent keel help to form the flared ends of the cells
(Fig. 8A, D, I). The striae are composed of small poroid
areolae (puncta) (Fig. 8G, H). The closing membranes (?
hymenes Mann 1981) lie close to the external valve surface
(Fig. 8F), and internally the areolae are rounded (Fig. 8G,
H). Some of the internal openings may be covered with
extra silica (Fig. 8H) and this accounts for the mottled
4~
O',
465
appearance of the valve when seen with LM (Fig. 8D) and
hence the name N. scabra. The internal openings of the
areolae beneath the conopeum (Fig. 8H) may also be more
regularly covered by silica. Mann (1986) has previously
noted that the change in valve structure at this position
also contributed to the longitudinal line seen on both sides
of the raphe with LM.
The sub-central raphe is uninterrupted along its entire
length. A row of horizontally elongated slits perforates the
outer canal wall above the point where the valve face joins
the raphe before turning outwards to form the conopeum
(Fig. 8F, H). Internally the raphe system is subtended by
small thin fibulae irregularly spaced along the raphe
length. The bases of the fibulae extend into the face
(Fig. 8G, H). At the valve apex, a tear-drop shaped interspace is formed by the juxtaposition of the valve mantles
and the last fibula (Fig. 8G).
The cingulum is composed of at least four bands
(Fig. 8I). The first two are wide with a single row ofpuncta
lying closest to the advalvar margin, followed by a nonperforated space and then three or four regular rows of
puncta and scattered puncta beneath these rows. The third
band is narrow with one (two) row(s) of puncta on the
advalvar margin again followed by the non-perforated
space and one (two) row(s) of smaller puncta. The fourth
band, also narrow, lacks the first row of puncta and the
non-perforated space is on the advalvar margin. Beneath
this, the other row of puncta is formed. The hypovalve on
Fig. 8I bears only the first band.
We presume that this species was identified in the
Prudhoe Bay samples as either (or both) Nitzschia sigma
W. Smith or N. sigmoidea W. Smith by Horner and
Schrader (1982). Both of these taxa are sigmoid in girdle
view with an eccentric raphe but can be separated from
N. scabra by coarser striae but finer fibulae in 10/~m.
N. sigma is sigmoid in valve view and lacks a conopeum
(Mann 1978).
G). The parallel striae are slightly radiate opposite the
central nodule (Fig. 9H). Within each stria the areolae
become occasionally biseriate along the dorsal margin
(Fig. 9F). Mann (1977) found that in the specimens of
H. weyprechtii he examined the striae were regularly biseriate. The interstriae are more strongly developed externally and the striae are recessed from the external valve
surface (Fig. 9H). The ventral valve margin is also more
strongly silicified (Fig. 9H, I). The striae along this margin
are "trough-like" when viewed externally and are composed of 1-4 puncta (Fig. 9E, H).
The raphe system lies atop a low keel. The outer canal
wall is perforated on the dorsal side of the raphe by a single
row of large puncta and on the ventral side by two rows of
small puncta (Fig. 9E). The raphe slit is interrupted by a
distinct central nodule. The central endings meet coaxially
internally (Fig. 9E, J) but are deflected dorsally on the
external surface of the central nodule (Fig. 9H). At the
poles, the hook-shaped terminal fissures curve towards the
ventral margin (Fig. 9G, I). The fibulae are irregularly
spaced with two to five striae corresponding to the interspace between the fibulae (Fig. 9E). Each fibula is narrow
and attached at its base to a silica rib on the valve face. At
each apex, the last fibula spans the valve.
Cleaned valves might easily be mistaken for a Nitzschia species because H. weyprechtii does not exhibit the
strong dorsi-ventrality of other Hantzschia species. Nitzschia hyperborea Grun. resembles H. weyprechtii in valve
outline but lacks a central nodule and presumably possesses nitzschioid symmetry. The illustration of H. weyprechtii in Schmidt's Atlas (1922, pl. 345 Figs. 1-3) is of a
taxon without a central nodule. Its closest relative, Hantzschia petitiana Grun., has coarser striae.
Hantzschia weyprechtii Grunow in Cleve and Grunow
1880, p. 104; Grunow 1884, p. 107, pl. 1, fig. 60a, b.
Type Locality: Franz Josef Land.
Neotype: BM 81562 from IMBB 1615.
Material Examined: Cleve and M611er slide 314, BM Coll.;
IMBB samples 568, 1615, 2706; Cleve and M611er slide 292
of Hantzschia petitiana, Firth of Tay, Scotland, BM Coll.
Nitzschia stellata Manguin 1957, p. 132, pl. 7, fig. 47a-e;
Manguin 1960, p. 335, pl. 19, figs. 234-236, pl. 31,
figs. 379-380
Type Locality: Cap Margerie, Terre Ad61ie.
Lectotype: Manguin slide 1.
Material Examined: Manguin slide l, Terre Ad61ie,
Antarctica; Heiden slides BRM 283/83,283/90, 283/92 and
284/1, all from Kaiser Wilhelm II Land, Antarctica; Quad
1; Ant III/13, Cores 6c and 7; Site L; IMBB samples 2589,
2590, 2596 and 2707.
These solitary cells have linear frustules without the
obvious dorsi-ventrality seen in other Hantzsctu2a spp.
Valves are lanceolate with a curved dorsal margin and a
straight ventral margin slightly indented at the central
nodule (Fig. 9A-C). The valve ends are drawn out, slightly
capitate and turned towards the dorsal margin (Fig. 9D,
Fig. 7, Nitzschia brebissonii var. borealis. A Valve view, focus on
apices, NIC, lectotype material, Mys Vankarem, x 1000. B Same
specimen as A, focus on valve centre, NIC, x 1000. C Girdle view,
rinsed preparation, note flared tips of frustute, NIC, Prudhoe Bay,
x 1000. D Internal valve view, SEM, as for C, x 1000. E External
view of valve with bands, SEM, as for C, • 1200. FGirdle view,detail
of valve apex, NIC, as for C, • 1000. G Detail of internal valve apex,
Observations from Antarctic Material
Manguin (1957, 1960) first described this species forming
arborescent colonies from sediment collections and plankton tows taken along, the coast of Terre Ad61ie and
note final interspace formed by the last fibula spanning both valve
margins, SEM, as for C, x 5500. H Internal valve view near centre,
note arched valve face, SEM, as for C, x 4400. I Detail of bands from
bottom to top: valvocopulae (v) plus 2 bands from epivalve followed
by valvocopulae (v) of hypovalve, SEM, as for C, x 6300. J External
valve view near centre, note prominent keel and rib (r), SEM, as for
C, x 6300
466
Fig. 8. Nitzschia scabra all figures lectotype material from Prudhoe
Bay. A Sigmoid girdle view, NIC, x 400. B Lectotype specimen,
Valve view with slightly eccentric raphe, PC, x 600. C Valve view,
SEM, x 600. D Detail of broken valve showing eccentric raphe and
mottled appearance of striae, PC, x 1000. E Detail of external valve
apex showing conopeum (c) extending from both sides of raphe,
SEM, x4500. F Detail of external surface fractured near valve
centre, note enfolding of valve on both sides of raphe to form
channel, SEM, x 3700. G Detail of internal valve apex showing
irregular spaced fibulae and large tear-drop shaped interspace
beyond the last fibula, SEM, x 4500. H Detail of internal surface
fractured near valve centre, note fibulae spanning enfolded regions
adjacent to raphe and the irregularly perforated striae, SEM, x 5600.
I Detail of epivalve (e) with four bands and hypovalve (h) with only
the valvocopulae (v), note channel opening beneath conopeum,
SEM, x 2600
467
Fig. 9, Hantzschia weyprechtii. A Valve view, NIC, IMBB 1615,
x 2000. B Valve view, PC, IMBB 1615, x 2000. C Whole frustule,
rinsed, PC, IMBB 2706, × 600. D Valve view from central nodule to
apex, TEM, IMBB 1615, x 3400. E Detail of central nodule, note
partially occluded striae, TEM, IMBB 1615, × 6700. F Detail of
distal valve margin, TEM, IMBB 1615. x 20000. G Detail of valve
apex and terminal fissure, TEM, IMBB 1615, x 25000. H Detail of
external valve view showing central nodule and ventral valve margin,
note deflection of central raphe endings to dorsal margin, SEM,
IMBB 1615, x 8800. I Detail of external view of valve apex and
ventral valve margin, note deflection of terminal fissure to ventral
margin, SEM, IMBB 1615, x 8800. J Detail of central nodule, SEM,
IMBB 1615, × 8700
468
Nitzschia taeniiformis Simonsen 1987, p. 452, pl. 673,
figs. 1-6.
Synonym: Nitzschia taenia Hustedt 1958, p. 180, Fig. 195
non Nitzschia taenia W. Smith 1853.
Type Locality: 69~
06~
Lectotype: BRM W5/23 and Isolectotype BRM 276/100b
(Simonsen 1987, p. 452).
Material Examined: Hustedt Collection type slide BRM
276/100b; Heiden slides BRM 283/90, 283/91,283/92 and
284/1; Quad 1, 1-7; IMBB samples 58(10), 1592 and 2486.
This species was first described by Hustedt (1958) from
single valves seen in the stomach contents of salps near
Ad61ie Land and along the coast of Queen Maud Land
(04~
and 06~
Antarctica. It has been recently
renamed by Simonsen (1987) because the specific epithet
was already occupied.
Cells occur in short chains of up to ten cells formed by
the interlocking of the keels of the cells along most of their
length except at the apices (Fig. 11 A, B). A similar type of
ribbon colony formation has been reported for Nitzschia
hybrida Grun. found attached to the ice in the Karajakt]ord (Gran 1897). We also have reported N. pellucida
Grun. from ice cores in the Arctic forming similar colonies
(Medlin in Medlin and Priddle, in press).
The valves are strongly convex and tend to lie on one
face, i.e., in girdle view (Fig. l lC, D). Hustedt (1958)
described the valve shape not unlike a "bracket". The valve
faces on either side of the central raphe system are in close
proximity to each other and are spanned by robust fibulae.
Once the two faces have been braced by the fibulae, they
flare away from each other at about a 45 ~ angle (Fig. 11E,
F).
The punctate striae extend across the face stopping at
the keel where there is a groove on one side of the raphe slit
and on the other side a rib and flange (Fig. l l E - H ) . The
outer canal wall is perforated by a single row of puncta on
either side of the raphe slit. The striae do not extend
exactly to the valve margin and this non-perforated area
has been called the marginal strip by Mann (1978).
The raphe slit runs atop a prominent keel and is
interrupted by a central nodule (Fig. llC, D, I). The
frustule is slightly depressed here. The terminal fissures
curve towards the grooved side of the raphe (Fig. 11F).
Internally a small helictoglossa can be seen (Fig. 11E).
Colony formation is accomplished by the interlocking of
the flanges of adjacent cells. Note that both "left-hand"
central nodules are in focus in this short chain of N.
taeniiformis (Fig. 11B).
The few intact cells encountered in the samples possess
numerous bands. A wide non-perforated space separates
the two rows of regularly spaced puncta (Fig. 11H).
N. taeniiformis was present on several slides in the
Heiden collection from the Gauss Antarctic Expedition.
We think that N. taeniiformis was identified as N. laevissima by Heiden in Heiden and Kolbe (1928), but as this
species is not illustrated, we cannot be sure of the identification. However, N. taeniiformis is quite abundant on
several of these slides (e.g., 284/1) and it seems doubtful
that Heiden would not have identified it. The only species
cited in Heiden and Kolbe that could be mistaken for
N. taeniiformis is N. laevissima and this species is listed as
being present on all of the slides that we examined which
contained N. taeniiformis. Some of the specimens on these
slides are slightly long and twisted and this is probably
Fig. 10. Nitzschia stellata. A Arborescent colony, BF, Cape Armitage, x 300. B Valve view, type slide, PC, Terre Ad61ie x 1000. C
Valve view, striation just visible, NIC, lectotype material, Manguin
slide 1, x 2000. D VaNe view,NIC, Cape Armitage, x 2000. E Detail
of valve apex, TEM, Cape Armitage, x 7500. F Detail of central
nodule, note irregular striation, TEM, Cape Armitage, x 10,000. G
Detail of 9 bands, each with rows of puncta decreasing abvalvarly,
TEM, Cape Armitage, x 10,000
seaward from the ice edge. Specimens from Manguin slide
1 are illustrated in Fig. 10B, C. Specimens forming the
same arborescent colonies were dominant in ice cores from
Cape Armitage (Fig. 10A, D) and beneath 60 cm thick ice
at the Japanese Syowa Station.
The frustulcs are narrowly linear in girdle view and are
attached at their poles to adjacent cells. The lanceolate
valves appear almost hyaline with light microscopy but
faint striae can be resolved using Nomarski interference
contrast optics (Fig. 10D). Each stria is composed of
poroid areolae (puncta) arranged in irregular undulate
rows (Fig. 10E, F). Often there are homogeneously silicifled areas within each stria, especially near the central
nodule. The outer wall of the raphe canal is perforated but
usually only on the side adjacent to the valve face. The
proximal mantle (that closest to the raphe) is also perforated but these puncta appear smaller than those on the
face itself (Fig. 10F).
The eccentric raphe system lies primarily in the mantle
and is interrupted by a central nodule (Fig. 10B-D). The
two central fibulae are very widely spaced (3-4/~m) and
the remaining fibulae are irregularly spaced. The central
raphe endings meet coaxially and are not deflected onto
the valve face. The polar endings terminate into small
helictoglossae internally and form a slightly curved terminal fissure externally.
The cingulum has nine or more bands (Fig. 10 G). The
valvocopula is perforated by three rows of puncta: the first
being separated from the remaining two by a non-perforated space. The number of rows of puncta per band
decreases abvalvarly.
Although Nitzschiafrigida and N. stellata form arborescent colonies, the shape of their respective valves is
different and this feature can be used to differentiate
between the two. Upon closer examination the structure of
the valve and the arrangement of decreasing number of
rows of pores on the girdle bands are identical and these
two taxa must be closely related, despite being geographically separated. Therefore, reports of N.frigida from
the Antarctic by Heiden and Kolbe (1928) from the Gauss
Expedition material, by Everitt and Thomas (1986), and
by McConville and Wetherbee (1983) are misidentifications of N. stellata.
469
470
471
what has prompted the identification of this taxon as
N. laevissima. We have found a few specimens slightly
resembling N. taeniiformis from IMBB sample 1014 from
Newfoundland, but without SEM obsei'vations we are
unable to exactly determine the raphe position. These cells
are slightly wider than N. taeniiformis and may be very
large cells of N. hybrida.
Nitzschia neglecta Hustedt 1958, p. 175, pl. 13, figs.
162-164.
Synonym: N. angularis vat. tenuistriata Van Heurck 1909,
p. 19, pl. 3, figs. 60, 61; Nitzschia spec? Van Heurck 1909,
pl. 3, fig. 58.
Non Nitzschia dippelii Grun. sensu Krammer and LangeBertalot (1988, p. 66, pl. 52, Figs. 3-5, pl. 53, Fig. 1-6, 8).
Type Locality: 69~
06~
Holotype: BRM 276/99b.
Material Examined: BRM Hustedt Collection type slide
276/99b; BRM Heiden slide 283/96; Ant II/4, core 5; Ant
III/3, core 6c and 7, IMBB 2596.
This species was originally described as Nitzschia angularis var. tenuistriata by Van Heurck (1909) from ice. His
fig. 60 and 61 depict this cell in valve view and fig. 58 is
the girdle view of the same species, although van Heurck
lists it as Nitzschia spec?. Hustedt (1958) found it in the
stomach contents of salps and gave it the name neglecta
because the specific epithet tenuistriata was already occupied and because the presence of a central nodule precluded it from remaining a variety of N. angularis.
Cells do not form colonies. The frustule is broadly
rectangular in girdle view and slightly pinched in at the
central nodule (Fig. 12A, C, D, G). The valves are asymmetrically placed in the frustule. The valve faces either side
of the raphe are not the same width (Fig. 12F). The valves
are arranged so that on one girdle side the wide side of one
valve is placed with the narrower side on the opposing
valve so that the frustule is symmetrical (Fig. 12D).
The valves are linear-lanceolate to lanceolate with
small rostrate apices (Fig. 12B, F). The mantle is deepest at
the apex so that when the valves lie in girdle view, the apex
is rectangular (Fig. 12C). The valve is sharply angled up
towards a prominent central keel which bears the raphe
(Fig. 12G, I, J). No conopeum is formed.
The striae, composed of poroid areolae (puncta), are
parallel and can be randomly occluded particularly
around the central nodule (Fig. 12J). They continue into
the outer canal wall, while a narrow marginal strip is left
unperforated around the mantle edge (Fig. 12G, I).
The raphe runs along a prominent keel formed by the
angled up sides of the valve. The two sides of the external
fissure of the raphe are unequal in height and one side
Fig. 11. Nitzschia taeniiformis. A Four-celled ribbon colony, apices
free, PC, Cape Armitage, x 1000. B Three-celled colony, note central
nodule of both cells are in focus, NIC, Cape Armitage, x 1000. C
Girdle view, valve folded along raphe, NIC, IMBB 1592, • 1000. D
Girdle view, NIC, IMBB 1592, • 1000. E Detail of valve apex,
internal view, note valve flange (f) and the helictoglossa (h) just
barely visible because of the convexity of the valve SEM, Cape
protrudes above the other to form a narrow flange
(Fig. 12G, H). The terminal fissures continue down over
the valve apex and curve slight to one and the same side of
the valve at each apex (Fig. 12E). A small helictoglossa is
formed internally just beyond the valve apex in the mantle.
The raphe system is interrupted by a central nodule and
the distance between the two fibulae on either side of the
central nodule is quite distinct (Fig. 12J). The valve is
depressed at the central nodule towards the widest valve
face. Thus the central nodule is depressed in opposite
directions on opposing valves.
The raphe system is spanned internally by wide, irregularly spaced fibulae, which lie more or less flush with the
valve surface but attached to a narrow strip of silica
running along both sides of the raphe (Fig. 12J). This strip
of silica can be seen with LM, a feature noted earlier by
Hustedt (1958). This arrangement of the fibulae enables
the keel to protrude above the valve surface. The last fibula
before the apex is quite broad (Fig. 12I).
The cingulum is composed of at least six punctate
bands (Fig. 12H). The valvocopula has two rows of puncta
next to the pars interior followed by a non-perforated
strip, then three to four additional horizontal rows of
puncta aligned into equally spaced vertical rows. At the
apex the first two rows end and the vertical rows become
randomly orientated to perforate the ligulae of the band.
Internally the vertical arrangement of these rows is more
distinct because the non-perforated strip separating not
only the vertical rows but also the two major areas of
horizontal rows is strongly silicified.
Each subsequent band has more or less the same
construction but the number of rows in each band decreases abvalvarly. The last band has only one row of
puncta separated by a non-perforated space and beneath
it, the puncta are randomly arranged.
This species is quite distinct and would be difficult to
confuse with other species especially if seen in girdle view.
The species identified as N. polaris by Krebs (1983) from
Antarctic waters is of a lanceolate cell and is N. neglecta.
Krammer and Lange-Bertalot (1988) have put N.
neglecta in synonymy with Nitzschia dippelii. However this
cannot be upheld because N. neglecta has a central raphe
subtended by broad, but thin fibulae attached to a strip of
silica along side of the raphe, while N. dippelii has a slightly
eccentric raphe subtended by narrow, but thick fibulae
attached directly to the valve surface. N. dippelii occurs in
inland saline ponds.
Nitzschia lecointei Van Heurck, 1909, p. 21, pl. 3, fig. 57.
Type Locality: 65~
64~
Material Examined: IMBB 2596.
Armitage, x 10,000. F Detail of valve apex, external view, note
groove (g) beside raphe, SEM, Signy Island, x 7800. G Detail of valve
fracture at the raphe, internal view, note flange (f) and groove (g)
beside external raphe slit (s), SEM, Cape Armitage, x 30,000. H
Detail at valve apex, epivalve (e) at top with 4 bands, SEM, Cape
Armitage, x 6600. I Detail of central nodule, internal view, SEM,
Signy Island, x 10,000
472
473
The morphology and ecology of this species has been
discussed in detail by Hasle (1964) and we have included
here only additional information on valve variation and
girdle band construction.
This species has been reported forming gelatinous
tubes underneath the sea ice by Watanabe (1988) but we
have not seen such tubes in this sample from Signy Island
nor did Hasle (1964) see this in any of the Brategg samples
she examined from the Southern Ocean.
Hasle (1964) has illustrated the change in valve shape
throughout the size range of this taxon. Despite its delicate
appearance with LM, the valve margins and the area
around the central nodule are always distinct (Fig. 13A, B,
E). With TEM these features appear to be areas of heavier
silicification (Fig. 13B, E). A heavy deposit of silica also
appears along side of the raphe beneath the fibulae
(Fig. 13B, E). The exact nature of these areas and their
variation can be seen with SEM.
In those cells that are heavily silicified (e.g. Fig. 13D, F,
H, J), the following characters are well developed. A ridge
of silica occurs along the valve margin opposite the raphe,
which makes this side of the valve appear distinct with
LM. If this ridge is formed, then the distal mantle will also
be well demarcated from the valve face (Fig. 13H). If not,
then the valve face will tend to slope gently into the distal
mantle (Fig. 13I). In heavily silicified valves, the central
nodule is quite prominent and protrudes above the valve
surface (Fig. 13H). The distal side of the central nodule is
perforated by two-three enlarged pores. The central raphe
endings are very closely spaced (Fig. 13H, I). A siliceous rib
also runs along side the raphe for its entire length
(Fig. 13B, E) and can be easily seen externally in heavily
silicified valves (Fig. 13F) but not in those more weakly
silicified (Fig. 13G). In heavily silicified valves, the poroid
areolae have smaller openings and are occasionally randomly occluded (Fig. 13H). In both types of valves, the
row of puncta perforating the outer canal wall appears
slightly larger than those in the corresponding stria and
also slightly displaced from that stria. Each punctum is
closed near the external valve surface (Fig. 13J) with a rica
of randomly scattered pores (Fig. 13E).
The cingulum is composed of three bands, each containing one or two rows of puncta separated by nonperforated space (Fig. 13J).
Auricula compacta (Hust.) Medlin comb. nov.
Basionym: Nitzschia compacta Hustedt 1958, p. 169
fig. 160; Simonsen 1987, p. 450, pl. 670, fig. 1.
Type Locality: 69~
06~
Holotype: BRM 276/100b.
Fig. 12. Nitzschia neolecta all figures from IMBB 2596. A Girdle
view, complete frustule, note valve depressed at central nodule, NM,
x 1000. B Valve view,note dark line on either side of the fibulae,PC,
x 2000. C Girdle, note rectangular valve apex, PC, x 2000. D
Complete frustule, note wide valve face (w) of one valvepaired with a
shallow face(s) of the opposite valve, SEM, • 1600. E Detail of valve
apex showing raised keel and terminal fissure of raphe, SEM,
x 13,800. F Valve view showing central raphe with valve faces of 2
Material Examined: BRM Hustedt Collection type slide
276/100b; Heiden slides 283/90, 283/92 and 284/1; Quad, 1,
1 7; IMBB samples 2589, 2596 and 2707.
This species was originally described as a member of the
genus Nitzschia by Hustedt who saw only single valves in
the stomach contents of salps. Certainly single valves
would be easily confused with Nitzschia because the cell
symmetry which places this species in Auricula is destroyed with acid cleaning.
The frustule is asymmetrical with an elongated elliptic
outline. Cells are depressed at the central nodule (Fig. 14F)
in the narrow girdle view, while the broad girdle view is
more elliptic (Fig. 14G). Valves may be presented in
various aspects. Beginning at each apex the raphe branches traverse the valve face to meet at the central nodule
on one valve margin (Fig. 14A-D). The raphe system
essentially divides the valve into a broad (distal see
Fig. 14E) and narrow (proximal) face (Fig. 14A). Isolated
valves usually lie with the distal valve face uppermost and
the proximal valve face hidden from view by being folded
beneath the raphe (Fig. 14E).
The valve is highly vaulted with the raphe system lying
atop the highest point (Fig. 14H, I). Here the fibulae brace
the two valve faces to form the canal raphe (Fig. 14K). The
external central raphe endings are deflected towards the
broad valve face (Fig. 14J).
The striae, parallel in the valve midregion, become
radiate towards the apices and are composed of a double
row of small, regular poroid areolae (puncta) (Fig. 14L).
This perforation pattern continues into the outer canal
wall, but the perforation here is isolated from the valve
striae by a rib of silica, which runs along both sides of the
canal raphe and provides the attachment for the fibulae
(Fig. 14K). The interstriae are more strongly silicified
internally than externally.
The cingulum is composed of several open bands, each
with one row of puncta. There may be fewer or perhaps
narrower bands in the narrow girdle view than in the
broad girdle view (unpublished observation).
This species occurs as single cells and was also present
on the slides we examined from the Heiden Collection. We
compared the distribution of each Nitzschia with the slides
we examined and came to the conclusion that this species
was probably misidentified as N. hybrida Grun. Again this
species was not illustrated by Heiden and Kolbe (1928)
and we cannot be sure how they identified it. Auricula
compacta could possibly be misidentified as N. hybrida if it
were seen in the narrow girdle view.
widths, TEM, x 1300. G External valvesurfacea central nodule, note
raised perforated keel (k) and raphe flange (f), SEM, • 6000. H
Epivalve (e) with 5 bands, note differentmorphology of external and
internal surface of the valvocopulae(v), SEM, x 1200.I Internal view
of valve apex, note small areolae and fibulae nearly flush with valve
surface, SEM, • 7200. J Internal view of central nodule, note
perforations of canal wall and central raphe endings, SEM, x 7200
474
475
Discussion
Species Distribution
One of the most common approaches to identifying
species from new areas or habitats is to use existing
literature from other, often comparable habitats. This has
been a distinct problem in examining diatoms from both
polar regions because most of the early descriptive works
were done from Arctic material and these were then later
used for identifying Antarctic material. Taxa have often
been given the same name as their seemingly morphological Arctic counterpart. If the taxon in question is cosmopolitan, then it may well range into both polar regions.
However, truly bipolar species are rare indeed and it is
more likely that a new, closely related taxon is involved.
This new taxon is simply described as a new variety of a
previously described species, in this instance an Arctic
taxon, e.g.N, polaris var. antarctica Per. In either case,
careful examination of material from early polar expeditions as well as that more recently taken is necessary
to ensure that exact species comparisons are made and the
addition of superfluous taxa is not made.
If a taxon exhibits a particular shape or distinctive
colony formation, it has often been assumed that this
feature can be used almost exclusively to identify that
taxon. Because of this assumption, rarer forms are often
included in the distribution of more cosmopolitan taxa,
e.g., Lithodesmium intricatum (West) H. & M.Per. with
Lithodesmium undulatum Ehrenb. (Von Stosch 1980), and
Rhizosolenia phuketensis Sund. with Rhizosolenia stolterfothii H. Per. (Sundstr6m 1980) and extensive recordings of
various Nitzschia spp. of the marine planktonic section
Pseudonitzschia as N. seriata Cleve (Hasle 1972).
This certainly seems to have occurred in some of the
taxa we have studied here. Identifications of Nitzschia
frigida from the Antarctic (see above) must have been
based on the similarity of the colony formation between N.
frigida and N. stellata. Enough differences were found
between the two diatoms to maintain them as distinct
species rather than placing N. stellata as a variety of
N.frigida. Nitzschia taeniiformis and Auricula compacta
were present in the material we examined from the GaussExpedition but, we presume, cited by Heiden and Kolbe
(1928) under different taxa based on the distinctive shape
of those species, i.e.N, laevissima and N. hybrida, respectively. Similarly, the sigmoid Nitzschia scabra from the
Arctic ice has probably been identified as the sigmoid
N. sigma or N. sigmoidea from the littoral and the linear
hyaline N. polaris from the Arctic confused with the
lanceolate hyaline N. neglecta from the Antarctic.
Fig. 13. Nitzschia lecointel. A Valve view, note well defined valve
outline, PC, IMBB 2596, x 2000. B Valve view, note distinct raphe
rib (r) and marginal ridge (In), IMBB 2596, x 3500. C Internal valve
view, note evenly spaced fibulae, SEM, IMBB 2589, SEM, • 2400. D
External valve view, note marginal ridge (m), IMBB 2589, SEM,
x 3800. E Detail valve apex, note raphe rib (r), marginal ridge, and
rica detail in areolae, IMBB 2596, TEM, x 20,000. F Detail valve
apex, external valve view with distinct raphe rib (r), IMBB 2596,
Slowly, the situation of distinguishing between Arctic
and Antarctic taxa is rectifying itself as detailed examinations of species from each region are completed. In our
examinations we were able to question the report of four
Arctic species, Nitzschia frigida, N. polaris, N. laevissima,
and N. hybrida as being present in the Antarctic. However,
we have only begun a more extensive examination of fast
ice-associated Nitzschia species from Antarctic material.
Of the species studied here only Nitzschia frigida,
N. laevissima, N. promare, and Hantzschia weyprechtii
were present in the ice and plankton samples we examined
from the Barents Sea in the Eurasian sector of the Arctic.
Most of the plankton samples in which these species
occurred were taken near the marginal ice zone in more
open water sites. These same species are commonly reported from the North American sector of the Arctic
(Grontved 1950; Horner and Schrader 1982; Hsiao 1983;
Ostrup 1895; Poulin and Cardinal 1983). The remaining
species, N. neofrigida, N. polaris, N. brebissonii var. borealis, and N. arctica were predominant in samples or
reported from the literature (e.g. Cleve 1883, 1896; Hsiao
1983; Ostrup 1895; Poulin and Cardinal 1983) from the
North American sector of the Arctic, particularly in sites
located closer to land. The only report of any of these
species from the Eurasian sector of the Arctic is that of
N. arctica by Jorgensen (1905) from northern Norwegian
fjords, again in sites located closer to land. We also found
one valve of N. scabra in the plankton samples taken in
Kings Bay, Spitzbergen. It appears that these six species
may be part of a more littoral community, but it is difficult
to be more precise in their distribution because of the bias
of the samples we examined. We have no samples from the
Russian coast between Mys Vakarem and Franz Josef
Land as well as few littoral ice samples from the northern
coast of Norway. The first four species appear to be
circumpolar in distribution and more abundant in ice and
in plankton samples taken near the marginal ice zone in
more open water.
In the Antarctic, Nitzschia stellata, N. taeniiformis,
N. lecointei, and Auricula compacta appear to have a
circumpolar distribution, being present in all of the fast ice
samples we examined. We have limited observations of
N. neglecta and it is absent from the samples collected in
Halley Bay and in the Ross Sea.
Taxonomic and Systematic Considerations
Another aim in taxonomic studies such as we have carried
out is to contribute to the overall understanding of major
groups, in this case the Nitzschiaceae. The genus Nitzschia
Hass. is very much in need of revision and works by Hasle
SEM, x 20,000. G Same as F, but without well developed rib, note
proximal mantle, IMBB 2589, SEM, • 20,000. H valve mid-region,
note well developed central nodule raised above valve surface,
distinct valve marginal ridge (m) and enlarged pores along outer
raphe canal wall, IMBB 2596, SEM, x 20,000. I Same as H, except
central nodule weakly developed, marginal ridge not developed,
IMBB 2589, SEM, x 10,000. J Detail of central nodule and bands
attached to the epivalve (e). IMBB 2596, SEM, x 12,000
476
477
(1964, 1965a, b), Lange-Bertalot (1976, 1980), LangeBertalot and Simonsen (1978), and Mann (1978, 1986)
have certainly made a start. As seen in these works, some
sections of Nitzschia, such as Fragilariopsis, Pseudonitzschia, Tryblionella, Panduriformes, and the sub genus Nitzschia including the sections Nitzschiae and Spathulatae, are
quite well defined with distinct valve structures, such as
number and kinds of areolae, presence of a conopeum
and/or colony formation as the defining characters. Others
in the genus, such as sections Lanceolatae, Lineares,
Vivaces and Nitzschiella as one group and Bilobatae and
Dubiae as another, tend to grade one into another and
there is little strong morphological evidence, at present, to
split them into distinct entities.
From our studies, we can place some of the taxa we
have examined from Nitzschia into a well-defined section.
There is no doubt that Nitzschia scabra belongs in the
subgenus Nitzschia, section Nitzschiae (Mann 1986). It
possesses an uninterrupted sub-central raphe with a conopeum and is sigmoid in girdle view. Its girdle bands with
numerous punctate rows allies it with the section Spathulatae, another section in this subgenus that also has a
conopeum. Obviously within this distinct subgenus,
characters, such as raphe position and valve symmetry, are
more important in defining distinct sub-groups, while the
development of the conopeum and structure and number
of girdle bands will tend to vary between species although
they are included in the range of characters that define the
subgenus as a whole, e.g., the conopeum, the lack of a
central nodule, and the possession of numerous punctate
girdle bands (Mann 1986; Lobban and Mann 1987).
Another taxon, Nitzschia brebissonii var. borealis was
also placed in the section Nitzschiae by Cleve (1883). Our
studies show that it lacks the features necessary to place it
here. This taxon is not sigmoid in girdle view, but only
tends to be enlarged in the mid-region of the frustule
because the valve tapers to quite narrow apices. This may
give the impression of being sigmoid when viewed from
this aspect. All other valve features, e.g. the curvature of
the valve up towards a central raphe, the external rib
accompanying the raphe along its length, the shape of the
fibulae, and the lack of a central nodule as well as a
conopeum, tend to ally it with the genus Bacillaria, an
observation made earlier by Ostrup (1895) when he described this same species as Bacillaria socialis var. septentrionalis. As far as we are aware, this species does not
form colonies characteristic of the genus Bacillaria Gmel.
We have also seen Bacillaria socialis var. kariana Grun.
with similar valve morphology from the inner Oslol~ord
but with no observations on colony formation. An as yet
unidentified species of Bacillaria has been seen with its
distinctive colony formation in benthic samples taken
from Signy Island (Gilbert, personal communication). It
may be more satisfactory to define the genus Bacillaria
using frustule morphology if it proves that the distinctive
colony formation heretofore used to define it is only a
specific character e.g., found in Bacillaria paxillifer (Miill.)
Hend., Bacillaria socialis (Greg.) Ralfs, and Bacillaria
linkei (Hust.) Mann. We feel that this issue can only be
settled by genetic evidence to support or refute this
observation. Nitzschia brebissonii var. borealis remains in
Nitzschia without an appropriate section to which it can
be assigned.
The sigmoid Nitzschia laevissima presents another
problem because it cannot be allied with any sigmoid
section as they are presently defined. It lacks the conopeum of the section Nitzschiae (Mann 1986). Its central
raphe endings are not deflected as in the section Obtusae
(Germain 1986) and it possesses a central nodule which
precludes in from being placed in the other sigmoid section
Sigmata. As Mann (1978) has already pointed out there are
several other sigmoid species, like Nitzschia laevissima,
which cannot be relegated to well-established sections and
may form a fourth natural sigmoid grouping.
Nitzschia neofrigida, Nitzschia polaris and Nitzschia
taeniiformis form a cluster that have a centrally positioned
raphe accompanied by a rib or flange and the raphe is
interrupted by a central nodule. The structure of the girdle
bands in these taxa is virtually identical. These taxa can
probably be assigned to the section Dubiae (containing
Bilobatae see Mann 1978, 1986 for review). Thus, both
arborescent and ribbon colonies would be found in this
section. Those forming ribbon colonies do so by interleaving the flanges of sister valves, found in at least three
species of this section.
Nitzschia neglecta also possesses a central raphe system with a small flange that is formed by the uneven
openings of the raphe fissure. The raphe fissure is interrupted by a central nodule. This taxon is probably best
placed in the Section Dubiae although its girdle bands ally
it more closely with the Section Spathulatae. However, it
lacks the conopeum and absence of a central nodule that
would allow it to be placed here. The superficial resemblance of this taxon to this section as seen with LM is
noted by the fact that N. neglecta was first described as a
variety of N. angularis Wm. Smith.
The remaining four taxa studied here, Nitzschiafrigida,
N. stellata, N. promare, and N. arctica, must be placed in
the Section Lanceolatae (including Lineares as proposed
by Lange-Bertalot and Simonsen 1978) as it is presently
defined, although the girdle band structure of Nitzschia
arctica is close to the cluster of species above assigned to
Dubiae. We can offer no new information to help separate
the continuum in valve structure seen in these sections. No
Fig. 14. Auriculacompactaall figures from Cape Armitage. A Proximal valve view, NIC, x 1000. B Central nodule seen from proximal
valve view, NIC, x 1000. C. Central nodule seen from distal valve
view, NIC, x 1000. D Canal raphe, focus across valve, NIC, x 1000.
E Distal valve view, NIC, x 1000. F Complete frustule, proximal
valve face in focus, broad girdle view, NIC, x 1000. G Complete
frustule, distal valve face in focus (arrows point to edge of valve),
narrow girdle view, NIC, x 1000. H Internal valve view, showing
both proximal and distal valve faces, SEM, x 1500. I Internal valve
view, valve tilted to viewcanal raphe, SEM, x 1500.J External valve
view of central raphe endings and striae and canal raphe areolae,
SEM, • 20,000. K Detail of I, at central nodule, note ridge of silica
separating canal wall from the valve face, SEM, x 10,000.L Detail of
valve apex showing striae composed of two rows of poroid areolae,
SEM, x 10,000
478
real differences can be seen in the valve structure of these
four t a x a as c o m p a r e d with that of o t h e r t a x a a l r e a d y
p l a c e d in this section. As m o r e species are studied with
electron m i c r o s c o p y , it m a y be possible to find n a t u r a l
g r o u p i n g s within this r a t h e r large a n d unsatisfactory
defined section.
Nitzschia lecointei has been p l a c e d in the section
Nitzschiella by Hasle (1964). C e r t a i n valve features, such as
the r a p h e rib a n d m a r g i n a l ridge have been f o u n d in o t h e r
Nitzschia species b e l o n g i n g to the section Lanceolatae a n d
this only serves to underline h o w ill-defined s o m e of the
Nitzschia sections are.
T h e r e m a i n i n g two species studied here, Auricula
compacta a n d Hantzschia weyprechtii, can easily be confused with the genus Nitzschia if whole cells are n o t seen
because single valves d o n o t exhibit the strong a s y m metries characteristic of their respective genera t h a t w o u l d
a i d in their identification. A. compacta represents the first
r e c o r d i n g of this genus from sea-ice samples.
As with all of the species s t u d i e d here, we h a d to rely on
i n f o r m a t i o n from whole cells as well as t h a t from cleaned
p r e p a r a t i o n s in o r d e r to establish the b o u n d a r i e s of each
species. C o l o n y f o r m a t i o n helped us in several instances to
delineate taxa. T h e type of c o l o n y f o r m a t i o n does n o t
a p p e a r to be restricted to one p a r t i c u l a r section as it does
for the sections Fragilariopsis a n d Pseudonitzschia.
Acknowledgements. We would like to thank all the people and the
various museums who kindly loaned us slides and material from
their collections and the various collectors who took samples for the
University of Oslo. The Electron Microscopical Unit at the University of Oslo and at the University of Bristol gave expert technical
assistance. Mr. R. Ross provided the Latin diagnoses and, with Miss
Pat Sims and T.B.B. Paddock (British Museum) and Dr. D.G. Mann,
gave advice on nomenclatural problems. We gratefully acknowledge
the support of the Norwegian Research Council for Science and the
Humanities who funded LKM's stay at the University of Oslo in
1985 (Grant D.50.42.052) and in 1989 Grant D.50.42.069).
References
Anonymous (1975) Proposals for a standardization of diatom terminology and diagnoses. Nova Hedwigia J Kryptogamenkd,
Beih 53:323-354
Cleve PT (1883) Diatoms collected during the expedition of the
"Vega". "Vega"- Exped Vetenskap Iakttag 3:455-517
Cleve PT (1896) Diatoms from Baffins Bay and Davis Strait. Bih K
Svenska VetenskAkad Handl 22:1-22
Cleve PT, Grunow A (1880) Beitr/ige zur Kenntniss der arctischen
Diatomeen. K. Svenska VetenskAkad Handl 17:1 121
Cleve PT, M611er JD (1882) Diatoms. Part VI, pp 277-324, Upsala
Everitt DA, Thomas D (1986) Observations of seasonal changes in
diatoms at inshore localities near Davis Station, East Antarctica.
Hydrobiologia 139:3-12
Garrison DL, Buck KR (1985) Sea-ice algal communities in the
Weddell Sea: Species composition in ice and plankton assemblages. In: Gray JS, Christiansen ME (eds) Marine biology of
polar regions and effects of stress on marine organisms, J Wiley,
New York, pp 103-122
Garrison DL, Buck KR, Fryxell GA (1987) Algal assemblages in
Antarctic pack ice and ice-edge plankton. J Phycol 23:564-572
Germain H (1986) The central nodule of Nitzschiae obtusae Grunow.
In: Ricard M (ed) Proc 8th Int DiatOm Symp. Koeltz, Koenigstein, pp 227-236
Gran HH (1897) Bacillariaceen vom Kleinen Karajakfjord. Bibl Bot
42:13-24
Grontved J (1950) Phytoplankton studies. I. Nitzschiafrigida Grun.,
an Arctic-inner-Baltic diatom found in Danish waters. K Dan
Vidensk Sels Medd 18:1 19
Grossi SM, Sullivan CW (1985) Sea ice microbial communities. V.
The vertical zonation of diatoms in an Antarctic fast ice community. J Phycol 21:401 409
Grunow A (1884) Die Diatomeen yon Franz Josef-Land. Denkschr
Akad Wiss, Wien 48:53-112
Hasle GR (1964) Nitzschia and Fraoilariopsis species studied in the
light and electron microscopes. I. Some marine species of the
groups Nitzschiella and Lanceolatae. Skr Nor Vidensk-Akad
Oslo 16:5-48
Hasle GR (1965a) Nitzschia and Fraoilariopsis species studied in the
light and electron microscopes. II. The group Pseudonitzschia.
Skr Nor Vidensk-Akad Oslo 18:5-45
Hasle GR (1965b) Nitzschia and Fragilariopsis species studied in the
light and electron microscopes. III. The genus Fragilariopsis. Skr
Nor Vidensk-Akad Oslo 21:5 49
Hasle GR (1972) Some specific preparations: Diatoms. In: Sournia A
(ed) Phytoplankton manual. UNESCO, Paris, pp 136 122
Hasle GR (1978) The distribution of Nitzschia seriata Cleve and
allied species. Nova Hedwigia J Kryptogamenkd, Beih
39:171-190
Hasle GR, Syvertsen EE (1985) An Arctic ice-diatom assemblage.
2nd Int Phycol Congr, Copenhagen, 4-10 August 1985 (abstr),
p 62
Heiden H, Kolbe RW (1928) Die marinen Diatomeen der deutschen S/idpolar-Expedition, 1901-1903. Dtsch S/idpol Exped
8:447-712
Horner RA (1984) Do ice algae produce the spring phytoplankton
bloom in seasonally ice-covered waters? A review of recent
literature. In: Mann DG (ed) Proc 7th Int Symp Living & Fossil
Diatoms, Koeltz, Braunschweig, pp 401-410
Horner RA (1985) Ecology of sea ice microalgae. In: Horner RA (ed)
Sea ice biota. CRC Press, Boca Raton, pp 83-103
Horner RA, Schrader GC (1982) Relative contributions of ice algae,
phytoplankton, and benthic microalgae to primary production in
nearshore regions of the Beaufort Sea. Arctic 35:485-503
Horner RA, Syvertsen EE, Thomas DP, Lange C (1988) Proposed
terminology and reporting units for sea ice algal assemblages.
Polar Biol 8:249-253
Hsiao S (1983) A checklist of marine phytoplankton and sea ice
microalgae recorded from Arctic Canada. Nova Hedwigia J
Kryptogamenkd 37:225-313
Hustedt F (1958) Diatomeen aus der Antarktis und dem S/idatlantik.
Wiss Ergebn Dtsch Antarkt Exped 1938 1939 2:103-191
Johansen J, Fryxell GA (1985) The genus Thalassiosira (Bacillariophyceae): studies on species occurring south of the Antarctic
Convergence Zone. Phycologia 24:155-179
Jorgensen E (1905) Protist plankton of Northern Norwegian Fjords.
John Grieg, Bergen, Ser 3, pp 49-151
Kobayasi H, Kobori S (1988) Nitzschia linearis W. Smith and two
related species. In: Simola H (ed) Abstracts, 10th Int Symp Living
& Fossil Diatoms (1988). University of Joensuu, Joensuu, p 63
Krammer K, Lange-Bertalot H (1988) S/isswasserflora von Mitteleuropa. Bacillariophyceae, 2. Teil: Bacillariaceae, Epithemiaceae,
Surirellaceae. Fischer Verlag, Stuttgart, 596 pp
Krebs WM (1983) Ecology of neritic marine diatoms, Arthur Harbout, Antarctica. Micropaleontology 29:267-297
Lange-Bertalot H (1976) Eine Revision zur Taxonomie der Nitzschiae lanceolatae Grunow. Die "klassischen" bis 1930 beschrieben.en S/isswasserarten Europas. Nova Hedwigia J Kryptogamenkd 28:253- 307
Lange-Bertalot H (1980) New species, combinations and synonyms
in the genus Nitzschia. Bacillaria 3:41-77
Lange-Bertalot H, Krammer K (1987) Bacillariaceae, Epithemiaceae, Surirellaceae. Bibl Diat 15:1-289
Lange-Bertalot H, Simonsen R (1978) A taxonomic revision of the
479
Nitzschia lanceolatae Grunow. 2. European and related extraEuropean fresh water and brackish water taxa. Bacillaria
1:11-111
Lobban CS, Mann DG (1987) The systematics of the tube-dwelling
diatom Nitzschia martiana and Nitzschia section Spathulatae.
Can J Bot 65:2396-2402
Manguin I~ (1957) Premier inventaire des Diatom6es de la Terre
Ad61ie Antarctique 6sp6ces nouvelles. Rev Algol 3:111 134
Manguin E (1960) Les diatom~es de la Terre Ad61ie. Campagne du
'Commandant Charcot' 1949-1950. Ann Sci Nat (Bot)
12:221-363
Mann DG (1977) The diatom genus Hantzschia Grunow
an
appraisal. Nova Hedwigia J Kryptogamenkd, Beih 54:323-354
Mann DG (1978) Studies in the Nitzschiaceae (Bacillariophyta).
University of Bristol, vols 1 and 2, PhD Dissertation, 386 pp
Mann DG (1981) Sieves and flaps: Siliceous minutiae in the pores of
raphid diatoms. In: Ross R (ed) Proc 6th Int Diatom Symp.
Koeltz, Koenigstein, pp 279-296
Mann DG (1986) Nitzschia, subgenus Nitzschia. (Notes for a monograph of the Bacillariaceae, 2). In: Ricard M (ed) Proc 8th Int
Diatom Symp. pp 215-226
Meunier A (1910) Microplankton des Mers de Barents et de Kara.
Duc d'Orl6ans, Campagne Arctique de 1907. Charles Bulens,
Bruxelles, 335 pp
McConville MJ, Wetherbee R (1983) The bottom-ice microbial
community from annual ice in the inshore waters of East
Antarctica. J Phycol 19:431-439
Medlin LK, Fryxell GA (1984) Structure, life history and systematics
of Rhoicosphenia (Bacillariophyta). IV. Correlation of size reduction with changes in valve morphology of Rh. genuflexa. J Phycol
20:101-108
Medlin LK, Priddle J (in press) Polar diatom manual. British
Antarctic Survey, Cambridge
Ostrup E (1895) Marine Diatom+er fra Ostgronland. Medd Groenl
18:395-476
Peragallo M (1921) Deuxi6me exp6dition Antarctique Frangaise.
Botanique. Diatom6es d'eau duce et diatom6es d'eau sal6e.
Masson et Cie, Paris, pp 1-98
Poulin M, Cardinal A (1983) Sea ice diatoms from Manitounuk
Sound, southeastern Hudson Bay, (Quebec, Canada). III.
Cymbellaceae, Entomoneidaceae, Gomphonemataceae, and
Nitzschiaceae. Can J Bot 61:107-118
Ross R, Cox EJ, Karayeva NI, Mann DG, Paddock TBB, Simonsen
R, Sims PA (1979) An amended terminology for the siliceous
components of the diatom cell. Nova Hedwigia J Kryptogamenkd, Beih 64:513-533
Schmidt A (1922) Atlas der Diatomaceen-Kunde III. R Reisland,
Leipzig, Plate 345 drawn by F Hustedt
Simonsen R (1974) The diatom plankton of the Indian Ocean
Expedition of the RV "METEOR" 1964-1965. "METEOR"
Forsch-Ergebn, Reihe D, 19:1-107
Simonsen R (1987) Atlas and catalogue of the diatom types of
Friedrich Hustedt, vol 3. Cramer/Borntraeger, Berlin-Stuttgart,
vol 1, Catalogue, 525 pp
Smith W (1853) A synopsis of the British Diatomaceae I. J van
Voorst, London, 104 pp
Sundstr6m BG (1980) Rhizosolenia phuketensis sp. nov. and Rhizosolenia stolterfothii H. Per. (Bacillariophyceae). Bot Notiser
133:579-583
Van Heurck H (1909) Exp6dition Antarctique Beige, R6sultats du
Voyage du S.Y. "Belgica" en 1897-1898-1899, J-E Buschmann,
Anvers, 129 pp
VanLandingham SL (1973) Catalogue of the fossil and recent genera
and species of diatoms and their synonym A. Part VI Neidium
through Rhoicosigma. Cramer, Vaduz, pp 2964-3605
Von Stosch HA (1980) The two Lithodesmium species (Centrales) of
European waters. Bacillaria 3:7-20
Watanabe K (I988) Sub-ice microalgal strands in the Antarctic
coastal fast ice near Syowa Station. Jpn J Phycol 36:221-226