A Guide
to the
Common Diatoms
at
Water Pollution
Surveillance
System Stations
June 1966
U.S. DEPARTMENT OF THE INTERIOR
Federal Water Pollution Control Administration
-------
A Guide to the Common Diatoms at
Water Pollution Surveillance System. Stations
UNITED SPATES DEPARTMENT OF THE INTERIOR
Federal Water Pollution Control Administration
Water Pollution Surveillance
Broadway, Cincinnati, Ohio ^5202
June 1966
-------
ii
Preface
Plankton studies were initiated in 1957 under the direction of Dr. Clarence M.
Tarzvell and Dr. C. Mervin Palmer. The studies -which they initiated were a part
of the Public Health Service program to collect "basic data on the quality of
water in major waterways. In the beginning plankton studies were limited to
Sedgwlck-Rafter counts of phytoplankton and zooplankton. As the phytoplankton
populations at the various stations were characterized, the dominat role of
the diatoms became apparent, and preparations were begun for more intensive
work with these forms. After the early species identifications were made
through consultations or correspondence with Dr. Matthew Hohn, Dr. Charles
Reimer, Dr. Friedrich Hustedt, and Dr. G. D. Hanna, routine diatom species
Identification and enumeration were inaugurated in 1959 ^7 Dr- Louis G. Williams,
who was in charge of plankton studies from September 1958 to December 1962.
Dr. Cornelius I. Weber assumed responsibility for the plankton studies in
September 1963.
Mr. Louis Grivetti who was on the staff of the plankton laboratory from
1962.196^ developed the first draft of this guide to consolidate information
uhich would be helpful to beginners in diatom identification work. The
present form of this guide is the result of extensive additions and revisions
by Dr. Weber and his staff.
The diatom studies have become a vital part of the plankton program.
The specificity of the diatom data has rendered it especially useful in
characterizing water quality.
Joseph B. Anderson
In Charge, Aquatic Biology
-------
iii
COWTEHTS
Page
1. Introduction 1
2. Collection and preparation of diatom material... 3
3. The diatom cell vail. k
4. Glossary 6
5. Generic key 9
6. Alphabetical list of genera 16
7* Illustrated species 17
8. Figure credits 18
9. Station map 99
10. Diatom distribution charts 100
-------
Introduction
A comprehensive treatise on the diatoms of the United States is
yet to be published. Existing references dealing with the algae of
this country are either very provincial or shallow in their coverage
of the diatoms, therefore a large number of domestic and foreign publi-
cations must be consulted to find descriptions of all of our common
species. This is a formidable task for the beginning diatom student.
Descriptions of the diatom species vhich are most frequently encountered
at WFSS stations have been assembled in this illustrated guide vhich was
prepared to serve as a bench reference for biologists in our laboratory
who are being trained in diatom identification. The guide also contains
a glossary and generic key. The key was constructed with the beginner
in mind, and is based entirely on the shape and markings of the diatom
cell wall as observed in material mounted in hyrax. No attempt was
made to place the taxa in their proper phylogenetic order. Laboratory
personnel are encouraged to consult the taxonomic references for species
identification.
We are indebted to Dr. Charles Reimer, Dr. Eugene Stoermer, and
Dr. Matthew Hohn for carefully reviewing the manuscript and making
many helpful suggestions. We are also grateful to the various authors
and publishers who have granted permission to use selected figures from
their publications.
-------
-2-
Staff biologists who have been engaged in diatom work and have
contributed to the preparation of this manual include, Carol Scott,
Julia Maloney, Albert Katko, Mary Jo Sage, Louis Grivetti, Ronald
Raschke, Mason Fenwick, Lydia Corrill, and Gretchen Oswald.
Cornelius I. Weber, Ph.D.
In Charge, Plankton Studies
-------
Collection and Preparation of Diatom Material
The Water Pollution Surveillance System plankton samples
used for diatom analyses are obtained from vater plant intakes
or directly from rivers or lakes at one hundred and thirty stations
across the United States. The algae in the samples are concentrated
by centrifuging twenty minutes at 10OO x G. Several drops of
plankton concentrate are placed on a #1 coverglass, the coverglass
is dried cautiously to avoid splattering*and incinerated thirty
minutes on a hot plate at 1000 P. This treatment drives off most
of the organic matter present, leaving only the siliceous diatom
cell walls (thin-walled forms such as Rhizosolenia eriensis and
Melosira crenulata may be difficult to observe). A drop of Hyrax
mounting medium is placed in the center of a 75 mm x 25 mm glass
slide heated to approximately 200°F. When the solvent has evapor-
ated (the solvent-free Hyrax is hard and brittle at room temperature),
the coverglass bearing the incinerated diatoms is inverted and placed
on the drop of Hyrax, the slide is removed from the heat,and pressure
is applied to the coverglass until the Hyrax cools and hardens
(10 - 15 sec.)« The finished slide is examined at 970X.
-------
THE DIATOM CELL WALL
The diatom cell wall (frustule) is made of silica and consists of two
overlapping halves, each composed of a more or less flat surface, the
valve, to which are Joined one or more hoop-like bands, the girdle and
intercalary bands (see below).
g —
•(
.1
^ vm
1 ib
|| gb
1
J
Girdle view of frustule showing valves, v; intercalary bands,
ib; girdle band, gb; girdle, g; and valve mantle, Yffl-
The valves of the centric diatoms are generally circular in outline, with
their markings arranged symnetrically about a central point; whereas, the
valves of the pennate diatoms are generally elongate (linear) with their
markings arranged in transverse rows along each margin.
Pennate Centric
Valve views of pennate and centric diatoms showing the central
area, a; raphe, r which usually occupies the medial axis of
the valve; striae, s; and costae, c.
-------
Planes and axes of symmetry are employed in keying out some of the pennate
genera. They are shown in the figures below.
Oblique view of a pennate frustule showing planes; apical plane
(along longitudinal or medial axis), a; transapical plane (along
the transverse axis), t.
Oblique view of a pennate frustule showing axes: apical axis,
a; transapical axis, t; and the pervalvar axis, p.
-------
6
GLOSSARY
Arcuate - bent like a bow (see Fragilarla arcus, p. 38)
Brackish - having a dissolved salt content intermediate between fresh
and salt water.
Capitate - swollen at one or both ends in valve viev (see Caloneis
amphisbaena, p. 63)
Carinal dots - circular or oval pores more or less evenly spaced along
the keel, usually appearing as dots or lines (see Nitzschia, p. 90)
Costae - internal or external linear thickenings of the valve surface
appearing as ribs; because of light diffraction, the tapered
shoulders of the costae may appear as dark lines (see Cyclotella
Meneghiniana, p. 26)
Facet - (alveola) a circular or hexagonal thin area in the valve sur-
face, surrounded by a ridge which may extend internally or extern-
ally from the valve surface (see Coscinodiscus, p. 31)
Frustule - the siliceous diatom cell vail consisting of two separate
halves.
Fusiform - broadest at the middle and tapering at each end, spindle-
shaped (naviculoid).
Girdle - region of the frustule between the two valves.
Girdle-bands - the two overlapping hoop-like bands which Join the two halves
of the frustule. They may be connected directly to the valve margins
or the intercalary bands.
Girdle view - side view of the frustule.
Intercalary bands - hoop-like bands located between the girdle-band and
the valve (see Rhizosolenia, p. 22)
-------
Keel - a ridge projecting from the valve-surf ace, enclosing the "canal"
raphe, visually not medial on the valve (see Nitzschia, p. 89)
Linear - long and nearly uniform in width.
Micron - 0.001 millimeter.
Multiseriate - having more than one row of punctae (see Stephanodiscus
astrea, p. 28)
Nodule - internal thickening of the cell vail in the central area or
terminal portions (poles) of the valves of pennate diatoms.
Ocellus - a raised, rounded or ovate thickening of the valve surface
having the appearance of a large pore (see Cyclotella ocellata,
P- 27)
Poles - extreme ends of the valves of pennate diatoms.
Pseudoraphe - a smooth, linear space between the medial ends of the
striae or costae on the valves of pennate diatoms. A term applied
only to valves without a true raphe (see Synedra ulna, p. ^5)
Punctae - small holes (pores) or thin,circular, sieve-like areas in the
frustule.
Raphe - a fissure or slit in the valve face which may be along or eccentric
to the medial axis of the valvej when located in a keel or wing it is
referred to as a "canal" raphe.
Rhomboid - a parallelogram in which the angles are oblique and the adjacent
sides are unequal (see Nitzschia, p.89)
Septae - internal partitions or cross walls, usually appearing as dark
lines (see Tabellaria fenestrata, p. 32)
Shadow-lines - dark "diffraction" lines which appear in the frustule wherever
abrupt changes in thickness of the valve face occur (see Caloneis, p. 63)
-------
8
Sigmoid - s-shaped (see Gyrosigma, p. 67)
Stellate - star-shaped, radiating from a point.
Striae - linear markings on the frustule which are due to closely placed
punctae, or to hollow chambers in the cell wall (may sometimes
appear as costae).
Sulcus - annular groove between the valve mantle and girdle (see Melosira
ambigua, p. 19)
Uniseriate - having one row of punctae (see Coscinodiscus, p. 31)
Valve - the face of the diatom frustule.
Valve mantle - the part of the valve which extends below the shoulder.
In the MElosiras the valve mantle is a cylindrical surface that
may be 30I-1 long (see Melosira granulata, p. 20)
Wing - a thin projection of the valve surface, more highly developed than
a keel; generally arising near the margin of the valve, but some-
times arising near the medial axis. May enclose the "canal" raphe
(see Surirella, p. 87)
-------
9
GENERIC KEY
la Valves with true raphe or pseudoraphe; ornamentation
transverse and/or longitudinal 8
Ib Valves without true raphe or pseudoraphe; ornamentation
radial about a central point 2
2a Frustules usually united into long filaments
Melosira (p. 19)
2b Frustules not usually united into long filaments; usually
solitary but may form short chains 3
3a Frustules with intercalary bands; usually seen in girdle
view; one or two long spines arising from each valve.... k
3b Frustules without intercalary bands 5
Ua One long spine arising from each valve
Rhizosolenia (p. 22)
Ub Two long spines arising from each valve....Attheya (p. 23)
5a Valves with two marginal protuberances or horns on
opposite sides of the valve; usually seen in girdle view.
Biddulphia (p. 23)
5b Valves lacking protuberances 6
6a Valve margin with costae; ornamentation in central area
different from margin Cyclotella (p. 2^)
6b Valve margin otherwise; central area not sharply distinct
from, margin; valves with radial rows of punctae or with
geometric facets 7
-------
10
7a Punctae in multiseriate rows near valve margin, each row
gradually or abruptly becoming uniseriate toward the
center; marginal spines always present
Stephanodiscus (p.28)
7b Punctae in uniseriate rows throughout, or with geometric
facets Coscinodiscus (p. 31)
8a True raphe present on at least one valve; raphe may be
very short or rudimentary, or may be concealed in a
keel or wing 15
8b True raphe absent, pseudoraphe present on both valves... 9
9a Frustules with thick longitudinal septae running parallel
to the valve faces Tabellaria (p.32)
9b Frustules without septae 10
lOa Valves with thickened internal transverse ribs (costae),
most of which extend completely across the valve face... 11
lOb Valves without thickened internal transverse ribs. 12
lla Valves symmetrical about the transapical plane
Diatoma (p. 33)
lib Valves asymmetrical about the transapical plane
Meridion (p. 36)
12a Frustules with bulbous ends, slightly concave in girdle
view, typically forming stellate colonies
Asterionella (p. 37)
12b Frustules without bulbous ends, typically not forming
stellate colonies 13
-------
n
13a Valves symmetrical about the transapical plane I.k
13b Valves asymmetrical about transapical plane
Opephora (p. 38)
Frustules typically forming long ribbon-like chains,
rarely solitary Fragilaria (p. 38)
Frustules typically solitary, sometimes forming stellate
colonies; striae often appearing as costae
Synedra (p.
15a Raphe evident on at lease one valve 16
15b Raphe not evident, concealed in a keel or wing 35
l6a Valves similarly ornamented, raphe on both valves 19
l6b Valves not similarly ornamented, raphe on one valve,
opposing valve with pseudoraphe, or with rudimentary
raphe near valve poles 17
17a Valves elliptical, never linear, sometimes bent along the
apical axis Cocconeis (p. V?)
17b Valves not elliptical, usually linear, and usually bent
along the transapical axis 18
l8a Valves symmetrical about the transapical plane, one
valve with completely developed raphe, opposing valve
with pseudoraphe Achnanthes (p. 50)
l8b Valves asymmetrical about the transapical plane, one
valve with completely developed raphe, opposing valve
with rudimentary raphe near valve poles
Rhoicosphenia (p. 52)
-------
12
19a Raphe rudimentary, short, near poles only..
Eunotla (p. 53)
19b Raphe fully developed, extending the length of the
valves * 20
20a Valves symmetrical about both the transapical and
apical plane 2k
20b Valves asymmetrical about either the apical or
transapical plane 21
21a Valves symmetrical about the transapical plane, asymmetrical
about the apical plane 23
21b Valves asymmetrical about the transapical plane,
symmetrical about the apical plane 22
22a Valve margins vith longitudinal "shadow"-lines
Gomphoneis (p.
22b Valve margins lacking longitudinal shadow"-lines
Gomphonema (p.
23a Valve faces parallel Cymbella (p. 57)
23b Valve faces not parallel,both valves faces can be seen
in girdle view Amphora (p. 60)
Valves with elongate central or terminal nodules 25
Valves without elongate central or terminal nodules 26
25a Central nodule drawn out to at least half the length
of the valve Amphipleura (p. 62)
25b Central nodule drawn out less than half the length
of the valve Frustulia (p. 62)
-------
13
26a Valves with longitudinal "shadow"-lines or blank
spaces 27
26b Valves without longitudinal lines or blank spaces 29
27a Transverse striae continuous, crossed by one or two
longitudinal "shadow"-lines paralleling valve margin....
Caloneis (p. 63)
27b Transverse striae discontinuous, interrupted by blank
spaces or "shadow"-lines 28
28a Longitudinal "shadow"-lines or blank spaces near valve
margins; ends of raphe near central nodule usually turned
in opposite directions Neidium (p. 6k)
28b Longitudinal "shadow"-lines or blank spaces scattered,
central pores of raphe near central nodule turned if at
all in the same direction Anomoeoneis (p. 65)
29a Valves and raphe sigmoid 30
29b Valves and raphe not sigmoid 31
30a Valves with transverse and longitudinal striae ..........
Gyrosigma (p. 67)
30b Valves with transverse and oblique striae ............ ...
Pleurosigma (p. 67)
31a Erustules with septae ............... Mastogloia (p. 68)
31b Frustules without septae ................................ 32
32a Raphe enclosed in a siliceous rib .......... Diploneis (p. 68)
32b Raphe not enclosed in a siliceous rib ................... 33
33a Valves with chambered striae appearing as heavy costae;
valves usually with parallel sides and broadly rounded poles.
Pinnularia (p. 70)
33b Valves with striae appearing otherwise
-------
Central area extending laterally to the margins of the
valve, striae absent along lateral margins of the
central area Stauroneis (p. 70)
Central area not extending to the margins of the valve,
striae present along lateral margins of the central
area ... Navicula (p. 71)
35a Keel elevated into a lateral "wing" or flattened on
the valve surface 37
35b Keel elevated into an axial "wing" extending along the
central axis of the valve 36
36a Keel sigmoid, usually seen in girdle view (hour-glass-
shaped), frustule twisted along the longitudinal axis;
girdle "broad with many longitudinal folds
Amphiprora (p. 80)
36b Keel not sigmoid, girdle simple, not folded, keel
eccentric Tropidoneis (p. 82)
3Ja Valves with numerous internal transverse ribs extending
completely across the valve 33
37b Valves without internal transverse ribs ^0
38a Raphe and axial area with 'V-shaped medial extension;
with transverse septae appearing as costae and alternat-
ing with two or more rows of punctae
Epithemia (p. 83)
38b Raphe and axial area without a "V"-shaped medial
extension 39
-------
15
39a Raphe canal with pores, valves symmetrical to longitudinal
axis Denticula (p. 84)
39b Raphe canal without pores, valves asymmetrical to the
longitudinal axis Rhopalodia (p. 84)
40a Valves -with lateral keel extending along both margins of
each valve 4l
40b Valves vith lateral keel extending along one margin of
each valve 42
4la Valve face longitudinally undulate, undulations
conspicuous in girdle view; with broad, short, peripheral
costae; longitudinal pseudoraphe present
Cymatopleura (p. 86)
4lb Valve face not longitudinally undulate; valve face with
longitudinal folds which appear as heavy costae, folds
not conspicuous in girdle view; girdle view rectangular,
naviculoid, wedge shaped or sigmoid; valve view linear,
elliptical, ovate or spirally twisted
Surirella (p. 87)
42a Keels eccentric to the median axis, diagonally opposite;
frustules rhombic in cross section, transversely striate,
punctate or lacking ornamentation; a row of circular pores
("carinal dots") developed within the keel; frustules
usually solitary but occasionally forming irregular ribbon-
like chains or stellate colonies.....Nitzschia (p. 89)
42b Keels eccentric to the median axis, directly opposite;
frustules rectangular in cross section, transversely striate
or punctate,capitate ends, medianly constructed...Hantzschia (p. 98)
-------
16
Alphabetical list of Genera
Genus Page
Achnantbes
Amphipleura
Amphiprora
Amphora
Anomoeoneis
Asterionella
Attheya
Biddulphia
Caloneis
Cocconeis
Coscinodiscus
Cyclotella
Cymatopleura
Cymbella
Denticula
Diatoma
Diploneis
Epithemia
Eunotia
Fragilaria
Frustulia
Genus
Page
50
62
80
60
65
37
23
23
63
^7
31
24
86
57
Ok
33
68
83
53
38
62
Gomphoneis
Gomphonema
Gyros igma
Hantzschia
Mastogloia
Melosira
Meridion
Navicula
Neidium
Nitzschia
Opephora
Pinnularia
Pleurosigma
Hhizosolenia
Rhoicosphenia
Rhopalodia
Stauroneis
Stephanodiscus
Surirella
Synedra
Tabellaria
Tropidoneis
5^
5^
67
98
68
19
36
71
64
89
38
70
67
22
52
84
70
28
87
42
32
82
-------
17
Illustrated Species
A total of 2.6k species are illustrated, representing ^3 of
the common genera found at the Water Pollution Surveillance System
stations. Some of the species were selected primarily to demonstrate
the morphological diversity within the genera. The figures have
been selected from a number of publications (p. 18) and the figure
credits are referred to by number immediately following the species
names. The cell dimensions given are generally those from the
figure source, but in some cases these have been supplemented with
our own observations. The geographical distribution of 96 of the
species is shown in the accompanying chart (p. 100), taken from
"Plankton Population Dynamics", by L. G. Williams, PES pub. No.
663, Suppl. 2, 1962. Additional information regarding diatom
distribution can be found in the WPSS Annual Compilations of Data,
1960-61, 1961-62, and 1962-63, PBS Pub. No. 663.
-------
18
FIGURE CREDITS
1. Boyer, Charles S., 1916. The Diatomaceae of Philadelphia and
Vicinity. J. B. Lippincott Co., Philadelphia.
2. Hohn, Matthew H., and Joan Hellerman, 19^3. The Taxonomy and
Structure of Diatom Populations Prom Three Eastern North American
Rivers Using Three Sampling Methods. Transactions of the American
Microscopical Society. 82(3):250-329.
3. Huber-Pestalozzi, G., and F. Hustedt, 19^2. Die Kieselalgen. In:
A.Thienemann, Das Phytoplankton des Susswassers, Die Binnengewasser,
Band XVI, Teil II, Halfte II. E. Schweizerbart'sche Verlagsbuch-
handlung, Stuttgart.
k. Hustedt, F., 1930. Die Kieselalgen. In: L. Rabenhorst, Kryptogamen-
Flora von Deutschland, Osterreich, und der Schweiz, Band VII. Akademische
Verlagsgesellschaft xa.b.H., Leipzig.
it
5. Hustedt, F., 1930. Bacillariophyta. In: A. Pascher, Die Susswasser-
Flora Mitteleuropas, Heft 10; Gustav Fischer, Jena.
6. Hustedt, F., 19^9- Sussvrasser-Diatomeen. Imprimerie M. Hayez,
Bruxelles.
7. Plankton Laboratory staff, WPSS.
8. Patrick, R., 1959- The Bacillariophyceae. In: W. T* Edmondson,
Fresh-water Biology, H. B. Ward and G. C. Whipple, 2nd Edition,
Wiley and Sons, N. Y.
9. Prowse, G. A., 1962. Diatoms of Malayan Freshwaters. Gardens'
Bulletin, Singapore. 19(1):!-!(&.
10. Smith, G., 1950. The Fresh-water Algae of the United States. 2nd
Edition, McGraw-Hill Book Co., Inc., N. Y.
11. Tiffany, L. H., and M. E. Britton, 1952. The Algae of Illinois.
Univ. Chicago Press, Chicago.
12. van der Werff, A., and H. Huls, 1957-1961, 1963. Diatomeeenflora
Van Nederland. Parts I, II, III, IV, V, VI. Stechert and
Hafer, N. Y.
-------
19
la
Ib
Valves with true raphe or pseudoraphe; ornamentation
transverse and/or longitudinal
Valves without true raphe or pseudoraphe; ornamentation
radial about a central point
8
2a Prustules usually united into long filaments - MELOSIRA
Fig. 1. Melosira ambigua, (3), valves 4-15n in diameter, 3-13(i
long; wide, angular sulcus. X 1000. Abundant in the
Ohio and Mississippi Rivers.
Notes :
o
valve view
girdle view
sulcus
Fig. 2.
Notes :
Melosira Binderana, (3), valves 4-25M in diameter, 3-7^
long; in valve view may be confused with Stephanodiscus
Hantzschii; has distinct pores on valve mantle (shoulder),
X 1000. Common in the Great Lakes.
girdle view
1. Valve length in Melosira is measured from the valve face to
the sulcus, along the pervalvar axis (half length).
2. This number refers to the figure source.
-------
20
Fig. 3.
Notes:
Melosira distans, (3), valves 4-20u in diameter,
4-8u long. X 1000. Abundant in southeastern rivers.
girdle view
var. lirata,
form lacusris
Fig. 4. Melosira granulata, (3),valves 5-21u in diameter,
5-l8u long; terminal cells usually with robust
spines. X 1000. Common in northern U. S.
girdle view
valve mantle
Notes:
Fig. 5. Melosira herzogii, (7), valves %i in diameter, 7u
long. X 2000. Found most often in southeastern U.S.
girdle view
Notes:
-------
21
Fig. 6. Meloslra islandlca, (3), valves 7-27u in diameter,
^-21n long; striae on valve mantle parallel to
pervalvar axis. X 1000. Common in the Great Lakes
and the Columbia River.
Notes:
girdle view,
subsp. helvetica
Fig. T. Melosira italica, (3), valves 5-28u in diameter, 8-21u
long; differentiated from M. ambigua by more robust
spines and narrow sulcus. X 1000. Common in the
Columbia River.
Notes:
valve view
w^
^•f'-V-v •• .-11
f -i- ?-•--•.--1;
J^S?F^?: -;«ii
^~=-^-£lttSiii£^EE^!\
girdle view,
var. valida
Fig. 8. Melosira varians, (3), valves 8-35^ in diameter, 9-13U
long; no visible ornamentation. X 1000. Widely distri-
buted.
valve view
girdle view
Notes:
-------
22
Notes on other species of MELOSIRA;
2b
3a
3b
ka.
Frustules not usually united into long filaments;
usually solitary but nay form short chains
Frustules with intercalary bands; usually seen in
girdle view; one or two long spines arising from each
valve
Frustules without intercalary bands
One long spine arising from each valve - RHIZOSOLENIA
4
5
Fig. 9. Rhlzosolenia eriensis, (If), cells 5-15fi in diameter,
40-150^ long; note the many intercalary bands in the
girdle area. X 1000. Common in the Great Lakes.
girdle view
Notes:
intercalary band
-------
23
Fig. 10. Rhizosolenia minima, (If.), cells if-Tu in diameter,
15-^CHi long (excluding spines). X 350* Southwestern
U. S. (Red River).
girdle view
Notes:
Two long spines arising from each valve - ATTHEYA
Fig. 11. Attheya Zachariasi,(io), cells 12-40^ in diameter;
spines 40-60u long. X 500. In Ohio and Tennessee
Rivers.
girdle view
Notes:
5a Valves with two marginal protuberances or horns on opposite
sides of the valve; usually seen in girdle view - B3DDULPHIA
-------
Fig. 12. Biddulphia laevis, (10), cells 20-150u in diameter,
50-150M. long; X 650. Southwestern U. S.
•f,.^f^^
*?;*.<&»*.'#..
Notes:
valve view
girdle view
Valves lacking protuburances.
6a Valve margin with costae; ornamentation in central
area different from margin - CYCLOTELLA
Fig. 13. Cyclotella atomus, (3), cells 4-5n
in diameter; every 5th or 6th
costae is thicker and darker than
the others; single ocellus in
central area. X 1500. Widely
distributed.
valve view
Notes:
Fig. 1^. Cyclotella antiqua, ( *Q, cells
10-30u in diameter; wedge-shaped
depressions in central area.
X 1200. In Great Lakes.
valve view
Notes
-------
25
Fig. 15. Cyclotella bodanica, (4), cells 20-SOn in diameter;
an isolated puncta occurs at the inner end of
several shortened marginal costae. X 1000. In
Great Lakes.
Notes:
Fig* 16.
girdle view
Cyclotella comta, (4), cells
15-20n in diameter; similar to
C. bodanica but lacking punctae
at the end of shortened costae.
X 1000. In Great Lakes.
valve view
valve view
Notes:
Fig. I?. Cyclotella glomerata,(3), cells
^-lOn in diameter; forming
chains; often seen in girdle
view. X 1000. In Great Lakes.
Notes:
1£?
Q
colony
-------
26
Fig. 18. Cyclotella Kutzingiana, (3), cells 10-20|i in diameter;
center ornamentation highly variable. X 1000. Common
in Great Lakes.
valve views
Notes:
Fig. 19-
Cyelotella Meneghiniana, 02), cells 10-30n in diameter;
heavy marginal costae give impression of scalloped
"border. X 1000. Widely distributed.
valve view
girdle view
Notes:
Fig. 20. Cyelotella michiganiana, (ll), cells 5-20|j. in diameter;
valve margin with pronounced rim. X 1000.
valve views
Notes:
-------
27
Fig. 21. Cyclotella ocellata, (3), cells 6-20|a in diameter;
central area with 3-4 ocelli. X 1000. In Great
Lakes.
Notes:
Fig. 22,
Notes:
valve views
Cyclotella pseudostelligera, (7),
cells 7-6^ in diameter; has
marginal spines. X 3000. Widely
distributed.
valve view
Fig. 23.
Cyclotella stelligera, (3), cells
5-25u in diameter. X 1000. Abun-
dant in the southeast.
Notes:
valve view
-------
28
Fig. 24. Cyclotella striata,
cells 10-50u in diameter.
Has a circular shadow line
passing through the costae,
X 1000. In Delaware and
Hudson Rivers.
valve view-
Notes:
Notes on other species of CYCiLOTELLA
6b Valve margin otherwise; central area not sharply distinct
from margin; valves with radial rows of punctae or with
geometric facets
7a Punctae in multiseriate rows near valve margin, each row
gradually or abruptly "becoming uniseriate toward the center;
marginal spines always present.- STEPEAHODISCUS
Fig. 25. Stepjianpdiscus astrea (3), cells
10-30{i in diameter; spines not at
end of each row of punctae. Outer
punctae in double to quadruple rows,
12 punctae in 10»i. X 1000. Widely
distributed.
valve view
Notes:
-------
29
Fig. 26. Stephanodiscus dubius, (3), cells 10-25U in diameter*
X 1000. In Great Lakes and Columbia River.
valve view
girdle view
Notes:
Fig. 27. Stephanodiscus Bantaschii,
cells a-20|i in diameter; 8-10
striae in 10u; striae very light;
frustule often collapses during
incineration; may be confused
with Melosira Binderana. X 2000.
Widely distributed.
Notes:
valve view
Fig. 28. Stepbanodiscus invisitatus, (7),
cells 5-15U in diameter; 15-20
striae in lOji; striae very light;
easily confused with_S.. Bantzschii.
X 2000. Ohio River Basin.
valve view
Notes:
-------
30
Fig. 29. Stephanodiscus niagarae, (3),
cells 30-lOOp. in diameter;
3-5 rows of punctae in marginal
region of striae, spines sub-
marginal and more robust than
in S.. astrea. X 900. Upper
Mississippi and Missouri Rivers,
Notes:
valve view
Fig. 30. Stephanodiscus tenuis,
cells 8-2b|i in diameter;
spines at end of each row
of striae. X 1000.
Notes:
valve view
Notes on other species of STEPHANODISCUS.
-------
31
Punctae in uniseriate rows throughout; or with geometric
facets - COSCINODJBCUS
Fig. 31• Coscinodiscus denarius,
cells 40-90|i in diameter.
X 1000.
Notes:
facet
valve view
Fig. 32.
Coscinodiscus lacustris,
cells 20-50p. in diameter,
with marginal spines. X 1000.
Notes:
valve view
Fig. 33-
Coscinodiscue Rothii, (8),
cells 25-40(1 in diameter.
X 1000. In Red and Lower
Mississippi Rivers.
Notes:
-------
32
Other species of COSCINODISCIIS.
8a True raphe present on at least one valve; raphe may be
very short or rudimentary, or may be concealed in a keel
or wing 15
8b True raphe absent, pseudoraphe present on both valves *. 9
9a Frustules with thick longitudinal septae running parallel
to the valve face - TABKf.TARIA,
Fig. 3**-. Tabellaria fenestrata, (3), cells 30-l^Ou long, 3-9" wide;
18-20 striae in 10u;if-8 intercalary bands per cell. In
Great Lakes and Columbia River.
septum
girdle view. X 1000
c
o
Colony
X 250
Notes:
valve view. X 1000
-------
Fig. 35.
33
Tabellaria flocculosa, (5), cells 12-50fi long, 5-l6|i wide;
about 18 striae in lOp.; many intercalary bands. X 1000.
In Great Lakes and Columbia River.
valve view
girdle view
Notes:
9b Frustules without septae 10
lOa Valves with thickened internal transverse ribs (costae), most
of which extend completely across the valve face 11
lOb Valves without thickened internal transverse ribs 12
Ha Valves symmetrical about the apical plane - DIATOMA
Fig. 36. Diatoma anceps, (5), cells 15-lOOp. long, k-Q\i wide," internal
costae narrow, 3-6 in 10u; striae delicate, 18-20 in
X 1000. In Colorado River.
valve view
girdle view
colony
Notes:
-------
Fig. 37- Diatoma elongatum. (5), cells 30-120n long, 2-k\i wide;
internal costae narrow, 6-10 in 10u; striae delicate,
about l6 in 10^. X 1000. In Great Lakes and Columbia
River.
FTlTgMTl im-lJt
girdle view
valve view of var.
tenuis
valve view
Notes:
Fig. 38. Diatoma hieaale,(4);,cells 15-lOQl* long,T - 20u wide? internal
costae robust, 2-*f in 10u; striae prominent, 18-20 in
X 1000.
girdle view of
part of colony
valve
view
girdle view
of part of
colony of var.
mesodon
valve view
of var. mesodon
Notes:
-------
35
Fig. 39- Diatcma vulgare, (5), cells 30-60fi long, 10-13^ vide;
internal costae narrow, 6-8 in 10u; striae very delicate,
about 18 in 10p. Widely distributed.
Girdle view of
part of colony
X 500
Notes:
valve view
X 1000
valve view,
var. torevis,
X 1000
Notes on other species of DIATOMA.
-------
3b
lib Valves asymmetrical about the transapical plane - MBRIDION
Fig. kO. Meridion circulare, (12), cells 12-80u long, k-8\i wide;
3-5 internal costae in lOu; about 15 striae in lOu.
X 1000. Widely distributed.
valve view
girdle view
Notes:
-------
37
12a Frustules with bulbous ends, slightly concave in girdle view,
typically forming stellate colonies - ASTERIONflT.T.A
Fig. 4l. Aaterionella formosa, (3), cells 30-l40u long, l-2p. wide;
free ends inflated less than Joined ends. Widely distributed.
valve view
X 1500
Colony
X 500
Notes:
Fig. 42. Asterionella gracillima, (3), cells *K)-130u long, l-2p wide;
similar to A. formosa except that the two poles of the cell
are of equal size in "both valve and girdle view.
jnmmVmiiini'
valve view
x 1500
Colony
X 500
Notes:
-------
38
12b Frustules vithout bulbous ends, typically not forming
stellate colonies
13
13a Valves symmetrical about the transapical plane i4
13b Valves asymmetrical about the transapical plane - OPEPHDRA
Fig. 43. Opephora Martyi, (k), cells 5-60u long, 4-8n vide; X 1000.
valve view
girdle views
Notes:
Frustules typically forming ribbon-like chains, rarely
solitary - FRAGILARIA
Fig.
Fragilaria arcus, (5), cells 15-150M long, k-J\i wide; 15-18
striae in 10u; cells swollen on the concave side near the
central area. X 1000. Abundant in the Delaware and
Columbia Rivers.
imiilTimiiiltiHlll
-—*«s^^
valve views
Notes:
-------
39
Fig. 1*5• Fragilaria brevistriata, ( 5 ), cells 12-28|i long, 3-5H vide;
striae short, 13-17 in 10u.
valve
view
var. trigibba
X 600
Notes:
valve
view
var. inflata
X 600
TTTT
1
ill
girdle
view
A
V
valve
view
X 1000
Fig. 46. Fragilaria capucina, ( 3 ), cells 25-100n long, 2-5u wide;
striae delicate, about 15 in lOu; clear central area.
X 1000. Abundant in northern waters.
valve view
valve view
var. roesolepta
girdle view
Notes:
-------
40
Fig. 47. Fragilaria construens, ( 5 }, cells ?-25n long, 5-12|i vide;
striae delicate, 1^-17 in 10|i; pseudoraphe broader in
central region. X 1000. Abundant in northern waters.
valve view-
girdle view
var. subsalina
•JrtW^W Vt^f
girdle view
Notes:
valve view
Fig. 48. Fragilaria crotonensis^ (3^5)^ cells 40-150|i long, 2-3u wide;
15-15 striae in 10u. X 1000. Widely distributed.
girdle view
valve view
Notes:
Fig. 49. Fragilaria inflata, (12), cells l8-50u long, 6-10fi wide,
X 12OO. In Great Lakes.
Ttm-rr
valve
view
girdle
view
Notes:
-------
Pig. 50. Fragilaria intermedia, ( 5 ), cells 15-60ji long, 2-5u vide;
9-13 striae in 10u; central area clear on one side only.
X 1000.
-TVTtTTTTTTTITTTTTTTTrnTTTr
valve view
23»
girdle view
Notes:
Fig. 51 • Fragilaria leptostauron, (12), cells 13-30H long, 10-l6fi
vide; striae coarse, 6-9 in lOfi. X 1000.
.Sr-g
i
valve views
girdle view
Notes:
Fig. 52. Fragilaria pinnata, { 5 ), cells 3-30n long, 2-6u wide;
striae coarse 10-12 in 10*1. X 1000. Widely distributed.
valve view
girdle view
Notes:
-------
Prustules typically solitary, sometimes forming stellate
colonies; striae often appearing as costae - SYNEDRA
Fig. 53- Synedra actinastroides, (5), cells 35-64^ long, 2-k\i
wide; striae short, marginal, lk in lOjx. X 580.
a-c, girdle views
d, valve view
Notes:
Pig. 54. Synedra acus, ( 5), cells 100-300u long, 5-6V wide; striae
12-14 in 10u,finer than S. ulna. X 500. Widely distributed.
valve view, var. angustissima
valve view
Notes:
valve view, var. radians
-------
Fig. 55- Synedra nana, ( 5 ), cells 50-°Ai long, l-2n wide; striae
very light, 25-30 in lOfj. X 1000. Widely distributed.
valve view
Notes:
Fig. 56. Synedra parasitica, (5 ), cells 10-25n long, 3-5P- wide;
striae delicate, somewhat radial, 16-19 in 10|u. X 1000.
Sometimes parasitic on Nitzschia sigmoides.
valve
Notes: views
S. parasitica var.
"~ subconstricta
Fig. 57. Synedra pulchella, (5 ), cells 33-150^ long, 5-8^ wide; about
12-15 striae in 10u (sometimes as many as 20); large clear
refractive central area. X 1000.
valve views
S. putchella
var. lanceolata var. var. naviculacea
form conatricta minuta
Notes:
-------
Fig. 58. Synedra rumpens, (5 ), cells 15-?0u long, 2-3n vide; 19-20
striae in 10n; central area variable or completely absent,
X 1000.
valve views
S. rumpens
var. familiaris
var. scotica
TTTIIimrtTTt
Notes:
var. fragilarioides
Fig. 59. Synedra tabulata, ( 5 ), cells 60-150ji long, 2-5u wide;
striae short, 10-l4 in 10^. May form chains. X 1000.
valve views
S. tabulata
var. fasciculata
Notes:
-------
Fig. 60. Synedra ulna, (5 ), cells 50-350fi long, 5-9u wide; striae
delicate, distinctly punctate, 8-12 (usually about 10)
in lOfJi; highly variable. X 600. Widely distributed.
girdle view, S. ulna
valve views, S. ulna
valve views
var. oxyrhynchus
=* -
var oxvrhvtichus
" * ^ .^ ' '
rona contracta
var. impressa
Notes:
-------
Fig. 6l. Synedra Vaucherlae, ( 5 ), cells 10-40^ long, 2-k\i wide;
12-16 striae in 10u; central area clear and thickened only
on one side. X 1000. Widely distributed.
- capitellata
, ,
*
valve vievs
valve views,
S. Vaucheriae
Notes :
Notes on other species of SYNEDRA.
-------
15a Raphe evident on at least one valve 16
15b Raphe not evident, concealed in a keel or wing 35
l6a Valves similarly ornamented, raphe on both valves 19
l6b Valves not similarly ornamented, raphe on one valve,
opposing valve with pseudoraphe, or with rudimentary
raphe near valve poles 17
17a Valves elliptical, never linear, sometimes bent along
the apical axis - COCOONSIS
Fig. 62. Cocconeis diminuta, ( 5 ), cells 7-15U long, 5-9^ wide, flat;
raphe less valve with 32 delicate striae in lOu; raphe-
bearing valve with 13 coarsely punctate striae in 10u.
X 1000.
valve valve
with raphe without raphe
Notes:
-------
Fig. 63. Cocconeis pediculus, (5 ), cells 15-5&V long, 10-37H wide,
strongly bent along the apical axis; valve with raphe has
16-18 distinctly punctate striae in 10|i; raphtless valve
with 15-1? striae in 10p, which are crossed by several widely-
spaced, undulating, longitudinal rows of coarse punctae.
X 1000. Widely distributed.
raphe-bear ing
valve
raphe 3 ess
valve
section through
transapical
plane; raphe-bearing
valve in ventral
position.
Notes;
Fig. 6U. Cocconeis placentula, (5 ), cells ll-70u long, 8-^Ou wide,
flat or only slightly curved; raphe-bearing valve with about
23 striae in 10u, rapheless valve with about 25 striae in
lOu. X 1000. Widely distributed.
raphe -bearing
valve
raphe leas
valve
Notes:
-------
Fig. 65. Cocconels scutellum, (5 ), cells 20-60p. long, 12-^Ofji vide,
flat. Rapheless valve vith coarsely punctate striae.
X 1000.
Rapheless valve
Notes:
raphe-bearing valve
Notes of other species of COCCONEIS.
-------
17b Valves not elliptical, usually linear, and usually bent
along the transapical axis •
18
l8a Valves symmetrical about the transapical plane, one valve
vith completely developed raphe, opposing valve with
pseudoraphe - ACHKAMTHSS
Fig. 66. Achnanthes brevipes, (5), cells 20-125*1 long, 12-30ji wide;
coarsely punctate. X 1000.
girdle view
Notes:
rapheless valve
raphe-bearing valve
Fig. 67. Achnanthes flexella, (11), cells 20-80M long, 10-26u wide;
sigmoid raphe. X 1500.
raphe-bearing valve
Notes:
rapheless valve
-------
51
Fig. 68. Achnanthes inflata, (5), cells 30-65n long, 10-l8u wide.
X 1000.
raphe-bearing valve
Notes:
rapheless valve
Fig. 69. Achnanthes lanceolata, ( 5 ), cells 5-kQ\i long, 4-10^ vide;
striae prominent, 13-17 in lOp.; central area of rapheless
valve with horseshoe-shaped spot. X 1500. Common in
Great Lakes.
raphe -tearing
valve
rapheless
valve
rapheless valve of
var. rostrata
Notes:
Fig. 70. Achnanthes minutissima, ( 5 ), cells 5-^0|i long, 2-k\i wide;
striae delicate, about 35 in 10u. Curved girdle view very
common. X 1500. Widely distributed.
raphe-bearing
valve
rapheless
valve
girdle view
Notes:
-------
Notes on other species of ACBNAWTHES.
l8b Valves asymmetrical about the transapical plane, one valve with
completely developed raphe, opposing valve with rudimentary
raphe near valve poles - RBDIOOSPHENIA
Fig. 71. Rhoicosphenia curvata, ( 5 ), cells 12-75u long, k-Q\i vide,"
curved and vedge-shaped in girdle view; 12-15 striae in
10n. X 1000. Widely distributed.
valve views
girdle view
Notes:
-------
53
19a Baphe rudimentary, short, near poles only - EUNOTIA.
Fig. 72. Eunotia pectinalis, ( 5 ), cells 40-l^Op. long, 5-10u vide;
arcuate in valve view, rectangular in girdle view; 7-12
striae in 10|i. X 1000. Common in soft waters.
valve views
E. pectinalis
var. ventralis
var. undulata
var. minor
var. minor
form impressa
Notes:
girdle view
E. pectinalis
* .".V.1
-------
19b Raphe fully developed, extending the length of the valves 20
20a Valves symmetrical about both the transapical and
apical plane 2k
20b Valves asymmetrical about either the apical or transapical
plane 21
21a Valves symmetrical about the transapical plane, asymmetrical
about the apical plane 23
21b Valves asymmetrical about the transapical plane, symmetrical
about the apical plane 22
22a Valve margins with longitudinal "shadow"-lines - GOMPBOMEIS
Fig. 73. Gomphoneis herculeana, (11), cells 30-136V long, 12-22p
wide; 9-12 striae in lOu; central area rounded with an
isolated puncta. X 1000.
valve view
Notes:
22b Valve margins lacking longitudinal "shadow"-lines - GOMPBOKEMA
Fig. 7^. Gomphonema abbrevlatum, (5), cells 7~3^U long, 2-6V wide;
19-22 striae in lOu. X 1000.
valve view
Notes:
-------
55
Fig- 75' Gomphonema acuminatum, (5), cells 20-70^ long, 5-llU vide;
10-13 striae in 10n; one isolated puncta in the central
area. X 10OO.
valve views
var. turris
var. coronata
Notes:
Fig. 76. Gomphonema angustatum, (5), cells lO-^U long, 5~9u wide;
9-1^4- striae in 10|i; one isolated puncta in the central
area; easy to confuse with G. parvulum. X 1000.
var. producta
valve views
Notes:
Fig. 77. Gomphonema constrictum, (5), cells 25-65ii long, 8-l^u wide;
1O-12 striae in 10^; one isolated puncta in the central
area. X 1000.
valve view
Notes:
-------
56
Fig. ?8. Gomphonema olivaceum, (12), cells 10-^Op long, 5-10n wide;
10-14 striae in lOfi; no isolated punctae in the central
area. X 1000. Widely distributed.
Notes:
valve views
girdle view
Fig. 79. Gomphonema parvulmu, (5), cells 8-30fi long, k-J\i wide;
1^-16 striae in 10u; one isolated puncta in the central
area. X 1000.
valve views
var. var.
subelliptica mlcropus
Notes:
-------
57
Notes on other species of GOMPHONEMA.
23a Valve faces parallel - CYMBflLTA
Fig. 80. Cymbella affinis, (5), cells 20-70p. long, 7-l6u vide;
9-12 striae in lOjij ventral median striae ending in an
isolated prominent puncta. X 1000.
valve views
Notes:
-------
58
Fig. 8l. Cymbella cistula, (5), cells 35-l80u long,15-36u wide;
6-9 striae in 10u; two or more prominant punctae in the
central area. X 1000.
valve view
Notes:
Fig. 82. Cymbella mexicanum, (l), cells 50-100u long, 20-^Ou wide;
central area with a prominant puncta; similar to C.
tumida, but striae have coarser punctae. X 800.
valve view
Notes:
Fig. 83. Cymbella prostrata, (5), cells 20-100u long, 10-30p wide;
7-10 striae in 10|i. X 1000.
valve view
Notes:
-------
59
Fig. 84. Cymbella sinuate, (5), cells 10-40n long, 4-9n wide;
9-11 striae in 10n; do not confuse with Achnanthes sp.
X 1000.
valve viev
Notes :
Fig. 85. Cymbella tumida, (5), cells 40-105H long, 15-23V- vide;
8-10 striae in 10n; central area with a ventrally placed
isolated puacta. X 1000.
valve view
Notes:
Fig. 86. Cymbella turgida, (5), cells 30-100 n long, 9-25^ wide; 7-9
striae in lOu; similar to C. ventrlcosa. "but larger
and with more conspicuous punctae. X 1000.
valve view
Notes :
-------
60
Fig. 87. Cymbella ventricosa, (5), cells 10-40n long, 5-12fi wide;
12-18 striae in 10»i; raphe straight. X 1000.
valve views
Notes:
Notes on other species of CYMBELLA.
23b Valve faces not parallel, both valve faces can "be seen in girdle
view - AMPHORA
A diagrammatic polar view of Amphora, (7).
-------
6l
Fig. 88. Amphora coffeaeformis, (5), cells 20-50u long, 10-18*1 vide;
16-25 striae in lOuj intercalary bands fine, about 21 in
10u. X 1000.
valve view
Notes:
girdle view
Fig. 89. Amphora ovalis, (5), cells 20-1^0|i long, 17-63U wide;
10-13 striae in 10u. X 1OOO.
girdle view-
Notes :
Notes on other species of AMPHORA.
-------
62
2k& Valves with elongate central or terminal nodules....
Valves without elongate central or terminal nodules.
25
26
25a Central nodule drawn out to at least half the length
of the valve - AMPHIPLEURA
Fig. 90. Amphipleura pellucida, (8), cells 50-l^Ofi long, 7-9U
wide; punctae delicate and difficult to see. X 1000.
valve view
Notes:
25b Central nodule drawn out less than half the length of the
valve - FRUSTULIA
Fig. 91. Frustulia rhomboides, (8), cells 50-l60u long, 20-30|i wide.
X 1000.
valve view
Notes:
-------
63
92. Frustulia vulgaris, (5), cells 30-?0n long, 10-13u wide.
X 1000.
valve view
var. capitata
Notes:
26a Valves with longitudinal "shadow"-lines or blank spaces 27
26b Valves without longitudinal lines or blank spaces 29
27a Transverse striae continuous, crossed by one or two
longitudinal "shadow"-lines paralleling valve margin - GALONEIS
Fig. 93« Gal one is amphisbaena, (5), cells 36-80u long* 20-30fi wide.
X 1000. Common in the Rio Grande River.
valve view
Notes:
Fig. 9^. Caloneis bacilium, (5), cells 15-^5u long, 4-9u wide;
can be mistaken for Stauroneis sp. X 1000.
valve view
Notes:
-------
Notes on other species of CALONEIS*
2fb Transverse striae discontinuous,interrupted by blank spaces
or"shadow"-lines 28
28a Longitudinal "shadow"-lines or blank spaces near valve
margins; ends of raphe near central nodule usually turned
in opposite directions - HE3DIUM
Fig. 95- Heidium dubium, (11), cells 30-46fi long, 10-16V wide.
X 1000.
valve view
Notes:
-------
65
Fig. 96. Neidium iridis, (ll), cells 60-100u long, 23-24u vide,
X 1000.
valve view
var. fizma
Notes:
Notes on other species of NEIDIUM
28b Longitudinal "fliadow"-lines or blank spaces scattered, central
pores of raphe near central nodule turned if at all in the
same direction - ANOMOEONEIS
-------
66
Fig. 97 • Anomoeoneis exilis, (11), cells 10-35U long, k-6v wide.
X 1000. Abundant in the southern Colorado River.
valve viev
Notes:
Fig. 98- Anomoeoneis sphaerophora, (8), cells lfO-80p long, 13-20ji
vide. X 1000.
valve view
Notes:
Notes on other species of ANOMOEONEIS
-------
6?
29a Valve and raphe sigmoid 30
29b Valves and raphe not sigmoid 31
30a Valves vith transverse and longitudinal striae - GYROSIGMA
Fig. 99. Gyrosigma Kutzingii, (5), cells 60-120u long, 5-15u vide,
X 1000.
''
lli
&i*i&:.:&ii^^
valve viev
Notes:
Fig. 100. Gyrosigma scalproides, (5), cells 25-70u long, 5-10u
vide. X 1000.
iCT;i;0aipi^
i;;':^;"''k;^:i"1;-;^fr"v"Tf:^!? 'ffi-'^vK.'-^'S
iS^^
valve viev
Notes:
Valves vith transverse and oblique striae - PLEUROSICTdA
-------
68
Fig. 101. Pleurosigna delicatulum. (10), cells 60-100u long, 10-15p.
wide.
valve view
Notes:
valve view
XL300
31a Frustules with septae - MASTOGLOIA
Fig. 102. Mastogloia Braunii, (5), cells 35-95H long, lk-27v wide.
X 1000.
valve view
Notes:
girdle view
31b Frustules without septae
32a Raphe enclosed in a siliceous rib - DIELONEIS
-------
69
Fig. 103. Diploneis interrupta, (5), cells 30-80n long, 7-15n wide.
X 1000.
valve view
Notes:
Fig. 104. Diploneis Smithii, (5), cells 8-20u long, 5-10n wide,
X 1000. Abundant in the southwest.
valve view
Notes:
Notes on other species of DIPLONEIS.
-------
70
32b Raphe not enclosed in a siliceous rib,
33
33a Valves vith chambered striae appearing as heavy costae; valves
usually with parallel sides and broadly rounded poles - P33MULARIA
Fig. 105. Pinnularia borealis, (5), cells 20-110n long, 8-l8u wide;
4-6 striae in 10u. X 1000.
valve view
Notes:
Fig. 106. Pinnularia gibba, (5), cells 50-l^Ou long, 7-l8u wide;
wide axial area and broad capitate ends. X 1000.
!^jjSi^m^^m
rENglEM
valve view
Notes:
33b Valves with striae appearing otherwise.
Central area extending laterally to the margins of the valve,
striae absent along lateral margins of the central area - STAURONEIS
-------
71
Fig, 10?. Stauroneis crucicula, (l), cells 30-34»Ji long, 8-12u vide;
striae parallel to the branches of the stauros, 2k in
X 800.
valve view
Notes:
Fig. 108. Stauroneis phoenicentron, (ll), cells JO-325U long, 16-53M
vide; striae distinctly punctae, 12-20 in 10(i. X 1000.
valve viev
Notes:
Central area not extending to the nargins of the valve, striae
present along lateral margins of the central area - NAVICULA
-------
72
Fig. 109. Navicula fracillum, (5), cells 20-80u long, 10-20fi vide;
central area rounded not quadrangular; middle striae, 12
in 10u, 18-20 striae in lOu near the poles; do not
mistake for N. pupula. X 1000.
Notes:
Fig. 110. Navicula canalis, (2), cells 10-27n long, 3-5u vide;
16-18 striae in 10n. X 1000.
valve viev
Notes:
Fig. 111. Navicula confervacea, (4), cells 10-28n long, 5-8|i vide;
15-22 striae in 10u; may toe found in chains like Fragilaria;
raphe can be seen in girdle viev. X 1000.
valve vievs
girdle viev
Notes:
-------
73
Fig. 112. Navicula contenta, (5), cells 5-15U long, 2-3^ wide.
X 1500. May reach high numbers in southeastern brackish-
water stations.
valve views
N. contenta
Notes:
form gar
-------
Fig*
Navicula cuspidata, (5), cells 50-170p. long, 17-37ii wide;
striae fine, 11-19 in lOvu X 1000.
valve views
N. cuspidate,
var. ambigua
Notes:
var. Heribaudi
Pig. 115. Navlcula exigua, (5), cells 10-35ti long, T-15u wide;
12-1^ striae in ICHu X 1000.
valve view
Notes:
-------
75
Fig. 116. Navicula gastrum, (5), 25-60n long, 12-20fi wide; 8-10 striae
in 10u. X 1000.
valve view
Notes:
Fig. 11?. Navicula hungarica, (5), cells 10-30p long, 4-7u wide;
8-10 striae in lOpi. X 1000. Abundant in the southwest.
valve views
N. hungarica var. capitata
Notes:
-------
Fig. 118. Mavicula mutica, (5), cells 10-*K)u long, 7-12|i wide; 15-20
striae in 10n; single eccentric puncta in the central area.
X 1500.
valve view
Notes:
Fig. 119. Nayicula peregrina, (5), cells 50-150u long, 10-30ji wide;
5-6 striae in 10n. X 1000.
valve view
Notes:
Fig. 120. Navicula pupula, (5), cells 20-^Ou long, 7-lOji wide; 22-26
striae in 10n; no striae at the poles; central area
quadrangular; can mistake for N. bacillum. X 1000.
|
Notes:
valve view
var. capitata
-------
77
Fig. 121. Navicula pygmaea, (5), cells 10-4|?u long, Q-2k\i wide;
about 26 striae in 10n. X 1000.
valve view
Notes:
Fig. 122. Havicula radiosa, (5),cells
12 striae in 10u. X 1000.
long, 8-20|i wide; 10-
valve view
Notes:
Fig. 123. Navicula Reinhardtii, (5), cells 35-70U long,
wide; 7-9 striae in 10u. X 1000.
valve view
Notes:
-------
78
Fig. 124. Havicula tripunctata, (5), cells 35-60n long, 6-10u wide;
11-12 striae in 10n; central area quadrangular. X 1000.
valve view
Notes:
Fig. 125. Navicula viridula, (5), cells 36-80u long, 10-15|i wide;
10 striae in 10|i; central area rounded. X 1000.
valve view
Notes:
Fig. 126. Navicula Zanoni, (6), cells 27-60u long, 7-llu wide;
13-12*- striae in 10p; can "be confused with _IL
valve view
X 1000
Notes:
valve view
X2000
-------
79
Notes on other species of NAVICULA.
-------
80
35a Keel elevated into a lateral "wing" or flattened on the
valve surface
35b Keel elevated into an axial "wing" extending along the
central axis of the valve
37
36
36a Keel sigtnoid, usually seen in girdle view (hour-glass-shaped),
frustule twisted along the longitudinal axis; girdle broad with
many longitudinal folds - AMPHIPROBA
Fig. 127. Amphiprora alata, (5), cells 40-l60p long, 20-60p. wide;
striae fine,punctae discernable. X 1000. Abundant in
the southwest.
girdle view
Notes:
Fig. 128. Amphiprora paludosa, (5), cells 30-130*1 long, 15-50U wide;
striae fine, punctae not discernable. X 1000. Abundant
in the southwest.
girdle view
Notes:
-------
Fig. 129. Amphlprora ornata, (5), cells 35-115U long, 15-*K)(i wide;
appears to be twisted in girdle view. X 1000.
girdle view
Notes:
Notes on other species of AMPHIIRORA
-------
82
3&> Keel not sigmoid, girdle simple, not folded, keel eccentric -
TROPIDONEIS
Fig. 130. Tropidoneis lepidoptera, (9), cells ifO-lOOp long, 10-
wide; girdle view easily confused with Amphiprora sp.
X 2000.
valve views
girdle view
Notes:
-------
83
Valves vith numerous internal transverse ribs extending
completely across the valve
3?b Valves without internal transverse ribs,
38
1*0
38a Raphe and axial area with "V"-shaped medial extension; with
transverse septae appearing as costae and alternating with
two or more rows of punctae - EPITHEMIA
Fig. 131 • Epithemla sorex, (12), cells 20-65u long, 8-15u wide;
5-7 septae in lOu.; 12-15 punctae rows in lOu.. X 1000,
valve view
girdle view
Notes:
Fig. 132. Epithemia turgida, (12), cells 60-220u. long, 15-lbV wide;
3-5 septae in lOu, 7-9 punctate rows in lOu. X 1000.
valve view
girdle view
Notes:
-------
Notes on other species of EPITHEMIA.
38b Raphe and axial area without a "V"-shaped medial
extension
Raphe canal vith pores, valves symmetrical to longitudinal
axis - DENTICULA
39
Fig. 133. Denticula elegans, (5), cells 15-kQ\i long, 5-7u wide;
3-5 transverse ribs in 10u; 15-17 striae in 10u.
valve view
girdle view
Notes:
39b Raphe canal without pores, valves asymmetrical to the
longitudinal axis - RHOPALODIA
-------
85
Fig. 13^. Rhopalodia gibba, (12), cells 35-300|-L long, 6-30^ wide;
6-ti costae in lOji; 12-l6 punctate rows in
Notes:
girdle view
X 1200
valve view
X 750
section of valve
X 2000
Fig. 135. Rhopalodia gibberula, (5), cells 25-80u long, 12-40u
wide; 3-4 ventral costae in 10u, 14-17 punctate rows
in lOpi. X 1000.
valve view
var. van Heurckii
Notes:
girdle view
-------
86
Notes on other species of RHOPALODIA.
Valves with lateral keel extending along both margins of
each valve
Valves vith lateral keel extending along one margin of
each valve
Valve face longitudinally undulate, undulations conspicuous
in girdle view; with "broad, short, peripheral costae; longi
tudinal pseudoraphe present - CJYJ4ATOPLEURA
Fig. 136. gymatopleura solea, (5), cells 30-SOOu long, 1
wide. X 750.
valve view
girdle view
Notes:
-------
8?
Valve face not longitudinally undulate; valve face with longi-
tudinal folds vhich appear as heavy costae, folds not conspic-
uous in girdle view; girdle view rectangular, navieuloid,
wedge -shaped ,or sigmoid; valve view linear, elliptical, ovate,
or spirally twisted - SURIRKT.TA
wing
Diagrammatic cross-section
of Surirella, (7)
Fig. 137. Surirella angustata, (5), cells l8-70|a long, 6-20u wide;
6-9 longitudinal folds in 10n; striae delicate, the
only "common" Surirella that is transversely symmetrical,
X 1000.
rn 1.1.! mil
valve view
girdle view-
Notes :
Fig. 138. Surirella brightwellii, (7), cells 30-50\i long, 15
wide; longitudinal folds not extended to the center;
border raised. X 1000. In Arkansas and Colorado Rivers.
valve view
Notes:
-------
Fig. 139. Surirella ovalis, (5), cells 20-100u long, lO-^Ou vide;
1.5-5 longitudinal folds in lOu; striae distinct, about
16 in 10u. X 1000.
valve view
girdle view
Notes:
Fig. 1^0. Surirella ovata, (5), cens 10-?0p long, 8-23*1 wide;
longitudinal folds extend to the center, k-J in 10p;
striae fine but distinct, 16-20 in lOfi. X 1000. Conmon
in the southwest.
valve views
Notes:
-------
Fig.
89
Surirella striatula, (5), cells 80-260u long, 50-l60u
wide; longitudinal folds very wide, 0.6-1.2 in lOu;
small distinct protruberances on the outer edge
of the longitudinal folds . X ^00.
valve view
Notes:
Keels eccentric to the median axis, diagonally opposite;frustules
rhombic in cross section, transversely striate, punctate or
lacking ornamentation; a row of circular pores ("carinal dots")
developed within the keel; frustules usually solitary but occasion-
ally forming irregular ribbon-like chains or stellate colonies -
NTTZSCHIA
Diagrammatic cross-section of Nitzschia, (7)
-------
90
Fig. 1^2. Nitzschia acicularis, (5), cells 40-150ji long, 3-^p. wide;
carinal dots small, 17-20 in 10n; frustule delicate.
X 1000.
valve view
Notes:
Pig. 1^3. Nitzschia amphibia, (5), cells 12-50ji long, 3-5u vide;
7-9 carinal dots in 10n; striae vith distinct jjunctae,
15-19 in 10u. X 1000.
valve views
A JUS^
\
Notes:
carinal dot
Fig.
Nitzschia angustata, (5), cells 20-110ji long, 5-
wide; carinal dots indistinct; 12-18 striae in lOji
X 1000.
valve view
Notes:
-------
Fig.
91
Nitzschia apiculata, (5), cells 20-50u long, 5-8n wide;
differs from N. hungarica by having indistinct carinal
dots; about 17-20 striae in 10u. X 1000. Common in
the Arkansas River.
valve view
Notes:
Fig. 146. Nitzschia denticula, (5), cells 10-lOOu long, 3-8n vide;
carinal dots rib-like and extended, 5-8 in 10|i; 1^-20
striae in 10p. X 1000. In southwest.
valve view
Notes:
Fig. 147. Nitzschia dissipata, (5), cells 15-?0u long, k-J\i wide;
keel slightly eccentric, 6-8 carinal dots in 10u; striae
indistinct. X 1000.
valve view
Notes:
-------
92
Fig. M. Nitzschia elliptica, (6), cells 13-22n long, 5-6V wide;
carinal dots small, 16-20 in 10|i; striae indistinct;
frustule delicate. X 1000. At tines abundant in the
Arkansas River.
A
A
\J
J
valve view
Notes:
Fig. 1^9. Nitzschia filiformis, (5), cells 20-100n long, k-6*! wide;
8-11 carinal dots in 10u; about 36 striae in lOu. X 1000.
valve view
girdle view
Notes:
Fig. 150. Nitzsehia fonticola, (5), cells ll-30u long, 2-k\i wide;
12-15 carinal dots in 10p; striae fine, but distinct,
28-30 in 10u. X 1000. In the Snake River.
valve view
Notes:
-------
93
Fig. 151. Nitzschia holsatica, (5), cells 20-55p. long, 1.5-2^
wide; 1^-17 carinal dots in 10n; striae fine; indistin-
guishable from other forms unless in the stellate colony.
X 1000. Common in the southwest.
Colony
Notes:
Fig. 152. Nitzschia hungarica, (5), cells 20-110 \i long, 6-941 vide;
carinal dots distinct, 7-9 in lOuj 16-20 striae in 10u.
X 1000. Abundant in the southwest.
valve view
Notes:
Fig* 153. Nitzschia lacunarum, (5), cells 65-75H long, 6-8ji wide;
carinal dots small, 7-8 in lOu; about 30 striae in 10u.
X 1000.
valve view
Notes
-------
Fig. 15k. Nitzschia linearis, (5), cells 70-l80ji long, 5-6V wide,-
8-13 car Trial dots in lOji; striae fine, 28-30 in
X 1000. Common.
valve view
girdle view
Notes:
Fig. 155. Nitzschia Lorenziana, (5), cells 65-l60u long, 3-5U videj
6-8 carinal dots in lOji; striae distinct, 17-19 in
X 1000.
valve view
Notes;
Fig. 156. Nitzschia palea, (l2),20-65u long, 2-5M vide; 10-15
carinal dots in lOu; striae very fine, 35-^40 in 10^.
X 1000. Widespread.
valve view
Notes:
-------
95
Fig. 157. Nitzschia paradoxa, (5), cells 60-100u long, k-6v wide;
6-6 carinal dots in 10|i; 20-25 striae in lOp,; do not
confuse with N. dissipata.
valve view
X 1000
Notes:
colony in
girdle view
X 500
Fig. 158. Nitzschia parvula, (5), cells 20-40^ long, 3-6*i wide;
5-8 carinal dots in 10u; striae fine, 30-35 in 10u.
X 1000.
valve view
Notes:
-------
Fig. 159-
96
Nitzschia sigma, (5), cells 50-70n long, 4-15M wide;
7-12 carinal dots in 10n; 22-30 striae in 10u. X 1000.
valve view
Notes:
Fig. 160. Hitzsehia sigmoidea, (3), cells l60-500u long,
wide; 5-7 carinal dots in !OM; striae distinct, 23-26
in lOfi.
girdle view
X 500
valve view
X 1000
Notes:
Fig. l6l. Nitzschia sinuata, (5), cells 20-50u long, 5-8n wide;
5-6 carinal dots in 10n; about 18 striae in 10fJ. X 1000.
valve views
Notes:
-------
97
Fig. 162. Nitzschia tryblionella, (5), cells 30-100n long, 15-26y.
vide; about 6 carinal dots in 10u; 5-7 rits in 10|i.
X 1000.
valve view
var. vlctoriae
Notes:
Notes on other species of NITZSCHIA
-------
98
Keels eccentric to the median axis, directly opposite;
frustules rectangular in cross section, transversely striate
or punctate, capitate ends, medianly constructed - HAJETZSCHIA
Diagrammatic cross-section of Hantzschla, (7)
Fig. 163. Bantzschia amphioxys, (5), cells 20-lOOti long, 5-lOu wide;
carinal dots not elongate, 5-8 in 10u; 13-20 striae in
lOu. X 1CXX>. In the southwest.
valve view
Notes:
Fig. loll-. Bantzschia virgata, (5), cells 20-150u long, 6-12u wide;
carinal dots elongate, 4-6 in 10u; 9-15 striae in 10u.
X 1000.
valve view
Notes:
-------
PHS Water Pollution Surveillance System
SAMPLING STATIONS
2 Stations in Alaska not shown
Anchorage and Fairbanks
8-64
-------
Occurrence of Four Most Abundant Diatom Species
OCCURRENCE AS ONE OF THE FOUR
MOST ABUNDANT SPECIES OF DIATOMS
• - 1 to 25 PERCENT OF THE TIME
A - 26 to 50 PERCENT OP THE TIME
A - 51 to 75 PERCENT OF THE TIME
jK - 76 to 100 PERCENT OF THE TIME
RIVER STATION
ANIMAS CEDAR HILL
APALACHICOLA CHATTAHOOCHEE
ARKANSAS 1'ENDLETON FERRY
PONCA CITY
COOLIDCE
CHATTAHOOCHEE COLUMBUS
ATLANTA
COLORADO YUMA
PAGE
LOMA
COLUMBIA CLATSKANIE
BONNE VILLE
PASCO
WINATCHEE
DELAWARE PHII.ADKLPHIA
MARTINS CREEK
GREAT LAKES BUFFALO
MILWAUKEE
I.I Mini 1
DULUTH
GARY
PORT HURON
HUDSON POUCHKEEPSIE
ILLINOIS PEORIA
KANAWIIA W1NF1EI.II
KLAHATH KENO
LITTLE MIAMI CINCINNATI
MISSISSIPPI E. ST. LOUIS
(upjier) BURLINGTON
DUBUQUC
ST. PAUL
(lowr) NEW ORLEANS
DELTA
WEST MKMI'lll::
CAPE GlRAHDEAll
• , :' r, i ST. LOUIS
KANSAS CITY
ST. JOSEPH
OMAHA
YANKTON
BISMARCK
WILLISTON
OHIO CAIRO
EVAMIVILLC
CINCINNATI
HUNT1NCTON
EAST LIVKUI'inil
POTOMAC GREAT FALLS
WILLIAMS PORT
lll.li (north) GRAND FORKS
RED (South) ALEXANDRIA
DtNISOU
RIO GRANDE lUOWH'.V 1 U.r.
EL PASO
ST. LAURENCE MASSENA
SAVANNAH PORT UENTWORTH
NORTH AUGUSTA
SCHUYLKILL PHILADELPHIA
SNAKE WAUAWAI
WISER
TENNESSEE CHATTANOCXJA
YELLOWSTONE SIDNEY
1 ,
X S . 3 " '.
-A O -i O H i -it
Wlfl-g -• TJ -r« .0 W JJ C
a *3 a -ri « > M p u i
H 1 d • ti M i 4 & •< !
•fl S. * ri 3 J5 JS
j| P p S 5 * 1 • "* •
4J H IJ rt O • Q. <** D • <
C 0. CL, L. j, J ^ tt 0 I
3 -H rl O 5 -< 3 B u O .
Jr^^j 3 S 3 B B .
I
|
i /
'
'
,.'
> 4
1
1
3 1 1 j, 3
« ep -H u w M '
•n it C x: • O u«
2*4 • •"! * 4-
!• y 1 it ^ a -H c
ago 'MI * "
u C — * t> u • u
4 U «* 1 5 ft- « <
J3 .3 3 3^3 3 j
tl U « U V « 11 i
a o o o o o a '
u u u u u u u i
XXX X X X X !
•
X
'•'
He
i
T
i
f
1
T
•
4
i
>
(.JL,
•
t
.
I
5.2 !
no i-f h n r
,8 ** S g e
*f B ? 1
S «
. s a s a •
,ilH!
j
2 o
3 B • a
!U M i a •
u e 3 e 3 •
H .tH «d • «•] H B • t
"fillsllSlil
S ^ 1 . « ^ a a .3 3 s :
I
q
•
i
'^
|,
^
,
i
i
'
!>
B
|
• .
I
' » !
i
i
:
•
i I - S,
8 1 4 ^ 3
? I 5 Ti 3 S
d 5 3 f S 1
o a g a Jj c
^ 1 -H
f 1 1 i s s
, "8. 4 S 3 6 j
•B B M C r-l r-
T
-
=
1
•
i
fj
1
,
|
|
i
J
±
^
!
^
, ,
i
J
:
.
.
•
i
,
-------
Occurrence of Four Most Abundant Diatom Species
OCCURRENCE AS ONE OF THE FOUR
MOST ABUNDANT SPECIES OF DIATOMS
. - 1 to 25 PERCENT OF THE TIME
A - 26 CO 50 PERCENT OF THE TIME
A - 51 to 75 PERCENT OF THE TIME
tl - '6 to 100 PERCENT OF THE TIME
RIVER STATION
ANIMAS
APALACHICOLA
ARKANSAS
CHATTAHOOCKEE
COLORADO
COLUMUIA
GREAT LAKES
HUJ)SON
ILLINOIS
KANAUHA
KLAMATH
LITTLE MIAMI
MISSISSIPPI
(upper)
RED (North)
RED (South)
ST. LAURENCE
SAVANNAH
SCHUVUtlLU
SNAKE
CEDAR HILL
CHATT/IHOCCHEE
PENDLETON FERRV
PONCA CITY
COOLIDGE
COLUMBUS
ATLANTA
YUMA
PAGE
LQMA
CLATSKAHIE
I10NBEV1LLE
PASCO
WE IATCH1 i
PHILADELPHIA
MARTINS CREEK
BUFFALO
Mil HA . -.1
DETROIT
DULUTH
GARY
SAULT STE. MARIE
PORT HURON
POUCHKEEPSIE
PEORIA
UINFIELD
KENO
CINCINNATI
E. ST. LOUIS
DUBUOUE
ST. PAUL
NF.W OHLliANS
DELTA
WEST MEMPHIS
CAPE GIRARDEAU
ST. LOUIS
KANSAS CITY
ST. JOSEPH
OMAIIA
YANKTON
|] MARI »
UILLISTON
CAIRO
EVANSVILLE
CINCINNATI
HUNTINGTON
EAST LIVERPOOL
GREAT FALLS
WILLIAMS PORT
GRAND FORKS
ALEXANDRIA
INDEX
DENISON
BRUUNSV1LLE
LAREDO
EL PASO
PORT WENTWOKTH
NORTH AUGUSTA
I'llIUMlELPHIA
WAWAWA1
WEISER
CHATTANOOGA
ii
•
'
1
:
<4
1 i
"
.'
;
: :
1 4
' I
r
;
i
:
•
i
1
i
1
i
i
,
•
*>
'
:
a
.
•r
1 S
-
•
4
'
.
1
•;
4.
!
1
3
',
!
.
i
1
a
:
i
•n
S
.
. 4
J
/
,
.
L
L_
K
,
'
c
i
•
n
i-
E
'
1
.
•
• ,
:
•
,
'
:
Z
'
,
;E
M
/
..
.
•
1
1
•
1
.
•
z
.
.
•
•
z
1
T-
£
4
.
•
£
{
1
•r
7
1
J
•
.r
X
|
,
*
.
,
IJ
•<-
2
•
•
|
J
i
.
:
V
:
It
c
l
.
u
i
j
.
E
u
(
•
j=
i
!
i
i
:
3
U
:
:
a
::
ai
• '
------- |