Bull . Natn. Sci. Mus., Tokyo. Ser. B, 24( I). pp. 1- 13 , March 23, 1998

Studies on Planktonic Blue-green Algae 8.
Anabaena species with twisted trichomes in Japan
Masayuki Watanabe
Department of Botany, Nati onal Sc ience Museum . Tsukuba, 305- 0005 , Japa n

Abstract One new and e leven prev ious ly known spec ies of the genu s Anabaenawith tw isted trichom es Anabaena circinalis, A. crassa, A. jfos-aquae, A. lemmermannii , A. mendotae, A. minispora sp. nov., A. mucosa , A. oumiana , A. pseudocompacta, A. reniformis, A. spiroides, and A. ucrainica, have bee n re ported to ex ist in
many water bodies fro m Hokkaido, down to Tottori and Hyogo Prefectures in western Honshu , with descripti ons a nd illustra ti ons.
Key words:

Anabaena, plankton , blue-g reen algae, Cya nophyta , taxonomy.

Though many a uthors have reported finding A. spiroides and its vari ety crassa indifferent locations throughout Japan, in many cases they have not me ntioned anything
abo ut akinete morphology (U mezaki & Watanabe, 1994 ). Many a uthors of those reports must have used such taxo nomic names as a general te rm for the Anabaena
forming spiral trichomes. Through hi s studi es of planktonic blue-green algae inJapan , the present author has become acq uainted w ith different types of Anabaena in
cel l, akinete a nd coil morpho logy among the coiling spec ies. In thi s paper the author
describes and com pares the coiling spec ies.
In their " Illu stration s of the Japanese Fresh-water Algae", Hirose and Hirano( 1977) recorded 28 taxonomic names in the genus Anabaena from Japan. Thi s includes four planktonic species with twi sted trichomes: A. circinalis, A. crassa (as A.
spiroides var. crassa) , A. mendotae (as A. spiroides var. treleasii) , a nd A. spiroides.
Niiyama ( 1992) studi ed planktonic Anabaena of Japan with culture material s of TAC(T sukuba Algal Collection), National Science Museum as well with her original isolates which were also added to the TAC. She reported seven Anabaena species andadded two species with twi sted trichomes, A. lemmermannii a nd A. reniformis to theJapanese flora . Recently, the present auth or recorded A. ucrainica and a new spec ies
A. oumiana through a stud y of bloom-forming Cyanophytes in Lake Biwa, Shiga Prefecture (Watanabe, 1996). He also recorded A. mucosa (Watanabe, 1998) and a new
species A. pseudocompacta (Watanabe, 1996a) from Lake Inba-numa in C hiba Prefecture.
In thi s paper the author proposes one new spec ies of Anabaena which is characterized by its formation of wide co il s and spherica l, comparatively sma ll er akinetes.

2

Masayuki Watanabe
Table I.
Specimen no.
or C ulture no .

Specimens and cultures used in this study.

Locality

Date of collect.

Co llector

50102
50172

L. Akan
L. Akan

1966- 7- 14
1966-8--4

Watanabe
Watanabe

51588
52803
52807
52823
53621
53626
53658
53679
53685
(A-20)
53716
53750
53844

L. Kasumigaura
L. Koyama-ike
L. Suigetsu
L. Kutsuzawa
L. Tega-numa
L. Toro-ko
L. Biwa-ko
L. Sagami-ko
Sikata-futago pond

1978- 7- 25
1984-9- 7
1984- 9- 8
1984- 9- 12
1989- 9- 12
1990- 8- 28
1994- 8- 22
1990- 8--4
1990- 9- 16

TAC436

L. 1nba-numa
L. Koya-ike
L. Sagami-ko
L. Hime-numa
L. Sagami-ko
L. Kasumigaura
L. Higurasi-ike
L. Akan

1995- 10- 14
1996- 7- 26
1997- 10- 16
1969- 8- 18
1990- 7- 16
1991 - 6-25
1992- 9- 19
1990- 8TAC437

L. Akan

1990- 8

Watanabe
Watanabe
Watanabe
Watanabe
M. F. Watanabe
Watanabe
IchisePark
Kato(Niiyama cult.)
Watanabe
KimuraWatanabeloriya & Haga
TanakaWatanabe
Saito
Watanabe(Niiyama cult.)
Watanabe(Niiyama cult.)

Species name

A. mendotae
A. mendotae,
A. circina/is
A. flos-aquae
A. spiroides
A. flos-aquae
A. crassa
A. pseudocompacta
A. mucosa
A. oumiana
A. ucrainica
A. reniform is
A. minispora nov. sp.
A. reniform is
A. mucosa
A. mucosa
A. ucrainica
A . .flos-aquae
A. mucosa
A. crassa
A. lemmermannii

Materials and Methods
The sources of the materials used in this study are shown in Table 1. A large partof the observations and measurements were done with natural samples, however cultured materials were also supplementally used, especially for observations of
akinetes. The specimens were deposited in the herbarium of the National Science
Museum in Tokyo (TNS) and the cultures were maintained in the stock room of the
Botany Department in the National Science Museum in Tsukuba (TAC, Tsukuba
Algal Collection).

Observations and Discussion
1.

Description of species
In this paper three species with irregularly twisted trichomes and eight species

Anabaena species w ith twi sted trichomes in Japan3

with more or less regularly coiled trichomes are reported. The latter group are divided further into two subgroups, one of which forms spherical akinetes and the otherelongated ones. In the following description the species in each subgroup arearranged from smallest to largest in cell size. Distribution in Japan is based on specimens examined during this study and by selected references from " Enumeration of
the Cyanophyta of Japan" by Umezaki & Watanabe ( 1994).

Irregularly twisted forms
Anabaenafios-aquae Brebisson ex Bornet & Flahault
Figs. 1- 3.
Trichomes free-floating , irregularly twisted, forming floccose colonies, sometimes forming somewhat irregular coils, without a mucilaginous sheath. Cells spherical or barrel-shaped, 5- 6 pm broad. Heterocytes spherical, 5- 6.5 J..Lm broad. Akinetes
remote from heterocytes, cyl indrical, with rounded ends, slightly curved, 9 J..Lm broad,l8J..Lm long.
Distribution: Sarobetsu, Lake Akan, Lake Abasiri , Kiritappu , Sapporo (Hokkaido); Tsugaru-12-ko, Hirosaki (Aomori Pref.); Oze (Gunma Pref.); Lake Kasumigaura(Ibaraki Pref.); Lake Inba-numa (Chiba Pref.); Lake Suwa, Kuwabara (Nagana Pref.);
Lake Mikata (Fukui Pref.); Lake Biwa (Shiga Pref.); Lake Koya-ike (Osaka Pref.).

Anabaena mendotae Trelease
Figs. 4-5.
Syn. Anabaena spiroides var. treleasei Born. & Flah.
Trichomes free-floating, irregularly twisted, forming floccose colonies, sometimes forming somewhat irregular coils, without a mucilaginous sheath. Cells barrelshaped or cylindrical, 3- 5 J..Lm broad, 4-12 J..lm long. Heterocytes barrel-shaped to ellipsoidal 4-8 J..lm broad, 5.2- 10 J..lm long. Akinetes cylindrical , with rounded ends,
4.5- 8.5 J..lm broad, 15--40 J..lm long.
Distribution: Nemuro, Sarobetsu, Lake Akan, Sapporo (Hokkaido); Sarusawaike pond (Nara Pref.).
This spec ies was originally described from Lake Mendota, Wisconsin (Trelease,1889) and recorded for the first time in Japan by Negoro (as Anabaena spiroides var.
treleasei, 1937) at Lake Akan, where the alga was found abudantly together with
Ceratium sp. and Asteronella sp. The alga is di stributed widely in Hokkaido andflourish in the northern part of Japan.
Anabaena lemmermannii P. Richter
Fig. 6.
Niiyama, Jpn. J. Phycol. (Sorui), 44 : 2, f. 9, 10.
Trichomes free-floating, irregularly twisted, forming floccose colonies. Cells
spherical , hemi spherical, ellipsoidal, 4- 6 J..lm broad, 2.5- 7 J..lm long. Heterocytes almost spherical , 5- 6 pm broad, 5- 7.5 J..Lm long. Akinetes cylindrical, with rounded
ends, more or less curved, attaching at one or both sides of the heterocytes, one tothree in series, 8.5- 11 .5 J..lm broad, 13.5- 24 pm long.

Masayuki Watanabe

4

.

3

,.,..,

-~··

...

·~

.·

Figs. 1- 6. I, A.flos-aquae (L. Suigetsu) ; 2, A. jlos-aquae (L. Kasum igaura); 3, A. j/os-aquae (L.
Suwa); 4, 5, A. mendorae (L. Aka n); 6, A. /emmermannii (L. Akan); 1-5, X200, 6, X400.

A record of this species in Japan is based only on cultured materials (TAC 437,438) isolated from a plankton sample which was collected in Lake Akan by the present author in August 1990 (Niiyama, I.e .).

Anabaena speci es with twisted trichomes in Japan

5

Coiled forms'species with spherical akinete'

Anabaena reniformis Lemmermann emend. Aptekarj
Figs. 7, 8, 26
Niiyama, Jpn. J. Phycol. (Sorui) , 44: 2, f. 14. 1996.
Trichomes free-floating, regularly twisted, solitary or densely aggregated. Cells
spherical to slightly elongated, 4.1 - 5.1 pm broad, 2.7- 5.4 pm long. Heterocytes
spherical to slightly elongated, 4.6- 5.7 pm broad, 5.1 - 6.9 pm long. Akinetes spherical, attaching usually at the both sides of heterocytes, 8.2- 11 pm broad. Coils regularly twisted, closely contracted, 15.5- 17.9(- 21.7)pm broad, 4.1 - 6.1 pm apart.
Distribution: Lake Koya-ike (Osaka Pref.); Shikata-futago pond (Hyogo Pref.).
This alga was described for the first time by Lemmermann ( 1898) in Germany
without an observation of akinetes. Aptekarj found the alga in some locations around
Dniepurpetrovsk, Ukraine and emended the species by adding morphological observations of akinetes in 1927. The time alga was found in Japan was in a plankton sample collected at Shikata-futago pond in September 1990. Dr. Yuko Niiyama isolated
the alga and soon added two cultures to TAC. She made precise observations and reported the alga (Niiyama, I.e.). Recently the alga was found again in a water-bloom
sample from Lake Koya-ike, which is located about 50 kilometers east of Shikata-futago pond and several kilometers west of ltami Air port in Osaka Prefecture. Professor Yukio Kimura of Mukogawa Women's University sent the specimen to the present
author for identification. According to Prof. Kimura the habitat of the alga is highly
eutrophicated and the alga is found to be the main component of water-bloom together with Anabaenaflos-aquae, Arthrospira maxima and some Microcystis species.
Anabaena oumiana M. Watanabe
Figs. 9, 10, 27
Watanabe, Bull. Natn . Sci. Mus. , Ser. B (Botany) 22: 3, f. 5- 7, 14, 15, 19, 21,
1996.
Trichomes free-floating, solitary, more or less regularly coiled, covered withthick mucilage. Coils 28-46 pm broad, I 0-20 pm apart. Cells spherical or barrelshaped, 6.0- 7.1 pm broad, 3.0- 6.5 pm long. Heterocytes spherical, 6.8- 8.5 pm broad,
6.4- 8.0 pm long. Akinetes spherical, I 0- 12 pm broad, solitary or in pairs, attachingat one or both sides of the heterocytes.
Distribution : Lake Biwa (Shiga Pref.).
Anabaena minispora M. Watanabe sp. nov.
Figs. 11 , 12, 28
Trichomata libere natantia, solitaria, irregulariter circinata, vaginis crassis mucosis circumcincta. Spirae 80- 100 pm in diametro, circiter 40 pm distantes. Cellulae
vacuo lis gaseosis includentes, sphaeroideae vel cupiformes, 6.8- 7.8 pm latae,
4- 7 pm longae. Heterocytae sphaericae, circiter 9 pm latae. Akineta sphaerica, I 012 pm lata, ab heterocytis remota , solitaria vel 2, 3 seralia.

6

Masayuki Watanabe

...

.

~·\a

~

9

11

/

12

Figs. 7- 12. 7, 8, A. reniform is (L. Koya-ike, culture Ko-19) ; 9, 10, A. oumiana (L. Biwa); 11 , 12,
A. minispora (L. lnba-numa); 7- 12 , X200.

Iconotypus: Figulae 11, 12, 28 .
Locus typicus: in lacu lnbanuma, Chiba, Japoniae.
Trichomes free-floating, solitary, irregularly coiled, covered with thick mucilage.
Coils 80- 100 ,urn broad, about 40 ,urn apart. Cells spherical or barrel-shaped, 6.87.8 ,urn broad, 4-7 pm long. Heterocytes spherical, about 9 ,urn broad. Akinetes spherical, I 0- 12 pm broad, distant from heterocytes, one or 2, 3 in series.
Distribution : Lake lnba-numa (Chiba Pref.).

Anabaena species with twisted trichomes in Japan

7

Anabaena ucrainica (Schkorbatow) M. Watanabe
Figs. 13, 14, 29.
Watanabe, Bull. Natn. Sci. Mus. Ser. B (Botany) 22 : 3, f. 8, 16- 18, 1996.
Syn. Anabaena spiroides var. ucrainica Schkorbatow
Trichomes free-floating, solitary, forming regular coils, with a thick mucilaginous sheath. Coils about 45- 75 ,urn broad, 25- 70 ,urn apart. Cells spherical or barrelshaped, 7- 11,um broad, 3.5- 9.9 ,urn long. Heterocytes spherical, 9- 13 ,urn broad, 71 I ,urn long. Akinetes spherical, 13- 23 ,urn broad, 14-19 ,urn long, remote from theheterocytes.
Distribution: Lake Sagami-ko (Kanagawa Pref.); Lake Biwa (Shiga Pref.).
Anabaena mucosa Komarkova-Legnerova & Eloranta
Figs. 15, 16, 30.
Trichomes free-floating , solitary, forming more or less irregular coils, with thick
mucilaginous sheath. Coils 82- 126 ,urn broad, 45- 65 ,urn apart. Cells spherical or barrel-shaped, 9- 11 .3 ,urn broad, 4- 10 ,urn long. Heterocytes spherical, 10- 12.3 ,urnbroad, 9.5- 12,um long. Akinetes spherical, 16.3- 20.4,um broad, 17.6- 21.3,um long,
remote from the heterocytes.
Distribution: Lake Hime-numa, Lake Toro-ko (Hokkaido); Lake Higurashi-ike(Aomori Pref.); Lake Sagami-ko (Kanagawa Pref.).
The Japanese alga differs in several morphological points from the original one
which was described from Finland (Komarkova-Legnerova & Eloranta, 1992). The
former is a little larger in dimensions of cells and heterocytes, and a little smaller inthose of akinetes than the latter.
' species with elongate akinetes 'Anabaenapseudocompacta M. Watanabe
Figs. 17- 19, 31.
Watanabe, Bull. Natn. Sci. M us . Ser. B (Botany) 22: 93 , f. 1- 11, 1996.
Trichomes free-floating, solitary, regularly coiled, without mucilaginous sheath.
Coils generally closely contracted, 18- 24 ,urn broad, 50- 250 ,urn long. Cell s sphericalor barrel-shaped, 5.2- 7 ,urn broad, 3- 6.8 ,urn long. Heterocytes spherical, 5.5- 7.5 ,urnbroad. Akinetes ellipsoidal , sometimes slightly curved or asymmetrically curved(nearly straight at the inner side), 7.5- 11.3 ,urn broad, 16.8- 21 .3 ,urn long, 1.8- 2.6
times longer than broad, remote from the heterocytes.
Distribution: Lake Kasumigaura (lbaraki Pref.); Lake Inba-numa, Lake Teganuma (Chiba Pref.).
This alga from Lake Kasumigaura was first recorded as Anabaena spiroides (M.
Watanabe & Chihara, 1980) and described as a new species, A. pseudocompacta, by
the present author lately (Watanabe, 1996). A. pseudocompacta resenbles A. compacta Nygaard superficially, however the former is larger in cell dimensions and in
akinete form. Length/width ratios of the akinetes are 1.8- 2.6 and 1.2- 1.4 respectively.

8

Masay uki Watanabe

13

. f6

18

19

Figs. 13- 19. 13. 14, A. ucrainica (L. Sagami): IS , A. mucosa (L. Toro); 16, A. mucosa (L. Him enum a); 17- 19,A. pseudocompacta (L. Tega-numa): 13- 17. X200, 18. 19, X400.

Figs. 20, 21 , 32.
Anabaena spiroides Klebahn
Trichomes free-floating, solitary, more or less regularly coiled, without mucilaginous sheath. Coils 27- 37 pm broad, 7- IOpm apart. Cells spherical or barrelshaped, 4.9- 6.3 ,urn broad, 3.0- 7.6 ,urn long. Heterocytes nearly spherical, 6.3- 7 . I pm
broad, slightly shorter than broad. Akinete ellipsoidal, usually curved, 9.1 - 10.1 pm
broad, 21 - 24 pm long.
Distribution: Lake Koyama-ike (Tottori Pref.).

Anabaena species with twisted trichom es in Japan

9

"

24

25

Figs. 20- 25. 20, 21, A. spiroides (L. Koya ma-ike); 22, A. crassa (L. Kutsuzawa) ; 23, A. crassa(L. Bi wa); 24, 25, A. circinalis (L. Akan); 20- 25, X200.

Anabaena crassa (Lemmermann) Komarkova-Legnerova & Cronberg
Figs. 22, 23, 33.
Syn. Anabaena spiroides var. crassa Lemmermann
Trichomes free-floating, solitary, regularly coiled. Coils 33- 57 pm broad, 2060 pm apart. Cells spherical or barrel-shaped, 8.1 - 12.2 pm broad, 4.9- 9.6 pm long.
Heterocytes spherical , I 0- 12.8 pm broad . Akinetes ellipsoidal, 12.5- 17.7 pm broad,
15.5- 23.4 pm long, remote from the heterocytes.

10

Masayuki Watanabe

@
@

DD
31

Figs.

26- 34. 26, A. reniformis; 27, A. oumiana; 28, A. minispora; 29, A. ucran ica; 30, A. nwcosa; 3 1, A. pseudocompac1a; 32, A. spiroides; 33. A. crassa ; 34, A. circinalis; X500.

Di stribution: Lake Akan (Hokkaido); Lake Kasumigaura (lbaraki Pref.); Lake
Kutsuzawa-ko (Nagano Pref.); Lake Biwa-ko (Shiga Pref.).

Anabaena species with twisted trich omes in Japan

11

Anabaena circinalis Rabenhorst ex Bornet & Flahault
Figs. 24, 25 , 34.
Trichomes free-floating , solitary, more or less regularly coiled, covered withthick mucilaginous sheath. Coils 47- 99 pm broad, 36- 73 pm apart. Cells spherical orbarrel-shaped, 8- 12 pm broad. Heterocytes spherical, I 0- 14 pm broad. Akinetes
cylindrical, with rounded ends, sometimes slightly curved, 12- 14(- 20) pm broad, 2530pm long.
Distribution: Lake Akan (Hokkaido); Kiryu-gawa dam (Gunma Pref.).
2.

Morphological relationships among nine coil-forming species
In order to help our understanding of coil forming species in planktonic Anabaena , the present author proposes two hypothetic lines of species: species developing
spherical akinetes such as A. reniformis, A. oumiana, A. ucrainica and A. mucosa andthose developing elongate akinetes such as A. pseudocompacta , A. spiroides, A. erassa and A. circinalis. These nine coil-forming species are shown in figures 26- 34 together for comparison, and measurements of the diameters of cells, akinetes and coilsof each population base are shown in Tables 2 and 3.
A. reniformis has the smallest dimensions of cells and coils among the nine
spec ies under discuss ion (Tables 2, 3), and it is characterized by its cylindrical tendency in cells, which consequently cause reniform cells. In such characteristics thisspecies may not be adequate for comparison with the other eight species.
A. oumiana, as well as the above-mentioned alga and A. ucrainica, is characterized by its development of spherical akinetes at both sides of the heterocytes. However it is between the other two species in its dimensions of cells and coils.
A. minispora shows similar dimensions in cell s and akinetes to A. oumiana but
is di scontinuously larger than the latter in coil diameter which is comparable withthat of A. mucosa.
A. ucrainica is characterized by formation of quite regular coils which is comparable to A. crassa, and consequently both algae show stout ap pearance. Length/width
ratios in akinetes are 0.9- 1.2 in A. ucrainica and 1.2- 1.4 in A. crassa. The coil di ameter of A. ucrainica is between that of A. oumiana and A. mucosa.
A. mucosa is the largest in dimensions of cells and coils among the above fivespecies with spherical akinetes.
A. pseudocompacta is the smallest in dim ensions of cells and coils among thefour spec ies forming elongate akinetes (Table 3 ), and is superficially quite similar to
A. reniformis, especially in a ste rile state. It is interesting that the habitats of thosealgae are both highly eutrophicated water bodies. A. pseudocompacta is known in the
Kanto area and A. reniformis in the Kansai area .
A. spiroides is one of the commonest names of the genus Anabaena, especiallyof the spec ies forming spiral trichomes, and is believed to be widely distributed .
However the present studies have so far indicated that thi s alga is, in fact, rather rare
at lea st in Japan. Many of the algae which were recorded as A. spiroides were like lyTable 2.

Comparison of the diameter of cells, akinetes and coi ls among ten populations forming spherical akinetes.
10

A. mucosa

c

20

N

50

=

L. Toro-ko (Watanabe orig.)
L. Sagami-ko (Watanabe orig. )L. Hime-numa (Watanabe orig.)

A. ucrainica

L. Biwa-ko (Watanabe 1996)
L. Sagami-ko (Watanabe orig.)
L. Sagami -ko (Watanabe orig.)=

A. minispora•

A. oumiana•0

L. lnba-numa (Watanabe orig. )=0Lake Biwa (Watanabe 1996)-

A. renilormis

10

L. Koya -ike (Watanabe orig. )Sikata-futago pond (Watanabe orig.)
20

30

40

100

50

$:

l SOtt.m

"'

<J>

"'c:
'<
Table 3.

Comparison of the diameter of ce ll s, akinetes and co il s among e ight populations forming elongate akinetes.

"'

~

10

20

6>

50

A. circinalis::lKiryu-gawa..dam (Chimuro 1995)
Lake Akan (Watanabe 1971)

A. crassa

Lake Biwa-ko (Watanabe 1996)
Ka sumigaura (Watanabe & Chihara 1980)
Kutsuzawa-ko (Watanabe orig. )Lake Akan (Niiyama 1996)

A. spiroides

L. Koyama -ike (Watanabe orig. )A. pseudocompaclil

Lake Teganuma (Watanabe 1996a)

10

20

30

40

50

1001-Lm"'a"'Anabaena spec ies with twisted trichomes in Japan13

other species.

A. crassa is commoner than the previous alga, though some of the records might
be identified with A. ucrainica. This species resembles A. circinalis in cell dimensions but differs in akinete form and in coil diameter.
A. circinalis is distinguished by broader coil diameter and by more cylindricaltendency in akinetes from A. crassa.
Acknowledgme nts
The author expresses his sincere thanks to Prof. Makoto M. Watanabe (National
Institute for Environmental Studies) for his valuable comments on the manuscript,
and to Prof. Yukio Kimura (Mukogawa Women's University), Dr. Teru Ioriya (Tokyo
University of Fisheries) and Prof. Masaru Haga (Hokkaido University of Education),
Prof. Shoichi Saito (Hirosaki Univ.) and Mr. Kazuaki Tanaka (Water Supply Agencyof Kawasaki City) for collecting materials.

References
Chimuro, M., 1995. Volatile compounds excreted by planktonic Anabaena isolated from lakes and reserviors. Master thesis of the Meiji Universi ty in 1994. (In Japanese)
Hirose, H. & M. Hirano, 1977. Cyanophytes. In: Hirose, H. & T. Yamagishi (eds.) Illustrat ions of theJapanese Fresh-water Algae, 933 pp. Uc hidaroukakuho-shinsha, Tokyo. (In Japanese)
Konu\rkova-Legnerova, J. & P. Eloranta, 1992. Pl anktic blue-green algae (Cyanophyta) from Central Finland (Jyvaskyla region) with spec ial reference to the genus Anabaena. Algological Studies, 67: 103133 .
Lemmermann, E., 1898. Beitrage zur Kenntniss der Pl anktona lgon. Bar. Cenrralbl., 76: 150- 156.
Niiyama, Y. , 1996. Morphology and systematics of Anabaena strains in National Science Museum. Jpn .
J Phvco/. (Sorui), 44: 1- 8. (In Japanese)egoro, K. , 1937. Planktoncyanophyceen in japanischen Seen und Teichen 11 . Jap. J Limnol., 7: 9- 12,
pis. 1- 11. (In Japanese)
Trelease, W., 1889. The working of the Madison Lakes. Trans. Wis. Acad. Sci .. Arrs and Let/., 7: 121 129.
Umezaki, I. and M. Watanabe, 1994. Enumeration of the Cyanophyta (b lue-g reen algae) of Japan. 2.
Nostocales and Stigonematales. Jpn. J Phyco/. (S6rui), 42: 301 - 324.
Watanabe, M ., 1971. The species of Anabaena from Hokkaido. J Jap. Bot., 46: 263- 277, figs. 1- 30. ( InJapanese)
Watanabe, M., 1996. Studies on Planktonic Blue-green Algae 6. Bloom-forming species in Lake Biwa
(Japan). Bull. Natn. Sci. Mus .. Toi.J'O, Ser. B (Botany), 22 : 1- 10.
Watanabe, M., 1996a. Studies on Planktonic Blue-green Algae 7. Anabaena pseudocompacta sp. nov.
from eutrophic lakes in central Japan. Bull. Natn. Sci. Mus .. Tokyo, Ser. B (Botany) , 22: 93- 97.
Watanabe , M. , 1998. Cyanophyta in C hiba Prefecture. (In press)
Watanabe, M. and M. Chihara, 1980. Algal flora of Tsukuba-gakuen campus V Blue-green alga l plankton in Kasumigaura. Tsukuba Univ. Environ Group. Studies of"Environmenr in Tsukuba , SA: 80- 86 .
( In Japanese)