Rikunomizu（Limnology in Tokai Region of Japan）97 : 35 - 43（2023）

ReportMorphological characteristics of Spirogyra neglecta (Zygnemataceae) collectedfrom spring water in the urban area of Nagoya City, Aichi, JapanNOZAKI Kentaro
Abstract
Morphological characteristics of Spirogyra neglecta (Hassall) Kützing collected from spring water inthe urban area of Nagoya City on 8 August 2016 were described using microscopic photographs of thevegetative cells, conjugation processes, and zygospores. The vegetative cells with plane end walls were
54–74 m wide, 79–377 m long, as well as three chloroplasts making 1–2 turns (n = 171). The fertile
cells had cylindrical shape. Both gametangia formed tubes, which were ladder-like during conjugation.
The zygospores were ellipsoidal or ovoid, which were 49–69 m wide and 67–127 m long, with asmooth, thick yellow-brown median spore wall. (n = 156). Considering that S. neglecta closely resembles S.
ternata Ripart in morphology, the description of these two species was compared using some monographs.
The water temperature, pH, and electrical conductivity in the sampling site were 26.6°C, 7.0, and 19.3
mS m-1, respectively. The concentration of the dissolved inorganic nitrogen was 4500 gN L-1 (NO3--N
contributed approximately 99 %) and PO43--P was only 1 gP L-1.
Key words: conjugation, Spirogyra neglecta (Hassall) Kützing, Spirogyra ternata Ripart, vegetative cell,zygospore(Received: 30 November 2022; Accepted: 20 February 2023)

Ripart (1876) reported that S. neglecta morphologicallyresembles S. ternata and is difficult to classify. Transeau(1951), Devi and Panikkar (1994), and Johnson (2011) all
have similar viewpoints. Only S. ternata is listed in the two
above-mentioned Japanese representative monographs.
Therefore, this study was conducted considering thedifferences in the morphological features of cells andzygospores of S. neglecta and S. ternata. The Japan Society
for the Promotion of Science provided NOZAKI Kentaro witha grant-in-Aid for Scientific Research (C) to support thisresearch (21K02911).

Introduction
Spirogyra neglecta (Hassall) Kützing was describedin Hassall (1842) as Zygnema neglectum and renamedin Kützing (1849). S. neglecta is commonly found in
freshwater habitats worldwide, including Africa, Asia,
Europe, and North America (Transeau, 1951; Kadlubowska,
1984; Devi and Panikkar, 1994; Johnson, 2011). However,this species is not listed in any representative monographof the Japanese freshwater algal flora (Yamagishi, 1966;
Yamagishi, 1977). In Japan, S. neglecta has only beenreported in Hyogo Prefecture in the Kinki region (Sato,2013), with no records in other regions. In this study,
the morphology of the vegetative cells, conjugation, andzygospores of S. neglecta are reported using fresh samples
collected from spring water in the urban area of Nagoya
City in the Tokai region of Japan.

Methods
Samples of S. neglecta were collected from spring water inthe schoolyard of Sugiyama Jogakuen Elementary School in
the urban area of Nagoya City on 8 August 2016, located at

School of Education, Sugiyama Jogakuen University, Moto-machi 17-3, Hoshigaoka, Chikusa, Nagoya 464-8662, Aichi, Japan(E-mail: ken@sugiyama-u.ac.jp)

35

Ⓒ2023

The Tokai Branch of the Japanese Society of Limnology

Kentaro NOZAKI

A

N

Gifu prefecture

Nagano prefecture

Chikusa-ku
Nagoya City
Mie prefecture

Aichi prefecture0
Ise Bay

10 km

Shizuoka prefecture

Mikawa Bay

Pacific Ocean

C

B

E

C

D

E

D

Figure 1. Map and photos of the sampling site. A: Location of Chikusa-ku, Nagoya City, Aichi Prefecture in Tokai region ofJapan. B-E: Spring water located at the schoolyard of Sugiyama Jogakuen Elementary School in the urban area of Nagoya City.

Ⓒ2023

The Tokai Branch of the Japanese Society of Limnology

36Morphological characteristics of Spirogyra neglecta (Zygnemataceae)A

100 mm

B

50 mm

C

100 mmD

100 mm

50 mm
EFigure 2. Microscopic photographs of Spirogyra neglecta. A and B: Vegetative cells on 9 August 2016. C: Fertile cells on 9
August 2016. D: Conjugation on 13 August 2016. E: Conjugation and zygospores on 20 August 2016.

37

Ⓒ2023

The Tokai Branch of the Japanese Society of Limnology

Kentaro NOZAKI

A

B

C

50 mm

50 mm

50 mm

D

E

50 mm

50 mm

Figure 3. Microscopic photographs of zygospores of Spirogyra neglecta. A and B on 14 September 2016. C on 22 September
2016. D on 16 October 2016. E on 31 August 2016.

Ⓒ2023

The Tokai Branch of the Japanese Society of Limnology

38Morphological characteristics of Spirogyra neglecta (Zygnemataceae)

ellipsoidal or ovoid, 49–69 m wide and 67–127 m long,with a smooth and thick yellow-brown median spore wall.
The suture line could not be observed. Table 1 shows themorphological characteristics of S. neglecta and S. ternata
based on previous studies. However, the original description
studies of both species provide insufficient information
for classification and lack an illustration plate. Thus, S.
neglecta refers to morphological information from Transeau(1951) to Schagerl and Zwirn (2015), whereas S. ternata
refers from Yamagishi (1966) to Johnson (2011).
The morphology of the gametangia and the orientationof zygospores in the filament show differences between
S. neglecta and S. ternata in some monographs. Although
Transeau (1951) and Johnson (2011) reported that
fertilized gametangia of S. neglecta is usually inflated,with zygospores developing at right angles to the long axisof the filament, the zygospores were not so orientated intheir illustration plates. On the microscopic photographof the conjugation of S. neglecta in Schagerl and Zwirn(2015), zygospores were orientated in right angles to thefilament. On the other hand, Ripart (1876), Kadlubowska(1984), Yamagishi (1966), and Yamagishi (1977) reported
the same morphological characteristics in S. ternata.
On the microscopic photograph of the conjugation of S.
ternata in Yamagishi (1987), zygospores in shorter cells
were orientated in right angles to the filament. Moreover,the illustration of S. ternata in Johnson (2011) showedzygospores orientated in right angles to the filament,
which is contrary to the description. This result indicatespossible mistakes in illustrations. Devi and Panikkar (1994)
reported that the sterile cells of S. neglecta inflated, which
is described as the only difference in S. ternata. However,the sterile cells in this study did not inflate (Figures 2D
and 2E). Therefore, the morphology of the gametangia
and the orientation of the zygospores are insufficient for
distinguishing between S. neglecta and S. ternata.
Because the form of conjugation and the shape of thezygospores of S. neglecta are very similar to those of S.
ternata (Table 1), the width and length of the vegetative cells
and zygospores are examined as classification characteristics
in this study. The relationship between the width andlength of the vegetative cells is shown in Figure 4. The solidline quadrate represents the minimum and maximum valuesof S. neglecta, and the dotted line quadrate represents theS. ternata (Table 1). Approximately 77% of all measured
values (n = 171) were within the range of S. neglecta. The
relationship between width and length of the zygospores

latitude 35 03'53''N and longitude 136 57'04''E (Figures 1A–
1C). The S. neglecta community resembled a mat, and thefragments of the community were floating (Figures 1D and
1E). The water temperature, pH (WAK-pH, KYORITASURIKA Co.), and electrical conductivity (CM21P, TOADKK) were measured at 10:40 AM at the sampling site.
The S. neglecta and water samples were stored in a box
with ice and were returned to the laboratory within 1 h after
sampling.
Filaments of S. neglecta were gently washed in distilledwater and placed in a 10-cm glass Petri dish filled withfiltered water in the sampling site and kept in a growthchamber (MLR-351H, SANYO Co.) at 25 ℃ under 170
mol photon m-2 s-1 (approximately 20000 lux) on a 13:11
h light and dark cycle. The filaments of S. neglecta wereobserved under an optical microscope (BX51, OLYMPUS
Co.) and microscopic photographs were taken using a digital
camera (DP27, OLYMPUS Co.). The width and length ofcells and zygospores in fresh samples were measured using
software (cellSens Standard, OLYMPUS Co.). Specimens
were donated to the Department of Botany, National
Museum of Nature and Science (TNS-AL61281ma-md in
TNS).
The turbidity of the water sample was measured using awater analyzer (WA1, NIPPON DENSHOKU Co.) and raw
water. The water sample was filtered to a glass fibre filter(GF-75, ADVANTEC Co.) to analyze water colour andnutrient concentrations. The water colour was also measured
using a water analyzer (WA1, NIPPON DENSHOKU Co.).
A spectrophotometer (U-100, HITACHI Co.) was used
to perform nutrient analyses on NH4+-N, NO2--N, NO3-N and PO43--P concentrations using. The nutrient analysis
procedures followed those of Matsumoto and Nozaki (2014).

Results and Discussion
Figures 2A–2E show microscopic photographs ofvegetative cells and conjugations. The vegetative cells
were 54–74 m wide and 79–377 m long with plane end
cell walls. In each cell, three chloroplasts made 1–2 turns(Figure 2A and 2B). The conjugation was ladder-like withtubes formed by both gametangia (Figures 2C–2E). The
fertile cells had a cylindrical shape, which did not inflate.
Chloroplast numbers and gametangia morphology are sameas in original description of S. neglecta (Hassall, 1842).
Microscopic photographs of various shapes of zygosporesare shown in Figure 3A–3E. Well-ripened zygospores were

39

Ⓒ2023

The Tokai Branch of the Japanese Society of Limnology

Ⓒ2023µmµm

Number, turn

Chloroplast

The Tokai Branch of the Japanese Society of Limnology

100-300

49-60

55-67

40

3, 1-2 turns

3-4, n.d.

66-149

n.d.

49-66

54-70

ladder-likescalariform

ladder-like

3-4, n.d.

n.d.

n.d.

54-70

3, 0.5 turnscalariform

n.d.

ladder-likescalariform

ladder-like andlateralinflatedcylindric

55-70

42-53

55-70

50-72

cylindric,inflated
inflated

77

49-69

56-68

54-64

inflatedcylindricenlarged

inflated49-57

cylindric, sterilecells inflated

scalariform

54-68

cylindricladder-like andlateral54-64

enlarged,
inflatedscalariform andlateraln.d.

66-125

59-73

66-12594-104n.d

67-12768-80

75-10069-83

70-11075-100

n.d.

n.d.

m

m
n.d.

LengthWidth

Zygosporen.d.

no inflation

Gametangia

n.d.

n.d.

Conjugation

Fertile cell(55-) 60-85 (48-) 85-330 3-4, 1-2 turns

70

3, 1-2 turns

2-3, n.d.

3, 1-2.5 turns

Spirogyra ternata Ripart 187679-377115-215

57-67

54-74

2-4, n.d.

n.d.

55-67

n.d.

3, 1-2.5 turns

100-300

47

58-68

3, n.d.

n.d.

3, 2-4 turns

3, <6 turns

n.d.

n.d.

Spirogyra neglecta (Hassall) Kützing 1849

LengthWidth

Vegetative celln.d.

ColourMedian wall,n.d.

Orientation

n.d., brown oblique to thefilament
oblique andellipsoid,
smooth,right angles to
ovoid
yellow
the filament
thick andoblique andellipsoid
smooth,right angles toyellow brown the filamentsmooth,not soellipsoid
yelloworientatedthick andnot soellipsoid
smooth,orientatedyellow brown
ellipsoid

n.d.
n.d.
globularthick andright angles to
ovoid
smooth,the filament
yellow
thick, smoothwith a suture
not soovoidline, yellow- orientatedbrownsmooth,not soellipsoid
yelloworientatedthick, smoothright angles towith a suture
ovoid
long axis ofline, yellowfilamentbrown
right angles toellipsoid
smooththe filament
thick and
ellipsoid,
not sosmooth,ovoid
orientatedyellow-brown

n.d.

Shape

Table 1. Morphological characteristics of Spirogyra neglecta and S. ternata based on previous studies. n.d. indicates no description.

Johnson (2011) p.601, p.594
Plate 148G

Devi and Panikkar (1994)
p.71, p.122 Figures 284-285

Kadlubowska (1984) p.315,
p.316 Figure 490

Yamagishi (1966) p.97, Plate 6
Figures 4-6; Yamagishi (1977)
p.451, p.450 Plate 156 Figure 3

Ripart (1876) p.162-163

This study

Schagerl and Zwirn (2015)
p.78, p.75 Figure 3f

Johnson (2011) p.157, p.594
Plate 148F

Devi and Panikkar (1994)
p.50-51, p.108 Figures 171-172

Kadlubowska (1984) p.304,
p.303 Figure 464

Transeau (1951) p.175, p.298299 Plate27 Figures 14-15

Kützing (1849) p.441

Hassall (1842) p.37

Reference

Kentaro NOZAKI

Morphological characteristics of Spirogyra neglecta (Zygnemataceae)
400

130

A. Vegetative cell110

S. neglecta

200

Length (mm)Length (mm)300

S. ternata

S. ternata

90

100

70

0

50

40

50

60

70

80

S. neglecta

B. Zygospore
40

90

50

60

70

80

Width (mm)Width (mm)Figure 4. Relationship between the width and length of thevegetative cells of Spirogyra neglecta (n=171). The solid line
quadrate represents the ranges of minimum and maximum
values of S. neglecta based on previous studies and the dottedline quadrate represents the S. ternata.

Figure 5. Relationship between the width and length of thezygospores of Spirogyra neglecta (n=156). The solid line
quadrate represents the ranges of minimum and maximum
values of S. neglecta based on previous studies and the dottedline quadrate represents the S. ternata.

is shown in Figure 5. Approximately 94% of all measured
values (n = 156) were within the range of S. neglecta.
Although the range of width and length of the vegetative
cells and zygospores of S. neglecta reported in previous
studies are smaller than those of S. ternata, 80%–90% of
the values obtained in this study site are within the range ofS. neglecta. Therefore, the Spirogyra collected in this study
was appropriately identified as S. neglecta. Considering that
Transeau (1951) did not describe S. ternata and Yamagishi(1966) did not describe S. neglecta, the results of this study
also suggest that these two species are synonymous.
Schagerl and Zwirn (2015) reported that many Spirogyra
species morphologically identified could have been
described too narrowly, based on 16 Spirogyra strains
collected from Central Europa that were compared withspecies descriptions provided in previous monographs.
Therefore, S. neglecta and S. ternata seem to be alsodifficult to distinguish morphologically. In recent years,
studies that collate Spirogyra morphology and its genetic
information have been published in the United States(Stancheva et al., 2013) and Japan (Takano et al., 2019).
To advance the taxonomic study of Spirogyra, the reexamination of the descriptions of previous monographs
using clear microscopic photographs of cells, conjugations
and zygospores will be required as in Ferrer and Caceres(2017).
The abiotic habitable conditions of the study site aredescribed in the following section. The physical andTable 2. Physical and chemical parameters at the sampling siteon 8 August 2016.
Sampling time
10:40
Water temperature
26.6℃
pH
7.0
Electrical conductivity
19.3 mS m-1
Turbidity
1.0 mg L-1
Water Colour
4.7 mg L-1
Dissolved oxygen12.1 mgO2 L-1
NH4+-N
29 gN L-1
NO2 -N
30 gN L-1
NO3 -N
4450 gN L-1
3PO4 -P
1 gP L-1
SiO2
10 mgSiO2 L-1

chemical parameters of the water sample collected from thesampling site are shown in Table 2. The water temperature,
pH, and electrical conductivity are 26.6 ℃ , 7.0, and 19.3
mS m-1, respectively. The water was clear and slightly
brownish, as shown in the turbidity and colour values. The
saturation value calculated from the water temperatureand dissolved oxygen concentration (12.1 mgO 2 L -1)
was 150 % supersaturated. Therefore, this result showsthat the photosynthesis activities of S. neglecta and otherphotosynthetic organisms were high at the time of thesampling. The concentration of dissolved inorganic nitrogen(NH4+-N + NO2--N + NO3--N) was 4500 gN L-1 (NO3--N
contributed approximately 99 %), and PO43--P was only 1
gP L-1. Nozaki and Matsumoto (2022) reported similar
results for water chemistry at this sampling site, with anannual mean concentration±SD of dissolved inorganic

41

Ⓒ2023

The Tokai Branch of the Japanese Society of Limnology

Kentaro NOZAKI

nitrogen being 5200±450 gN L-1 and PO43--P being only
3±3 gP L-1.
The results show that S. neglecta could form zygospores
during the summer. Simmons and van Beem (1990)
reported that Spirogyra species with filaments wider than
50 µm, such as S. neglecta produced zygospores during
summer in the Netherlands. However, the factors andmechanisms affecting the reproductive stage during summerof S. neglecta are still unknown clear and further research is
required.

Ripart, M. (1876) Notes sur quelques espèces rares ou
nouvelles de la flore cryptogamique du centre de laFrance. Bulletin de la Société Botanique de France, 23:
158-168 (in French).
Sato, H. (2013) A list of freshwater algae in Hyogo
Prefecture. Human and Nature, 24: 63-83 (in Japanese).
Schagerl, M. and M. Zwirn (2015) A brief introduction
to the morphological species concept of Spirogyra andemanating problems. Algological Studies, 148: 67-86.
Simons, J. and A. P. van Beem (1990) Spirogyra species
and accompanying algae from pools and ditches in The
Netherlands. Aquatic Botany, 37: 247-269.
Stancheva, R., Hall, J. D., McCourt, R. M. and R. G. Sheath(2013) Identity and phylogenetic placement of Spirogyra
species (Zygnematophyceae, Charophyta) from California
streams and elsewhere. Journal of Phycology, 49: 588607.
Takano, T., Higuchi, S., Ikegaya, H., Matsuzaki, R.,
Kawachi, M., Takahashi, F. and H. Nozaki (2019)
Identification of 13 Spirogyra species (Zygnemataceae)
by traits of sexual reproduction induced under laboratory
culture conditions. Scientific Reports, 9: 7458.
Transeau, E. N. (1951) The Zygnemataceae: 175, 298-299.
The Ohio State University Press, Columbus.
Yamagishi, T. (1966) Studies on the Genus Spirogyra
Collected in Japan. Science Report of the Tokyo Kyoiku
Daigaku, Section Biology, 12: 73-105.
Yamagishi, T. (1977) Family Zygnemataceae. In
Illustrations of the Japanese freshwater algae, Hirose,
H. and T. Yamagishi (eds.): 416-461. Uchida Roukakuho
Publishing, Tokyo (in Japanese).
Yamagishi, T. (1987) Spirogyra ternata Ripart var. ternata.
Photomicrographs of the Fresh-water Algae, 7: 66.
Uchida Roukakuho Publishing, Tokyo.

References
Devi, K. U. and M. V. N. Panikkar (1994) Species of
the Genus Spirogyra from Kerala, India. Bibliotheca
Phycologica Band 97, J. Cramer, Berlin.
Ferrer, N. C. and E. J. Caceres (2017) Vegetative andreproductive morphology of five Spirogyra species(Zygnematales, Charophyta) in Argentina. AlgologicalStudies, 153: 17-34.
Hassall, A. H. (1842) Observations on the genera Zygnema,
Tyndaridea, and Mougeotia with descriptions of new
species. Annals and Magazine of Natural History, Series 1,
10: 34-47.
Johnson, L. R. (2011) Phylum Chlorophyta. Family
Zygnemataceae. In The freshwater algal flora of the
British Isles. An identification guide to freshwater andterrestrial algae. Second edition, John, D.M., Whitton,
B.A. and A. J. Brook (eds.): 576-608. Cambridge
University Press, Cambridge.
Kadlubowska, J. Z. (1984) 10. Spirogyra Link 1820. In
Chlorophyta Part 8, Conjugatophyceae I: Zygnemales
Freshwater Flora of Central Europe, Ettl, H., Gerloff,J., Heynig, H. and D. Mollenhauer, D. (eds.): 258-494.
Gustav Fischer, Stuttgart (in German).
Kützing, F. T. (1849) Species algarum: 441. F. A.
Brockhaus, Lipsiae (in Latin).
Matsumoto Y. and K. Nozaki (2014) 3. Mizu No Kagaku
Bunseki (Analysis of water chemistry). In Midika Na
Mizu No Kankyo Kagaku, Jisshu Sokutei Hen (Manual on
methods for environmental studies of inland waters): 81124, Asakura Publishing, Tokyo (in Japanese).
Nozaki, K. and Y. Matsumoto (2022) Relationship between
water chemistry and human impact on adjacent springs
in urban area: Possibility as a teaching material of naturalscience education in Japanese elementary school. Wetland
Research, 12: 43-72 (in Japanese with English abstract).

Ⓒ2023

The Tokai Branch of the Japanese Society of Limnology(Guest Editor: Dr. TUJI Akihiro, Department of Botany,
National Museum of Nature and Science)

摘要

愛知県名古屋市の都市部の湧水から採集されたアオミドロ
Spirogyra neglecta（接合藻綱）の形態的特徴
野崎健太郎
2016年8月8日に名古屋市の都市部に位置する湧水から採取されたアオミドロ属 Spirogyra neglecta (Hassall) Kützing

42Morphological characteristics of Spirogyra neglecta (Zygnemataceae)の形態的特徴を，栄養細胞，接合過程および接合胞子の顕微鏡写真を用いて記載した．栄養細胞は隔膜が平板状，葉緑体は3本で1～2回転，細胞幅54～74 m，長さ79～377 m（n = 171）であった．生殖細胞は円筒形，接合は梯子状で接合管は両端から伸びていた．接合胞子は楕円形あるいは卵形で，幅49～69 m，長さ67～127 m，胞子膜中層は平滑で厚く黄褐色であった（n = 156）．S. neglecta は S. ternata Ripartと酷似しているため，いくつかの先行研究を用いて，これら2種に関する記述を比較した．調査地の水温は 26.6℃，pH は7.0，電気伝導度は19.3 mS m-1であった。溶存無機態窒素濃度は4500 gN L-1で硝酸態窒素が約 99 % を占め，リン酸態リンはわずか1 gP L-1であった．
キーワード：接合，Spirogyra neglecta (Hassall) Kützing，
Spirogyra ternata Ripart，生殖細胞，接合胞子（椙山女学園大学教育学部 〒464-8662 愛知県名古屋市千種区
星が丘元町17-3，E-mail: ken@sugiyama-u.ac.jp）

43

Ⓒ2023

The Tokai Branch of the Japanese Society of Limnology