Bull. Natl. Mus. Nat. Sci., Ser. B, 33(3 · 4), pp. 127–132, December 21, 2007

Survey of Freshwater Hyphomycetes in Yakushima Island,Southern Japan
Tsuyoshi Hosoya1 and Kazuaki Tanaka2
1

Department of Botany, National Museum of Nature and Science,
Amakubo 4–1–1, Tsukuba, 305–0005 Japan
E-mail: hosoya@kahaku.go.jp
2
Faculty of Agriculture and Life Science, Hirosaki University,
Bunkyocho 3, Hirosaki, Aomori, 036–8561 Japan
E-mail: k-tanaka@cc.hirosaki-u.ac.jp

Abstract Fungal spores collected from streams in Yakushima Island are examined and reportedwith illustrations. Thirty two taxa of 22 genera were recognized, and their differences in occurrence in relation to hitherto known Japanese stream spora were noted.
Key words : aquatic hyphomycetes, freshwater hyphomycetes, fungal diversity, Ingoldian fungi,
local mycobiota.

Introduction
In spite of the past explorations of mycobiota
in Yakushima Island (literature cited in Hosoya
and Tanaka, 2007), there have been no records ofaquatic hyphomycetes. Aquatic hyphomycetes
were first found in Europe and are known for
their characteristic morphology of the spores (Ingold, 1942). Later, the more highly diverse morphology of aquatic hyphomycetes in subtropicaland tropical areas caught attention of many mycologists (e. g., Goh, 1997; Marvanová, 1997).
At present, more than 500 species are known
from freshwater habitats (Tsui and Hyde, 2003).
They are involved in the degradation of deadplant material and animal parts in freshwater
ecosystems (Wong et al., 1998).
Spores of aquatic hyphomycetes are caught inwater foam in streams, and can be analyzed byfixed samples. Miura (1974) compared stream
spora from three representative areas in Japan,and noted few overlap of mycobiota between anorthern area (Rebun Island) and a southern area(Yaeyama Islands). Because of the diverse vegetation, a diverse aquatic mycobiota is expected inYakushima Island. During the exploratory visit toYakushima in 2005 (Taxonomic research forplants and fungi in areas with remarkable biodiversity in Japan), the authors collected water
foam samples to contribute to elucidation of mycobiota in aquatic habitats. In the present paper, alist is provided with taxonomic notes.
Materials and Methods
Five sites along major rivers and water falls inYakushima Island were explored and 8 samples
were obtained (Fig. 1, Table 1). Water foam was
scooped up with an aluminum spoon, and immediately fixed on site by formalin with cotton blue
stain. For examination, a drop of fixed sample
was applied onto a slide glass, and water-soluble
resin “Neo-shigaral” (Shiga konchu-fukyu-sha,Tokyo) was applied and mixed with the sample
for solidification. The prepared slides were examined by a compound microscope for identification.
Results and Discussion
In total, 32 taxa (including six unidentified and10 not identified to specific rank) belonging to 22

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Tsuyoshi Hosoya and Kazuaki Tanaka

Fig. 1. Map of Yakushima Island showing collection sites by solid circles.
Numbers represent site numbers shown in
Table 1.

genera were recognized (Figs. 2–4, Table 2). No
clear differences were observed in samples at thesame site, and the mycobiota at the given site
seemed to be stable during the observed period.
The biodiversity and the numbers of stream
spora differed from site to site, Triscelophorus
spp. and Triramulispora sp. being the most frequently occurring members from all sites. Samples from Shiratani-unsui-kyo (Site 1), where thestream was running through deep forest, wererich in diversity, while those in rocky stream in
Nunobiki-no-taki (Site 2) and Yudomari-gawariver (Site 5) were not.
Tubaki and Sugino (1982) studied stream
spora in Mt. Tsukuba through the year, and identified 19 genera, 27 species. Miura (1967, 1974)
found 33 spore types from Sugadaira based on
multiple sampling around the year. In compari-Fig. 2. Representatives of stream spora in Yakushima Island (mainly tetra-radiating spores). A, Culicidosporagravida; B, Triscelophorus sp. 1; C, Alatospora sp. 1; D, Triscelophorus sp. 2; E, Tetrachaetum elegans (?); F,Alatospora sp. 2; G, Tricladium splendens; H, Tricladiospora brunnea; I, Clavariopsis aquatica; J,Triscelophorus sp. 3; K, unidentified 1; L, unidentified 2; M, unidentified 3; N, Flabellospora tetracladia; O,Trisulcosporium acerinum; P, Fontanospora eccentrica; Q, Tricladiosproa sp.

Freshwater aquatic hyphomycetes of Yakushima
Table 1.

129

Collection sites in Yakushima Island.

Site no.

Site

Elevation (m)Date

No. of samples

123
45

Shiratani-unsui-kyo
Nunobiki-no-taki
Upstream of Yudomari River
Sarugawa Gajumaru Park
Oko-no-taki

620
20250
1101502005-X-18, 19
2005-X-19
2005-X-20
2005-X-21
2005-X-21

3
1
1
12

Table 2.

Stream spora of Yakushima Island.
Site*
1

Alatospora sp. 1 (Fig. 2C)
Alatospora sp. 2 (Fig. 2F)
Anguillospora crassa Ingold (Fig. 3E)
Anguillospora sp. (Fig. 4B)
Campylospora parvula Kuzuha (?) (Fig. 4J)
Clavariopsis aquatica De Wild. (Fig. 2I)
Clasterosporium flexum (Matsush.) B. Sutton et R. T. A. Cook (Fig. 3B)
Condylospora spumigena Nawawi (Fig. 3F)
Culicidospora gravida R.H. Petersen (Fig. 2A)
Dendrospora sp. (Fig. 4A)
Entomophthora sp. (Fig. 4E)
Fontanospora eccentrica (R. H. Petersen) Dyko (Fig. 2P)
Flabellospora tetracladia Nawawi (Fig. 2N)
Lateriramulosa uniinflata Matsush. (Fig. 4I)
Lunulospora cymbiformis K. Miura (Fig. 4G)
Obelispora sp. (Fig. 4C)
Tetrachaetum elegans Ingold (Fig. 2E)
Tetraploa aristata Berk. et Broome (Fig. 4H)
Tricladiospora brunnea (Nawawi) Nawawi et Kuthub. (Figs. 2H, 2Q)
Tricladium splendens Ingold (Fig. 2G)
Triramulispora sp. (Fig. 4F)
Triscelophorus sp. 1 (Fig. 2B)
Triscelophorus sp. 2 (Fig. 2D)
Triscelophorus sp. 3 (Fig. 2J)
Trisulcosporium acerinum H. J. Huds. et B. Sutton (Fig. 2O)
Wiesneriomyces laurinus (Tassi) P. M. Kirk (Fig. 3A)
unidentified 1 (Figs. 2K, 4K)
unidentified 2 (Fig. 2L)
unidentified 3 (Fig. 2M)
unidentified 4 (Fig. 3C)
unidentified 5 (Fig. 3D)
unidentified 6 (Fig. 4D)

23

45

* Site numbers represent those in Table 1.
Number of  shows abundance of spores.

son to these data, the biodiversity of stream spora
in Yakushima Island seems to be similar to or
more diverse than that of central Honshu inJapan.
Spores typically observed in a subtropical area

(e.g., Tricladiospora brunnea and Obelispora sp.;
Goh, 1997) were also frequently observed, whilesome of the common fungi in temperate zones
were not observed (e.g., Heliscus, Lemoniera;
Miura, 1974).

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Tsuyoshi Hosoya and Kazuaki Tanaka

Among the 36 specifically identified fungiwith hyaline, thin-walled, radiately branched
spores listed by Miura (1974), only five species
were found in the present study: two (Clavariopsis aquatica and Lateriramulosa uniinflata) wereknown to be distributed widely, two (Culicidospora gravida and Tricladium splendens) were
found from northern areas, and Flabellospora
tetracladia was thought to be a subtropical element.
Dematiaceous spores that characterize subtropical stream spora (Goh, 1997; Marvanová,1997), and others characteristic to subtropical regions were frequently observed. Spores of Beltrainia and Sporoschisma, coniophores of otherdematiaceous fungi, and aseptate fusiform dematiaceous spores were also often encountered.
Among the stream spora observed, the followings were noteworthy. Unidentified 1 (Figs. 2K,4K) superficially resembles Laterilamulosa in thecomplex main axis, but differs in having dematiaceous color and more filamentous, apparent central body. Unidentified 2 (Fig. 2L) is similar toArticulospora in the radiating branch connected
at a point, but differs in the longer branches.
Unidentified 4 (Fig. 3C) is similar to Lunulospora with crescent-shaped spores, but lacks vestigeof attachment to the sporophore. This shape ofconidia was encountered multiple times at twosites and the spore shape seemed to be stable.
Unidentified 5 (Fig. 3D) resembles Flagellospora
penicilloides, but differs in having more than one
septa while F. penicilloides usually have one septum. Unidentified 6 (Fig. 4D) differs from known
taxa in having a main axis strongly curved at one
end. This fungus is cited as “fungus imperfectus
non nominatus” (Matsushima, 1975: 206). Triramulispora sp. (Fig. 4F) was found in all the samples. It is characterized by the four radiating acicular arms, arising from two different levels; twoarising from the upper level extending upward,
and two arising from the lower level, extending
below, shorter than the rest. The configuration of
the spore arms seems to be close to Triscelophorus, but differs from Triscelophorus in the armsof this fungus occurring from the different levels.

Fig. 3. Representatives of stream spora inYakushima Island (mainly sigmoid to filiform
spores). A, Wiesneriomyces laurinus; B, Clasterosporium flexum; C, unidentified 4; D,unidentified 5; E, Anguillospora crassa; F,Condylospora spumigena.

Although the spore morphology of Clasterosporium fllexum was relatively consistent with Matsushima (1975), it varied considerably, having avarious elongation of the apical extention up to
600 m m, possibly due to adaptations to streams.
This is the first report to apply water soluble
resin to a study of aquatic hyphomycetes. Although application of resin interferes transparency of the sample, the conformation of the stream

Fig. 4. Representatives of stream spora in Yakushima Island. A, Dendrospora sp.; B, Anguillospora sp.; C, Obelispora sp.; D, unidentified 6; E, Entomophthora sp.;
F, Triramulispora sp.; G, Lunulospora cymbiformis; H, Tetraploa aristata; I, Lateriramulosa uniinflata; J, Campylospora parvula (?); K, unidentified 1.

Freshwater aquatic hyphomycetes of Yakushima
131

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Tsuyoshi Hosoya and Kazuaki Tanaka

spora can be maintained in more natural mannerthan temporal slide preparation with volatile
mounting fluid. One year after the preparation,
the spores maintained without morphologicaldamage.
Seasonal fluctuation of the strem spora has
been pointed out (e.g., Ingold, 1942; Nilsson,1964; Iqbal and Webster, 1973), and more samples are required for quantitative analysis ofstream spora of Yakushima.
Acknowledgements
The authors wish to express their gratitude toDr. Naoshi Nakamura for his valuable advises
and guidance in identification of the stream
spora. The authors also express their thanks toDr. Yasuyuki Hiratsuka for his critically reviewing the manuscript.
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