Bull. Natl. Mus. Nat. Sci., Ser. B, 37(4), pp. 169–174, December 22, 2011

First Record of Compsopogon caeruleus (Balbis ex C.Agardh)
Montagne (Compsopogonophyceae, Rhodophyta) fromOgasawara Islands, Japan
Taiju Kitayama
Department of Botany, National Museum of Nature and Science,
4–1–1 Amakubo, Tsukuba, Ibaraki 305–0005, Japan
E-mail: kitayama@kahaku.go.jp(Received 28 August 2011; accepted 28 September 2011)

Abstract A benthic freshwater red alga, Compsopogon caeruleus (Balbis ex C.Agardh) Montagne (Compsopogonophyceae, Rhodophyta) was recorded from Ogasawara Islands, Japan, for thefirst time. This species differs from the other species of the genus Compsopogon, in having cortex
of less than three cell-layer, without spinous or curling branchlets, though the size of monosporangia is not considered to be a useful taxonomic character in this genus. Finding of C. caeruleus
from the extraordinary isolated islands suggested that this alga has any means of dispersion otherthan flooding of the river’s water (e.g., remnant of marine regression, transportation by migratory
birds).
Key words : Compsopogon caeruleus, Compsopogonales, Compsopogonophyceae, Ogasawara
Islands, red algae.

A freshwater red alga referable to Compsopogon caeruleus (Balbis ex C.Agardh) Montagne(Compsopogonales, Compsopogonophyceae,Rhodophyta) was collected from the stream on
Chichi-jima Island, the largest island in Ogasawara Islands (Bonin Islands), Japan. This
species has a wide distribution in the world: Europe, North America, Caribbean Islands, Western
Atlantic, Asia, Australia, Hawaiian Islands, Vanuatu (Guiry and Guiry, 2011), though this is thefirst report from the Ogasawara Islands. In Japan,“Compsopogon oishii Okamura” had been usedfor this alga (Nakamura, 1993), which was believed to be endemic to Japan for a long timesince its original description by Okamura (1915).
He described the new species based on the plants
collected by Yoshizo Oishi from “the mouth ofTamagawa River, Haneda-mura” (Haneda, OtaWard, Tokyo) and “Yanokuchi, Prov. Musashi”(Komae City, Tokyo). But Vis et al. (1992) synonymized C. oishii under the cosmopolitan
species, C. caeruleus as C. coeruleus (This spe-cific epithet is often spelled “coeruleus”, though
C. Agardh (1824: 122) used “Conferva caerulea”(Guiry in Guiry and Guiry, 2006)). Since 2000,
however, the Ministry of the Environment ofJapan and the International Union for the Conservation of Nature treat this alga as a threatened
species (Vulnerable) (Brodie et al., 2009), because in recent years the habitats of this alga arebeing lost by rapid urbanization of the rural districts including isolated islands. It is also expected that addition of the Ogasawara Islands to UNESCO’s list of the natural “World Heritage Site”
on June 24, 2011 will have any influence on thehabitat of the alga.
The genus Compsopogon Montagne (1846, p.
152) is a macroscopic genus placed under thefamily Compsopogonaceae with another macroscopic genus Compsopogonopsis Krishnamurthy(1962) and a microscopic genus Pulvinaster
West, Zuccarello et Scott (2007). Compsopogon
is distinguished from Compsopogonopsis in lacking rhizoidal cortication throughout thallus. The

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Taiju Kitayama

delimitation of these genera in this family is not
so disputed, while there are differing views upon
the number of species in the Compsopogon. Viset al. (1992) recognized only two species of thegenus, Compsopogon caeruleus (Balbis ex C.
Agardh) Montagne (as C. coeruleus) and C. prolificus Yadava et Kumano, using multivariate
morphometrics and image analyses for compsopogonalean taxa in North America and examining the type specimens of seven taxa of thegenus. On the other hand, Seto and Kumano(1993) also examined type specimens of almost
the same taxa of the genus and reappraised theseveral species of the genus: C. aeruginosus (J.
Agardh) Kützing (1849), C. corticrassus Chiharaet Nakamura (1980), C. chalybeus Kützing(1849).
In this study, to confirm the identity of the present plants collected from Ogasawara islands andto clarify the morphological characters for thespecies of Compsopogon in Japan, anatomicalobservations were made on the material using amicroscope. For preservation, the material wasdried on sheets of paper or fixed in 10% formalin-seawater. Voucher specimens were depositedin the algal herbarium of the National Museumof Nature and Science (TNS). In addition, to define geographical distribution of the species inJapan, the dried specimens were investigated in
the herbaria of Department of Botany, TNS andHokkaido University Museum (SAP).

Description
Order Compsopogonales Skuja, 1939
Family Compsopogonaceae Schmitz inEngler et Prantl, 1897
Compsopogon caeruleus (Balbis ex C.Agardh)
Montagne in Durieu De Maisooneuve, Exploration scientifique de l’Algérie pendant lesannées 1840, 1841, 1842. Sciences physiques.
Botanique. Cryptogamie 1: 154 (1846).
Basyonym: Conferva caerulea Balbis ex C.
Agardh, Systema algarum: 122 (1824) [Type locality: Puerto Rico, Antilles, Caribbean (Setoand Kumano, 1993)].
Synonyms: Conferva chalybeus Kützing,Species algarum: 432 (1849); Conferva corinaldii Kützing, Tabulae Phycologicae 7: 35(1857); Conferva oishii Okamura, Icones ofJapanese Algae 3: 128 (1915).
[Figs. 1–7]
Plants bluish green or reddish brown in color,entangled, epilithic on stone or epiphytic on
withered branches of tree in the stream (Fig. 1).
Thalli filamentous, slender, branched repeatedly
and profusely, up to 40 cm in length and 25–360
m m in width (Figs. 2, 3). Young laterals uniseriate, rounded at the apex, acute angle with themain branch (Fig. 4). Mature branches uniaxial,
corticated, composed of an axial cell and 1–2
celled cortical layers, without rhizoidal filamentson the surface (Fig. 5). Axial cells colorless,barrel-shaped. Cortical cells small, spherical tocuboidal, 12–32 m m in width15–48 m m inlength in surface view. Spinous or curing branchlets absent.
Monosporangia pigmented, scattered over mature branches, spherical or triangle to polygonal,
12–16 m m in width in surface view (Fig. 6). The
sporangia embedded in the cortical layer, formedby dividing unequally from the upper side of thecortical cell (Fig. 7).
Specimens examined: Near Ose-bashi Bridge,Yatsuse-gawa River, Kominato, Chichi-jima Island, Ogasawara Isls., Japan (27°0334N,142°1218E), 11 July 2010, leg. T. Kitayama(TNS-AL 17302–17304).
Distribution: Asia: Japan (Fig. 8), China (Huand Wei, 2006); Oceania: Hawaii (Sherwood,2004), Vanuatu (West et al., 2007); Australia:Lord Howe Island (Millar and Kraft, 1993);
North America: Florida (Taylor, 1960), Louisiana(Taylor, 1960); Central America: Dominica(Taylor, 1969); Africa: Algeria (Krishnamurthy,1962); Europe: England (Krishnamurthy, 1962).
Discussion
The present Compsopogon plants from Chichijima Island, Ogasawara Islands, are identified as

Compsopogon caeruleus from Ogasawara Isls.

171

Figs. 1–7. Compsopogon caeruleus (Balbis ex C.Agardh) Montagne from Chichi-jima Island, Ogasawara Isls.,
Japan. 1. Habitat. 2. Habit. (TNS-AL 17302). 3. Erect filaments. 4. Young uniseriate lateral on maturebranches. 5, 6. Surface view of erect filament showing cortical cells with monosporangial cells (arrowheads)
on barrel-shaped axial cells. 7. Transverse section of erect filament showing monosporangia (arrowheads)
produced from cortical cells by unequal cell division.

C. caeruleus because of the frequent ramificationin erect filaments, formation of a few cell-layers
in cortex, lacking spinous or curling branchlets.

These characters also agree mostly to the description in C. oishii, which has been recorded
from many sites of main land of Japan since172

Taiju Kitayama

Okamura (1915).
However, the plants from Chichi-jima Island
have small monosporangia, which are 12–16 m min width, while size of monosporangia or monospores of C. caeruleus (or C. oishii) had been described large as 15–21 m m in diameter (Nakamura, 1984), 7.5–27.5 m m in length (Vis et al.,1992), (16–)20–23 m m in diameter (Seto and Kumano, 1993). According to Seto and Kumano(1993) and Kumano (2002), C. chalybeus, which
is European species, has small monospores,
10–16 m m in diameter. In their system for Compsopogon, the Chichi-jima’s plants can be identified as C. chalybeus. There was no record of C.
chalybeus in Asia including Japan, but recently
Liu and Wang (2004) reported this species from
Pingtung County, Taiwan, following Kumano(2002)’s system. The plants from Taiwan are alsosimilar to the plants of the Chichi-jima Island inhaving small monosporangia, which are 12–16
m m in diameter. In India, Ratha et al. (2007)
reported three ecotypes of C. caeruleus (as C.
coeruleus), whose monosporangia differ in size,depending on difference of water habitats (e.g.,water temperature, pH, conductivity, salinity):
the first ecotype, 16.4–22.3 m m in diameter; thesecond, 10–18.3 m m in diameter; the third 8.6–14m m in diameter. In Japan, it was observed thatthe seasonality made a difference to size ofmonospores in the plants of C. caeruleus (as C.
oishii) living in the little irrigation canal in Katori City, Chiba Pref. in 1992: Diameters ofmonosopres from the same population were measured as 13.2–16.8 m m on 29 May 1992, and then
17.2–22.1 m m on 23 October 1992 (Yamaoka,unpublished). Thus I consider that size of monospore and monosporangia is not so useful as ataxonomic character for Compsopogon and treat
the alga from Chichi-jima as C. caeruleus provisionally until the system of the genus will be stabilized.
Fig. 8 shows the geographical distribution ofCompsopogon caeruleus in Japan based on theherbarium specimens deposited in SAP and TNS,and literature data. It suggests that habit of thisalga has a tendency to be close to seacoasts or es-tuaries along the Pacific side of the Japan Archipelago. Thaxter (1900) collected Compsopogon
spp. from Cocoanut Grove, along the shores ofBiscane Bay, Florida and Tayor (1960) noted thatC. caeruleus is often abundant in tidal creeks
near the coast of Florida and Louisiana. Ratha etal. (2007) collected C. caeruleus from the channel of an estuary and Chilika lagoon in the Orissa
state, India. There is a possibility that Compsopogon caeruleus is a brackish and freshwateralga. Nozawa (1971) studied the effect of salinity
on the germination of monospores in C.
caeruleus (as C. oishii) and showed that formation and liberation of monospores was stimulated
in between 0.8–16.6‰ (max in 6.8‰). He concluded that the reproduction and distribution ofthis alga might have connection with seawater orsaline water. Also Glazer et al. (1994) showedthat C. caeruleus (as C. coeruleus) has a capability to grow and reproduce in salinities up to 35‰
and a possibility of its being adapted secondarily
to freshwater from marine habitats. Finding of
the alga from Chichi-jima Island, where is a volcano island formed around 46–48 million years
ago (Ishizuka et al., 2006) and isolated geographically from main lands extraordinarily, suggests that this alga has any means of dispersion
other than flooding of the water between tworivers. Thus two hypotheses are possible: 1) remnants of the algal habitats by marine regression
in geological eras, and 2) recent transportation of
the algal plants among the islands or continents
by migratory birds. In particular, it is suspectedthat long distant migrants living on both rivers
and seacoasts (e.g., Scolopacidae, Charadriidae)
are movers for the alga. Judging from the distribution clustering to Pacific side of Japan, if migratory birds flying from the South Pacific carry its
plants or spores, there may be also a possibilityof that the habitats of C. caeruleus are rest areas
for them. More information on distribution of thespecies is required for verifying these hypotheses.
Acknowledgments
I am grateful to Mr. Shigeo Ichiki, member ofCompsopogon caeruleus from Ogasawara Isls.

173

Fig. 8. Geographical distribution of Compsopogon caeruleus (Balbis ex C.Agardh) Montagne in Japan based ondried specimens from the herbaria (SAP, TNS) and literatures.
Filled circles (): specimens investigated. 1. Yamatosawa, Hirosaki, Aomori Pref., 19 Feb. 2008, leg. Y.
Ishitoya (TNS-AL 163530). 2. Tatebayashi, Gunma Pref., 23 Sep. 1971, leg. M. Chihara (TNS-AL 152359).
3. Mitsukaido, Ibaraki Pref., 14 May 2004, leg. A. Higa (TNS-AL 164542). 4. Yorogo, Katori, Chiba Pref.,10 Aug. 1991, leg. Y, Yamaoka (TNS-AL 173605). 5. Yachiyo, Chiba Pref., 15 Dec. 2001, leg. M. Suzuki(TNS-AL 166738). 6. Omiya, Tokyo Metr., 3 Jan., leg. K. Hisauchi (TNS-AL 166014). 7. Honjo, SaitamaPref., 19 Nov. 1972, leg. T. Hashimoto (TNS-AL 157097). 8. Sakai, Gumma Pref., 20 Aug. 1969, leg. M.
Hasei (TNS-AL 24055). 9. Akamatsu, Anjo, Aichi Pref., 1951 (?), leg. Anonymous (TNS-AL 157116). 10.
Imafuku, Ogaki, Gifu Pref., 26 Oct. 2001, leg. S. Arai (TNS-AL 164286). 11. Okada, Himeji, Hyogo Pref.,13 Dec. 1952, leg. H. Kiyose (TNS-AL 157117). 12. Kojima Lake, Okayama Pref., 8 Aug. 1974, leg. Anonymous (TNS-AL 157099). 13. Gobo River, Takamatsu, Kagawa Pref., 4 Dec. 1985, leg. R. Seto (TNS-AL157122). 14. Hiratsuka River, Amagi, Fukuoka Pref., 2 Nov. 2004, leg. T. Yoshida (SAP 101406). 15. Imizu,Kumamoto Pref., 15 Feb. 2004, leg. T. Yoshida (SAP 97970). 16. Takaharu, Nishimorokata, Miyazaki Pref.,18 Dec. 1999, leg. T. Minamiya (TNS-AL 164284). 17. Campus of Kagoshima University, Kagoshima,Kagoshima Pref., 13 Apr. 1974, leg. K. Nozawa (TNS-AL 157110). 18. Tatsugo, Amami-oshima, Kagoshima
Pref., 3 May 2005, leg. S. Arai (TNS-AL 164399). 19. Onna, Okinawa Pref., 9 Mar. 2004, leg. S. Arai (TNSAL 164350). 20. Oyama, Okinawa Pref., 10 May 1957, leg. S. Kamura (TNS-AL 157109). 21. Osato, Itoman, Okinawa Pref., 6 Apr. 1977, leg. R. Seto (TNS-AL 157107). 22. Kabira, Ishigaki Isl. Okinawa Pref., 19May 2007, leg. Suda (TNS-AL 164463). Open circles (): literature data. i. Lake Akan, Hokkaido (Kumano,2000). ii. Lake Hakuryu, Yamagata Pref. (Ohnuma and Hara, unpublished). iii. Marsh Yunuma, Urabandai,Fukushima Pref. (Kumano, 2000). iv. Ohmi-hachiman, Shiga Pref. (Kumano, 2000). v. Maikata, Osaka Pref.
(Kumano, 2000). vi. Doi, Ehime Pref. (Kobayashi, 2003). Star (H): the present alga.

174Taiju Kitayama

the village assembly of Ogasawara for useful
information about algal habitat in Chichi-jimaisland, and Mr. Yuji Aoki, director of the Ogasawara Fisheries Center for providing me the facilities to processing the specimens. I am gratefulto Dr. Kazuhiro Kogame and Dr. Tsuyoshi Abe,
Hokkaido University, for providing me the facilities to investigate specimens in the herbarium(SAP). I also thank Drs. Toshihiko Fujita,
Kazunori Hasegawa, Hironori Komatsu, Department of Zoology, National Museum of Natureand Science (NSMT) for their kind help in thefield study in the island, and Ms. Yoko Yamaoka,
Seibutsu Kenkyusha Co., Ltd., Tokyo, for her
useful suggestion.
References
Agardh, C. A. 1824. Systema algarum, xxxviii[1]-312
pp. Lundae, Berlin.
Brodie, J., Andersen, R. A., Kawachi, M. and Millar, A. J.
K. 2009. Endangered algal species and how to protect
them. Phycologia 48: 423–428.
Chihara, M. and Nakamura, T. 1980. Compsopogon corticurassus, a new species of fresh water red algae(Compsopogonaceae, Rhodophyta). Journal of Japanese Botany 55: 136–144 (in Japanese).
Engler, H. G. A. and Prantl, K. A. E. 1891–1897. Die
natürlich Pflanyenfamilien. 1. Englmann, Leipzig.
Glazer, A. N., Chan C. F., Karsten, U. and West, J. A.
1994. Salinity tolerance, biliproteins, and floridosidecontent of Compsopogon coeruleus (Rhodophyta).
Journal of Phycology 30: 457–461.
Guiry, M. D. and Guiry, G. M. 2011. AlgaeBase. Worldwide electronic publication, National University of Ireland, Galway (http://www.algaebase.org; searched on
23 August 2011).
Hu, H. and Wei, Y. 2006. The freshwater algae of China.
Systematics, Taxonomy and Ecology, China. 1023 pp.
Ishizuka, O., Kimura, J., Stern, Y. Li, R., Reagan, M.,Taylor, R., Ohara, Y., Bloomer, S., Ishii, T., Hargrove,
U. and Haraguchi, S. 2006. Early stages in the evolution of Izu–Bonin arc volcanism: New age, chemical,
and isotopic constraints. Earth and Planetary Science
Letters 250: 385–401.
Kobayashi, S. 2003. New locality of Compsopogoncoeruleus (Balbis) Montagne; freshwater algae, inEhime Prefecure, Shikoku, Japan. Bulletin of Ehime
Prefectural Science Museum 8: 17–19 (in Japanese).
Krishnamurthy, V. 1962. The morphology and taxonomyof the genus Compsopogon Montagne. Journal of Lin-nean Society (Botany) 58: 207–222.
Kumano, S. 2000. Taxonomy of Freshwater Rhodophyta.
Uchida Rokakuho, Tokyo. 395 pp (in Japanese).
Kumano, S. 2002. Freshwater Red Algae of the World.
Bristol: Biopress. xi375 pp.
Kützing, F. T. 1849. Species Algarum, F. A. Brockhaus,Leipzig. vi922 pp.
Liu, S.-L. and Wang, W.-L. 2004. Two new members offreshwater red algae in Taiwan: Compsopogon tenellus
Ling et Xie and C. chalybeus Kutzing (Compsopogonaceae, Rhodophyta). Taiwania 49: 32–38.
Millar, A. J. K. and Kraft, G. T. 1993. Catalogue of marine and freshwater red algae (Rhodophyta) of New
South Wales, including Lord Howe Island, South-western Pacific. Australian Systematic Botany 6: 1–90.
Nakamura, T. 1984. Compsopogon oishii Okamura. In:
Yamagishi, T. and Akiyama, M. (eds.), Photomicrographs of the fresh-water Algae 1: 27 (in Japanese).
Nakamura, T. 1993. Compsopogon oishii Okamura. In:
Hori, T. (ed.), An illustrated atlas of the life history ofalgae 2: 170–171 (in Japanese).
Nozawa, K. 1971. The effect of salinity on the germination and distribution of Compsopogon. Memoirs of theFaculty of Fisheries, Kagoshima University 20: 203–208 (in Japanese).
Okamura, K. 1915. Icones of Japanese algae 3: 123–218.
Ratha, S. K., Jena, M. Rath, J. and Adhikary, S. P. 2007.
The ecotypes of Compsopogon coeruleus (Rhodophyta)from Orissa State, east coast of India. Algae 22: 87–93.
Seto, R. and Kumano, S. 1993. Reappraisl of some taxa ofthe genera Compsopogon and Compsopogonopsis(Composogonaceae, Rhodophyta). Japanese Journal ofPhycology 41: 333–340.
Sherwood, A. R. 2004. Bibliographic checklist of the nonmarine algae of the Hawaiian Islands. Records of theHawaii Biological Survey for 2003. Bishop Museum
Occasional Papers 80: 1–26.
Taylor, W. R. 1960. Marine Algae of the Eastern Tropicaland Subtropical Coasts of the Americas. The Universityof Michigan Press, Ann Arbor. xi-870 pp., 14 figs, 80
pls.
Taylor, W. R. 1969. Notes on the distribution of West Indian marine algae particularly in the Lesser Antilles.
Contributions from the University of Michigan Herbarium 9: 125–203.
Thaxter, R. 1900. Note on the structure and reproductionof Compsopogon. Contribution from the cryptogamiclaboratory of Harvard University. XLIII.
Vis, M. L., Sheath, R. G. and Cole, K. M. 1992. Systematics of the freshwater red algae family Composopogonaceae in North America. Phycologia 31: 564–575.
West, J. A., Zuccarello, G. C., Scott, J. L., K. A. West,and Loiseaux de Goer, S. 2007. Pulvinus veneticus gen.
et sp. nov. (Compsopogonales, Rhodophyta) from Vanuatu. Phycologia 46: 237–246.