Bull. Natl. Mus. Nat. Sci., Ser. B, 45(4), pp. 131–136, November 22, 2019

First Record of Lychaete bainesii (F.Müller et Harvey ex Harvey)
M.J.Wynne (Cladophoraceae, Ulvophyceae) from 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 18 August 2019; accepted 25 September 2019)

Abstract A benthic marine green alga, Lychaete bainesii (F.Müller et Harvey ex Harvey)
M.J.Wynne (Cladophoraceae, Cladophorales, Ulvophyceae) was collected from the mesophoticzone (40–54 m in depth) of Chichi-jima Island and Ototo-jima, Ogasawara Islands, Japan. Thisalga is different from the other species of the genus Lychaete in having a long basal stipe (up to1.6 cm) and a main axis (up to 220 µm in diameter), numerous, ﬁne, tapering laterals (18–120 µmin diameter) with 1–3(4) branches and extremely slender apical cells (15–23 µm in diameter). The
presence of this species, which has been known only from southern Australia and Tasmania so far,raises a possibility that the mesophotic algal ﬂora of Ogaswara islands has some relationship withthe one of the South Paciﬁc Ocean.
Key words : benthic marine green alga, Cladophoraceae, Lychaete bainesii, Ogasawara Islands,Ulvophyceae.

A marine green alga, Lychaete bainesii(F.Müller et Harvey ex Harvey) M.J.Wynne had
recently changed its genus name in succession.
Since the original description of Harvey (1859),
this species had been treated for a long time as“Cladophora bainesii F.Müller et Harvey ex Harvey”, a member of the large genus CladophoraKützing. In 2016, the species was transferred to
the genus Acrocladus Nägeli by Boedeker et al.
(2016), who segregated a marine algal clade
from the genus Cladophora based on the resultsof their molecular analysis. This clade had been
known as “section Longi-articulatae Hamel”,
having several morphological characteristics:
acropetally organized branch systems, growth bydivision of conspicuous apical cells with subsequent considerable cell elongation, conspicuous
stipes, etc. (Hoek, 1963; Hoek and Chihara,2000). They proposed the resurrection of the oldgenus Acrocladus for this clade, assigning nin© 2019 National Museum of Nature and Scienceteen species including “Acrocladus bainesii(F.Müller et Harvey ex Harvey) Boedeker” (Boedeker et al., 2016). However, Wynne (2017)
pointed out that “Acrocladus mirabilis(C.Agardh) Boedeker” which was listed in thegenus Acrocladus emended by Boedeker, had
another name, Lychaete mirabilis (C.Agardh)
J.Agardh. This genus name, Lychaete, was lectotypiﬁed with L. mirabilis and validated by J.
Agardh in 1846 and thus predated the establishment of “Acrocladus” by Nägeli in 1847. Therefore, Wynne (2017) reinstated the genus
Lychaete and proposed to transfer eighteen species from “Acrocladus” to the older genus,Lychaete.
As a result, in Japan, six species and a varietyof “Acrocladus” were transfered taxonomically toLychaete by Wynne (2017): Lychaete dotyana(W.J.Gilbert) M.J.Wynne, L. herpestica (Montagne) M.J.Wynne, L. japonica (Yamada)
M.J.Wynne, L. japonica var. kajimurae (C.Hoeket Chihara) M.J.Wynne, L. minisakai (C.Hoek et132

Taiju KitayamaChihara) M.J.Wynne, L. ohkuboana (Holmes)
M.J.Wynne, L. sakai (I.A.Abbott) M.J.Wynne. In
this investigation L. bainesii (F.Müller et Harveyex Harvey) M.J.Wynne is added to the list ofJapanese Lychaete.
Ogasawara Islands (also called the BoninIslands) are oceanic islands located ca. 1,000 km
south of Izu Peninsula, Japan. In recent investigations of algal ﬂora around the Islands, several
rare algae were found from the mesophotic zone
or middle light zone (30–150 m in depth) using adredging apparatus: for example, mesophoticmarine algae, Aneurianna ogasawaraensis Kitayama (Kitayama, 2014), Codium mamillosum
Harvey (Kitayama, 2017), Discosporangia mesarthrocarpum (Meneghini) Hauck (Kitayama,2012), Zosterocarpus ogasawaraensis Kitayama(Kitayama, 2013). In addition to these species
unknown in the Japanese Archipelago, theappearance of Lychaete bainesii (F.Müller etHarvey ex Harvey) M.J.Wynne, which is known
only to be from the southern Hemisphere so far,suggests a possibility that the Ogasawara Islands
have a unique algal ﬂora derived from areas outside the Japanese Archipelago. In this study, toconﬁrm the identity of the present alga from theislands, the author made anatomical observations
on the material using microscopes.
Material and Methods
The green algal material refered to as Lychaetebainesii (F.Müller et Harvey ex Harvey)
M.J.Wynne was collected from the mesophotic
zone of Chichi-jima Island (40–54 m in depth)
and Ototo-jima Island (56–63 m in depth) in theOgasawara Islands, Japan used a dredging apparatus and the ﬁshing vessel “The 7th Ushiwomaru” (steering by Captain Y. Takase), on 16 and
17 July 2017. For preservation, the material was
ﬁxed and stored in 10% Formalin-seawater, andspecimens were mounted in glycerine jelly. Anatomical observations were made on the materialby using a microscope. Voucher specimens weredeposited in the algal herbarium of the Department of Botany, National Museum of Nature andScience (TNS).
Results
Class Ulvophyceae K.R.Mattox
et K.D.Stewart, 1984
Order Cladophorales Haeckel, 1894
Family Cladophoraceae Wille in Warming, 1884
Lychaete bainesii (F.Müller et Harvey ex Harvey)
M.J.Wynne
Notulae Algarum 31: 1 (2017).
[Figs. 1–7]
[Type locality: Port Phillip, Victoria, Australia.
Lectotype: TCD (Womersley, 1956: 358), Herb.
Harvey, Algae Australicae Exsiccatae 579F
(Womersley, 1984: 194; Guiry in Guiry andGuiry, 2019).]
Basionym: Cladophora bainesii F.Müller etHarvey ex Harvey, Phycologia Australica, vol. 2.
pl. 112, 1859.
Synonym: Acrocladus bainesii (F.Müller etHarvey ex Harvey) Boedeker, Journal of Phycology, 52: 919, 2016.
Habitat: Grew on rock in the mesophotic zone
(40–54 m in depth).
Morphology: Plants are light to medium green,erect, up to 8 cm in height (Figs. 1 and 2), with
one long stipe basally attached on rocks by aholdfast with branched haptera (Fig. 3, arrow).
Stipes are elongated, up to 1.6 cm in height.
Thalli are ﬁlamentous, monosiphonous, composed of main axes and numerous laterals, acropetal (intercalary cell divisions apparently absent
in the lower portions) (Fig. 4), growing by apicalcells (Fig. 5) and intercalary divisions in theupper portions (Fig. 6). Filaments are gently
tapering and branched often above every 1–4
cells, forming delicate, fastigiate tufts (Fig. 7).
Main axes are elongated, up to 220 µm in diameter. Lateral branches are ﬁne, 18–120 µm indiameter, ultimate, arising di-, tri- or tetrachotomous at acute angles from each parent cell (Fig.
4). Cross walls are almost horizontal to parentcells. Apical cells are obtuse to acute, small,slender, needlelike, 15–23 µm in diameter (Figs.

Lychaete bainesii new to Japan133

Figs. 1–6. Lychaete bainesii (F.Müller et Harvey ex Harvey) M.J.Wynne from Ogasawara Islands., Japan. 1.
Thallus from Chichi-jima Island, Ogasawara Islands, Japan (TNS-AL 210218). 2. Thallus from Ototo-jimaIsland, Ogasawara Islands, Japan (TNS-AL 210219). 3. Holdfast of the thallus from Ototo-jima (Fig. 2) showing a hapteron (arrow). 4. Tetrachotomous branching at acute angles from a parent cell in the lower portion ofthe thallus. 5. Apical cell with an acute apex. 6. Various laterals branching at acute angles showing an apicalcell with obtuse apex (arrowhead).

5 and 6, arrow). Reproductive organs were notobserved (According to Womersley (1984), zooidangia were transformed from upper cells of theﬁlaments and then quadriﬂagellate zoospores
were observed once).

Specimens examined: Ogasawara Islands,
Japan: Off Kurazone (53.5–53.9 m in depth), Chichi-jima Island (27°5′N, 142°11′E), 17 July 2017,leg. T. Kitayama (TNS-AL 210218) (Fig. 1); Off
Small-hama beach (ca. 40 m in depth), Ototo-jima

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Taiju Kitayama

Fig. 7. Lychaete bainesii (F.Müller et Harvey exHarvey) M.J.Wynne from Ogasawara Islands,
Japan. Upper branch system.

Island (27°8′N, 142°11′E), 16 July 2017, leg. T.
Kitayama (TNS-AL 210219) (Fig. 2).
Japanese name: Sakiboso-shiwogusa (nov.).
Distribution: Indian Ocean: South Australia(type locality), Tasmania, Victoria (Womersley,1984); Paciﬁc Ocean: Japan (Ogasawara Islands,the present study).
Comparisons of apical and intercalary cells
among the seven species (including one variety)of Lychaete distributed in Japan are showed inTable 1.
Discussion
The present cladophoracean alga collectedfrom the mesophotic zone of the Ogasawara

Islands possesses the characteristics of Lychaetebainesii (F.Müller et Harvey ex Harvey)
M.J.Wynne in morphology. It agrees well withthe description of L. bainesii by Womersley(1984), while different from all species of Japanese Lychaete in the diameters of both apicalcells and intercalary cells (Table 1). In Japan
there have been no known species of Lychaete
having extremely thin apical cells below 25 µmin diameter. This is the ﬁrst record of L. bainesii
from Japan.
Outside of Japan, Lychaete pseudobainesii(C.Hoek and Searles) M.J.Wynne, which is distributed to the Atlantic coast of North America, isvery similar to L. bainesii in having extremely
slender apical cells (12–20 µm in diameter).
However, this Atlantic species differs from L.
bainesii by the larger number of branches which
can be formed at a node: L. pseudobainesii has
1–4(6) branches, while L. bainesii has 1–3(4)branches (Hoek and Searles, 1988). In addition,
L. pseudobainesii has intercalary divisions which
divide the internodes in the basal portions ofthalli, forming a thin stipe. In L. bainesii has nointercalary division in the basal portions and sohas actually one huge basal stipe cell (Hoek andSearles, 1988).
The presence of Lychaete bainesii suggests thatmesophotic marine algal ﬂora of Ogasawara
Islands has close relationships to the one of theSouth Paciﬁc Ocean. L. bainesii as well as
Aneurianna ogasawaraensis Kitayama, Codium
mamillosum Harvey, Discosporangia mesarthrocarpum (Meneghini) Hauck, Zosterocarpus ogasawaraensis Kitayama, which were recorded fromOgasawara Islands in recent years (Kitayama,2012; 2013; 2014; 2017), has no distribution in
not only the Japanese Archipelago but all overAsia. Thus the author considers that in the Ogasawara Islands expansion mechanism of geographic distribution of algae is different in depth.
In the shallow zone there are many algal species
common in the Japanese Archipelago (in particular the Ryukyu Islands), because of the strong
inﬂuence of the surface currents, mainly branchesof the Kuroshiwo Current (the Japan Current)Lychaete bainesii new to Japan

135

Table 1. Comparisons of apical and intercalary cells among the Japanese species of Lychaete based on Hoek andChihara (2000) and Womersley (1984).
Apical cells
Shape of tip

Intercalary cells

Distribution**

Diameter

DiameterL. bainesii*
Obtuse to mucronate 14–25(–35) µm
L. bainesii
Obtuse to acute
15–23 µm(the present study)
L. dotyana
Rounded160–340 µm

15–300 µm
18–120 µm

South Australia, Tasmania, Victoria
Japan (Ogasawara Isls.)

180–700 µm

L. herpestica*

Rounded240–370 µm

240–370 µm

L. japnica var.
japonica
L. japnica var.
kajimurae
L. minisakaii
L. ohkuboana

Rounded150–280 µm

150–300 µm

Rounded70–150 (–170) µm 70–150 µm

Fiji, Hawaii, Japan (Miyake-jima
Isl., Misaki, Oki Isl., Philippines,Queensland, South Africa, Taiwan, Tanzania
Austlaria, Chile, Fiji, India, Indonesia, Japan (Honshu, Shikoku,Kyushu, Nansei Isls.), Kenia,Kuwait, Malaysia, Micronesia,
New Caledonia, New Zealand,Oman, Philippines, Taiwan,Thailand, Vietnam etc.
Hawaii, Japan (Paciﬁc Ocean),Philippines
Japan (Sea of Japan), Korea

RoundedBlunt

135–185 µm
470–710 µm

155–205 µm
470–1420 µm

L. sakaii

Blunt

60–150 µm

60–250 µm

Japan (Okinawa)
China, Japan (Paciﬁc Ocean),
Korea, New South Wales, Oman,
Papua New Guinea, Taiwan
California, Japan (Hokkaido, Honshu, Shikoku, Kyushu), Korea,
Philippines, Taiwan, Vietnam* Womersley (1984), ** Guiry and Guiry (2019)from Japan. On the other hand, most algae in themesophotic zone is uncommon in the JapaneseArchipelago, because of few inﬂuence of the currents from Asia. There is a possibility that themesophotic algal ﬂora in Ogasawara Islands were
derived from Oceania or the South Paciﬁc Ocean.
Presently seven species and one variety ofLychaete are dispersed throughout Japan, though

their exact distribution may not be accurate
because they are so similar each other in outward
morphology. To clarify the whole distribution ofL. bainesii, anatomical observations and molecular analyses on more samples from various ﬁelds
and more specimens in various herbaria arerequired.

Key to the species of Lychaete in Japan(based on van den Hoek and Chihara, 2000)
1a. Basal cross wall of lateral branches absent, leaving the lateral and parent cell in open connection..........................................................................................................................................L. herpestica
1b. Basal cross wall of lateral branches present at or near junction of cells............................................2
2a. Apical cells less than 340 µm in diameter ..........................................................................................32b. Apical cells 470–710 (–930) µm in diameter .................................................................L. ohkuboana
3a. Thalli forming spreading pompon-like tufts up to 7 cm in height. Basal stipes short, mostly onecelled (to two-celled)...........................................................................................................................43b. Thalli forming erect tufts up to 30 (–40) cm in height. Basal stipes elongated, 2 or more cells .......54a. Apical cells relatively long, 135–185 µm in diameter. Basal cells relatively narrow, 170–205 µm in

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Taiju Kitayama

diameter ............................................................................................................................L. minisakaii
4b. Apical cells relatively short, 160–340 µm in diameter. Basal cells relatively thick, 400–700 µm indiameter ............................................................................................................................... L. dotyana
5a. Apical cells thin, 15–25(–35) µm in diameter, having an obtuse to acute tip .....................L. bainesii
5a. Apical cells thick, 50–300 µm in diameter, having a blunt or round tip ............................................66a. Apical cells (50–) 60–150 µm in diameter. Basal cells much less conspicuous, 170–250(–300) µmin diameter...............................................................................................................................L. sakaii
6b. Apical cells 70–280 µm in diameter. Basal cells conspicuous, 580–1100 µm in diameter....................................................................................................................................... 7. L. japonica
7a. Apical cells 150–280 µm in diameter. Basal cells 700–1100 µm in diameter...................................................................................................................... L. japonica var. japonica
7b. Apical cells 70–150 µm in diameter. Basal cells 580–800 µm in diameter.................................................................................................................... L. japonica var. kajimurae
Acknowledgments
I am grateful to Mr. Yoshiyasu Takase, theOgasawara-jima Fisheries Cooperative for collecting the material by dredging with his ship. I
thank Mr. Masataka Kikuchi, the union representative of the Ogasawara-jima Fisheries Cooperative for permission and cooperation for collecting, and Kotaro Seno and Mr. Miyazaki, theOgasawara Fisheries Center, Tokyo Metropolitan
for providing me the facilities to process thespecimens. This study was supported by Grantsin-Aid for Scientiﬁc Research (No. 16K07496)
from the Ministry of Education, Culture, Sports,
Science and Technology, Japan.
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