Marine algae and seagrasses of the Dahlak Archipelago, southern Red Sea

90 Pages·2006·1.21 MB·English

Nova Hedwigia 75 1—2 1—90 Stuttgart, August 2002
Marine algae and seagrasses of the Dahlak Archipelago,
southern Red Sea
by
Y. Lipkin
Department of Botany, Tel Aviv University, Tel Aviv, Israel
and
P.C. Silva*
Herbarium, University of California, Berkeley, California 94720-2465, U.S.A.
With 7 figures and 4 tables
Dedicated to the memory of G.F. Papenfuss (1903-1981), distinguished scholar,
teacher, and colleague, who laid the groundwork for this paper.
Lipkin, Y. & P.C. Silva (2002): Marine algae and seagrasses of the Dahlak Archipelago, southern
Red Sea. - Nova Hedwigia 75: 1-90.
Abstract: Two Israeli expeditions to the Eritrean (then Ethiopian) coast in 1962 and 1965 obtained
127 specific and infraspecific taxa of benthic marine algae representing 73 genera and 4 species of
seagrasses representing 3 genera. Collections were made mainly in the Dahlak Archipelago, but also
on the adjacent mainland coast. The spring (1962) expedition yielded 94 species of algae, whereas
the autumn (1965) expedition yielded 77, with 44 present in both seasons. Among these algae, 13
genera and 47 species had not been recorded previously from the Red Sea. Some of these 47 species
have been reported subsequently from the northernmost part of the basin. There were 58 Rhodophyta,
33 Chlorophyta, and 31 Phaeophyta. Blue-green prokaryotes (Cyanophyta) were well represented in
the collections, but only 5 species were identified.
Two new species of algae are described: Pterocladia microscopica Lipkin et Papenfuss and Hypnea
anastomosans Papenfuss, Lipkin et Silva. Two other new species have been published elsewhere:
Turbinaria papenfussii W.R. Taylor and Chlorodesmis papenfussii Ducker. A new name, Sargassum
steinitzii, is proposed for S. tenue J. Agardh, non S. tenue (Kützing) Endlicher. Two new combinations
are made: Gelidiopsis capitata for Acrocarpus capitatus Kützing and Chondrophycus glanduliferus
for Chondria glandulifera Kützing.
*Address for correspondence: [email protected]
DOI: 10.1127/0029-5035/2002/0075-0 0 0 1 0029-5035/02/0075-0001 $22.50
© 2002 J. Cramer in der Gebrüder Borntraeger
Verlagsbuchhandlung, D-14129 Berlin · D-70176 Stuttgart
1
Introduction
The benthic marine flora of the southern Red Sea in general and the Dahlak Archi-
pelago in particular is very poorly known. Of 493 species and subspecific taxa of
benthic marine algae recorded from the Red Sea prior to 1968 (Papenfuss 1968a),
only 218 are attributed to the area south of the Suakim-Al Qunfudhah line (ca.
19°N). Only 164 had been reported from the Ethiopian coast and only 26 from the
Dahlak Archipelago. All of these numbers are inflated as a result of taxonomic
recognition by Grunow (1915, 1916) of many ecological forms of Sargassum.
The Red Sea, which is situated between the latitudes 13°N and 30°N, with its mouth
to the southeast, received its algae from nearby African and Arabian coasts, which
are occupied chiefly by members of the widespread tropical Indo-Pacific marine
flora. In Papenfuss’s catalogue (Papenfuss 1968a), 101 algae (including 57 taxa of
Sargassum) were recorded only from the southern Red Sea. Because the northern,
temperate reaches of the Red Sea have been well investigated, the absence of these
101 algae in that area is evidence that the richness of the marine flora of the Red Sea
decreases northward.
The Dahlak Archipelago is located in the southern Red Sea off the Eritrean coast,
between the latitudes 15°N and 17°N and the parallels 39°E and 41°E (Fig. 1). It is
situated on a rather shallow shelf ca. 150 km wide and 200 km long. Maximal depths
between the islands range mostly between 10 and 60 m, with the exception of the
Mesewa Channel, which runs between the Eritrean mainland and Dahlak Kebir Is-
land. This channel has a general depth of ca. 120 m, reaching almost 160 m in a
small area west of Dur Gaarn Island. Waters surrounding the islands of the archipelago,
because of their tropical location and shallowness, are very warm, even at the bottom,
being between 27°C and 30°C away from the islands and reaching nearly 40°C in
very shallow bays around the islands. At such high temperatures the concentration of
dissolved gases, particularly O and CO , are low. Salinities are even higher than in
2 2
the open Red Sea, which, with salinities of ca. 40 ppt, is the most saline open sea on
earth. The shallowness exaggerates fluctuations of water conditions in response to
changes in weather, thus stressing the marine biota. To the northeast of the archipelago
lies the deep main channel of the Red Sea from which the swell comes in to wash the
outer islands, providing somewhat better conditions for marine life. Further
information on the environment is given by Lipkin (1987).
In the early 1960s two Israeli expeditions studied the marine life, and incidentally
certain aspects of terrestrial life, in the Dahlak Archipelago. The first Israel South
Red Sea Expedition (ISRSE) visited the archipelago in March-April 1962, camped
on Entedebir Island (where much of the work was done), and visited several other
islands, all with rocky and sandy beaches and surrounded by shallow shelves. Most
locations sampled were sheltered from severe wave action and yielded only a few
species. Exceptions were Romia Island and Harmil Island, located at the eastern
edge of the archipelago and exposed to the swell from the deep waters of the main
navigation channel of the Red Sea. Here a rather diverse biota was found, a short
visit yielding many species not encountered in other parts of the archipelago. The
mangrove habitat was visited only briefly, at Melita Bay in the Gulf of Zula on the
Eritrean mainland.
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Fig. 1. Map of Dahlak Archipelago showing shore collection sites of the Israel South Red Sea
Expeditions, 1962 and 1965. (See Table 1 for legend to numbered collection sites.) Map redrawn
from nautical chart 62008, Red Sea sheet IV, Masamirit I. to Zubair Is., published by the Hydrographic
Office, Washington D.C., Dec. 1912.
The second Israel South Red Sea Expedition, which visited the archipelago in October
1965, provided a glimpse of the autumn flora compared with the spring flora sampled
by the first expedition. It camped (and carried out much of its work) on Museri
Island, which differs markedly from Entedebir Island in having much of its coast
occupied by mangroves. Although collections were made at many habitats similar to
those studied in 1962 (in some cases the same sites), additional islands with different
habitats were visited briefly. General information was published by Oren (1962) for
ISRSE 1962 and by Lewinsohn & Fishelson (1968) for ISRSE 1965. Ecological
aspects of the marine flora of the archipelago were summarized by Lipkin (1987).
The present paper is a systematic treatment of the marine algae and seagrasses collected
by the two Israeli expeditions in the Dahlak Archipelago and on the adjacent Eritrean
coast.
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Material and methods
ISRSE 1962 camped on Entedebir Island (No. 6 on Fig. 1 and Table 1) and ISRSE 1965 camped on
Museri Island (No. 11 on Fig. 1 and Table 1). Collecting on the shores of the base camp island was
undertaken: between 9 March and 6 April during ISRSE 1962, and between 7 and 27 October during
ISRSE 1965. On these islands marine algae and seagrasses were collected from several sites,
representing various habitats (Oren 1962; Lewinsohn & Fishelson 1968; Lipkin 1987). Nine other
islands and three mainland sites (Fig. 1 and Table 1) were also visited, but briefly, with only a few
hours devoted to collecting. Cundabilu Island, situated close to Entedebir Island, was visited twice,
allowing almost three full days of collecting.
The marine algae and seagrasses of the first expedition were collected by G.F. Papenfuss and, to a
lesser extent, by I.E. Friedmann, who unfortunately had to quit the expedition after only a few days
because of illness. A few samples were taken from the intertidal zone by C. Lewinsohn and L.
Fishelson. Collections in 1965 were made by Y. Lipkin, who also carried out ecological studies
(Lipkin 1987). The 1962 samples came predominantly from shallow water, and in 1965 SCUBA
technique was added in order to collect algae from subtidal habitats to depths of ca. 10 m. Dredging
from a trawler was used to get samples from depths between 10 and 120 m.
Samples taken during ISRSE 1962 were numbered with the prefix E62/, whereas those of ISRSE
1965 bear the prefix ISRSE 65/. Many samples included both pressed and liquid-preserveds pecimens,
while others were in either one form or the other. Complete sets of specimens from both expeditions
are deposited at the Phycological Collection of the National Natural History Museum of Israel,
temporarily housed at Tel Aviv University (TELA). The first set of duplicates is deposited at the
University of California (UC). Other herbaria cited in this paper are abbreviated in accordance with
Holmgren et al. (1990).
Representatives of a few genera among the 1962 collections have been studied and the results have
been published, as follows: Turbinaria (Taylor 1964); Caulerpa (Taylor 1967), Chlorodesmis
(Ducker 1967, 1969), Cystoseira (Papenfuss & Jensen 1967), Hormophysa (Papenfuss 1968b),
Leveillea (Scagel & Chihara, 1968) and Sarconema (Papenfuss & Edelstein 1974). Halimeda was
studied by L. Hillis-Colinvaux, but not reported. Y.M. Chiang identified most other algae from the
first expedition, but a few were identified by M. Chihara and R.H. Simons.
Concerning the 1965 collections, W.R. Taylor identified some specimens of Caulerpa and confirmed
our determinations of others, F. Drouet identified Calothrix pilosa, M.D. Hoyle confirmed iden-
tifications of some Gracilaria species, and H.W. Johansen confirmed identifications of the articulated
corallines.
Two of the samples of ISRSE 1962 were made the types of newly described species: Turbinaria
papenfussii W.R. Taylor (1964) and Chlorodesmis papenfussii Ducker (1969).
Taxa not recorded from the Red Sea prior to the collections of the two Israeli expeditions are marked
with an asterisk.
SYSTEMATIC LIST
CYANOPHYTA
CHROOCOCCALES
CHAMAESIPHONACEAE
*CHAMAECALYX Komárek et Anagnostidis
*Chamaecalyx clavatus (Setchell et Gardner) Komárek et Anagnostidis (Arch.
Hydrobiol., Suppl. 73: 199, 1986).
Chamaesiphon clavatus Setchell et Gardner (Proc. Calif. Acad. Sci., ser. 4, 19: 118, pl. 4, fig. 1,
1930).
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Table 1: Shore collection sites in the Dahlak Archipelago (plotted on Fig. 1).
Type from Isla Guadalupe, Baja California, Mexico, leg. H. Mason 63, CAS 173619
in UC.
ISRSE SPECIMENS STUDIED: Museri Island: in front of Scopus Ridge, 8.x.1965, on
Sphacelaria brachygonia and S. tribuloides (ISRSE 65/2333ea).
DISTRIBUTION: Reported from Islas Revilla Gigedo off the Pacific coast of Mexico
(Setchell & Gardner 1930); Indonesia (Geitler 1932); Vietnam (Pham-hoàng 1969),
and now the Red Sea. Probably widely distributed in warm Indo-Pacific waters.
COMMENTS: Our plants grew in loose clusters on the hosts. Cells were clavate, 30-
40 µm tall and 8-10 µm in maximum diameter.
OSCILLATORIALES
OSCILLATORIACEAE (nom. cons.)
LYNGBYA C. Agardh
Lyngbya confervoides C. Agardh (Syst. Alg., p. 73, 1824).
Type from Cádiz, Atlantic coast of Spain, in the Agardh herbarium at LD (see Drouet
1968, p. 264).
ISRSE SPECIMENS STUDIED: Museri Island: in front of Scopus Ridge, 8.x.1965, on
Turbinaria triquetra (ISRSE 65/2333f), 9.x.1965, on Acanthophora nayadiformis
(ISRSE 65/2351k), 23.x.1965, epilithic (ISRSE 65/3091).
DISTRIBUTION: Widespread in warm and temperate waters.
COMMENTS: Our plants had filaments 13-17 µm in diameter, trichomes 11-13 µm in
diameter and hyaline sheaths. They formed a rather loose growth on other algae,
whereas on rock they formed mats 1-2 mm thick.
5
This alga has been reported from the northern Red Sea (see records in Papenfuss
1968a; Lipkin 1972a, 1972b; Aleem 1978a; Potts 1980), but not from the southern
part.
Lyngbya majuscula (Dillwyn) Harvey (in Hooker Brit. Fl. 2(1) [= J.E. Smith,
Engl. Fl. 5(1)], p. 370, 1833).
Conferva majuscula Dillwyn (Brit. Conferv., p. 40, suppl. pl. A, 1809).
Type from England, in LD (see Drouet 1968, p. 263).
ISRSE SPECIMENS STUDIED: Entedebir Island: Landing Bay, 21.x.1965 (ISRSE
65/3135, 3139). Museri Island: in front of Scopus Ridge, 8.x.1965 (ISRSE 65/
2331), 10.x.1965, on Halimeda discoidea (ISRSE 65/2315c), 16.x.1965 (ISRSE
65/3072).
DISTRIBUTION: Widespread in warm and temperate waters.
COMMENTS: Our plants formed large masses. Their filaments were thick, 40-75 µm
in diameter, sometimes tending to curl. The trichomes were 35-67.5 µm in diameter,
with hyaline sheaths.
NOSTOCALES
RIVULARIACEAE
CALOTHRIX C. Agardh
*Calothrix pilosa Harvey (Smithsonian Contr. Knowl. 10(2) [Nereis Bor. Amer.
3]: 106, pl. XVIII.C, 1858).
Type from Key West, Florida, leg. W.H. Harvey, in BM (ex K) (see Drouet 1973, p.
39).
ISRSE SPECIMENS STUDIED: Museri Island: Rhizophora Lagoon, 12.x.1965, on
pneumatophores of Rhizophora mucronata (ISRSE 65/2386), on mud (ISRSE 65/
2387); south of Rhizophora Lagoon, 15.x.1965, on Avicennia marina pneumatophores
(ISRSE 65/0329, 2283-2286). Melita Bay in the Gulf of Zula, 2.iv.1962, on
pneumatophores of Avicennia marina, along with Caloglossa leprieurii, Bostrychia
simpliciuscula and Brachytrichia lloydii (E62/20232c). Desta Island: 26.x.1965, on
A. marina pneumatophores (ISRSE 65/3170).
DISTRIBUTION: Widespread in warm seas.
COMMENTS: Our plants had filaments 18-30 µmm in diameter, green trichomes 10-
20 µm in diameter and thick yellow to brownish sheaths. Pseudobranching was not
common. They grew in sheltered habitats, forming mats on pneumatophores of
Avicennia marina and rhizophores of Rhizophora mucronata as well as on mud.
Mats on A. marina reached 1 cm in thickness, on R. mucronata only 2-3 mm, and on
mud 1-2 mm. On the upper parts of pneumatophores of A. marina they often occupied
sectors 6-10 cm long, giving the pneumatophores a bottle-brush appearance (Lipkin
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1987, fig. 5). A similar, but less common situation occurs in Sinai, in the northern
Red Sea (Dor 1984). Dor regarded the Sinai material as belonging to either Scytonema
cincinnatum Thuret or S. polycystum Bornet et Flahault.
Part of sample ISRSE 65/0329, which was sent to Francis Drouet for determination,
was cited by him (Drouet 1973, p. 73) under Scytonema hofmanii C. Agardh (Syn.
Alg. Scand., p. 117, 1817) as Lipkin 2305 in PH. Calothrix pilosa is one of numerous
species referred by Drouet to S. hofmanii.
STIGONEMATALES
MASTIGOCLADACEAE
*BRACHYTRICHIA Zanardini
*Brachytrichia lloydii (Crouan) P.C. Silva (in Silva, Basson, & Moe, Univ. Calif.
Publ. Bot. 79: 78, 1996).
Rivularia lloydii P. et H. Crouan (Fl. Finistère, p. 117, 1867).
Type from Belle-Ile, France, ix.1854, in Lloyd, Algues de l’Ouest de la France, no.
303, in herb. Bornet-Thuret, PC (see Drouet 1973, p. 232).
ISRSE SPECIMENS STUDIED: Melita Bay, Gulf of Zula, 2.iv.1962, on pneumatophores
of Avicennia marina, along with Caloglossa leprieurii, Bostrychia simpliciuscula
and Calothrix pilosa (E62/20232b).
DISTRIBUTION: Warm eastern Atlantic waters, Mediterranean Sea, Red Sea.
COMMENTS: Our plants formed small dark patches, 1-3 mm in diameter and
hemispherical when wet, on pneumatophores of Avicennia marina, in one instance
immediately below a sector covered by Bostrychia simpliciuscula.
This species has been reported from intertidal rocks and A. marina pneumatophores
in the northern Red Sea and the Suez Canal as Brachytrichia balani (Safriel &
Lipkin 1964; Lipkin 1972a, b; Dor, 1984), but the collections of the ISRSE are the
first from the southern Red Sea.
RHODOPHYTA
ERYTHROPELTIDALES
ERYTHROTRICHIACEAE
ERYTHROTRICHIA J. Areschoug (nom. cons.)
Erythrotrichia carnea (Dillwyn) J. Agardh (Lunds Univ. Års-Skr., Afd. Math. och
Naturvitensk. 19(2): 15, 1883).
Conferva carnea Dillwyn (Brit. Conferv., fasc. 12, pl. 84, 1807).
Type from Loughor [Llwchwr], West Glamorgan, Wales, U.K., leg. W.W. Young,
in BM (ex herb. Forster).
7
ISRSE SPECIMENS STUDIED: Museri Island: in front of Scopus Ridge, 19.x.1965, on
Ceramium flaccidum, (ISRSE 65/3084n).
DISTRIBUTION: More or less cosmopolitan.
ACROCHAETIALES
ACROCHAETIACEAE (nom. cons.)
ACROCHAETIUM Nägeli
*Acrochaetium gracile Børgesen (Dansk Bot. Ark. 3: 26, figs. 19, 20, 1915).
Type from St. Thomas Harbor, St. Thomas, U.S. Virgin Islands, on Sargassum vulgare,
presumably in C.
ISRSE SPECIMENS STUDIED: Entedebir Island: Mersat Abiad, 12.iii.1962, on a snail’s
shell with other microscopic algae (E62/20031a); Landing Bay, 21.x.1965, on
Gelidiopsis acrocarpa (ISRSE 65/3141fa).
DISTRIBUTION: Widespread in warm seas.
COMMENTS: Our plants were 1-1.25 mm tall with filaments ca. 5 µm in diameter, cell
length 13-19 µm, and sporangia ca. 7.5 × 10 µm.
We follow the classification of the Acrochaetiaceae proposed by Feldmann (1962)
(see discussion by Silva et al. 1996, p. 94).
NEMALIALES
GALAXAURACEAE
GALAXAURA Lamouroux
Galaxaura rugosa (Ellis et Solander) Lamouroux (Hist. Polyp. Corall. Flex., p.
263, 1816).
Corallina rugosa Ellis et Solander (Nat. Hist. Zooph., p. 115, pl. 22, fig.3, 1786).
Type from Jamaica (presumably gametophyte) (see Papenfuss et al. 1982, p. 421).
ISRSE SPECIMENS STUDIED: Entedebir Island: outside Landing Bay to the north,
13.iii.1962, 3 m depth (E62/20035), northern shore of Ras Papenfuss, 25.iii.1962
(E62/20149).
DISTRIBUTION: Widespread in warm seas.
COMMENTS: Our plants formed clumps about 40 cm in diameter. No Galaxaura was
found during the second ISRSE. Although several species are very common in the
northern Red Sea (Lipkin, unpublished; see Papenfuss 1968a, for localities), the
genus is rather rare in the Dahlak Archipelago. Actinotrichia fragilis, another member
of the Galaxauraceae that is very common in the northern Red Sea, is apparently
absent from the Dahlak Archipelago.
8
Our plants agree with Galaxaura lapidescens var. annuligera Piccone et Grunow (in
Piccone, Nuovo Giorn. Bot. Ital., 16: 312, 1884; type from the Bay of Assab, Eritrea)
regarded as a taxonomic synonym of G. subverticillata by Papenfuss et al. (1982,
pp. 424, 425). Galaxaura subverticillata in turn was synonymized under G. rugosa
by Huisman & Borowitzka (1990, p. 153).
Many records of G. lapidescens (Ellis et Solander) Lamouroux from the Red Sea
(see Papenfuss 1968a, p. 72), including De Toni & Levi (1888, p. 53) and Lipkin
(in Mergner & Schuhmacher 1974, pp. 263, 291, 303, misspelled G. lepidescens),
were probably based on G. rugosa.
GELIDIALES
GELIDIACEAE
GELIDIUM Lamouroux (nom. cons.)
Gelidium corneum (Hudson) Lamouroux (Ann. Mus. Hist. Nat. [Paris] 20: 129,
1813).
Fucus corneus Hudson (Fl. Angl., p. 474, 1762).
Type from Devonshire, England, leg. D. Miller, in BM (ex herb. Buddle, Sloane
collection) (see Dixon 1967).
ISRSE SPECIMENS STUDIED: Entedebir Island: entrance to Landing Bay, 15.iii.1962,
1 m depth, on a snail (E62/20053); Goliath Bay, 16.iii.1962 (E62/20069), 23.iii.1962
(E62/20153), 6.iv.1962 (E62/20258).
DISTRIBUTION: Nearly cosmopolitan.
COMMENTS: Our plants were to 2-3 cm tall, and fairly well branched.
Gelidium crinale (Hare ex Turner) Gaillon (Dict. Sci. Nat. [Levrault] 53: 362,
1828).
Fucus crinalis Hare ex Turner (Fuci, vol. 4, p. 4, pl. 198, figs. a-c, e-g, 1815).
Lectotype from Ilfracombe, Devonshire, England, leg. R. Hare, in BM (ex K) (see
Dixon & Irvine 1977a: 140).
ISRSE SPECIMENS STUDIED: Entedebir Island: Goliath Bay, 23.iii.1962 (E62/20154),
6.iv.1962, on Digenea simplex (E62/20257).
DISTRIBUTION: Widespread in warm and temperate waters.
COMMENTS: Gelidium crinale and G. pusillum are traditionally recognized as two
distinct species, the former characterized as being caespitose and having filiform
branches, the latter as forming a turf and having flat, oval or lanceolate branches
(Feldmann & Hamel 1936, p. 107). They have been merged by Dixon & Irvine
(1977a, b), however, on the basis of a study that included sequential observations of
marked plants. We have no reason to doubt the validity of this conclusion, especially
9
when considering the fact that both type localities are in Devonshire, England, within
Dixon & Irvine’s study area. In the Red Sea, however, as in many other parts of the
world, the name G. pusillum has been applied to any very small turf-forming
Gelidium. It is unlikely that any of these recipients of the name is conspecific with
G. pusillum, which in Britain reaches a height of 15 cm. Realizing that taxonomic
problems within Gelidium cannot be solved in a floristic account, we follow
traditional, albeit faulty, species concepts in recognizing both G. crinale and G.
pusillum among collections at hand. Our plants of G. crinale reached 4 cm in height,
comparable with nearly fully developed plants in the northern Red Sea and eastern
Mediterranean.
Gelidium pusillum (Stackhouse) Le Jolis (Mém. Soc. Imp. Sci. Nat. Cherbourg
10: 139, 1863).
Fucus pusillus Stackhouse (Nereis Brit., p. 16, pl. VI, 1795).
Lectotype from Sidmouth, Devonshire, England, in BM (see Dixon & Irvine 1977a:
139).
ISRSE SPECIMENS STUDIED: Museri Island: off Mangrove Bay, 14.x.1965, on rock,
ca. 1 m depth (ISRSE 65/2397-tetrasporic, 3020g-tetrasporic); Camping Bay, off
Ras Pandion, 16.x.1965, on dendroid crustose coralline (ISRSE 65/3047g).
DISTRIBUTION: Cosmopolitan.
COMMENTS: Our plants were to 3 cm tall, but mostly only 10-15 mm tall, all bearing
tetrasporangia.
This species has been reported from the Red Sea only three times, all from the
northernmost part (Nasr 1947; Rayss & Dor 1963; Natour et al. 1979b).
Piccone & Grunow (in Piccone 1884) described G. pusillum var. conchicola from Mesewa,
Eritrea. In this variety, the axes were said to be somewhat broader (to 1 mm), more
complanate, and more proliferous than in other forms of the species. In our plants, the
axes were 1.5-2 mm wide, somewhat flat, and not much branched, thus agreeing with
the description and illustration given by Stackhouse (1795). Several varieties and formae
have been described within this morphologically variable species, but their taxonomic
value remains to be demonstrated (see Dixon & Irvine 1977b, p. 129).
*PTEROCLADIELLA Santelices et Hommersand
This genus was segregated from Pterocladia by Santelices & Hommersand (1997)
on the basis of the following suite of characters: intercalary carpogonia directed
towards both surfaces of the thallus; nutritive filaments growing centripetally and
forming a virtually solid cylinder around the central axis; and cystocarps usually
attached to one side of the cystocarp floor with chains of carposporangia on the
remaining three sides. The type is P. capillacea (S.G. Gmelin) Santelices et
Hommersand (Fucus capillaceus S.G. Gmelin), a well-known species widely dis-
tributed in warm temperate and subtropical waters. but not reported from the Red Sea.
10