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1188
Accepted by C. Wallace: 7 Mar. 2006; published: 28 Apr. 2006 55
ZOOTAXA
ISSN 1175-5326 (print edition)
ISSN 1175-5334 (online edition)
Copyright © 2006 Magnolia Press
Zootaxa 1188: 55–62 (2006)
www.mapress.com/zootaxa/
Porites decasepta: a new species of scleractinian coral
(Scleractinia, Poritidae) from Oman
MICHEL R. CLAEREBOUDT
Sultan Qaboos University, College of Agricultural and Marine Sciences, Department of Marine Science and
Fisheries, Box 34, Al-Khod 123, Sultanate of Oman. E-mail: michelc@squ.edu.om
Abstract
A new species of scleractinian coral, Porites decasepta spec. nov. (Scleractinia, Poritidae) is
described from the Bar Al-Hikman reef complex along the Arabian Sea coast of the Sultanate of
Oman. Porites decasepta spec. nov. forms encrusting, bright blue colonies rarely exceeding 7 cm in
diameter. Corallites, about 1mm in diameter, have only 10 septa: the two lateral septa of the ventral
triplet typical of Porites septal arrangement are missing or strongly reduced.
Une nouvelle espèce de scleractiniaire, Porites decasepta spec. nov. (Scleractinia Poritidae) est
décrite du complex récifal de Bar Al-Hikman situé le long de la côte de la mer d’arabie du Sultanat
d’Oman. La nouvelle espèce forme de petites colonies encroûtantes, de couleur bleu-violet, ne
dépassant guère 7 cm de diamètre. Les corallites d’à peu près 1mm de diamètre n’ont que 10 septa:
les deux septa latéraux du triplet ventral étant le plus souvent manquants ou fortement réduits.
Key words: Cnidaria, Scleractinia, Porites, Poritidae, new species, Arabian Sea, Oman
Introduction
The Bar Al-Hikman reef complex, located along the Arabian Sea Coast of the Sultanate of
Oman (Fig. 1), is one of the few true reefs of the Sultanate of Oman. The complex is
composed of a string of large (tens of km) reefs aligned parallel to the southern tip of the
Bar Al-Hikman Peninsula and West of the Island of Masirah. The framework of these reefs
consists of a single species of a yet unidentified folicaeous Montipora sp. The south facing
fore reef shows a well defined spur and groove structure in which a more diverse
scleractinian coral community develops. In the deeper part of this fore reef, around 4–7 m
in depth, numerous small colonies of an unidentified poritid coral were observed in the
field and photographed. Collected specimens were then compared to corals of congeneric
species; they appeared to belong to a new species with distinctive skeletal characters.
CLAEREBOUDT
56 © 2006 Magnolia Press
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ZOOTAXA Material and methods
Numerous colonies were photographed in the fore reef spur and groove area of the Bar Al-
Hikman Reef complex and some collected by SCUBA. Collected specimens where rinsed
overnight in freshwater, energetically hosed to remove as much soft tissue as possible,
bleached in commercial sodium hypochlorite solution for 24 h, then rinsed again in fresh
water, and dried in the sun. Cleaned skeletons were photographed on an Olympus
dissecting microscope mounted with a digital camera.
Systematic Account
Family Poritidae Gray, 1842
Genus Porites Link, 1807
Porites decasepta spec. nov. (figs. 2–4)
Material examined
Holotype: Sultan Qaboos University, SQU05080, Oman, Bar Al-Hikman, 4.0 m, 20º
20.301’ N, 58º 22.914’ E . Collector: Michel Claereboudt. Colony 6x4 cm (figs. 2A, 3A,
3B).Paratypes: 1—Florida Museum of Natural History, UF5672 , Oman, Bar Al-Hikman,
4.5 m, 20º 20.301’ N, 58º 22.914’ E . Collector: Victor Bonito.
2—Institut Royal des Sciences Naturelles de Belgique, IG30418, Oman, Bar Al-
Hikman-, 5.0 m, 20º 20.301’ N, 58º 22.914’ E (). Collector: Michel Claereboudt (figs. 2B,
3B).
Diagnosis
Corallites are about 1mm in diameter, almost circular. There are only 10 septa in six
groups: one ventral, one dorsal and four pairs of lateral septa fused along their inner
margins. A short columella is present and connects to the six groups of septa by well
developed radii. Living colonies have small polyps, retracted during the day. All colonies
were small and incrusting. They appeared and photographed bright blue-violet underwater.
A very distinctive species in its environment.
Previous records
This species has been previously recorded and photographed but not identified (Blue
Porites) near Masirah Island (Paulay & Meyer, 1999).
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FIGURE 1. Map of the Sultanate of Oman with the location of the Bar Al-Hikman Peninsula.
Description
Colonies are encrusting and small: rarely more than 7 cm across. Corallites are nearly
circular in outline and small (slightly less than 1.0 mm in diameter on average). The wall is
CLAEREBOUDT
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ZOOTAXA relatively thin and consists of complex anastomosing and irregular denticles. Calices are
superficial. There are 10 septa in six groups: one dorsal, one ventral and two pairs of
lateral septa on either side of the axis of symmetry. The two lateral septa of the ventral
triplet characteristic of Porites are absent. The six groups of septa connect to a short pillar-
like columella by six well developed radii slightly below the upper margin of the septa. A
columella is present and there are no distinct pali but irregular, poorly defined granulated
denticles are present on the margin of the septa. The coenosteum between corallites is
coarse and porous.
FIGURE 2. Porites decasepta spec. nov. A: Holotype, (SQU05080); B: Paratype (IG30418).
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FIGURE 3. Porites decasepta spec. nov. Details of the corallites. A,B: Holotype (SQU05080); C:
Paratype (IG30418); D: other colony (SQU05091).
Living colonies have small polyps normally retracted during the day. All observed
colonies appeared bright blue-violet, contrasting with all specimens of other species of
Porites present. The coral also photographed blue-violet under artificial light.
Etymology
The specific epithet decasepta “with 10 divisions” was chosen to illustrate the
characteristic septal pattern of this species.
Habitat and distribution
All colonies were found attached to hard substrates: often fragments of dead
folicaceous Montipora, between 3 and 7 m in depth in the “spur and groove” fore reef of
the large reef complex extending south of the Bar Al-Hikman Peninsula (20º20.3’ N,
58º23.1’E) and Masirah Island (20º20.6’ N, 58º38.0 E). Despite extensive surveys this
species was not observed in the Gulf of Oman and appears restricted to the Arabian Sea.
Where present, Porites decasepta appeared quite common and easily identifiable
underwater by its apparent bright blue color.
CLAEREBOUDT
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FIGURE 4. Porites decasepta spec. nov.: A, B: Underwater photographs of live colonies. Note the
bright blue-violet color.
Discussion
Porites decasepta spec. nov. differs from all other species of Porites by its unusual septal
arrangement. Altough this septal pattern differs from that of most other Porites species by
the lack of a ventral triplet, the new species is retained in the genus Porites because several
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other species of Porites have lost partially, or totally, the fusion pattern characteristic of
the genus (Veron, 2002) although none has the characteristic 10 septa of the present group
of specimens. Porites desilveri Veron 2002 has only four to eight developed septa (Veron,
2000) whereas Porites profundus Rehberg, 1892 and Porites heronensis Veron 1985 have
12 septa but highly underdeveloped fusion pattern (Rehberg, 1892; Veron, 1985). The size
of the calices fall within the range published for other species of Porites (0.6–2.0 mm).
At various point in the taxonomic history of Porites, three taxa have been considered
as separate genera, synomyms of Porites or as subgenera: Stylaraea Edwards and Haime
1851, Napopora Quelsch, 1886 and Synaraea Verrill, 1864. More recently, Poritipora
Veron 2002 was added to this small series of poritid genera with small calices and small
polyps. Napopora was established by Quelsh (1886) and only used once by subsequent
authors (Nemenzo, 1976) for a small group of species with coenosteal ridges between
corallites. The genus Synaraea was created by Verrill (1864) for species with small
corallites and large areas of granular inter calicial coesnoteum. Most authors since have
considered Synaraea as a subgenus of Porites. With the progressive addition of new
species with morphological characteristics intermediary to Porites, Synaraea and
Napopora, and a large intra-specific variability the general opinion, promoted by Veron
(2000, 2002), has been to consider only a single genus: Porites. The two monospecific
genera Stylaraea Edwards and Haime and Poritipora Veron are on the other hand
sufficiently distinct to keep them separate from Porites. Stylaraea has 12 un-fused septa
and a well developed columella whereas Poritipora has two cycles of 12 septa each and no
columella. In Porites decasepta spec. nov., the fusion pattern, although with only 10
septa, is similar to that of Porites and does not warrant at this stage the erection of a new
genus. Future genetic analysis will certainly help elucidating the complex relationships in
poritids.
Acknowledgements
I thank Victor Bonito for long discussions about this and other series of specimens
collected along the reef of Bar Al-Hikman as well as Nancy Stauft and Bert Hoeksema for
constructive comments that improved the manuscript. This research was supported in part
by a SQU grant to the author (IG/AGR/FISH/05/01).
References
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Bulletin, 28, 229–276.
Paulay, G. & Meyer, C. (1999) Corals and marine invertebrates of the Sultanate of Oman.
ARDOUKOBA, Paris, France, pp. 5.
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CLAEREBOUDT
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ZOOTAXA 1873–1876. Reports of the Scientific Results of the Voyage of H.M.S. Challenger Zoolology.,
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