Sea Anemones and Corallimorpharians of Oman,

1
Sea Anemones and Corallimorpharians of Oman,
with discussion of the generic circumscription
of Rhodactis
Ha-Rim Cha Department of Ecology and Evolutionary
Biology, Natural History Museum and Biodiversity
Research Center The University of Kansas,
Lawrence, KS 66045, USA

• SEA ANEMONES AND CORALLIMORPHARIANS OF OMAN
• 12 species of sea anemones and three species of
  corallimorpharians
• 3 may be new species

• TAXONOMY OF Rhodactis Milne Edwards and Haime,
  1851
• Problem 1. The original description of the type
  species of Rhodactis (Metridium rhodostomum
  Hemprich and Ehrenberg in Ehrenberg, 1834)
  contains few diagnostic characters.
• Problem 2.
• Most generic characters are not consistently used
  among authors.
• WHAT are the CHARACTERS of the type species of
  Rhodactis?Rhodactis rhodostoma (Hemprich and
  Ehrenberg in Ehrenberg, 1834)
• Type specimens no longer extant
• Type locality Tor, the Red Sea
• Material examined Oman -- KUNHM 002077 (x3),
  KUNHM 002093 (x5)
• Description 1) Column short, smooth,
  mesenterial insertions visible.2) Oral disc
  densely covered with tentacles. 3050mm diameter
  in life, preserved specimens 1525mm. No
  tentacle-free zone.3) Pedal disc about half as
  wide as oral disc. 4) Color greenish purple to
  purple 5) Tentacle Two kinds of tentacles
  digitate and branched in form. No distinction
  between marginal and discal tentacles. Peripheral
  tentacles and those around the mouth digitate
  most intermediate tentacles branched. In life to
  5mm long.6) Nematocyst size and
  distribution7) Musculature no sphincter
  muscle weak retractor muscles8) Habitat live
  in patches on dead coral or rocks 310m deep9)
  Behavior Feeding by envelopment. Mesenterial
  filaments extruded when disturbed. 10)
  Symbiont zooxanthellae (size 89.5µm in diameter)

INTRODUCTION The actiniarian and
corallimorpharian fauna of Oman was surveyed in
May 2004 12 species of sea anemones and three
species of corallimorpharians were found. During
the survey specimens of the type species of genus
Rhodactis were collected. The definition of the
genus Rhodactis has been unclear because of the
small number of diagnostic characters detailed in
the original description of the type species. I
documented morphological characters not currently
used for taxonomy of Rhodactis.
Corallimorpharians of Oman
Discosoma n. sp.?
Discosoma sp.
Rhodactis rhodostoma

• THE GULF OF OMAN
• No corallimorpharians have been reported from
  the Gulf of Oman (Figure 1)
• The scleractinian coral fauna is diverse and
  distinct from that of the Red Sea or Indian Ocean
  (Sheppard 1987 Sheppard Salm 1988)
• The area is strongly influenced by seasonal
  monsoon cycles associated with upwelling and
  algal blooms
• The coast of Oman includes three distinct
  habitats muddy and sandy shores, rocky shores,
  and coral communities (Coles 1996)

Nematocysts Tissue Holotrichs Holotrichs Microbasic p-mastigophors Microbasic p-mastigophors Microbasic b-mastigophors Microbasic b-mastigophors
Nematocysts Tissue Length (µm) Width (µm) Length (µm) Width (µm) Length (µm) Width (µm)
Outermost tentacles 27.9447.98 5.0910.34 20.5924.51 4.558.93 14.7128.66 5.899.49
Inner tentacles 41.2149.93 13.0319.23 20.0827.74 7.269.09 19.4123.95 5.427.68
Mesenterial filaments 147.71183.58 / 33.1444.46 58.1482.72 /16.4118.13 25.6933.15 4.336.74
Sea anemones of Oman
Figure 1. Distribution of corallimorpharians.
Green dots indicate known distribution of
corallimorpharians and red box indicates the Gulf
of Oman.
Triactis sp.
Edwardsiidae n. sp.1
Edwardsiidae n. sp.2

• Characters of genus Rhodactis based on the
  examination of type species
• Nature of tentacles DIGITATE and BRANCHED
  tentacles
• Distinction between marginal and discal
  tentacles NONE
• Tentacle-free zone on oral disc NO
• Nematocyst composition holotrichs (large and
  small), microbasic p-mastigophores, microbasic
  b-mastigophores
• Sphincter muscle NO
• Behavior Feeding by ENVELOPMENT

Entacmea quadricolor
Actinodendron sp.
Heteractis sp.

• SURVEY IN OMAN
• May 7 30, 2004
• Part of a study on the biodiversity of sea
  anemones of Oman
• Participants Marymegan Daly, Adorian Ardelean
  and Ha-Rim Cha
• Collaborator Dr. Michel Claereboudt, Department
  of Marine Science and Fisheries, Sultan Qaboos
  University (SQU), Muscat, Oman

• ACKNOWLEDGMENTS
• Michel Clareboudt
• Daphne Fautin, Meg Daly, Adorian Ardelean
• American Association for the Advancement of
  Science, National Science Foundation, KU Natural
  History Museum Biodiversity Research Center

• REFERENCES
• Coles SL. 1996. Corals of Oman. CYK
  publications, Muscat, Oman. http//www.bishopmuseu
  m.org/research/pbs/Oman-coral-book.
• Ehrenberg DG. 1834. Beiträge zur physiologischen
  Kenntniss der Corallenthiere im allgemeinen, und
  besonders des rothen Meeres, nebst einem Versuche
  zur physiologischen Systematik derselben. Abh. K.
  Akad. Wiss. Berl. 1 225-380.
• Milne-Edwards H, Haime J. 1851. Monographie des
  polypiers fossiles des terrains palfozooques,
  pricidie d'un tableau gineral de la
  classification des polypes. Arch.Nat. Paris 5 pp
  502.
• Sheppard CRC, Salm RV. 1988. Reef and coral
  communities of Oman, with a description of a new
  coral species (Order Scleractinia, genus
  Acanthastrea). J. Nat. Hist. 22 263-279.
• Sheppard CRC. 1987. Coral species of the Indian
  Ocean and adjacent seas a synonymized
  compilation and some regional distribution
  patterns. Atoll Res. Bull. 307 1-32.

Megalactis sp.
Heteractis cf. aurora
Phymanthus sp.
Boloceroides cf. mcmurrichi
Anthopleura sp.
Stichodactyla haddoni