Wikisource:WikiProject Open Access/Programmatic import from PubMed Central/A new species of Ovabunda (Octocorallia Xeniidae) from the Andaman Sea Thailand with notes on the biogeography of this genus

A new species of Ovabunda (Octocorallia, Xeniidae) from the Andaman Sea, Thailand with notes on the biogeography of this genus
Michael P. Janes; Catherine S. McFadden; Thanongsak Chanmethakul
ZooKeys , iss. , pp.1-17


AbstractA survey of xeniid octocorals was carried out in the waters off Southwestern Thailand in September, 2007. Microscopic investigation of the colonies revealed that three specimens belonged to the genus Ovabunda. Gross morphological examination is presented here accompanied by scanning electron micrographs of the sclerites. Molecular phylogenetic analysis showed identical genotypes at mtMutS, COI, and 28S rDNA for all three specimens and supports their generic assignment. Colony size and shape, sclerite size, and pinnule arrangement differ from nominal species of Ovabunda and thus a new species, O. andamanensis is introduced here. This work also presents a new eastern geographical record for the genus Ovabunda.


Ovabunda Alderslade, 2001 is a genus of tropical, shallow water zooxanthellate soft corals belonging to the family Xeniidae. They are an abundant component of benthic communities throughout the Red Sea ([1]; [2]; [3]; [4]). To date, Ovabunda has been documented from a relatively small geographical range with only three species recorded beyond the Red Sea, occurring in the Seychelles Islands ([5]) and Madagascar ([4]), Western Indian Ocean. Ovabunda sclerites are unique among xeniids. Unlike the flattened figlet-like sclerites comprised of radially arranged dendritic rods commonly found in many xeniid genera, Ovabunda sclerites are round or oval to irregular spheroids comprised of aggregations of minute corpuscular-shaped microscleres ([6]). Eleven nominal species previously described as belonging to the genus Xenia were reassigned to Ovabunda ([6]; [5]; [7]; [4]) primarily based on the type of sclerite they exhibited: Ovabunda ainex Reinicke, 1997; Ovabunda arabica Reinicke, 1995; Ovabunda benayahui Reinicke, 1995; Ovabunda biseriata Verseveldt and Cohen, 1971; Ovabunda crenata Reinicke, 1997; Ovabunda faraunensis Verseveldt and Cohen, 1971; Ovabunda gohari Reinicke, 1997; Ovabunda hamsina Reinicke, 1997; Ovabunda impulsatilla Verseveldt and Cohen, 1971; Ovabunda macrospiculata Gohar, 1940; Ovabunda verseveldti Benayahu, 1990. An additional species, Ovabunda andamanensis sp. n., is described and illustrated below (Fig. 1). Molecular analyses of the mtMutS, COI, and 28S rDNA genes have shown relatively few genetic differences among species of Ovabunda or between Ovabunda and some species of Xenia ([8]; [9]; A. Halász et al. in review).

Here we describe a new species of Ovabunda from recent collections in the Andaman Sea. Additionally, we report the first record of this genus outside of the eastern Indian Ocean and Red Sea.


Collection and Morphological examinationEdit

All specimens were collected using SCUBA to a maximum depth of 10 meters. Photographs of living colonies were taken for each specimen. Specimens were fixed in 90% ethyl alcohol immediately after collection. The corals examined in this survey are deposited in the reference collection of the Phuket Marine Biological Center, Phuket, Thailand (PMBC).

Morphological examination of the preserved colonies was performed under a dissecting microscope at 20× power. Polyps were photographed; number of pinnule rows, pinnules along the outermost row and inner row when present for each specimen were recorded. Sclerites were prepared for light microscope examination ([10]); 20–25 sclerites were selected and measured to the nearest 0.001 mm on a compound microscope fitted with a Filar Micrometer. Scanning electron microscope (SEM) images of sclerites were made from preparations following the method given by [7]. Sclerites were sputter coated with a gold/palladium blend for 75 seconds. They were then examined using a FEI XL30 Environmental Scanning Electron Microscope (ESEM) at 10 kV and a Nova 200 NanoLab Focused Ion Beam (FIB) Microscope at 5 kV, 0.40 nA.

Molecular phylogenetic analysesEdit

Extraction of DNA from ethanol-preserved tissue samples, PCR amplification, and sequencing of two mitochondrial (mtMutS, COI + igr1) and a nuclear (28S rDNA) gene followed the protocols published in [11]. Sequences were aligned to a reference set of published sequences for other xeniid taxa ([8]; [9]) using the L-INS-i method in MAFFT ([12]). Pairwise genetic distances (Kimura 2-parameter) among specimens were calculated using the DNADist program in PHYLIP v. 3.69 ([13]). MOTHUR v. 1.29 ([14]) was used to cluster sequences into molecular taxonomic units (MOTUs) based on an average neighbour distance threshold of 0.3%, a value that has been shown previously to yield a high concordance between molecular and morphological identifications in other octocoral taxa including xeniids ([9]). Modeltest 3.0 ([15]) was used to select appropriate models of evolution for maximum likelihood analyses that were run for 100 bootstrap replicates using GARLI 2.0 ([16]). The 28S rDNA and mitochondrial gene (mtMutS + igr1 + COI) datasets were analyzed separately, and in a combined analysis with different models of evolution applied to separate data partitions (mt genes: HKY+I+G; 28S: GTR+I+G). Bayesian analyses were run using MrBayes v. 3.2.1 ([17]) with the same data partitions. Analyses were run for 2,000,000 generations (until standard deviation of split partitions < 0.005) with a burn-in of 25% and default Metropolis coupling parameters (i.e., 2 runs, 4 chains (3 heated), sample frequency = 500 generations).


===Systematic section Order Alcyonacea Lamouroux, 1812 Family Xeniidae Ehrenberg, 1828 Genus Ovabunda Alderslade, 2001: 49–52===

Ovabundaandamanensissp. n.Edit

Taxon classificationAnimaliaAlcyonaceaXeniidae

Figs 1–5


Holotype: PMBC 11860, Koh Doc Mai, Thailand, 07°47.76'N, 98°32.09'E, depth 8 meters, 26 September 2007 (1 colony), M. P. Janes collector. Paratypes: PMBC 11861, Koh Phi Phi, Hin Bida, Thailand, 07°39.20'N, 98°45.83'E, depth 10 meters, 28 September 2007 (1 colony), M. P. Janes collector. PMBC 11862, same data as the holotype.


The holotype is comprised of multiple short, branched stalks sharing a common base attached to coral rock. In life, the holotype (Fig. 1a) is thickly beset with monomorphic polyps which were observed to be non-pulsatile. The tentacles are cylindrical, slender and up to 2.0 cm long (Fig. 1b). In a preserved state, the holotype consists of multiple stalks; two of the stalks are divided into two short branches (Fig. 2a). The stalks measure up to 8.0 mm tall and 5.0 mm wide at the base. A slightly convex capitulum is present at the distal end of the stalks from which moderately dense aggregations of polyps are growing. The polyp bodies are cylindrical, shrunken and measuring from their attachment at the capitulum to the base of the tentacle they are 1.5 mm long by 0.5 mm wide. Tentacles are slender, measuring up to 8.0 mm long by 0.2 mm wide with a blunt tip. There is one row of pinnules present on either side of the tentacle (Fig. 2b at arrow) with 17 to 19 pinnules in a row. The pinnules are barrel-like with a rounded tip and slight taper at the end. They measure 0.2 to 0.3 mm long by 0.1 mm wide. There is an open space on the tentacles between adjacent pinnules measuring 0.1 to 0.15 mm wide, nearly equal to their width. Zooxanthellate.

Sclerites are present in all parts of the holotype. They are moderately dense in the polyps (Fig. 3a–b) and fewer are found in the basal portion of the stalk. All of the sclerites are round to slightly oval or irregularly shaped spheroids (Fig. 4a). They measure from 0.010 to 0.018 mm in diameter on average with a few sclerites as large as 0.020 mm in maximal diameter and the smallest recorded at 0.005 mm in diameter. The sclerites are comprised of numerous, minute circular to egg-shaped corpuscular microscleres that quickly disassociate when extracted from the coral tissue with sodium hypochlorite. Rarely, a second form of sclerite can be found in the polyp tissue, which contains a solid calcite core coated with microscleres (Fig. 4b). The microscleres measure from 0.00035 to 0.00060 mm in diameter. SEM imaging revealed that they have a fine, granular surface ultrastructure (Fig. 4c) when viewed under moderately high magnification (×40,000). The ultrastructure of the surface is comprised of a series of ridges, furrows, and coarse nodules (Fig. 4d) when examined at 65,000 power. Most microscleres are intact but occasionally fractured ones are found (Fig. 4e). Broken microscleres reveal the presence of a cavity or cavities within. Further evidence of these can be seen in FIB imaging where the microsclere has been sliced longitudinally, demonstrating the depth of the furrows (Fig. 5a) and size of cavities (Fig. 5b) when magnified at 200,000 power.


The preserved specimens are cream colored with whitish tentacles and light tan pinnules. Living colonies exhibit tan colored stalks; white polyp bodies and tentacles, and pinkish pinnules (Fig. 1a–d).


The name is derived from the collection location, the Andaman Sea.

Distribution and ecology.Edit

This species was collected from Koh Doc Mai (Fig. 6) and Koh Phi Phi, Hin Bida located along the eastern coast of Phuket Island, Thailand. Colonies occur in low abundance, spaced 1-2 meters apart on small ledges of vertical walls growing among sea fans, corallimorpharians, and Dendronephthya sp. soft corals. Ovabunda andamanensis sp. n. has also been observed in situ in the Mergui Archipelago, Myanmar (T. Chanmethakul, personal observation).


Both the holotype (PMBC 11860) and one paratype (PMBC 11861) were very similar in size (up to 7.0 cm in life), sclerite dimensions, exhibited non-pulsatile polyps, pinnule rows and number of pinnules per row. The other paratype (PMBC 11862) was smaller in life (Figs 1c, 2c), measuring up to 5.0 cm tall and exhibited tentacles that curved inward (Fig. 1d). It differed from the holotype in having shorter tentacles and two rows of 13–14 pinnules in each row (Fig. 2d) instead of one row with 17–19 pinnules.


In comparing the morphology of Ovabunda andamanensis sp. n. to nominal Ovabunda species colony size, sclerite size and shape, and pinnule arrangement were examined, with the later considered a more variable diagnostic character. Among species of Ovabunda described as having one or two rows of pinnules, O. arabica, O. biseriata, O. gohari, O. faraunensis and Ovabunda verseveldti most closely resemble Ovabunda andamanensis sp. n. Ovabunda gohari and Ovabunda verseveldti are similar to the holotype in having primarily one row of pinnules although occasionally two rows are present in polyps of Ovabunda gohari. The overall range of sclerite sizes is larger in Ovabunda gohari, 0.033–0.063 mm, compared to the 0.010–0.018 mm in Ovabunda andamanensis sp. n., there are 18–22 pinnules in a row compared to 17–19 pinnules in Ovabunda andamanensis sp. n., and Ovabunda gohari has pinnules spaced at 2–3 times the pinnule width along the tentacles whereas in Ovabunda andamanensis sp. n. pinnules are more closely set. According to [1]: 31) Ovabunda gohari sclerites are “… packed between polyp bases and in the syndete’s wall between mesenteries, giving a longitudinal whitish banding”; this feature was not observed in the Thailand material. Ovabunda verseveldti contains much larger sclerites (up to 0.030 × 0.049 mm) than were found in Ovabunda andamanensis sp. n. and the pinnules are “densely set in each row, almost touching each other” ([4]) compared to the wider pinnule spacing in the Thailand specimens.

The pinnule number in Ovabunda faraunensis agrees well with the 17–19 pinnules observed in the holotype of Ovabunda andamanensis sp. n., however Ovabunda faraunensis has larger sclerites ([1]: 35). The sclerite sizes in Ovabunda arabica 0.028–0.036 mm ([4]), Ovabunda biseriata 0.018–0.035 mm ([18]: 60), 0.029–0.063 mm ([1]: 33), and Ovabunda faraunensis 0.028–0.044 mm ([4]) are all notably larger than the average range of 0.010-0.018 mm observed in Ovabunda andamanensis sp. n.

Among species of Xenia, Xenia puerto-galerae Roxas, 1933 most closely resembles Ovabunda andamanensis sp. n. The holotype is described by Roxas (1933) as branched, measuring 20.0 mm tall and 8.0 mm in diameter with polyps comprised of thick tentacles that are proportionately small and “two rows of slender pointed pinnules, fifteen to seventeen in a row”. The tentacles are 8.0 mm long by 1.0 mm wide at the base and pinnules measure 0.7 to 0.8 mm long by 0.2 to 0.3 mm wide. However, in the colony with two rows (PMBC 11862) in Ovabunda andamanensis sp. n., the stalks are smaller, 8.0 mm by 5.0 mm, the tentacles are narrower, 8.0 mm by 0.2 mm, the pinnules are smaller, 0.2 to 0.3 mm by 0.1 mm, and there are fewer pinnules (13 to 14). Most notable are the sclerites, which are described as “thin, oval discs 0.018 mm long and 0.018 to 0.0124 mm wide” in Xenia puerto-galerae compared to the 0.010 to 0.018 mm in diameter sphere shaped sclerites observed in Ovabunda andamanensis sp. n. Unfortunately, the location of the holotype of Xenia puerto-galerae remains unknown so a direct SEM comparison of the sclerites could not be performed.

In situ images of Ovabunda andamanensis sp. n. type material Holotype (PMBC 11860): a colony (smallest) b close up of polyps. Paratype (PMBC 11862): c colony (smallest) d close up of polyps.
Preserved specimens of Ovabunda andamanensis sp. n. Holotype (PMBC 11860): a colony b polyp. Paratype (PMBC 11862): c colony d polyp. Scale bars: a and c 10 mm; b and d 4 mm.
Ovabunda andamanensis sp. n. Holotype (PMBC 11860) sclerites: a–b uncoated ESEM wet mount images of tentacle sclerites in situ. Scale bars: a 0.04 mm; b 0.015 mm.
Ovabunda andamanensis sp. n. Holotype (PMBC 11860) SEM image of coated sclerites: a whole sclerite most common form b whole sclerite least common form c microscleres from a disintegrated sclerite d surface ultrastructure of loose microscleres e fractured microscleres. Scale bars: a–b 0.020 mm; c 0.001 mm; d–e 0.0005mm.
Ovabunda andamanensis sp. n. Holotype (PMBC 11860) sclerites: a FIB image of the surface ultrastructure of microscleres b FIB image showing interior cavities of a microsclere.
Distribution of Ovabunda andamanensis sp. n. in the Andaman Sea: 1 PMBC 11860 2 PMBC 11861 3 PMBC 11862. Circled number denotes holotype.

Molecular analysisEdit

All three Ovabunda specimens in this collection had identical genotypes at mtMutS, COI + igr1 and 28S rDNA. Phylogenetic analyses placed them in a well-supported clade with all other species of Ovabunda as well as several species of Xenia from the Red Sea (Fig. 7). Within that clade, only four MOTUs were distinguished by an average genetic distance of 0.3% or greater. The three Thai specimens belonged to a MOTU that was separated from all other species by 0.5%. The two species of Xenia (Xenia umbellata, Xenia hicksoni) found within the clade belonged to a MOTU that was separated from Red Sea Ovabunda species by 0.4%. All Red Sea Ovabunda species belonged to just two MOTUs that were separated by 0.3%: the group of [USNM1201941, USNM1201943 and ZMTAUCO34077] and all others. Based on its sclerite size, colony size and form, pinnule arrangement, and unique phylogenetic position, we hereby designate a new species Ovabunda andamanensis sp. n. for our material.

Maximum likelihood reconstruction of family Xeniidae based on a partitioned analysis of mtMutS, COI and 28S rDNA sequences (2255 bp). Numbers above nodes are bootstrap percentages (100 replicates) from ML analyses; numbers below nodes are Bayesian posterior probabilities. Some clades have been collapsed to triangles to facilitate readability.


Octocorals are thought to exhibit their greatest species richness in the Indo-Malayan region consisting of Indonesia, the Philippines and New Guinea ([19]; [20]; [21]; [22]; [23]), an area also known for its scleractinian diversity ([24]; [25]). Ovabunda is mainly found in the Red Sea, where the highest number of species (11) occurs (Fig. 8). [3] note only three species from the southern Red Sea, Ovabunda biseriata, Ovabunda faraunensis, and Ovabunda verseveldti. A higher number of Ovabunda species (10) are recorded from the central Red Sea including the holotypes of Ovabunda ainex, Ovabunda crenata, and Ovabunda hamsina. This is likely due to extensive collection efforts in Sudan ([26], [1]) and Saudi Arabia ([8]). Similarly, nine species have been identified from the northern Red Sea in the Gulf of Suez and the Gulf of Aqaba. Extensive octocoral research in Eilat, Israel ([27], [28], [29]; [2]) accounts for the numerous records at the northern most end of the Gulf of Aqaba. [5] recorded three species from the Seychelles Islands (Fig. 9). There are additional reports of specimens collected from Madagascar ([1]; [4]) and Reunion Island ([30]) in the Western Indian Ocean.

This new record from Thailand increases the know distribution of Ovabunda in the Indian Ocean approximately 5000 km eastward. Both the holotype and one paratype of Ovabunda andamanensis sp. n. were collected from Koh Doc Mai (Fig. 6) located along the eastern coast of Phuket Island. An additional paratype was collected from Koh Phi Phi, Hin Bida located at the southern end of the Gulf of Thailand. Xeniids have been recorded previously from the Andaman Sea ([31]) so it is likely that this or other species of Ovabunda will be found elsewhere in the Andaman Sea or eastern Indian Ocean if a thorough octocoral survey is carried out. Specimens of Ovabunda andamanensis sp. n. were all collected from horizontal shelves on vertical walls, and it is perhaps on horizontal surfaces such as this where Ovabunda species might occur.

The gross morphology, sclerite dimensions, and molecular results all support the description of Ovabunda andamanensis sp. n. as a new species. The range of intraspecific variability among xeniid species is poorly known. Living colonies of Ovabunda andamanensis sp. n. were observed to be smaller and less numerous than Ovabunda colonies found on the coral reefs in the northern Gulf of Aqaba (M. Janes, personal observation) and the largest sclerites found in Ovabunda andamanensis sp. n. had a maximal diameter of 0.020 mm, notably smaller than the 0.035–0.040 mm maximal diameter recorded by [4]: 36) in Red Sea species; whether this is a result of environmental factors such as light or water flow ([26]) or is typical for colonies of Ovabunda andamanensis sp. n. remains unknown. The solid sclerite form (Fig. 4b) coated with microscleres that was rare in the Thai material is similar to sclerites recorded from Ovabunda impulsatilla collected in the Seychelles ([5]: 612). While the smaller maximal diameter of sclerites from Ovabunda andamanensis sp. n. are considered a taxonomic character of this species, the occasional hollow cavities in the microscleres are not; primarily due to limited sampling of the microscleres.

The results of our study suggest both the holotype and two paratypes of Ovabunda andamanensis sp. n. are the same species which can exhibit one or two rows of pinnules. Previous authors have suggested the number of rows of pinnules can be variable within a species and is therefore not a highly reliable taxonomic character. Early on both [32]: 410) and [33]: 6) recognized the variability in pinnule size and their arrangement. Later, [34]: 79) noted that “The number of rows increases with age…” and cited Heteroxenia fuscescens juveniles with two rows of pinnules where the adult colonies had up to five. Further, in their revision of Ovabunda[4] mentioned the difficulty in identifying irregular rows of pinnules in the species Ovabunda crenata and Ovabunda hamsina. All three Thailand samples were nearly identical with regards to gross morphology, sclerite shape and size, pinnule spacing, lack of pulsation, and molecular genotype. Ovabunda andamanensis sp. n. differs from other Ovabunda species by having the following unique combination of characters: sclerites measuring from 0.010 to 0.018 mm in diameter on average, small colonies with slender tentacles up to 2.0 cm long in life, exhibits one or two rows of pinnules, and distinguished from all other Ovabunda species by a genetic distance of 0.5%.

Distribution of Ovabunda species in the Red Sea: 1Ovabunda ainex2Ovabunda arabica3Ovabunda benayahui4Ovabunda biseriata; 5Ovabunda crenata; 6Ovabunda faraunensis; 7Ovabunda gohari8Ovabunda hamsina9Ovabunda impulsatilla10Ovabunda macrospiculata11Ovabunda verseveldti. Circled number denotes holotype.
Distribution of Ovabunda species in the Seychelles Islands: 1Ovabunda impulsatilla2Ovabunda benayahui3Ovabunda hamsina.

Supplementary MaterialEdit

XML Treatment for OvabundaandamanensisEdit



We are grateful for the generous support provided by Charatsee Aungtonya for curatorial assistance; Zhenquan Liu and Kenneth Mossman for SEM operations; Dr. Karl Weiss and the LeRoy Eyring Center for Solid State Science, Arizona State University for use of their microscopy facilities. Principle funding and laboratory facilities were provided by AquaTouch, Phoenix, Arizona USA. Our sincere thanks to Dr. Phil Alderslade and an anonymous reviewer whose comments improved this manuscript; also to Dr. Yehuda Benayahu and the organizers of the International Conference on Coelenterate Biology, 1-6 December 2013, Eilat, Israel for the opportunity to present this work.

Supplementary materialEdit

Supplementary material 1Edit

Supplement S1.[10.3897/zookeys.431.7751.app1 doi: 10.3897/zookeys.431.7751.app1]Data type: specimens dataExplanation note: Specimens and sequences included in molecular phylogenetic analysis of xeniids.



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