A revision of the octocoral genus Ovabunda Alderslade, 2001 (Anthozoa, Octocorallia, Xeniidae)

Abstract The family Xeniidae (Octocorallia) constitutes an abundant benthic component on many Indo-West Pacific coral reefs and is ecologically important in the Red Sea. The genus Ovabunda Alderslade, 2001 was recently established to accommodate previous Xenia species with sclerites comprised of a mass of minute corpuscle-shaped microscleres. The aim of the present study was to examine type material of Xenia species in order to verify their generic affiliation. We present here a comprehensive account of the genus Ovabunda, using scanning electron microscopy to depict sclerite microstructure. We assign three Xenia species to the genus: O. ainex comb. n., O. gohari comb. n., and O. crenata comb. n.; and synonymize several other species of Ovabunda. We provide a key to Ovabunda species and conclude that they are mainly confined to the Red Sea, with some occurrence in the West Indian Ocean.


introduction
Members of the octocoral family Xeniidae form a major component of shallow coral-reef communities in the tropical Indo-West-Pacific region, and in the Red Sea in particular (e.g., Gohar 1940;Benayahu 1990;Reinicke 1997). In the Red Sea, a remarkably high number of 34 species have been recorded from the family prior to this revision, 24 of which were originally described from the region (Reinicke 1995(Reinicke , 1997. Some of these species have not been reported in any other region, thus emphasizing their high diversity and importance in the Red Sea. The xeniids comprise for the most part small and soft colonies, which are often slippery due to the secretion of large amounts of mucus (Fabricius and Alderslade 2001). A morphological feature unique to most of them is that the pinnules along the margins of the polyp tentacles are arranged in more than one longitudinal row. The number of pinnule-rows and the number of pinnules in the outermost row have been considered diagnostic features used for species identification (e.g., Hickson 1931a;Verseveldt and Cohen 1971;Benayahu 1990;Reinicke 1997). Several additional characteristics have been considered of taxonomic value, such as the size, shape, and coloration of the colonies, as well as polyp retractability and pulsation in live colonies (e.g., Gohar 1940;Verseveldt 1960;Reinicke 1995Reinicke , 1997Fabricius and Alderslade 2001).
The discovery of a corpuscular sclerite-type among previously described Xenia species led Alderslade (2001) to establish the genus Ovabunda while retaining those with the dendritic surface in the original genus. Consequently, he assigned seven of the originally described Xenia species to the new genus. Those assignments were made based on examination of type colonies of X. benayahui and X. verseveldti by L.P. van Ofwegen and the last author of the current study. For the remaining species, the assignment was not based on examination of types, but rather on sclerite descriptions in Reinicke (1997) for X. biseriata Verseveldt & Cohen, 1971 (p. 18) and X. faraunensis (Fig. 9a, b), and in Reinicke (1995) for X. obscuronata (p. 18, fig. 6h, i). The assignment of X. macrospiculata was based on examination of Red Sea material by the last author of the current study (Alderslade 2001: fig. 30), and that of X. arabica Reinicke, 1995 was not justified by Alderslade. In a later study, Janes (2008) depicted sclerites of Ovabunda benayahui, O. hamsina Reinicke, 1997 andO. impulsatilla Verseveldt &Cohen, 1971, as well as of his new species, O. aldersladei, all collected in the Seychelles and featuring Ovabundatype sclerites with corpuscular microstructure. Aharonovich and Benayahu (2011) employed high-resolution environmental SEM (ESEM) for a study of sclerites of type material of O. biseriata, O. faraunensis and O. impulsatilla, which revealed how the microscleres adhere.
Establishment of the genus Ovabunda by Alderslade led us to examine type material that was originally described as Xenia, in order to verify its generic affiliation. Not only were the types of the species assigned to Ovabunda by Alderslade examined, and their sclerites studied using SEM, but the types of a number of other nominal species of Xenia were also studied (see Table 1). Consequently, the current study has assigned three Xenia species to Ovabunda and retained 20 in the former genus; it also synonymizes several other species and designates a neotype for Ovabunda macrospiculata. The findings of the study emphasize the importance of re-examination of type material and the use of SEM to study xeniid sclerite microstructure for taxonomic purposes.

Methods
The study examined ethanol-preserved type specimens obtained on loan from the British Museum of Natural History (BML); National History collections of the Hebrew University of Jerusalem (HUJ); Museum of Natural History, Wroclaw University, Poland (MNHHWU); The Naturhistorisches Museum Wien (NHMW); the Naturalis Bio-table 1. List of Xenia type material examined during the current study along with corresponding museum numbers.
To examine the sclerites, the tissue was treated with 10% sodium hypochlorite followed by repeated rinses in distilled water. Wet preparations of the clean sclerites from polyps, colony stalk, the coenenchyme and canal walls within were examined and photographed under an Optishot Nikon light microscope at × 400 magnification. After comparison of these sclerites we concluded that there are no differences in appearance and  Hickson (1931a). dimensions between sclerites in different colony parts. Therefore, only polyp sclerites were examined under SEM and presented in this paper. SEM stubs for polyp sclerites were prepared following Aharonovich and Benayahu (2011), and examined with a Jeol 840Å electron microscope. Measurements of sclerite images, taken by both light microscopy (images not presented) and SEM, were carried out using ImageJ 1.440 (National Institute of Health, USA). At least 20 randomly selected sclerites were measured for each colony in order to determine sclerite size variation. Number of sclerites measured is indicated in the text for each species. Since the sclerites are mostly spheroids, their dimensions are presented as the range of their minimal-to-maximal smallest diameters × range of their minimal-to-maximal largest diameters. The current study undertakes to clarify some confusion that resulted from differences between Reinicke (1995) and Reinicke (1997) which can be found in some descriptions in the Remarks section (e.g. O. crenata, O. hamsina).
The zoogeographical species distribution is based on the examination of types and other material, unless specified otherwise in the text. Table 1 lists Xenia types that were examined by us and maintained their original generic affiliation.

Systematic section
Order Alcyonacea Lamouroux, 1812 Family Xeniidae Ehrenberg, 1828 http://species-id.net/wiki/Xeniidae Genus Ovabunda Alderslade, 2001: 49-52. Diagnosis. Colonies are small and soft with cylindrical stalks, undivided or branched, terminating in one or more domed polyp-bearing regions. Polyps are not retractile and are always monomorphic. Sclerites are oval spheroids, usually abundant in all parts of the colony, mostly up to 0.035 mm in maximal diameter, and comprised of a mass of minute corpuscle-shaped microscleres.

Key to species
1 Non-pulsating polyps in live colonies 1. Description. The holotype is 45 mm high; its stalk is 15 mm long and splits at the base into three branches, two of which split again into two, 22 and 18 mm above the colony base; the latter branches are 35 and 30 mm long, 8 and 10 mm wide at their base, 4 and 6 mm wide at their uppermost part, respectively. The third branch splits 20 mm above the base into three branches, and is 40 mm long and 7 mm wide at its base and 5-7 mm wide at the uppermost part. The polyp's body is up to 10 mm long, and the tentacles are up to 5 mm long, featuring three rows of pinnules on each side. The pinnules are relatively slender, up to 1 mm long and 0.08 mm wide, 17-20 in the outermost row with a space of one to two pinnule widths between adjacent pinnules. The spheroidal sclerites, typical regular Ovabunda sclerites, are scarce in all parts of the colony, measuring 0.011-0.030 × 0.018-0.042 mm in diameter (n=25), composed of a mass of corpuscle-shaped microscleres. The original description indicated non-pulsating polyps for the live colonies. The ethanol-preserved holotype is light yellowishbeige, almost transparent.
The paratype is 20 mm long; its stalk is 15 mm wide at its base, splitting into two branches, each 5 mm long and 10 and 8 mm wide at the base. The polyp's body is up to 5 mm long, and the tentacles up to 5 mm long, bearing three rows of pinnules and 15-17 pinnules in the outermost row. The pinnules are 1.6 mm long and 0.16 mm wide, with a gap between adjacent pinnules ranging from one to three pinnule widths. The sclerites are Ovabunda-type, regular or irregular in shape (Fig. 3a, c), 0.012-0.026 × 0.02-0.04 mm in diameter (n=21 sclerites). When two sclerites fuse they reach 0.039 mm in maximum diameter (Fig. 3b). The original description indicated nonpulsating polyps for live colonies. The ethanol-preserved colony is light beige.
Remarks. RMNH Coel. 23535 features polyps with three rows of pinnules on each side of the tentacles and 16-19 pinnules in the outermost row. The sclerites are Ovabunda-type, measuring 0.016-0.026 × 0.022-0.030 mm in diameter (n =13). Reinicke (1997) Fig. 32". The description of X. ternatana given by Kükenthal (1913) indicated two rows of pinnules, with 18 pinnules on average, and sclerites measuring 0.017 mm in diameter, thus differing from the features of O. ainex (see above). The NHMW 2250 specimen of X. ternatana was examined and found to match O. ainex, as stated by Reinicke (1997). X. crassa was suggested to be a synonym of O. ainex (Reinicke 1997). The current examination of the types of X. crassa and X. ternatana indicates that their sclerites distinctly differ from those of O. ainex, and thus those species' original generic assignment should be retained.
Conclusions. Our findings confirm the original description of Reinicke (1997) of O. ainex, but the structure of its sclerites justifies the generic re-assignment of the species to Ovabunda. Similar species. O. ainex is most similar to O. macrospiculata. Although they both have three rows of pinnules, the number of pinnules in the outermost row ranges from 15-20 in O. ainex compared to 14-18 in O. macrospiculata. The major difference between them, however, is that O. macrospiculata has pulsating polyps in live colonies and O. ainex does not.
Distribution. Red Sea: Gulf of Aqaba, Sudan. Ovabunda arabica (Reinicke, 1995) http://species-id.net/wiki/Ovabunda_arabica Figs 4, 5 Xenia arabica Reinicke, 1995: 37, figs 47-49;1997 Description. The holotype is 45 mm high; its stalk is 15 mm long, 7 mm wide at its base and 7 mm wide at its upper part. The polyp's body is 12 mm long, and tentacles up to 11 mm long. The pinnules are 2 mm long and 0.2 mm wide at the base; the gap between adjacent pinnules is one pinnule wide. There are two rows of pinnules on each side and 24-25 pinnules in the outermost row. The sclerites are spheroids of the Ovabunda-type, measuring 0.028-0.036 mm at largest diameter.
One paratype (RMNH Coel. 18675) has a total height of 20 mm; its stalk is 16 mm long, 10 mm wide at the base, and 18 mm wide at its uppermost part. The polyp's body is 9 mm long; the tentacles are 6 mm long, featuring two rows of pinnules 2.2 mm long and 0.2 mm wide on each side, and 24-29 pinnules in the outermost row. The pinnules mostly feature a one pinnule width gap. Sclerites are Ovabunda-type, regular and pear-shaped (Fig. 4a, c), measuring 0.016-0.030 × 0.022-0.038 mm in diameter (n=27 sclerites). Occasionally, two sclerites are fused (Fig. 4b), measuring up to 0.048 mm in diameter. The sclerites are more abundant on the aboral side of the tentacles than the oral one. The second paratype (RMNH Coel. 18676) has 2 rows of pinnules on each side of the tentacles, 24-27 in the outermost row. The sclerites are Ovabunda-type, measuring 0.026-0.036 mm at maximal diameter. The original description indicated non-pulsating polyps for live colonies. Colour of the ethanol-preserved holotype is light brown.
Remarks. The number of rows of pinnules and pinnules in the outermost row correspond to the original description of the holotype and paratypes of X. arabica. Their sclerites are Ovabunda-type ( Fig. 4) and, therefore, the species should be reassigned to that genus. Sclerite sizes given for the holotype and paratype in the original description exceed those obtained by us, as follows: holotype 0.043-0.053 mm vs. 0.028-0.036 mm at the larger diameter, and paratypes (RMNH Coel. 18675) 0.039 × 0.043 vs. 0.016-0.030 × 0.022-0.038 mm and (RMNH Coel. 18676) 0.043 × 0.051 vs. 0.026-0.036 mm, respectively. The larger size of 0.053 and 0.051 mm indicated by Reinicke (1997) falls within that of other Ovabunda species, such as O. crenata for the fused sclerites and O. gohari for larger and rare individual sclerites.
The holotype of X. crista (RMNH Coel. 18677) is 50 mm high and its stalk is 27 mm long, split into two branches 17 mm above its base. The branches are 10 mm long and 8 mm wide at their base and uppermost part. The polyp's body is up to 10 mm long. The tentacles are up to 10 mm long; pinnules up to 1.5-2 mm long and 0.2 mm wide, featuring one pinnule-width gap between adjacent pinnules. The tentacles have two rows of pinnules on each side, with 22-30 pinnules in the outermost row. Sclerites are Ovabunda-type ( Fig.  5a), measuring 0.014-0.030 × 0.017-0.037 mm in diameter (n=48 sclerites). Occasionally, two sclerites are fused, reaching a maximal diameter of 0.042 mm (Fig. 5b, c).
The paratype of X. crista (RMNH Coel. 18678) features tentacles with two rows of pinnules and 26-29 pinnules in the outermost row. The sclerites are Ovabunda-type, 0.025-0.036 mm in maximal diameter. The original description of the species indicated non-pulsating polyps in live colonies. Conclusions. Both the original description of X. crista and the current examination revealed two rows of pinnules; however, we found 22-30 pinnules in the holotype and 26-29 in the paratypes, compared to 29-33 and 28-32, respectively, in the original description. Description. The holotype is 25 mm high; stalk is 10 mm long, 6 mm wide at colonybase, and 15 mm wide at the uppermost part. The polyp's body is up to 4 mm long, and the tentacles up to 4 mm long, featuring a single row of 6-7 pinnules along each edge. The pinnules are short, up to 0.7 mm long and 0.4 mm wide with a 0.2-0.3 mm gap between adjacent pinnules. The sclerites are Ovabunda-type spheroids (Fig. 6a) and measure 0.019-0.035 × 0.027-0.041 mm in diameter (n=22 sclerites). When two sclerites are fused they measure up to 0.043 mm in maximal diameter (Fig. 6b). The original description indicated non-pulsating polyps in live colonies. The ethanol-preserved colony is light brown-beige.
Remarks. ZMTAU Co 26043, originally identified by Benayahu (1990) as X. nana, comprises 13 colonies up to 17 mm in height. Their stalks are not divided, and are up to 8 mm long, 8 mm wide at the base, and 10 mm wide at the uppermost part. Polyp's body reaches up to 1.4 mm in length, tentacles up to 1.6 mm, featuring a row of 5-6 closely set pinnules, 0.4 mm long and 0.16 mm wide. Sclerites are Ovabunda-type spheroids (Fig.  7a), 0.016-0.029 × 0.020-0.039 mm in diameter (n= 34 sclerites); some are egg-shaped (Fig. 7c) and sometimes two spheroids are fused (Fig. 7b). ZMTAU Co 26044 comprises several disintegrated small colonies, similar in size to those of ZMTAU Co 26043. There are 5-7 pinnules in a single row on each side of the tentacles. The sclerites are Ovabunda-type, 0.015-0.031 × 0.022-0.039 mm in diameter (n=34 sclerites). Polyp pulsation was not noted by Benayahu (1990). The colonies (ZMTAU Co 26043-26044) were misidentified as X. nana by Benayahu (1990) and should be reassigned to O. benayahui. The type of X. nana (BML 1939.6.12.9) was examined by the last author of the current paper and found to be of the genus Aldersladum Benayahu & McFadden, 2011. Conclusions. The features of the holotype and paratypes of O. benayahui agree with the original description of the species, and the assignment to Ovabunda by Alderslade (2001) was confirmed in the current study.   (Reinicke, 1995) holotype (RMNH Coel. 19664). a Regular sclerites b Fused sclerite. Arrows indicate surface dents. Scale bar 10 µm.
Ovabunda biseriata (Verseveldt & Cohen, 1971) http://species-id.net/wiki/Ovabunda_biseriata Figs 8, 9 Xenia biseriata Verseveldt & Cohen, 1971: 60,   Description. The holotype is 28 mm high, stalk is 15 mm long, 11 mm wide at its base and 10 mm wide at the uppermost part; it is attached to the skeleton of a stony coral. Polyp's body reaches up to 8-10 mm, and the tentacles 6-7 mm, bearing pinnules up to 1 mm long and 0.24 mm wide, separated by less than a pinnule-width. Two rows of pinnules are aligned along each of the tentacles margins, with 13-15 pinnules in the outermost row. There are numerous sclerites, abundant in all parts of the colony except for the mid-line of the oral side of the tentacles, where they are scarce. The sclerites are Ovabunda-type (Fig. 8), measuring 0.013-0.029 × 0.018-0.039 mm in diameter (n=100 sclerites). Rarely, two sclerites are fused, reaching a maximum diameter of 0.048 mm and occasionally 0.060 mm. The paratypes are of similar size to the holotype, featuring tentacles with two rows of pinnules and 13-16 pinnules in the outermost row. The stalk of the smallest paratype is divided into two branches; the paratype tentacles bear two rows of pinnules with 10-12 pinnules in the outermost row. The sclerites of all paratype colonies are Ovabunda-type, ranging 0.018-0.025 × 0.023-0.039 mm in diameter. The original description of the species indicated non-pulsating polyps in live colonies. The preserved colonies are yellowish-light beige in colour.
Remarks. In general the original description of the species corresponds to the current findings. SEM micrographs of the holotype sclerites (Fig. 8) indicate that they are indeed  (Verseveldt & Cohen, 1971) holotype (HUJ I Co. 72). Arrow indicates surface dents. Scale bar 10 µm.
Ovabunda-type, and therefore further confirm the previous assignment to that genus (Alderslade 2001; Aharonovich and Benayahu 2011). The number of rows of pinnules, the number of pinnules in the outermost row, and the dimensions of the holotype colony of O. obscuronata (HUJ I Co. 120) correspond to the original description by Verseveldt and Cohen (1971). The sclerites are oval spheroids, Ovabunda-type, ranging 0.012-0.026 × 0.018-0.041 mm in diameter (Fig. 9, n=61 sclerites). Rarely, two sclerites are fused, reaching a maximal diameter of 0.060 mm. The original description indicated a maximum diameter of 0.045 mm for the stalk sclerites, 0.060 mm for those of the anthocodiae and "irregular spicules" in the tentacles (Verseveldt and Cohen 1971: 60). The latter probably referred to fused sclerites, which were not identifiable under light microscopy. The original description of O. obscuronata indicated non-pulsating polyps in live colonies, similar to O. biseriata. The ethanol-preserved holotype is light brown in colour. Reinicke (1997) noted under the description of X. obscuronata (p. 33): "nec Xenia ternatana; Kükenthal 1913: 8 (in part)". The type of X. ternatana was examined during the present study and its features do not agree with those of O. obscuronata. X. ternatana features platelets composed of dendritic rods, measuring up to 0.022 mm in maximal diameter. It should be noted that the description of X. ternatana by Kükenthal also does not correspond to the features of O. obscuronata. Figure 9. Scanning electron micrographs of polyp sclerites of Ovabunda obscuronata (Verseveldt & Cohen, 1971) holotype (HUJ I Co. 120). Scale bar 10 µm.

Conclusions.
Examination of the holotype of O. biseriata and O. obscuronata revealed certain similarities, as already noted in the original description (Verseveldt and Cohen 1971): two rows of pinnules, with 12-15 vs. 14-16 pinnules, respectively, in the outermost row. The original description noted differences in the size of sclerites;  Description. The holotype is 30 mm high and 10 mm wide at its base. The stalk splits into two branches. The first is 15 mm long, 6 mm wide at its base and 10 mm wide at its uppermost part; the second splits further into two branches, 15 and 7 mm long, each 5 mm wide at the base, and 10 and 7 mm wide at the upper part, respectively. Polyp's body is up to 5 mm long and the tentacles up to 5 mm long. The pinnules are mostly arranged in two rows, with an occasional third row. There are 12-16 pinnules in the outermost row, 1 mm long and 0.14 mm wide, with a 0.2 mm space between adjacent pinnules. Sclerites are very scarce in all parts of the holotype; they are Ovabunda-type spheroids, measuring 0.012-0.028 × 0.018-0.036 mm in diameter (n=35 sclerites). Occasionally, two sclerites are fused, reaching 0.050 mm in maximal diameter. SEM micrographs of sclerites were obtained only from the additional material due to low density of sclerites in the holotype. Reinicke (1997) recorded non-pulsating polyps for the species. The ethanol preserved holotype is light beige.
Remarks. RMNH Coel. 23517 is similar in size to the holotype. Polyp's body is up to 2 mm long, with 2 mm long tentacles, mostly bearing two rows of 1 mm long and 0.1 mm wide slender pinnules on each of the tentacle sides, and, rarely, a third row. The outermost row features 12-15 pinnules, up to one pinnule-width apart. Sclerites are of the Ovabunda-type, varying in shape from regular (Fig. 10a), egg-shaped (Fig. 10c) and more rectangular (Fig. 10d), ranging 0.016-0.026 × 0.028-0.040 mm (n=25 sclerites) in diameter. Occasionally, two sclerites are fused, reaching 0.047 mm in maximal diameter (Fig. 10b). Reinicke (1997) Table 1) revealed them to have platelet-shaped sclerites composed of dendritic rods, and to differ from O. crenata. Conclusions. The original description of the holotype indicated three rows of pinnules, whereas the present examination revealed mostly two rows, with an indication of a third one. There is agreement between our findings and the original description regarding the number of pinnules in the outermost row of the tentacles (12-16 vs. 12-15, respectively). Sclerites correspond to the original description in size but are Ovabunda-type spheroids; therefore, it is concluded that the species should be assigned to Ovabunda. Similar species. O. crenata is most similar to O. biseriata. Although they both have overlapping number of pinnules in the outermost row, 12-16 and 13-16, respectively, O. biseriata has two rows of pinnules and O. crenata occasionally presents a third row. They both have non-pulsating polyps in live colonies.
Distribution. Red Sea: Gulf of Aqaba, Sudan.
Remarks. At the time of examination the holotype was dry, and therefore precise dimensions of the pinnules could not be obtained. The original description (Verseveldt and Cohen 1971: 62) indicated that: "The colony is 25 mm high. The stem is 15 mm high and 5-6 mm wide at the base, then narrows to 3-4 mm and widens again to 7 mm or more at the beginning of the polyparium. The anthocodiae are up to 10 mm long... the tentacles are 5-6.5 mm long". It is evident that the dimensions of the dried holotype are smaller than those of the original. The other features of the holotype recorded correspond to the original description, including two rows of pinnules, 17-24 pinnules in the outermost row, and sclerite diameter up to 0.044 mm (vs. 17-23 and 0.042 mm, in the original description). Reinicke (1997) presented a SEM micrograph of a single sclerite of O. faraunensis which later led Alderslade (2001) to assign it to the genus Ovabunda.
Conclusions. The current examination of the holotype (Fig. 11) along with the examination of the holotype by Aharonovich and Benayahu (2011), further confirmed the previous assignment.
Similar species. O. faraunensis is most similar to O. arabica. Although they both have two rows of pinnules and both have non-pulsating polyps in living colonies, the number of pinnules in the outermost row ranges from 17-24 in O. faraunensis compared to 24-29 in O. arabica.
Ovabunda gohari (Reinicke, 1997), comb. n. http://species-id.net/wiki/Ovabunda_gohari Fig. 12 Xenia gohari Reinicke, 1997  Description. The holotype is 25 mm high; the stalk is 15 mm long, 10 mm wide at its base and 20 mm wide at its uppermost part and is divided into two. Polyp's body reaches 5 mm and the 11 mm long tentacles mostly feature a single row bearing 19-22, 3 mm long and 0.2 mm wide pinnules. The gap between the pinnules is up to twice their width; occasionally a second row exists and then the outermost row bears 19-22 pinnules. The gap between adjacent pinnules in the outmost row is almost twice their width, as in the case of a single row. The sclerites are Ovabunda-type spheroids, measuring 0.028-0.045 mm in diameter (Fig. 12). The paratype is 18 mm long. Its stalk is divided into two branches, 8 mm and 4 mm long; each branch is 3 mm wide at its base, and 5 and 4 mm wide at the uppermost part, respectively. Polyp's body is up to 3 mm long, and tentacles 5-8 mm long, each have one row of 18-21 pinnules on each side; some small polyps have only 11-13 pinnules. The pinnules are up to 3 mm long and 0.24 mm wide at the base and the gap between the pinnules is up to twice their width. The sclerites (Fig. 12a) measure 0.015-0.035 × 0.028-0.055 mm in diameter (n=30 sclerites). Occasionally, two sclerites are fused, measuring up to 0.060 mm in maximal diameter; the fusion of sclerites can be partial or almost complete (Fig. 12b). The sclerites are more abundant at the base of the pinnules along the tentacle midline compared to their distal part, and similarly at the aboral side of the tentacles compared to their oral side. The original description indicated nonpulsating polyps in live colonies. The ethanol-preserved colony is light yellowish, beige.
Remarks. The current study confirmed the number of rows of pinnules and number of pinnules of the original description. Sclerite dimensions of the latter are larger than our findings, probably due to measurements that included fused sclerites.
Conclusions. The sclerites are Ovabunda-type spheroids and justify assignment to that genus.
Similar species. O. gohari is most similar to O. faraunensis. Although they both have overlapping number of pinnules in the outermost row, 18-22 and 17-24, respectively, O. gohari has mostly one row of pinnules and O. faraunensis presents two rows of pinnules. They both have non-pulsating polyps in live colonies.
Remarks. The colonies RMNH Coel. 25905, 23907, 23908 feature three rows of pinnules with 17-22 pinnules in the outermost row. The tentacles of RMNH Coel. 23552 have four rows of pinnules and 18-21 pinnules in the outermost row; RMNH Coel. 25903 has three rows of pinnules with an indication of a fourth row, and 19-22 pinnules in the outermost row. All colonies feature Ovabunda-type sclerites.
Janes (2008) (Reinicke, 1997) holotype (RMNH Coel. 23904). a Regular sclerites b Fused sclerites. Scale bar 10 µm. Reinicke (1997) noted under the description of X. hamsina sp. n. (p. 49): "Xenia aff grasshoffi Reinicke, 1995: 59, Fig. 33". The type of X. grasshoffi was examined by us (see Table 1 Description. The now dry holotype is 18 mm high. The stalk is divided into two branches, 10 and 8 mm long, 6 and 4 mm wide at the base, and 8 and 4 mm wide at the uppermost part, respectively. Polyp's body is up to 2-2.5 mm long, and tentacles up to 1.5-2 mm, featuring two rows of pinnules on each side, with 8-11 pinnules in the outermost row. The sclerites are Ovabunda-type (Fig. 14a) and are almost evenly distributed in all parts of the colony, measuring 0.013-0.028 × 0.019-0.039 mm in diameter (n=36 sclerites). Occasionally, two sclerites are fused, measuring up to 0.045 mm in maximal diameter (Fig. 14b). The original description stated that polyp pulsation in this species occurs in live colonies. The ethanol-preserved colony is light brown.
Remarks. At the time of examination the type was dry and, therefore, the dimensions of the pinnules are lacking and the current measurements do not reflect the original ones given by Verseveldt and Cohen (1971), who stated that "The colonies are 8-15 mm high and 10-15 mm wide. Three to four branches arise from a short stem 1-2 mm high. These branches, 2-3 mm high and 3-4 mm wide... The anthocodiae are 2 mm high and 1.2 mm wide, and tentacles are up to 2 mm long". We encountered three colonies, one with a branched stalk and two with undivided stalks. It is possible that they originally belonged to a colony that disintegrated. The current findings in general agree with the original description, although the maximal diameter of sclerites noted in the original description is larger than our findings (0.030 vs. 0.044 mm, respectively). A colony from the Seychelles was also assigned to O. impulsatilla by Janes (2008). The SEM micrographs of the holotype sclerites given by Aharonovich and Benayahu (2011), along with the current ones (Fig. 14), confirm that the species should be assigned to the genus Ovabunda.  (Verseveldt & Cohen, 1971) holotype (HUJ I Co. 84). a Regular sclerites b Fused sclerites. Scale bar 10 µm.
The holotype of X. miniata (RMNH Coel. 23514) features two rows of pinnules on each side of the tentacles, with 8-13 pinnules in the outermost row. The sclerites are Ovabunda-type, some regular (Fig. 15a), some pear-shaped (Fig. 15b) measuring 0.017-0.034 × 0.022-0.053 mm in diameter (n=30 sclerites). Occasionally, two sclerites are fused, reaching 0.059 mm in maximal diameter (Fig. 15c). The paratypes of that species (RMNH 25411, 25412, 25413) feature tentacles with two rows, 11-13 pinnules in the outermost row and Ovabunda-type of sclerites, measuring 0.018-0.030 × 0.024-0.034 mm in diameter (n=24 sclerites). Although the original description of X. miniata indicated three rows of pinnules in the holotype and paratypes, we found only two rows. The original description of the species indicated non-pulsating polyps in live colonies. Colour of the ethanol preserved colony is beige. Consequently, we conclude that X. miniata should be synonymised with O. impulsatilla.
We also examined additional colonies that were identified by Reinicke (1997) as X. miniata. Specimen RMNH Coel. 6848 has two rows of pinnules, with 12-14 pinnules in the outermost row; its sclerites are Ovabunda-type, reaching up to 0.051 mm in maximal diameter. Based on sclerite size, number of pinnule rows and number of pinnules in the outermost row, this specimen should be reassigned to O. biseriata. Specimen RMNH Coel. 6847 has two rows of pinnules, with 10-11 pinnules in the outermost row; and its sclerites are also of the Ovabunda-type, reaching up to 0.045 mm in maximal diameter. RMNH Coel. 8938 has two rows of pinnules, but with only 8-9 in the outermost row; its sclerites are Ovabunda-type, reaching up to 0.047 mm in maximal diameter. Based on the number of rows of pinnules on the tentacles, the number of pinnules in the outermost row, and the size and microstructure of sclerites, the latter two colonies also belong to O. impulsatilla. Our measurements of the dimensions of the holotype of O. aldersladei (RMNH Coel. 38681) agree with those of the original description. It features 3 mm long polyp's body, 2 mm long tentacles, with two rows of pinnules on each side, and 8-12 pinnules in the outermost row. The densely set pinnules are up to 0.6 mm long and 0.2-0.3 mm wide and with almost no gap between adjacent pinnules. The sclerites are Ovabunda-type spheroids (Fig. 16), measuring 0.012-0.030 × 0.018-0.042 mm in diameter (n=46 sclerites). Janes (2008) did not mention polyp pulsation for that species. The ethanol-preserved colony is light beige. The features of the holotype match the original description of O. aldersladei, except for sclerite size, which was found to be larger in our examination (up to 0.042 mm vs. up to 0.026 mm). The sclerites are indeed Ovabunda-type (Fig. 16), similar to those depicted by Janes (2008: fig. 10). Based on similarity between O. aldersladei and O. impulsatilla in number of rows (two in both), number of pinnules in the outermost row (8-12 and 8-11, respectively), and the size and microstructure of the sclerites it is concluded that the junior species O. aldersladei should be synonymized with O. impulsatilla, giving priority to the latter. Reinicke (1997) noted under the description of X. miniata n.sp. (p. 39): "Xenia ternatana Schenk, 1896;Cohn 1908: 238 (ZMB 4991)" as well as: "nec Xenia ternatana; Kükenthal 1913: 8 (partim, NHMW C.16618)". These two colonies were not examined in the current study. However, the type of X. ternatana was examined (see Table 1) and found to have Xenia type sclerites. Moreover, Reinicke 1997  Xenia macrospiculata Gohar, 1940: 96-98;Benayahu 1990  Description. The neotype is 20 mm high. Its stalk is 10 mm wide at its base, splitting into three branches, 7, 5 and 5 mm long; 5, 4 and 4 mm wide at the base and 10, 6 and 7 mm wide at the uppermost part, respectively. Polyp's body reaches up to 2 mm and tentacles up to 5 mm, bearing three, occasionally two, rows of pinnules. The pinnules are 1 mm long and 0.2 mm wide, with less than a pinnule-width space between them, and there are 15-17 pinnules in the outermost row on each side of the tentacle. The sclerites are Ovabunda-type, both regular and pear-shaped, measuring 0.015-0.025 × 0.023-0.041 mm (n=34, Fig. 17a, b). Occasionally two sclerites are fused, reaching 0.041 mm in maximal diameter (Fig. 17c).
The other specimens (ZMTAU Co 35789,35790,35791) are of similar size to the neotype; all with three rows of pinnules aligned on both sides of the tentacles, and 14-18, 14-17 and 14-17 pinnules in the outermost row, respectively. Their sclerites are of the Ovabunda-type and vary in shapes from regular to irregular, pear-shaped or fused. Their size ranges through 0.016-0.025 × 0.023-0.043 mm; 0.014-0.03 × 0.019-0.043 mm (Fig. 18) and 0.015-0.027 × 0.022-0.046 mm (Fig. 19) in diameter, respectively (n=21 for each colony).  Remarks. X. macrospiculata was originally described by Gohar (1940) from Ghardaqa, Egyptian Red Sea, as having pulsating tentacles, bearing three, occasionally two, rows of pinnules, with 12-16 pinnules in the outermost row (and 10-14 pinnules on the middle row, 0-10 on the oral one). That study did not indicate the museum in which the type was deposited. The last author of the current study searched in the museums listed in the Methods and found no trace of it; over time this type was probably lost. The designation of a neotype in this revision is thus necessary. The purpose of the designation is to clarify the species' taxonomic status and its assignment to Ovabunda. Although the sclerites were described quite accurately in the original description (0.024-0.036 mm in diameter, and "spicules fused in pairs"), SEM micrographs of the sclerites are essential as in the other species of the revision.
The neotype was collected in proximity to the collection site of the original specimen collected by Gohar. The neotype is located at ZMTAU, and available upon request for future examination.
O. macrospiculata was also described by Verseveldt (1971: 64-65, fig. 39) from Nosy Be, Madagascar, referring to three and sometimes four rows of pinnules with 12-16 pinnules in the outermost row, and sclerites 0.020-0.042 mm in maximal diameter. Examination of RMNH Coel. 6702 from that study revealed that its tentacles have mostly four, rarely three rows of pinnules, and 14-16 pinnules in the outermost row (Reinicke 2013, pers. comm.). During our study the sclerites were examined and they are indeed Ovabunda-type, measuring up to 0.043 mm in maximum diameter, while fused sclerites are 0.055 mm in diameter. Based on the number of rows of pinnules and the number of pinnules at the outermost row, we conclude that it does not agree with O. macrospiculata.  Ovabunda verseveldti (Benayahu, 1990) http://species-id.net/wiki/Ovabunda_verseveldti Fig. 20 Xenia verseveldti Benayahu, 1990: 115-116, fig. 2, table 1;Reinicke 1997: 29-30, plate 16 Ovabunda verseveldti;Alderslade 2001: 49 Material. Holotype: ZMTAU Co 26048 and four paratypes: ZMTAU Co 31625 northern Red Sea, Gulf of Aqaba, Dahab (28°30'34.21"N, 34°31'18.26"E), 1 m, 9 November 1979, coll. Y. Benayahu. Description. The holotype is 18 mm high; its stalk is 9 mm long, 5 mm wide at its base and 13 mm wide at its uppermost part. Polyp's body is 1-4 mm long, and the tentacles 6 mm long, bearing 1.8 mm long and 0.2 mm wide pinnules separated from each other by a small gap, less than one pinnule width. A single row of 14-18 pinnules is aligned on each side of the tentacles. There are numerous sclerites in all parts of the colony, densely packed in the pinnules and scarce in the mid-line of the tentacles' oral side. The sclerites are Ovabunda-type, varying in shape from regular spheroids (Fig. 20b) to egg-shaped (Fig. 20a) and more rectangular forms (Fig. 20c), measuring 0.014-0.033 × 0.022-0.046 mm in diameter (n=45). Rarely, two sclerites are fused, reaching a diameter of up to 0.051 mm (Fig. 20d).
The four paratypes (ZMTAU Co 31625) are smaller than the holotype, 12-17 mm high; the stalk is 10-15 mm long, 4-6 mm wide at the stalk base and 6-8 mm wide at the upper part. Polyp's body is up to 5 mm long, and tentacles up to 3 mm long, featuring one row of 12-17 pinnules on each side. The pinnules are 1.2 mm long and 0.2 mm wide at their base, densely set in each row, almost touching each other. The sclerites are Ovabunda-type, measuring 0.018-0.030 × 0.022-0.049 mm in diameter (n=38). Occasionally, two sclerites are fused, reaching a maximum size of 0.049 mm. The original description did not mention polyp pulsation. The ethanol-preserved colonies are light brown.
Conclusions. The features of the holotype and paratypes agree with the original description of the species. The species was assigned by Alderslade (2001) to Ovabunda (see Introduction) and this is confirmed in the current study.
Similar species. O. verseveldti is most similar to O. benayahui. Although they both have one row of pinnules the numbers of pinnules in the outermost row ranges from 12-18 in O. verseveldti compared to 6-7 in O. benayahui.
Distribution. Red Sea: Gulf of Aqaba, southern tip of Sinai Peninsula.

Discussion
The current study revises the genus Ovabunda Alderslade, 2001, following examination of relevant type material. Examination of the types has confirmed the previous Figure 20. Scanning electron micrographs of polyp sclerites of Ovabunda verseveldti (Benayahu, 1990) Table 1) out of the 58 species listed in WoRMS (http:// www.marinespecies.org/aphia.php?p=taxlist), including SEM of their sclerites, has furnished the required data for revision of that genus (Halász et al. in prep.). The first taxonomic revision of the family Xeniidae was that by Kükenthal in 1902, who presented 26 Xenia species and five Cespitularia. That revision used various morphological features for the species description, such as colony dimensions, pinnule form, number of rows of pinnules and number of pinnules in the outermost row, and also specified the geographic distribution of each species. No details were given for the dimensions of the sclerites or their shape but occasionally their density or absence was noted. The subsequent revision by Hickson (1931a) listed 13 valid Xenia species, five Cespitularia, one Heteroxenia, and included a discussion of Sympodium. In that revision the number of rows of pinnules and the number of pinnules in the outermost row were presented for each species. Hickson pointed out the difficulty in counting the somewhat irregular rows along each edge of the tentacles, and referred to it as a general problem of the Xeniidae. In the current study we also encountered this difficulty (see Results: e.g., O. crenata and O. hamsina). Since Hickson's study (1931a), no revision has been published on any genus of the family Xeniidae. The above-mentioned two revisions failed to establish a standardized template for species descriptions within the family, which most probably hindered further attempts to carry out such a revision.
Here we discuss the reliability of each of the characteristics used to diagnose species, according to the order they appear in the species descriptions for each species. Colony dimensions as presented in the current study might in part be determined by age (Verseveldt 1960: 242) and environmental factors (Meestert et al. 2001) and also change according to collection and preservation conditions. Such dimensions might also exhibit a wide variation within a given species (Gohar 1940), therefore we doubt their value in species-specific taxonomic descriptions. However, pinnule length and width and the gap between adjacent pinnules are suggested here as a diagnostic trait: e.g. in O. arabica and its synonym X. crista, which had 1.8-2.2 mm long, 0.2 mm wide pinnules, with one pinnule-wide gap between adjacent ones. Similar to other studies (e.g., Gohar 1940, Verseveldt and Cohen 1971, Benayahu 1990, and Reinicke 1997, the number of pinnule rows and the number of pinnules in the outermost row are suggested to be of major taxonomic importance for species distinction, and the key (see above) is mainly based on these features.
The application of SEM for octocoral taxonomic studies, and Xeniidae in particular, has significantly increased the resolution of sclerite imaging and led to the establishment of new taxa based on their microstructural features (e.g. Ovabunda Alderslade, 2001;Fasciclia Janes, 2008;Yamazatum Benayahu, 2010). In the current study, SEM revealed for Ovabunda species the full shape and size range of the spheroidal sclerites including fused ones. The latter type of sclerite is found in all species, although sometimes rare (as in the case of O. verseveldti). For each species the dimensions of the individual sclerites and the fused ones are presented, which together are necessary for future species description. The range of the smallest diameter of the single Ovabunda spheroids was found to be similar in all the types, ranging 0.026-0.035 mm (e.g., O. ainex: Fig. 3, O. biseriata: Fig. 8 . 12); and in some species, such as O. gohari (Fig. 12) and O. verseveldti (Fig. 20), they occasionally reach a larger size, up to 0.046-0.055 mm. It is important to emphasize that these larger sclerites are rare in the above-mentioned types, which mainly have sclerites within a range of 0.035-0.040 mm. In order to present the actual range of sclerite sizes we measured at least 20 sclerites from each colony, a standard that we recommend for future studies. The lack of such a detailed account in past studies has led to taxonomic errors, as in the establishment of O. aldersladei (Janes 2008: sclerite maximal diameter range 0.018-0.026 mm), which is in fact a synonym of O. impulsatilla (sclerite maximal diameter range 0.018-0.042, Fig. 16). It should also be noted that only high-quality and sharp SEM images of Ovabunda sclerites reveal the morphological features of the sclerites, composed of corpuscular microscleres that are diagnostic for that genus. The current findings reveal that Ovabunda species feature spheroids of various sizes (e.g., O. benayahui: Fig. 6, O. gohari: Fig. 12), and shapes, some of which are regular, spherical (e.g. O. ainex: Fig. 3a, O. faraunensis: Fig. 11a) and others less so (e.g., O. macrospiculata: Fig. 18b; O. verseveldti: Fig. 20e; O. ainex: Fig. 3c). The sclerites in the latter species can be pear-shaped, or egg-shaped, or more rectangular (e.g. X. miniata: Fig. 15b, O. faraunensis: Fig. 20a; O. benayahui: Fig. 7d, respectively). Occasionally the sclerites feature surface dents or crests (e.g., O. crenata: Fig. 10; O. macrospiculata: Fig. 19c; O. ainex: Fig. 3; O. benayahui: Fig. 7). There is no apparent correlation between these different shapes and the different species and therefore sclerite shape has not been included in the key (see above). Prior to the current study, SEM micrographs and detailed sizes of fused sclerites were never recorded in Ovabunda species, and were recognized by light microscopy only in the original descriptions of O. macrospiculata (Gohar 1940) and O. obscuronata (Verseveldt and Cohen 1971). In most studies the fused sclerites were erroneously considered to be large individual sclerites, giving them a size of up to 0.060 mm in maximal diameter (e.g. O. benayahui, O. crenata: Reinicke, 1997). In the case of the fused sclerites, the use of SEM has enabled the full range of shapes to be captured, including some that were almost fully fused and could not be detected using light microscopy (e.g., O. benayahui: Figs 6b and 7b; O. gohari: Fig.  12b), partially fused figure-eight shapes (X. crista: Fig. 5b; O. impulsatilla: Fig. 14b), or spheroids with only a medial narrowing (O. hamsina: Fig. 13b). Undoubtedly, when measuring sclerites under a light microscope, the existence of both individual spheroids and fused ones should be taken into account. The occurrence of fused sclerites and their significance to the taxonomy of the genus and other xeniid genera should be further examined.
Polyp pulsation of living xeniid colonies was first noted by Lamarck (1816) (in: Kremien et al. 2013) and later by Hickson (1931a: 154) and Gohar (1940: 82-83). This feature was considered indicative for species identification. Recently, Kremien et al. (2013) found that such pulsation increases photosynthesis, which in absolute en-ergy gain greatly surpasses the added metabolic cost. Since 1940 it has been noted in most descriptions of Xenia and Heteroxenia species (e.g. Gohar 1940, Verseveldt andCohen 1971;Reinicke 1995Reinicke , 1997. Among Ovabunda species the state of pulsation (absence/presence) in living colonies has been noted for all species (Gohar 1940, Verseveldt andCohen 1971;Reinicke 1995Reinicke , 1997, except O. verseveldti. As in previous studies, we consider the pulsation state of living colonies an important characteristic and we recommend recording it when collecting colonies. Hickson's revision (1931a) and several later publications (e.g., Benayahu 1990; Reinicke 1997; Janes 2008) noted the color of the colonies. We doubt color is of taxonomic value, however, since it can change with preservation, and also depends on the type and density of the symbiotic zooxanthellae (Berner et al. 1987, Siebeck et al. 2006. We have also noted that sclerite density and distribution affect tissue coloration (Reinicke 1997: 18).
The current study indicates that the Red Sea is the type locality of most Ovabunda species (Fig. 21). Some species, such as O. hamsina, O. impulsatilla, and O. macrospiculata, were also recorded in the West Indian Ocean (e.g., Madagascar and the Seychelles). The possibility that the genus has a wider distributional range is not excluded, and remains to be confirmed by re-examination of already collected material deposited in various collections, or of freshly collected material from throughout the Indo-Pacific basin.
Re-examination and appropriate re-descriptions of octocoral type material, as conducted in the current study, is highly important in an era of molecular phylogeny and increasing phylogeographic studies, despite the difficulty or inability to extract DNA from the types themselves. This kind of comprehensive study based mainly on type material is a critical first step in the process of understanding phylogenetic relationships among species and genera, and their ecology. Due to similar morphologies in the case of Xenia and Ovabunda, further analysis is needed in order to reveal their radiation, especially in regions where they have a sympatric distribution. There is also a need to validate the current Ovabunda species, through an integrated taxonomic effort, combining molecular genetic evidence of species boundaries, ecological, and reproductive differences.