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Home , Acropora, Acropora aspera, Acropora horrida, Acropora humilis, Acropora muricata, Acropora nasuta

Turkish Journal of Zoology Turk J Zool (2013) 37: 308-320 http://journals.tubitak.gov.tr/zoology/ © TÜBİTAK Research Article doi:10.3906/zoo-1112-21

Preliminary study on (: Astrocoeniina: ) of the Persian Gulf, with emphasis on the north and northeastern areas

1,2, 1 Mohammadreza RAHMANI *, Hassan RAHIMIAN 1 Faculty of Biology, College of Science, University of Tehran, Tehran, Iran 2 University of Environment, Standard Square, Karaj, Iran

Received: 16.12.2011 Accepted: 02.10.2012 Published Online: 29.04.2013 Printed: 29.05.2013

Abstract: Due to a lack of adequate taxonomic information on Acropora Oken, 1815 in the Persian Gulf, especially those inhabiting the coasts of the northern and northeastern areas, an appraisal of the diversity of this required comprehensive and careful examination of a large number of specimens. To satisfy such a need, 10–15 cm pieces of more than 1100 colonies of staghorn were collected from the subtidal zones of different islands. The specimens were studied using both light stereo and scanning electron microscopes and were identified with regional and global keys. During the study, 9 species of Acropora were identified, including A. tortuosa (Dana, 1846) and A. mossambica Riegl, 1995, which are new to the Persian Gulf. Furthermore, A. horrida (Dana, 1846), A. nasuta (Dana, 1846), A. aspera (Dana, 1846), and A. muricata (Linnaeus, 1758) were identified, all of which were recorded for the first time from Iran. By adding these species to those previously reported from the area, the numbers of Acropora species in the study area and in the Persian Gulf reach 10 and 15, respectively.

Key words: Khark, Larak, Farur, taxonomic key, islands, Iran, , Acropora

1. Introduction Coles (2003) reported 11 species of Acropora, including The information available on different aspects of A. clathrata (Brook, 1891), in the Persian Gulf. In her scleractinian diversity and biology is exhaustive (Wallace, previous monograph, which included the Persian Gulf and 1999; Meyer and Paulay, 2000; Veron, 2000). From a the Gulf of Oman, Wallace (1999) reported 13 Acropora taxonomic point of view, staghorn corals, members species, but excluded A. clathrata. On the northern of genus Acropora Oken, 1815, are amongst the most coast of the Persian Gulf, however, only 5 Acropora controversial taxa due to their high intraspecific diversity species, including A. clathrata, have been reported so far and interspecific similarities. Those facts are evident in the (Maghsoudlou, 2008). constant changes of the total diversity estimates given by Due to the lack of adequate taxonomical information several authors (see Wallace, 1999; Veron, 2000). Although about the Acropora species of the Iranian parts of the recent molecular studies (van Oppen et al., 2001; Fukami et Persian Gulf, and taking into account the importance al., 2003; Wolstenholme et al., 2003, Wolstenholme, 2004; of the genus Acropora from an endemicity point of view Fukami et al., 2007; Chen et al., 2009) raised some hopes in and its use as a model for studying the effects of global solving such problems, morphological identification is still warming on marine taxa (Wallace and Muir, 2005), the the most preferred procedure in the taxonomical studies present study was conducted to ascertain the distribution conducted on such a group. Wallace (1999) resolved and the diversity of Acropora species in the area. most of the taxonomical problems of this genus, hence improving the accuracy of surveys. 2. Materials and methods Despite the numerous studies carried out on Acropora On the basis of the studies performed on the scale of worldwide, the data available on scleractinian species environmental stresses (see Kämpf and Sadrinasab, 2006; diversity in the Persian Gulf in general and on the genus Nezlin et al., 2007), the Persian Gulf was divided into 3 Acropora in particular are restricted (Spalding et al., 2001), distinct parts: the eastern, central, and western parts. even though the corals of the southern part of the Persian Taking this fact into consideration, in each part, a coral- Gulf are better known than those of the northern and rich island was selected for sampling: these were Larak northeastern parts. Island (26°49′N–26°53′N, 56°19′E–56°25′E), Farur Island * Correspondence: [email protected] 308 RAHMANI and RAHIMIAN / Turk J Zool

(26°14′N–26°19′N, 54°29′E–54°32′E), and Khark Island The specimens were bleached in 5 ppt sodium (29°12′N–29°16′N, 50°16′E–50°20′E), from the eastern, hypochlorite and transferred to the laboratory where central, and western parts of the Persian Gulf, respectively. further studies took place. To study the gross and fine Along the coasts of these 3 islands, 40 locations morphologies of the specimens, a Nikon SMZ 1000 were selected (Figure 1) for sampling. The geographic stereomicroscope and a Zeiss DSM960A scanning electron coordinates of each station were obtained using a Garmin microscope were used, respectively. Based on even minute Etrex GPS receiver. From the 1169 colonies, pieces of 10 morphological differences, 55 specimens representing to 15 cm were collected from October 2008 to December 9 species (excluding ) were selected 2009. The first author carried out the underwater and shipped to the Museum of Tropical Queensland for photography. At each station, the specimens were collected further studies and identifications. Of these specimens, by to the depths of 3, 6, and 9 m, along a line C.C. Wallace identified 45. Mostly due to their small size, at least 120 m long. 10 specimens remained unidentified. The morphological

N N c b W E W E a N S S W E S

Farur Khark Larak

2 km 2 km 2 km

IRAQ N

30° W E KUW IRAN TIR S AIT Khark Bushehr

28°

Farsi

Bandar Abbas Hormuz Lavan m Larak Hendourabi HeQeshngam Kish Persian Gu FarurTonbe-e Bozorg Tonbe-e Kouchak 26° BAHRAIN Farurgan OMAN lf SirrAbi u Musa 0 200km QATAR U.A.E. 48° 50° 52° 54° 56° Figure 1. Sampling sites in the Persian Gulf along the coasts of a) Larak Island, b) Farur Island, and c) Khark Island.

309 RAHMANI and RAHIMIAN / Turk J Zool descriptions as well as the terminology and measuring colonies); main branches of large colonies sometimes procedures used in this study were performed on the basis grow horizontally; size up to 45 cm (rarely more of the descriptions and the nomenclature suggested by than 55 cm) (Figure 2a); branches cylindrical to slightly Wallace (1978), Veron and Wallace (1984), Riegl (1995), tapering (Figure 2b); branch diameters: 6.5–11.9 mm, Wallace (1999), Veron (2000), and Wolstenholme et al. 7.3–11.7 mm, and 7.2–9.8 mm; branch length up to 29.4 (2003). mm; growth determinate or semideterminate depending In the present paper, a regional taxonomic key on on the corallum. the Acropora species is also suggested, in which the Axial : Conspicuous, cylindrical, twice the characteristics of the specimens found in the present study size of radial corallites; outer diameter 2.0–2.6 mm; calice were used for species of the northern and northeastern diameter and thickness of axial corallites walls similar parts of the Persian Gulf. For the species of the southern (0.8–1.2 mm); round opening; most axial corallites contain part, the descriptions given by Wallace (1999) were used. 2 septa cycles; primary septa up to 2/3R, but longer in the deeper parts of the calice; secondary septa up to 1/3R, 3. Results sometimes dentate; tertiary septa rarely present (Figure 2f). All 1169 specimens were examined, but from those, for Radial corallites: Appressed tubular with oval opening; each species a few specimens containing most of the more or less equal in size; profile length 2.0–3.3 mm; some plasticity range of the characteristics of that species were tubular or tubo-nariform corallites (usually having thick selected for description purposes. Throughout this article, lips) scattered along branches (Figures 2c and 2d); primary the specimens’ data are presented in the following order: septa present up to 2/3R; directive septa prominent; sampling location; coordinates of the sampling location; secondary septa development variable in different location depth, sampling date, and the museum reference corallites: up to 1/5R in those near the branch base, absent number. The order followed for the description of 2 or or partially developed in those near the branch tip. more specimens was also the same. Coenosteum: Broken-costate to costate on outer walls Whenever branch diameters are provided, they are of radial corallites (Figure 2e); densely arranged lines of presented in the following order: branch diameter at the laterally flattened spinules on the outer edge of radial base, at the midpoint, and at 5 mm below the tip of the walls; reticulate with simple to slightly elaborated branch. spinules between radials (Figure 2g). From the northern and northeastern parts of the Color: Pale to cream brown. Persian Gulf, 9 species of Acropora were identified during Remarks: Comparison of the specimens of A. valida the study. Amongst those species, 6 are reported for the from this study with those described by Wallace (1999) first time from the area of the study, and 2 other species showed that the branches were relatively thinner and are new to the Persian Gulf. Although the ecological and shorter, and axial corallites were smaller and had thinner population data collected during the sampling are not walls in the specimens from the study area. analyzed in the present paper in general, amongst the Acropora aspera (Dana, 1846); Figures 3a–3g species found in this study, A. downingi and A. arabensis Material examined: Iran, Farur Island: 26°17′44.1″N, were the most common species, with A. valida next in 54°32′22.4″E; depth 6 m; 28 October 2009; MMTT Cnid. abundance and the rest of the species being rare. 1347. Khark Island: 29°16′33.8″N, 50°18′21.5″E; depth 3 The specimens described in this article are deposited m; 19 December 2009; MMTT Cnid. 1699. in the Zoological Museum of the University of Tehran Description: Branching pattern: Arborescent (Figure (ZUTC) and the National Museum of Natural History 3a); branch length up to 71.7 mm, tapering slightly towards (MMTT). the tip, and tapering abruptly at the tip (Figure 3b); branch In the description of each species, we chose not to diameters: 11.3–13.0 mm, 9.5–10.8 mm, and 6.8–8.4 mm; mention the synonyms, as they are available in detail from growth indeterminate. Wallace (1999). Axial corallites: Conspicuous; larger than radial (Dana, 1846); Figures 2a–2g corallites; dome-shaped; outer diameter 2.7–4.0 mm; Material examined: Iran, Larak Island: 26°53′10.1″N, calice diameter 1.3–1.6 mm; both primary and secondary 56°23′58.3″E; depth 6 m; 7 October 2008; MMTT Cnid. septa present, primary septa up to 2/3R, secondary septa 1024. Larak Island: 26°52′45.8″N, 56°20′26.8″E; depth up to 1/2R (Figure 3f). 6 m; 14 October 2008; MMTT Cnid. 1319. Larak Island: Radial corallites: Labellate; horizontal extension of the 26°53′12.1″N, 56°23′32.1″E; depth 3 m; 8 October 2008; outer walls and absence of inner walls give a gutter-shaped ZUTC Cnid. 1115. appearance (Figures 3c and 3d); profile length 1.2–1.7 Description: Branching pattern: Caespitose (usually mm; subimmersed radial corallites scattered between for small colonies) to corymbose (usually for large labellate corallites; crowded; radial corallites in 2 sizes,

310 RAHMANI and RAHIMIAN / Turk J Zool

Figure 2. Acropora valida: a) live colony; b) part of colony; c) Figure 3. Acropora aspera: a) portion of colony; b) portion of portion of branch; d) SEM micrograph showing micrograph branch; c) SEM micrograph showing terminal part of branch; d) showing a few radial corallites; e) SEM micrograph showing SEM micrograph from lateral view of radial corallites, note the coenosteum on a radial corallite; f) SEM micrograph showing gutter-shaped appearances formed by the outer walls; e) SEM top view of an axial corallite; g) SEM micrograph showing micrograph showing coenosteum on a radial corallite; f) top view coenosteum between radial corallites. of axial corallite showing extent of primary and secondary septa; g) SEM micrograph showing coenosteum between radial corallites. both with a round opening; development of septal cycles Description: Branching pattern: Arborescent; slightly varies depending on the position of the radial corallites tapering branches (Figures 4a and 4b); branch diameters: on the branch. In those located from the branch base to 7.9–11.3 mm, 7.2–10.5 mm, 6.0–9.4 mm; branch length up near its tip 2 complete cycles are present, but these are to 26.1 mm; growth indeterminate. incomplete and poorly developed in the radial corallites Axial corallites: Conspicuous; outer diameter 2.0–2.6 located at the branch tips; primary septa up to 1/2R, except mm; calice diameter 1.2–1.6 mm; primary septa present, for the directives that are well developed; secondary septa, maximum 3/4R; sometimes dentate; secondary septa if present, a low ridge maximum 1/3R. absent (Figure 4f). Coenosteum: Costate to broken-costate on radial Radial corallites: Extremely fragile; with different sizes; corallites proper (Figure 3e); sometimes densely arranged ragged surface (Figure 4c); profile length 2.0–4.5 mm; lines of laterally flattened spinules on radial corallites; round opening; septa poorly developed, particularly the coenosteum between radial corallites reticulate with dispersed, laterally flattened, and slightly elaborated inner septa; primary septa up to 1/3R; outer directive spinules (Figure 3g). septum more developed than the inner directive; Color: Brown to cream-brown or greenish brown. secondary septa absent. (Dana, 1846); Figures 4a–4g Coenosteum: Broken-costate to reticulate on radial Material examined: Iran, Farur Island: 26°17′44.1″N, corallites proper (Figure 4d); reticulate between radial 54°32′22.4″E; depth 6 m; 28 October 2009; MMTT Cnid. corallites; simple, laterally flattened spinules scattered on 1348. Larak Island: 26°52′45.8″N, 56°20′26.8″E; depth 6 and between radials (Figures 4e and 4g). m; 14 October 2008; ZUTC Cnid. 1305. Color: Brown.

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54°32′22.4″E; depth 6 m; 28 October 2009; MMTT Cnid. 1382. Khark Island: 29°16′34.4″N, 50°18′31.7″E; depth 9 m; 20 December 2009; ZUTC Cnid. 1708. Description: Branching pattern: Arborescent table, large, some up to 3 m in diameter (Figure 5a), both single and multilayered table forms present; some branches grow upwards; branches tapering slightly towards the tip (Figures 5b and 5c), anastomosed branches forming solid central plate; branch diameters: 5.4–14.8 mm, 4.8–13.6 mm, 4.2–9.1 mm; branch length up to 62.0 mm; growth determinate. Axial corallites: Small cylindrical; outer diameter 0.9–2.5 mm; calice diameter 0.6–1.6 mm; round to oval opening; 1 or 2 septal cycles present (Figure 5e), primary septa 1/2R, directive septa sometimes touching; secondary septa absent or inconspicuous; septal length increasing downwards. Radial corallites: Crowded and fragile; various sizes (Figure 5c); tubular, with oblique opening and upward sharp edges (Figure 5d); profile length 1–4 mm; some corallites immersed, especially those at the base of branches; primary septa seldom present (in most cases only directive septa present), when present maximum 1/4R. Coenosteum: Coenosteum on radial corallites proper costate (Figure 5d), broken-costate, or linearly arranged, Figure 4. Acropora horrida: a) portion of colony; b) portion of laterally flattened spinules; coenosteum between radials branch; c) SEM micrograph showing terminal part of branch; reticulate with simple spinules (Figure 5f). d) SEM micrograph showing coenosteum on radial corallite; e) Color: Brown to dark green or gray; branch tips pale SEM micrograph showing 2 simple, laterally flattened spinules between radial corallites; f) top view of axial corallite, note the or white. absence of secondary septal cycle; g) high-magnification SEM Remarks: Our preliminary studies indicated that micrograph showing ornamentations on coenosteum between Acropora downingi has 2 forms in the study area. In one radial corallites. form, some branches grow upwards, unlike in the second form, which has no upright branches on the table. The latter form might have been misidentified as A. clathrata. Remarks: Of this species, 1 specimen was sent to the Further taxonomic work on these growth forms is Museum of Tropical Queensland, where C.C. Wallace currently underway. A. clathrata was not found during identified it as Acropora cf. horrida. Detailed and careful the present study. Consequently, it is likely that either the examination of other specimens from the same dive and reports of A. clathrata from the southern (and western) of additional specimens collected later on allowed us to Persian Gulf (Sheppard and Sheppard, 1991; Hodgson confirm the identification. and Carpenter, 1996; Riegl, 1999; Abdel-Moati, 2011) are Comparison between the measurements of the a misidentification of A. downingi (see Wallace, 1999) or specimen found in the present study with those described that A. clathrata is restricted to the southern (and western) by Wallace (1999) indicated that branches of almost the part of the Persian Gulf, or it is an extremely rare species in same diameter were much shorter in our specimens. The this part of the Persian Gulf (see discussion). other measurements more or less overlapped. Acropora arabensis Hodgson and Carpenter, 1996; Acropora downingi Wallace, 1999; Figures 5a–5f Figures 6a–6g Material examined: Iran, Larak Island: 26°53′07.8″N, Material examined: Iran, Larak Island: 26°53′16.3″N, 56°23′59.0″E; depth 3 m; 7 October 2008; MMTT Cnid. 56°21′01.3″E; depth 6 m; 11 October 2008; MMTT 1022. Larak Island: 26°53′16.3″N, 56°21′01.3″E; depth 6 Cnid. 1153. Larak Island: 26°53′16.9″N, 56°21′00.4″E; m, 11 October 2008; MMTT Cnid. 1172. Khark Island: depth 9 m; 11 October 2008; MMTT Cnid. 1239. Larak 29°12′36.6″N, 50°19′56.5″E; depth 3 m; 14 December Island: 26°53′12.1″N, 56°23′32.1″E; depth 3 m; 8 October 2009; MMTT Cnid. 1404. Farur Island: 26°17′44.1″N, 2008; MMTT Cnid. 1125. Farur Island: 26°16′52.4″N,

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Figure 5. Acropora downingi: a) live colony; b) portion of colony; Figure 6. Acropora arabensis: a) live colony, note the distinct c) portion of branch, note different sizes of radial corallites; d) white branch tips; b) portion of the colony; c) portion of branch; SEM micrograph showing coenosteum on a radial corallite d) SEM micrograph showing close up view of radial corallites; proper; e) top view of axial corallite; f) SEM micrograph showing e) SEM micrograph showing broken costae ornamentation on coenosteum between radial corallites. radial corallite; f) top view of axial corallite; g) SEM micrograph showing coenosteum between radial corallites.

54°29′36.4″E; depth 9 m; 30 October 2009; MMTT Cnid. and between branches; at the base of branches first cycle 1377. Khark Island: 29°13′53.5″N, 50°17′53.5″E; depth 3 complete, maximum septal development 1/3R, directive m; 15 December 2009; ZUTC Cnid. 1503. septa prominent, sometimes touching, particularly Description: Branching pattern: Arborescent, towards the bottom of calice; near the branches tip primary sometimes caespitose; colonies mostly small, up to 35 cm cycle mostly incomplete, directive septa present maximum in diameter (Figure 6a), seldom larger colonies, up to 75 1/4R; secondary cycle usually absent (especially in radials cm in diameter; most branches upright, tapering slightly near the branch tip) or very short. towards the tip and terete (Figures 6b and 6c); branch Coenosteum: Broken-costate on radial corallites diameters: 5.5–14.0 mm, 5.3–13.5 mm, and 4.9–11.9 mm; (Figure 6e); reticulate with simple, dense, laterally flattened branch length up to 47.0 mm; growth semideterminate. spinules between radials (Figure 6g). Axial corallites: Conspicuous, outer diameter 2.3–3.1 Color: Dark brown to pale brown on branches, pale or mm; calice diameter 0.7–1.6 mm; at least 1 complete septal white on branch tips (Figure 6a). cycle present; primary septa maximum 3/4R; directive Remarks: In general, most colonies of A. arabensis septa well developed; secondary usually absent, when are arborescent in the study area, while those described present up to 1/4R (Figure 6f). in Wallace (1999) were caespitose to low arborescent. The Radial corallites: Regular and sturdy; appressed tubular branches were also relatively thinner and much shorter to nariform (Figure 6d), gradually changing from branch in our specimens. Conversely, axial corallites of the tip towards its base; calice mostly oblique, sometimes specimens found in these parts of the Persian Gulf were dimidiate; 2 sizes; profile length 1.2–5.4 mm; outer walls larger than those described by Wallace (1999). Differences extended along the branches; a few subimmersed corallites were also observed in the coenosteum: while that of the scattered on branches; dense immersed corallites at the base specimens in the present study is broken-costate on the

313 RAHMANI and RAHIMIAN / Turk J Zool radial corallites and reticulate between the corallites, it is uniformly reticulate in the specimens of Wallace (1999). Acropora mossambica Riegl, 1995; Figures 7a–7h Material examined: Iran, Larak Island: 26°52′45.8″N, 56°20′26.8″E; depth 6 m; 14 October 2008; MMTT Cnid. 1323. Larak Island: 26°53′12.1″N, 56°23′32.1″E; depth 3 m; 8 October 2008; MMTT Cnid. 1118. Description: Branching pattern: Corymbose; branches very thick (Figure 7a); some secondary branches fuse to main branches at branching area, forming flattened branches; branch diameters: 10.9–13.2 mm, 8.8–13.5 mm, and 7.8–11.3 mm; branch length up to 24.2 mm. Axial corallites: Size more than twice that of radials; walls thick; round to slightly oval opening; outer diameter 3.1–4.3 mm; calice diameter 1.3–1.8 mm; 1 or 2 septal cycles, poorly developed; primary septa maximum 1/3R; directive septa prominent, often touching at bottom of calice; secondary septa mostly absent, when present up to 1/5R (Figure 7g). Radial corallites: Tubo-nariform, different sizes (Figures 7d and 7e); some corallites appressed, scattered on branches (Figure 7c); subimmersed and immersed radials more numerous at the base and between branches (Figure 7b); oval opening; outer walls thick, roughly 7 times thicker than the inner walls; profile length 2–3 mm; septa poorly developed; primary septa maximum 1/5R; secondary septa absent or minute. Figure 7. Acropora mossambica: a) portion of colony; b) top view of plate; c) portion of branch; d) SEM micrograph Coenosteum: Costate to broken-costate on radial showing terminal part of branch; e) SEM micrograph showing corallites (in most cases, costate at the tips and broken- close up view of radial corallites; f) SEM micrograph showing costate at the bases of branches), sometimes densely coenosteum on radial corallite; g) top view of axial corallite; h) arranged lines of laterally flattened spinules on radial SEM micrograph showing coenosteum between radial corallites. corallites (Figure 7f); simple spinules between radials (Figure 7h). Color: Pale to dark brown. smaller in our specimens, but very limited details for other Remarks: So far, A. mossambica has only been reported measurements were provided by Riegl (1995). in the literature from high-energy intertidal habitats in (Linnaeus, 1758); Figures 8a–8i SE Africa (Riegl, 1995). Thus, finding this species in the Material examined: Iran, Larak Island: 26°53′15.9″N, Persian Gulf is noteworthy. For confirmation, a specimen 56°21′02.3″E; depth 6 m; 11 October 2008; MMTT Cnid. of this species was sent to the Museum of Tropical 1182. Larak Island: 26°53′15.9″N, 56°21′02.3″E; depth 3 Queensland, where it was identified by C.C. Wallace as m; 11 October 2008; MMTT Cnid. 1185. Acropora cf. mossambica. Characteristics supporting the Description: Branching pattern: Arborescent (Figure identification included the branch shape, size of axial 8a) with long branches (maximum 160 mm), slightly corallites, and shape of radial corallites. Consequently, this tapering (Figures 8b and 8c); branches relatively thick; is the first report of A. mossambica from the Persian Gulf. branch diameters: 10.0–16.6 mm, 9.7–15.4 mm, and 8.8– Misidentification of A. mossambica as similar species, e.g., 14.1 mm; growth determinate. A. selago and A. tenuis, both present in the area (Riegl, Axial corallites: Axial corallites thicker and substantially 1999; Wallace, 1999), was possible. However, the larger size larger than radials; outer diameter 2.5–3.2 mm; calice of axial corallites together with the differences observed in diameter 1.1–1.5 mm; calice usually not perfectly round; the forms of radial corallites supported the identification 2 complete septal cycles present (Figure 8g); primary septa as A. mossambica. up to 3/4R; secondary septa up to 2/3R. Comparison between measurements of the specimen Radial corallites: Two sizes, arranged spirally on found in the present study with those described by Riegl branches; mostly appressed tubular, some nariform, with (1995) suggests that the axial corallites are narrower and round to oval openings (Figures 8d and 8e); subimmersed

314 RAHMANI and RAHIMIAN / Turk J Zool and immersed corallites at base of branches; profile length literature records of A. pharaonis from the Persian Gulf up to 3.6 mm; 2 septal cycles developed (Figure 8g); inner (Coles and Fadlallah, 1991; Sheppard and Sheppard, and outer septa similar in size; primary septa maximum 1991; Mostafavi et al., 2010), there is actually no formal 3/4R; secondary septa up to 2/3R. confirmed record based on voucher skeletal specimens of Coenosteum: Similar both on and between radial A. pharaonis in this area. That, by itself, does not exclude corallites (Figures 8f and 8h), linear arrangement of the possibility of its presence in the area; however, our elaborated spinules on coenosteum, some spinules forked extensive and careful sampling did not reveal any A. (Figures 8h and 8i). pharaonis, either. Color: Pale brown, brick red, or pale yellow. From a morphological point of view, almost all Remarks: A. muricata has not been previously reported the characteristics of our specimens overlapped those in this part of the Persian Gulf. In the beginning, that described by Wallace (1999) except in the morphology of caused some doubts as to whether our specimens really coenosteum, which is costate on and reticulated between belonged to A. muricata, as in some areas of the Persian the radial corallites of the specimens examined by Wallace. Gulf A. pharaonis forms open arborescent colonies similar (Dana, 1846); Figures 9a–9g to those formed by A. muricata. Nevertheless, other Material examined: Iran, Larak Island: 26°53′07.8″N, characteristics, including the absence of branchlets in A. 56°23′59.0″E; depth 3 m; 7 October 2008; MMTT Cnid. muricata and the presence of a stalk in A. pharaonis, help 1018. Larak Island: 26°52′45.8″N, 56°20′26.8″E; depth to distinguish these 2 species. A specimen was sent to 6 m; 14 October 2008; MMTT Cnid. 1322. Larak Island: the Museum of Tropical Queensland, where C.C. Wallace 26°53′15.0″N, 56°20′59.3″E; depth 6 m; 13 October 2008; identified it as Acropora cf. muricata. Although there are ZUTC Cnid. 1260. Description: Branching pattern: Corymbose, but tending to form small tables; branches cylindrical (Figure 9a), tapering abruptly at the tip (Figure 9b), slender in attachment point to the colony; colonies small; irregular branching; branch diameters: 8.9–15.2 mm, 8.0–14.2 mm, and 7.7–10.5 mm; branch length up to 54.9 mm; growth determinate. Axial corallites: Cylindrical, larger than radial corallites; outer diameter 2.8–3.5 mm; calice diameter 1.1–1.3 mm; 2 complete septal cycles; primary septa maximum up to 2/3R; secondary septa 1/3R; directive septa slightly longer than the others (Figure 9f). Radial corallites: Nariform to tubo-nariform (Figure 9c); round to oblique opening (Figure 9e), 2 sizes; profile length 2.2–3.0 mm; immersed corallite number increasing towards the base and between branches (Figure 9a); 1 complete septal cycle always present; primary septa up to 1/2R; lines of laterally flattened spinules usually present; secondary septa absent, or sometimes forming lines of small spinules. Coenosteum: Broken costae or laterally flattened spinules in rows on radials, with spinules mostly joined by short lamellae (Figure 9d); between radials reticulate with simple spinules (Figure 9g). Color: Pale brown to brown. Remarks: By comparing the measurements of specimens found in the present study with those described Figure 8. Acropora muricata: a) live colony; b) portion of colony; in Wallace (1999), it was evident that the branches are c) portion of a branch; d) SEM micrograph showing branch tip; both thicker and shorter, and axial corallites are larger in e) SEM micrograph showing close up view of radial corallites; f) specimens of present study. SEM micrograph showing coenosteum on radial corallite; g) top Acropora tortuosa (Dana, 1846); Figures 10a–10h view of axial corallite; h) SEM micrograph showing coenosteum Material examined: Iran, Farur Island: 26°17′44.1″N, between radial corallites; i) SEM micrograph showing close up 54°32′22.4″E; depth 6 m, 28 October 2009; MMTT Cnid. view of coenosteum between radial corallites. 1387.

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Coenosteum: Covered with elaborate, laterally flattened spinules, both on and between radial corallites (Figures 10e, 10f, and 10h). Color: Pale yellow or dark cream to pale brown. Remarks: So far, Acropora tortuosa has only been recorded in the western and central Pacific Ocean (Wallace, 1999). Its presence in the Persian Gulf is therefore remarkable. For confirmation, a specimen of this species was shipped to the Museum of Tropical Queensland, where it was identified as Acropora cf. tortuosa by C.C. Wallace. Later on, with more detailed studies on the morphology and other characteristics of the colony, it became clear that the specimen was indeed Acropora tortuosa. Consequently, this is the first record of A. tortuosa from the Persian Gulf. Morphologically, the specimens of A. tortuosa from the Persian Gulf were very similar to those described by Wallace (1999), except that the branches were a little longer and the walls of axial corallites were thinner in the Persian Gulf specimens.

Figure 9. Acropora nasuta: a) portion of colony; b) portion of branch; c) SEM micrograph showing terminal part of branch; d) SEM micrograph showing coenosteum on a radial corallite; e) front view of few radial corallites; f) top view of an axial corallite; g) SEM micrograph showing coenosteum between radial corallites.

Description: Branching pattern: Arborescent (Figure 10a); branches thin and long (maximum 110 mm), slightly tapering (Figures 10b and 10c); branch diameters: 8.0–12.2 mm, 7.5–11.2 mm, and 5.0–6.6 mm; growth indeterminate. Axial corallites: Small but slightly larger than large radial corallites; outer diameter 2.0–2.8 mm; calice diameter 1.0–1.4 mm; wall thickness about half the calice diameter; oval opening; 1 complete septal cycle present up to 3/4R; directive septa larger than the others, sometimes touching at bottom of calice; secondary septa usually absent, but if present, only developed to maximum 1/4R (Figure 10g). Radial corallites: Arranged in rows on branches, 2 sizes, Figure 10. Acropora tortuosa: a) fresh colony out of water; b) tubular, round opening; calice large compared to radial portion of branch; c) portion of colony; d) SEM micrograph size (Figures 10b and 10d); profile length 2.05–2.83 mm; showing terminal part of branch; e) SEM micrograph showing appressed and subimmersed corallites scattered on the coenosteum on a radial corallite; f) SEM micrograph showing bases of main branches; septa poorly developed, primary close up view of coenosteum on radial corallite; g) top view of septa up to 1/4R, some septa dentate, sometimes only axial corallite; h) SEM micrograph showing coenosteum between directive septa present; secondary septa absent. radial corallites.

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4. Discussion Acropora species and their 15–20 years of succession cycles Because of the high morphological plasticity of staghorn in the Persian Gulf, and also keeping the young nature of corals (Todd, 2008), differences in the estimates of species the Persian Gulf in mind (Wallace and Muir, 2005) (water diversity in these corals might be expected in any given began entering the Gulf only 12,500 years ago (Lambeck, area. Such differences, however, should be within a 1996)), evaluations of ecological factors in addition to reasonable range. A number of studies carried out on evolutionary and historical factors are necessary in order the corals of the southern part of the Persian Gulf (Riegl, to study the reasons behind the relatively high diversity 1999; Wallace, 1999; Coles, 2003) showed that between and abundance of Acropora in the Persian Gulf. 11 and 13 Acropora species inhabit the area. That number However, in this part of the Persian Gulf, A. downingi for the northern and northeastern parts was only 5, which and A. arabensis are abundant, and A. valida is observed included Acropora clathrata (Maghsoudlou, 2008, 2011), to a lesser extent than the former 2 species (Maghsoudlou, before this study. In the present study, 9 staghorn corals 2008; Rahmani, 2012). were found, excluding Acropora clathrata and A. pharaonis, Except these 3 species, the rest can be defined as rare which have frequently been reported (Maghsoudlou, 2008, species, accounting for only about 5% of the Acropora 2011; Mostafavi et al., 2010) from Iranian coasts of the coverage (Rahmani, 2012). None of these corals, however, Persian Gulf. If the records of A. pharaonis were deemed are listed as vulnerable (Askari, 2012), and no or very few valid, the number of Acropora species of the northern and special protection measures have been applied to conserve northeastern parts of the Persian Gulf would reach at least these species. 10. It should also be mentioned that from our specimens, The necessity of conservation actions on behalf of the C.C. Wallace identified A. horrida, A. mossambica, A. coral reefs in this area is obvious considering the severe muricata, and A. tortuosa as ‘confer’ (cf.). The provisional conditions the Persian Gulf ecology must bear, especially identifications were caused by the small sizes of those its temperature, salinity (Coles, 1988; Coles and Fadlallah, specimens. More and closer examination of specimens 1991; Coles 1992; Riegl, 1999; Coles, 2003), and red from the same dives and of additional specimens collected tides, as well as anthropological activities including wars, later on allowed us to confirm the identification. offshore oil drilling, tanker traffic, ballast water discharge, Nevertheless, taking into account the reports of other the construction of several artificial islands, development species from the southern part of the Persian Gulf, namely of coastal areas, and destruction of coral reefs by divers. A. valenciennesi (Milne-Edwards and Haime, 1860 ) The need to conserve the corals of the Persian Gulf is even (Sheppard and Sheppard, 1991; Wallace, 1999), A. yongei more urgent considering the continuous trend of global Veron and Wallace, 1984, A. selago (Studer, 1878), A. warming and the fact that the Persian Gulf is a breeding divaricata (Dana, 1846) (Wallace, 1999), A. tenuis (Dana, ground for warmth-tolerant species of the future. 1846), and A. (Dana, 1846) (Riegl, 1999), the total As mentioned earlier, A. clathrata was not observed number of species of Acropora for the Persian Gulf would during the present work. This species has been reported as be at least 16. a common and dominant species by Maghsoudlou (2008, Acropora is not only the richest but also the most 2011). Such an abundant, common, and dominant species abundant coral genus in the Persian Gulf, so much so that could hardly be missed in an intensive sampling program. in some places along Larak Island the coverage by this Consequently, it seems that either A. clathrata does not genus is 100% (Rahmani, 2012). records suggest exist in these parts of the Persian Gulf, or it occurs at a very that Acropora has been the dominant coral on this island low density (see remarks on A. downingi). However, the at least since the Pleistocene (Samimi-Namin and Riegl, authors believe that the reports of A. clathrata in this area 2012). Regardless of the number of Acropora ancestral were, in fact, the result of a misidentification/confusion species in the Europe-Western Indian Ocean region during between the 2 forms of A. downingi. Further studies are the Miocene (which were responsible for the diversity and necessary to definitely confirm the presence or absence of dominance of the modern Acropora of the Indo-Pacific A. clathrata in the Persian Gulf. during the Plio-Pleistocene), Acropora species of the Indo- Coles (2003) suggested that the coral species of the Pacific are derived from their ancestral line(s) coming from Persian Gulf are a small sample of a larger fauna of the the Europe-Western Indian Ocean region that diversified Indo-Pacific area and maintained that the Acroporidae and dispersed during the Late Oligocene to the Miocene account for 16% of the total coral species of the Persian (Wallace and Rosen, 2006). Evidence for Acropora Gulf. This study changed that proportion in the Persian dominance in the Western Indian Ocean can be found Gulf to 25%. This value is much closer to the proportion in the Larak outcrops, too (Samimi-Namin and Riegl, of Acroporidae species to all corals species of the Indo- 2012). Considering the repetitious (Riegl, 1999, 2002) Pacific (30%). The 5% difference could be the result of the and periodical (Shinn, 1976) mass mortalities among the environmental stresses in the Persian Gulf.

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A review on the Acropora species of the area shows that D2) caespitose-corymbose; axial corallites smaller the Persian Gulf shares coral species with both the eastern than former (outer diameter 1.8–3.0 mm); axial and western parts of the Indian Ocean. Biogeographical corallites’ primary septa 1/2R, secondary septa analyses of the corals of the Persian Gulf, however, point up to 1/4R ...... A. divaricata to the similarities with those elements of the fauna E: Colony, axial, and radial corallites’ characters

(Sheppard and Sheppard, 1991). Nevertheless, when only E1) axial corallites’ outer diameter 2.8–3.5 mm; axial Acropora species are considered, the results are different, primary and secondary septa 2/3R and 1/3R, clustering the Persian Gulf with Hawaii and the East Pacific respectively; radial corallites mostly nariform (Wallace, 1999). Repeating the biogeographical analyses …...... A. nasuta with the new data and new records has not changed the E2) branches growing horizontally, forming plate; outcome (Rahmani, 2012). axial corallites larger than former (outer diameter This study indicates that in the area investigated, the 3.1–4.3 mm); axial primary and secondary septa number of Acropora species is higher than the previously 1/3R and 1/5R, respectively; radial corallites reported number. We believe that the real Acropora species mostly tubo-nariform ……..…... A. mossambica diversity may still be higher and that this assumption F: Colony, axial, and radial corallites’ characters could be extended to the other coral genera. A number of F1) corymbose to caespitose; growth determinate; the Iranian islands surveyed in the present study where axial corallites’ primary septa 2/3R; axial the Acropora diversity is relatively high, such as Larak, are secondary septa up to 1/3R; tertiary septa rarely located at the beginning of a migratory corridor formed present; radial corallites’ profile length 2.0–3.3 by the currents entering the Persian Gulf from the Indian mm; radial primary and secondary septa 2/3 and Ocean via the Gulf of Oman. Consequently, all of the coral 1/3R, respectively …...... A. valida species found in the Persian Gulf once entered through F2) caespitose; growth semideterminate; axial this corridor. Therefore, we surmise that at least some of corallites’ primary and secondary septa 3/4 and the species observed in the southern Persian Gulf and 1/4R, respectively; radial outer walls extended not yet found in the northern and northeastern parts of along the branches ...... A. arabensis it, e.g., A. valenciennesi, A. divaricata, A. selago, A. yongei G: Branches’ and axial and radial corallites’ characters

(Wallace, 1999), A. tenuis, and A. florida (Riegl, 1999), are G1) branch length up to 90 mm; axial corallites’ outer either too uncommon to be easily found or have become diameter 1.8–3.4 mm; radial primary septa 2/3R locally extinct due to one of the recent devastating events ...... ………...... ……………….……… A. tenuis

(such as red tide). More studies are necessary to obtain a G2) branches shorter than former (up to 40 mm); more accurate estimate of the diversity of the corals of the axial corallites’ outer diameter smaller than

Persian Gulf in general, and that of Acropora in particular. H1 above (up to 1.1–2.4 mm); radial corallites crowded, radial primary septa 1/3R ...... A. selago Taxonomic key to the Acropora of the Persian Gulf H: Radial corallites’ shape

A: Colony and growth form H1) tubular or appressed tubular ………….....……. I

A1) table and growth determinate ………...... … B H2) cochleariform ...……...... …...... ….. A. yongei

A2) corymbose to caespitose and growth determinate H3) labellate …...... …...... ….….. A. aspera or semi-determinate …...... C I: Branches’ appearance and radial corallites’ characters

A3) other growth forms …...... …….....….….. H I1) extremely fragile; branches with ragged B: Colony and radial corallites characters appearance ………...... ….. A. horrida

B1) colony flat; sometimes with upward branches; I2) branches and radial corallites unlike the former radial corallites tubular with sharp-pointed …...….…...... ……… J outer walls extending along the branches ...... J: Axial and radial corallites’ characters

...... A. downingi J1) axial corallite outer diameter 2.0–2.8 mm; axial

B2) sturdy and intertwining branches form stalk; secondary septa absent or 1/4R; round opening; branchlets present …...... A. pharaonis radial primary septa up to 1/4R, secondary septa C: Radial corallites’ shape absent ……………………………… A. tortuosa

C1) nariform or tubo-nariform …………...…..….. D J2) axial corallites larger than those of A. tortuosa

C2) appressed ………………………..…….....…… F (outer diameter 2.5–3.2 mm); axial secondary

C3) cochleariform …...... ….………...... …….. G septa up to 2/3R; oval opening; radial corallites’ D: Colony and axial corallites characters septa well developed, primary and secondary

D1) corymbose; axial corallites large (outer diameter septa up to 3/4 and 2/3R, respectively ...... 2.8–4.3 mm) …...... ….. E ...... A. muricata

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Acknowledgments microscopy and Mr Mohajeran, National Museum of This study was made possible thanks to the extensive help of Natural History, carried out the microphotography. We wish Dr C.C. Wallace, Museum of Tropical Queensland, Australia. to thank them. We also wish to thank Dr Fazel, Dr Shirdam, Without her help the identifications could not have been Dr Montazami, Captain Mansour, Captain Sorori, Captain confirmed. We express our gratitude to the administration Hoseini, Mr Namdar, Mr Shokri, Mr Moien, Mr Tollab, Mr of the Hormozgan and Bushehr Environmental Protection Hadi, and Mr Shirzad for their help and support during Agency and the Iranian Offshore Oil Company for their sampling. This study was partially financed by the Office valuable logistic support during sampling. Mr Hashemi, of Research Affairs, University of Tehran; their support is University of Tehran, carried out the scanning electron hereby acknowledged.

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