Obura-Journal_of_Biogeography

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D. O. Obura (a) (b) (c) Figure 1 Tectonic configurations during (a) the Eocene (45 Ma) and (b) the Oligocene (30 Ma) where shallow marine diversity was highest in the West Tethys Sea (WT) and East Africa-Arabian Province (EAAP), respectively, and (c) in the Miocene (15 Ma), when diversity was highest in the Indo-Australian Archipelago (IAA). The Mascarene Banks (MB) are shown in grey as it is uncertain to what extent they were submerged or emergent islands. Figure adapted from Lawver et al. (2010). Table 2 Extant western and northern Indian Ocean (W&NIO) coral genera and species showing evidence of Palaeogene and Neogene origins. Taxa Palaeogene (Eocene/Oligocene) processes Neogene (Miocene-Pliocene) processes Sources Acropora A. rudis, A. roseni A. hemprichii, A. forskali and A. variolosa – Eocene fossils in Somalia and Europe; basal clade species endemic or most common in W&NIO Coscinaraeidae Newly described family uniting poorly known mono-specific genera restricted to the W&NIO: Anomastrea irregularis, Horastrea indica, Craterastrea levis. Regional endemics, long unbranched clades, characteristics of relict species Euphylliidae Gyrosmilia interrupta and Ctenella chagius – regional endemics, long unbranched clades, characteristics of relict species. Stylophora Genetic divergence dated to Eocene, ancestral species found in Red Sea. Siderastrea Sclerophyllia Regional and sub-regional endemic spp. – A. maryae, branchi One W&NIO regional endemic Coscinaraea sp.,one species - C. monile – that is more characteristic of the WIO than the West Pacific Regional and sub-regional endemic spp. – 3 species in W&NIO, 2 endemic species in the Red Sea; Greater genetic diversity W&NIO species a sister clade to Atlantic species, derived from Pacific species (S. savignyana) (divergence date not established) Revived genus with just two species, restricted to the Red Sea, Arabian Sea and Gulfs. The age of the genus currently unknown. Carbone et al. (1994), Wallace (1999) and Wallace & Rosen (2006) Veron (2000), Claereboudt (2006), Benzoni et al. (2012) and Obura (2012a) Obura, (2012a) Flot et al. (2011); Stefani et al. (2011) and Keshavmurthy et al. (2013) Chuang (2006), Obura et al. (2007) and Y. Chuang, unpublished data Arrigoni et al., (2014) the IAA and surrounding regions, and the massive radiation of species that occurs today. The oldest clades of extant Acropora species are characteristic of the W&NIO, in particular A. rudis, A. roseni and a group including A. hemprichii, A. forskali and A. variolosa (Fig. 2a–c). Contrary to the radiation of lineages in the IAA in the late Oligocene and early Miocene, these taxa show little radiation of species, and limited dispersal eastwards to the IAA (Wallace & Muir, 2005). The Coscinaraeidae (Benzoni et al., 2012) is a newly described family uniting two monospecific genera previously classified in the Siderastreidae (Anomastrea, Horastrea), with one sometimes classified in the Agariciidae (Craterastrea), and Coscinaraea (Fig. 2d–f). Coscinaraea is widely distributed 4 across the Indian Ocean and West Pacific, though one undescribed species (Fig. 2g) appears restricted to the Gulf of Aden and WIO (Obura, 2012a). This species, a congener predominantly distributed in the WIO (C. monile, Veron, 2000), and the monospecific genera, tend to be uncommon and found in turbid, extreme or marginal reef habitats (e.g. Benzoni et al., 2012; Obura, 2012a; Smit, 2014). The family demonstrates the deep evolutionary history and low degree of radiation in W&NIO coral lineages comprising the ‘Indian Ocean fauna’ (Rosen, 1971; Pichon, 1978). Three other monospecific genera restricted to the Indian Ocean have variously been classified in the Caryophillidae and Meandrinidae, but are now reassigned to the Euphylliidae Journal of Biogeography ª 2015 John Wiley & Sons Ltd
Indian Ocean centre of origin (a) (b) (c) (d) (e) (f) (g) (h) (i) (j) (k) (l) Figure 2 Selection of endemic coral species of the western and northern Indian Ocean for which a Palaeogene/Tethyan origin is proposed; (a) Acropora roseni, Chagos Archipelago; (b) A. hemprichii, St. Brandons Island, Cargados Carajos Shoals, Mauritius; (c) A. variolosa, Djibouti; (d) Anomastrea irregularis, NE Madagascar; (e) Horastrea indica, Nacala, N. Mozambique; (f) Craterastrea levis, NE Madagascar; (g) Coscinaraea sp., Inhambane, S. Mozambique; this species is identified as an undescribed Psammocora species in Claereboudt (2006); (h) Siderastrea savignyana, Kiunga, N. Kenya; (i) Stylophora pistillata (morph M in Stefani et al., 2011, clade 4 in Keshavmurthy et al., 2013), Farquhar Atoll, Seychelles; (j) Ctenella chagius, St. Brandons Island, Cargados Carajos Shoals, Mauritius; (k) Gyrosmilia interrupta, Nacala, N. Mozambique; (l) Stylophora madagascarensis (in Stefani et al., 2012, Stylophora pistillata clade 3 in Keshavmurthy et al., 2013), NE Madagascar. All photos: David Obura. (Budd et al., 2012) – Gyrosmilia and Ctenella in the W&NIO (Fig. 2j,k), and Montigyra in the Eastern Indian Ocean. Like the monospecific genera in the Coscinaraeidae, two of these are highly restricted within the W&NIO. Ctenella is recorded only from the Chagos Archipelago and St. Brandons Island by Obura (2012a), with additional locations from Madagascar Journal of Biogeography ª 2015 John Wiley & Sons Ltd and Mauritius reported by Veron et al. (2015; and see Moothien Pillay et al., 2002). Additionally, the species are found in marginal habitats; turbid reefs for Gyrosmilia, and the seagrass-dominated Mascarene Banks for Ctenella. A recent revision adding to the ‘Indian Ocean fauna’ is the revived genus Sclerophyllia, with just two species, and 5
Page 1 and 2: Journal of Biogeography (J. Biogeog
Page 3: Indian Ocean centre of origin Table
Page 7 and 8: Indian Ocean centre of origin Creta
Page 9 and 10: Indian Ocean centre of origin diver
Page 11 and 12: Indian Ocean centre of origin Mozam
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