Acropora abrotanoides (Lamarck, 1816)

Santodomingo, Nadiezhda, Wallace, Carden C. & Johnson, Kenneth G., 2015, Fossils reveal a high diversity of the staghorn coral genera Acropora and Isopora (Scleractinia: Acroporidae) in the Neogene of Indonesia, Zoological Journal of the Linnean Society 175 (4), pp. 677-763 : 707

ACROPORA ABROTANOIDES ( LAMARCK, 1816)

FIGURE 13

Madrepora abrotanoides Lamarck, 1816: 280

Madrepora danai Milne Edwards, 1860: 149 , 560 = Madrepora deformis Dana, 1846 (non Michelin): 484, pl. 43 fig. 1

Madrepora crassa Milne Edwards, 1860: 135

Madrepora irregularis Brook, 1892: 458 ; 1893: 50, pl. 14 figs E, F

Madrepora rotumana Gardiner, 1898: 258 , pl. 23 fig. 2

Acropora mangarevensis Vaughan, 1906: 68 , pl. 6 fig. 2, pl. 8 fig. 1

Acropora tutuilensis Hoffmeister, 1925: 71 , pl. 19 figs 1a–c

Diagnosis

Radial corallites dimorphic, long tubular with dimidiate calices and subimmersed, coenosteum reticulate, simple spinules ( Wallace & Wolstenholme, 1998; Wallace, 1999).

Material studied

Java: RGM 893236 , Kalang Anjar, 1 specimen .

Modern comparative material: Lectotype of Madrepora irregularis junior synonym of A. abrotanoides ( Wallace, 1999) , NHMUK 1876.5.5.89, Rodriguez, South China Sea; MTQ G39781, Mauritius, Mascarene Islands; MTQ G46694 Nusa Lembongan , Nusa Tenggara , Indonesia.

Skeletal characteristics

Corallum . One branch tip, sturdy, tapering, length 26.83 mm, middle branch diameter 13.63 mm, branch tip diameter 7.19 mm.

Corallites. Axial corallite exsert 1.28 mm, outer diameter 2.93 mm, inner diameter 1.33 mm, septa not well developed; radial corallites dimorphic, tubular with dimidiate calices, profile length 2.58–3.08– 3.31 mm, exsert in wide angles of 45.45–53.08–60.07°, outer diameter 1.19–1.65– 2.07 mm, inner diameter 0.55–0.72– 0.87 mm, thickened lower wall 0.42–0.57– 0.71 mm, interspersed with subimmersed corallites, mostly not touching, closely arranged, distance between centres 2.17–3.24– 4.74 mm, primary septa present but worn out, secondary septa visible as points. Corallite arrangement sequence 1–2–[4–6]–[10–12]–?.

Coenosteum. Smooth costate on radial corallite walls, reticulate with simple spinules between radial corallites. Coenosteum amount 0.25–1.58– 5.89 mm.

Occurrence

Miocene to Recent. Previous fossil records include Holocene (8.2–9.6 ka) specimens from Mauritius ( Camoin et al., 1997). The studied specimen represents the earliest occurrence of the species. It was collected from the locality Kalang Anjar, Java, with a general Miocene age, 5.333–23.03 Ma. With the current available samples no precise date can be inferred for this locality ( Johnson et al., 2015b). In modern reefs, A. abrotanoides is primarily a reef-edge species that is common and widely distributed across the Indo-Pacific, including the southern part of the Red Sea ( Wallace, 1999; Wallace et al., 2012). In Indonesia, the species has been found in Sumatra, Sulawesi, Nusa Tenggara and the Banda Sea ( Table 4).

Palaeoenvironment

Other corals recovered from Kalang Anjar locality include specimens of Alveopora , Dipsastraea , Galaxea and Goniopora .

Remarks

Even though the single available specimen is a small branch tip, it has the typical dimorphic corallites characteristic of the robusta group. Specifically, it has the long-tubular corallites of irregular lengths that contrast with subimmersed radials as observed in the modern specimen of the South China Sea, NHMUK 1876.5.5.89. This species has morphological characteristics close to A. robusta , except that A. abrotanoides has fewer conical branch tips and different colour of colonies alive ( Wallace, 1999). Only skeletal traits can be assessed in our fossil material and they compare better with the branch tips of A. abrotanoides MTQ G 46694 from Nusa Tengara illustrated in Wallace & Wolstenholme (1998: 227, fig. 22C–F) and the specimen MTQ G39781 from Mauritius ( Wallace, 1999).

Figures

Figure 13. Acropora abrotanoides. RGM 893236893236, Kalang Anjar, Java, Miocene (5.3–23 Ma). Whole specimen is a branch tip showing the typical dimorphic radial corallites.