Fossils reveal a high diversity of the staghorn coral genera Acropora and Isopora (Scleractinia: Acroporidae) in the Neogene of Indonesia Author Santodomingo, Nadiezhda Author Wallace, Carden C. Author Johnson, Kenneth G. text Zoological Journal of the Linnean Society 2015 2015-11-18 175 4 677 763 http://dx.doi.org/10.1111/zoj.12295 journal article 10.1111/zoj.12295 0024-4082 5339562 ACROPORA PAPILLARE ( LATYPOV, 1992 ) FIGURE 19 Acropora papillare Latypov, 1992: 121 , fig. 6 Acropora indiana Wallace, 1994: 963 , fig. 4 Diagnosis Colonies with semi-determinate growth, sub-arborescent shape, branches cylindrical to conical. Axial corallite dominates branch diameter. Radial corallites short tubular to labellate. Coenosteum of elaborated spinules, reticulo-costate on and in between corallites ( Wallace & Wolstenholme, 1998 ; Wallace, 1999 ). Material studied East Kalimantan : NHMUK PI AZ 6977 , TF275 , 310 specimen fragments from the same colony. Modern comparative material : Holotype of A. indiana MTQ G 46445, Rowley Shoals , Western Australia ; MTQ G48563 Kupang , West Timor , Indonesia . Figure 19. Acropora papillare . NHMUK PI AZ 6977, TF275, Kari Orang, Bengalon, East Kalimantan, Early Miocene (18–20 Ma). A, aspect of a colony in situ as seen from below, showing corymbose to caepito-corymbose growth form. B, detail of a transverse section of a branch in the field, branch diameter approx. 15 mm. C, AZ 6977a–c, three cylindrical branches showing wide-open branching pattern and incipient branches. D, AZ 6977d, electron micrograph of a branch tip. E, AZ 6977d, top view of axial corallite. F, AZ 6977e, transverse section of branch showing eight radial corallites arranged around the axial. G and H, AZ 6977b: G, electron micrograph of radial corallites near the tip – short tubular and subimmersed radials; H, detail of tubular radial corallite with thickened lower wall. I, AZ 6977d, electron micrograph of reticulate coenosteum formed of a mix of simple and laterally flattened elaborated spinules. Skeletal characteristics Corallum . Probably sub-arborescent, branches tapering, length of specimen fragments 29.79–37.36– 46.14 mm , round in cross section, basal branch diameter 21.54–24.09– 26.48 mm , middle branch diameter 11.19–12.74– 14.96 mm , branch tip diameter 5.60–6.55– 7.45 mm . Branching in open wide angles 53.73–84.65– 119.14°, distance between branches at least 17–21.63– 31.53 mm . Corallites. Axial corallite, round calice, profile length to first radial 1.30–1.53– 1.80 mm , outer diameter 2.40– 2.90– 3.20 mm , inner diameter 1.40–1.58– 1.70 mm , wall thickness 0.40–0.49– 0.60 mm , primary septa threequarters R, secondary septa one-quarter R; radial corallites gradually sized, mainly labellate, some short tubular interspersed with subimmersed corallites, round calices, lower wall thickened, profile length 1.60–1.92– 2.20 mm , angle 32.79–41.36–48.48°, outer diameter 1.06– 1.13– 1.20 mm , inner diameter 0.62–0.73– 0.77 mm , wall thickness 0.20–0.24– 0.31 mm , not touching, closely arranged, distance between centres 1.85–2.30– 2.78 mm , primary septa developed three-quarters R, axial margins sinuous, sometimes reaching the centre of the radial corallite, secondary septa up to one-quarter R. Corallite arrangement sequence 1–8–12–[12- up to 14]. Coenosteum. Smooth costate on corallite walls, reticulate with simple spinules between radial corallites; coenosteum amount between adjacent corallites 0.97– 1.16– 1.51 mm . Occurrence Early Miocene to Recent. This record is the earliest occurrence of the species with specimens found in the locality TF275 , Kari Orang, East Kalimantan , of Early Burdigalian age, 18–20 Ma. In the Recent, A. papillare occurs mainly in intertidal reef flats and it is distributed in the Indo-Pacific from Cocos-Keeling Islands to the Great Barrier Reef ( Wallace et al ., 2012 ). Records from Indonesia include some localities in Sulawesi ( Table 4 ) . Palaeoenvironment The sediments exposed at locality TF275 were fine sand. Acropora papillare was found together with phacelloid colonies of Galaxea sp. , massive colonies of Dipsastraea sp. , and a few branching Porites specimens. This environment has been interpreted as a subtidal shallowwater environment with calm waters. The thin orange– yellow horizon containing reef corals overlies a bed> 5 m thick of grey silty clays with mollusc and azooxanthellate corals typical of the upper bathyal zone, ∼ 200 m depth. The erosive base of the reefal horizon on the upper bathyal bed suggests that the former bed containing corals is a turbidite carried down to bathyal depths (J. Todd, pers. comm., 2014). Remarks Specimens recovered from TF275 were collected together forming what could be interpreted as a single sub-arborescent colony with widely separated branches. The skeleton is porous and growth lamination was observed at the base of some branches ( Fig. 19C ). Morphological features and measurements for characters of branches and corallites resemble the modern specimen MTQ G48563 from Flores (Indonesia) . However, radial corallites of the fossil specimen are never touching but widely apart. The coenosteal structure composed of simple spinules ( Fig. 19I ) is typical of the aspera species group, and is a key character allowing identification of the fossil specimen as A. papillare . Most radials on branches have degraded walls giving the appearance of subimmersed corallites, yet original aragonite may be still present.