Coral barnacles: Cenozoic decline and extinction in the Atlantic/East Pacific versus diversification in the Indo-West Pacific


ABSTRACT The pyrgomatid coral barnacles, first appearing in the late Oligocene of the western Atlantic, underwent a Miocene diversification unparalleled by any other group of sessile barnacles. Diversification in the Indo- Pacific (eastern Tethys) coincided with retreat of the tropics from higher latitudes, especially in the Atlantic. Fragmentation of the tropics, due to the breakup of the Tethys seaway, and wholesale extinctions of their host corals beginning in the Oligocene of Europe, Mediterranean and eastern Pacific resulted in relictual distributions and regional endemism. This was followed by Neogene extinctions of many host coral genera in the western Atlantic which were not replaced by originations. The exceptional diversity of pyrgomatids now evident in the Indo-Pacific was tied to the survival and radiation of the corals found there. Curiously, our knowledge of pyrgomatid numbers and diversity has shifted from the Indonesian to peripheral centers of distribution.

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    ABSTRACT: A new species of coral inhabiting barnacle Cantellius cardenae spec. nov. (Crustacea, Cirripedia: Pyrgomatinae) is described. This barnacle was found on the staghorn coral Acropora (Isopora) brueggemanni (Scleractinia: Acroporidae). It is characterized by having transversally elongated scuta and narrow terga with a spur length more than half of the total tergal length. This species belongs to the secundus group of Cantellius, which includes barnacles with transversally elongated scuta, and which are limited to the Acroporidae. The distribution of C. cardenae supports the hypothesis that structurally specialized pyrgomatines occupy a more limited variety of hosts than do morphologicaly generalized ones.
    Zoologische Mededelingen, Leiden. 01/2003; 77.
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    ABSTRACT: This study describes the distribution and abundance patterns of the associate fauna on the living surface of the corals Siderastrea stellata Verril, 1868 and Mussismilia hispida (Verril 1902) using a non-destructive method, on the northern coast of Rio de Janeiro State. For each coral species, infestation density and proportions of infested colonies, colonies attached and unattached to the substrate were estimated. A total of 474 colonies of S. stellata and 452 colonies of M. hispida were examined. The barnacle Ceratoconcha floridana (Pilsbry, 1931) was the dominant coral associate found, followed by gall-crabs of the family Cryptochiridae Paulson, 1875 and the bivalve Lithophaga bisulcata (d’Orbigny, 1842). Both coral species presented similar patterns of infestation dominance. S. stellata colonies were more commonly infested and showed a greater mean infestation density of 0.62ind/cm2 at Armação dos Búzios, whereas M. hispida colonies had infestation densities of only 0.20ind/cm2. Infestation density does not appear to impact negatively on corals of Armação dos Búzios. A clear negative relationship between the number of associates in the coral colony and coral size was found. Evidently abundance and frequency of occurrence of associated fauna is highly related to coral community structure and composition and the results highlight the importance of local scale studies.
    Hydrobiologia 01/2006; 563(1):143-154. · 1.99 Impact Factor
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    ABSTRACT: The ranges of many tropical marine species overlap in a centre of maximum marine biodiversity, which is located in the Indo-Malayan region. Because this centre includes Malaysia, the Philippines, Indonesia, and Papua New Guinea, it has been named the East Indies Triangle. Due to its dependence on the presence of coral reefs, it has recently been referred to as the Coral Triangle. Because these reefs are severely threatened by human activities, large-scale nature conservation efforts involve the establishment of a network of Marine Protected Areas (MPAs), for which it is important to know the position of this diversity hotspot. Although it is recognized where this centre is located approximately, it is unclear where its exact boundaries are. Only in a limited number of biogeographical studies, ranges and diversity centres of Indo-West Pacific (IWP) taxa have been presented. In this regard, tropical corals, marine fishes, and molluscs have received most attention. However, just for reef corals alone several different diversity centres have been proposed. The boundaries of the centre are important for reconstructing the processes that were responsible for its present shape. They may relate to the area’s climatic and geological past or to the dispersal of larvae by currents in combination with ecological constraints that may prevent their settlement. Especially, in brooding organisms, without larvae or other propagules performing long-distance dispersal, isolation mechanisms may have been important for speciation and species diversity. Information on sea-level fluctuation and the past position of coastlines and data on molecular variation between and within species may help to support models that explain the present position of the centre of marine biodiversity. A detailed biogeographical study of the Fungiidae, a family of corals that disperse through larvae, is used to present a model for a diversity centre and the processes that may have caused its present position. For each species, presence-absence data were obtained from many areas in order to plot their distribution patterns. Since several species do not occur on Sunda shelf reefs, the western part of this diversity centre may have been moulded along the Sunda shelf margin since the end of the LGM (17.000–18.000 BP). Species diversity appears to be distributed unevenly among areas within this centre, which depends on habitat heterogeneity, such as cross-shelf gradients in salinity and turbidity. Eventually, the distributions of several model taxa need to be compared in a sufficiently high number of areas in order to find a more common delineation of the Coral Triangle. Many corals are widespread and have a long fossil record. Moreover, coral reefs have not always been located in their present positions. This makes it complex to find which processes have caused a present diversity maximum. Since most species are concentrated in the eastern part of the Indo-Malayan archipelago and part of the West Pacific, this may be the area where most of the youngest species have originated, but sea-level fluctuations probably have been responsible for excluding large continental shelf seas from the Coral Triangle.
    09/2007: pages 117-178;

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