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.
Full-textDOI: · Available from: William Anderson Newman, May 29, 2015
SourceAvailable from: Maria Celia (Machel) Malay[Show abstract] [Hide abstract]
ABSTRACT: Pyrgomatid barnacles are a family of balanomorphs uniquely adapted to symbiosis on corals. The evolution of the coral-dwelling barnacles is explored using a multi-gene phylogeny (COI, 16S, 12S, 18S, and H3) and phenotypic trait-mapping. We found that the hydrocoral associate Wanella should be excluded, while some archaeobalanids in the genus Armatobalanus should be included in the Pyrgomatidae. Three well supported clades were recovered: clade I is the largest group and is exclusively Indo-West Pacific, clade II contains two plesiomorphic Indo-West Pacific genera, while clade III is comprised of East and West Atlantic taxa. Some genera did not form reciprocally monophyletic groups, while the genus Trevathana was found to be paraphyletic and to include members of three other apomorphic genera/tribes. The highly unusual coral-parasitic hoekiines appear to be of recent origin and rapidly evolving from Trevathana sensu lato. Pyrgomatids include six-, four-, and one-plated forms, and exhibit convergent evolutionary tendencies towards skeletal reduction and fusion, loss of cirral armature, and increased host specificity. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, ●●, ●●–●●.Biological Journal of the Linnean Society 08/2014; 113(1). DOI:10.1111/bij.12315 · 2.54 Impact Factor
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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.
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ABSTRACT: We study a vermetid-coralline algal buildup from the lower Pliocene deposits of the Baix Ebre Basin (Sant Onofre, NE Spain). The bioconstruction framework is made up by the intergrowth of Dendropoma and encrusting coralline algae, mostly Spongites fruticulosus with rare Neogoniolithon brassica-florida. Thus, it can be considered a fossil analogue of the present-day Mediterranean Dendropoma reefs. The bioconstruction developed on top of a flat palaeotopographic high formed by pre-Pliocene substrate in a sheltered embayment. Submarine cliff sediments, consisting of big blocks and boulders, were deposited along the margin of the palaeohigh. Crusts of coralline algae, intergrowing with serpulids and vermetids, extend from the flat top downwards along the talus. Grey-bluish marl, yellowish silt and fine-grained sand, were deposited in the surrounded low areas. A rich and diverse dweller assemblage occurs in the buildup: bivalves (pectinids, venerids, Lithophaga), gastropods (muricids, nassarids, olivids, cancellarids), ahermatypic coral Cladocora?, barnacles of the family Pyrgomatidae, Balanus trigonus and regular echinoids. In the talus deposits, clusters of Neopycnodonte cochlear, Hinnites ercolanianus and Balanus sp. dominate the faunal assemblage. Further, the blocks of the talus are densely bored, showing Gastrochaenolites, Entobia, Maeandropolydora and Caulostrepsis. Faunal and boring assemblages indicate that the buildup settled and developed in very shallow conditions (most likely less than 10 m water depth). The whole fossil assemblage, framework and dweller community, are preserved in situ, maintaining their original growth positions. Development in a protected setting, together with rapid burial due to progradation of siliciclastics on top of the palaeotopographic high, accounts for this exceptional preservation in such a shallow environment. The vermetid bioconstruction of Sant Onofre represents the only carbonate deposits found in the lower Pliocene basins of NE Spain. Sequence stratigraphic architecture indicates that these carbonates represent the maximum flooding deposits. Thus, maximum carbonate production took place due to sediment starvation in the palaeohigh while terrigenous deposits were formed in the surrounded low areas.Palaeogeography Palaeoclimatology Palaeoecology 01/2013; 395. DOI:10.1016/j.palaeo.2013.12.011 · 2.75 Impact Factor