|Publication Type:||Conference Paper|
|Year of Publication:||2013|
|Authors:||A. Rösler, Braga J. C.|
|Conference Name:||SAGE 2013|
The onset of the biodiversity hotspot in the Indo-West Pacific region took place during the Miocene. Crustose coralline algae (CCA) of this epoch from South East Asia, however, are poorly known, despite their importance for the generation and maintenance of reef biodiversity.
We studied CCA in Miocene reefs in the Kutai Basin (East Kalimantan, Indonesia) to fill this knowledge gap, crucial to understand the evolutionary history of reef building algae. CCA are mostly found encrusting corals and forming nodules together with foraminifers. Two main CCA assemblages can be recognized in the studied reefs: 1) A shallow-water assemblage, comprising two species of Neogoniolithon, several Hydrolithon species, Spongites, Lithoporella, and also Sporolithon. 2) A melobesioid assemblage that preferentially grew in darker waters, consisting of Lithothamnion, Mesophyllum and Sporolithon. The recorded palaeodepth distribution of CCA assemblages is consistent with the one reported from modern and fossil coral reefs.
Miocene CCA of East Kalimantan include some extant species, which appeared earlier than previously known. These new first-occurrence dates are used to produce a detailed time tree of the main reef building CCA species with the help of a new molecular phylogeny, which is based on five genetic markers (18S, 28S, COI, psbA, UPA). The sequences have been obtained from samples from Indo-Pacific localities and Genbank. This study comprises the biggest set of reef building CCA taxa ever analysed before, and aims to disentangle the polyphyly of traditional taxa such as the mastophoroid and lithophylloid subfamilies.