Combining morphometrics with molecular taxonomy: how different are similar foliose keratose sponges from the Australian tropics?
Sponge taxonomy can be challenging as many groups exhibit extreme morphological plasticity induced by local environmental conditions. Foliose keratose sponges of the sub-family Phyllospongiinae (Dictyoceratida, Thorectidae: Strepsichordaia, Phyllospongia and Carteriospongia) are commonly found in intertidal and subtidal habitats of the Indo-Pacific. Lacking spicules, these sponges can be difficult to differentiate due to the lack of reliable morphological characters for species delineation. We use molecular phylogenies inferred from the nuclear Internal Transcribed Spacer 2 region (ITS2) and morphometrics (19 characters; 52 character states) to identify evolutionarily significant units (ESUs; sensu Moritz) within foliose Phyllosponginiids collected from seven geographic locations across tropical eastern and Western Australia. The ITS2 topology was congruent with the tree derived from Bayesian inference of discrete morphological characters supporting expected taxonomic relationships at the genus level and the identification of five ESUs. However, phylogenies inferred from the ITS2 marker revealed multiple sequence clusters, some of which were characterised by distinct morphological features and specific geographic ranges. Our results are discussed in light of taxonomic incongruences within this study, hidden sponge diversity and the role of vicariant events in influencing present day distribution patterns.
AIMS@JCU, James Cook University, Townsville, Queensland 4811, Australia; School of Marine & Tropical Biology, James Cook University, Townsville, Queensland 4811, Australia; Australian Institute of Marine Science, PMB 3, Townsville, Queensland 4810, Australia. Electronic address: muhammad.abdulwahab@my.jcu.edu.au.
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Abdul Wahab
Western Australian Museum, Locked Bag 49, Welshpool, Western Australia 6986, Australia. Electronic address: jane.fromont@museum.wa.gov.au.
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Fromont
Marine Ecology Research Centre, School of Environment, Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia. Electronic address: stephen.whalan@scu.edu.au.
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Whalan
Australian Institute of Marine Science, PMB 3, Townsville, Queensland 4810, Australia. Electronic address: n.webster@aims.gov.au.
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Webster
Australian Institute of Marine Science, PMB 3, Townsville, Queensland 4810, Australia. Electronic address: n.andreakis@aims.gov.au.
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Andreakis
D000818:Animals; D001315:Australia; D001499:Bayes Theorem; D017753:Ecosystem; D019143:Evolution, Molecular; D010802:Phylogeny; D011161:Porifera / Q000033:anatomy & histology* / Q000145:classification* / Q000235:genetics; D017422:Sequence Analysis, DNA; D014329:Tropical Climate
ITS2; Morphology; Phylogeography; Porifera; Systematics; Torres Strait