Phylogeography and taxonomy of the Indo-Pacific reef cave dwelling coralline demosponge Astrosclera 'willeyana': new data from nuclear internal transcribed spacer sequences

Astrosclera `willeyana' is a common `living fossil' coralline demosponge, living in cryptic areas of Indo-Pacific coral reefs with an alleged widespread distribution from the Red Sea to Tahiti. Spicule morphology (geometry, size, ornamentation) the main taxonomic character for sponge classification is highly variable between regional populations supporting the hypothesis that there may be more than one species of Astrosclera. An initial genetic (PCR-RFLP) survey of the internal transcribed spacer (ITS) regions of rDNA of several populations by Worheide (1998, Facies 38: 1-88) did not detect any genetic differences that would support species distinction based solely on phenotypic criteria. We have now sequenced the ITS regions of 12 specimens from the Red Sea, the Great Barrier Reef, Fiji, and Vanuatu and found small, but consistent differences in sequences from allopatric populations. These consistent morphological and genetic differences between populations are now regarded as clear evidence for the presence of at least two distinct cryptic species in addition to Astrosclera willeyana sensu stricto, originally described from the Loyalty Islands. Our Fiji/Vanuatu population most likely represents Astrosclera willeyana s.s., the two new cryptic species are Astrosclera sp. 1 (Red Sea), Astrosclera sp. 2 (GBR, Osprey Reef). Taxa will be formally described elsewhere. 1 Queensland Centre for Biodiversity, Queensland Museum, P.O. Box 3300, South Brisbane, Qld 4101, Australia. E-mail: GertW@qm.qld.gov.au 2 Department of Zoology and Entomology, The University of Queensland, St. Lucia, Qld 4072, Australia 3 Abt. Geobiologie, Gottinger Zentrum Geowissenschaften, Goldschmidtstr. 3, 33077 Gottingen, Germany