Iconaster vanuatuensis, Mah, 2005

Mah, Christopher, 2005, A phylogeny of Iconaster and Glyphodiscus (Echinodermata, Asteroidea, Valvatida, Goniasteridae) with descriptions of four new species, Zoosystema 27 (1), pp. 137-161 : 157

and on the abactinal surface only of I. vanuatuensis n. sp. Glassy tubercles have been interpreted as photoreceptors in the goniasterid starfish Ogmaster by Dubois & Hayt (1990), and in ophiocomid ophiuroids ( Aizenberg et al. 2001), and are convergently expressed in shallow-water valvatidans, including goniasterids, oreasterids, and ophidiasterids (C. Mah unpublished data). Expression may be associated with exposure to sunlight. Three of the four species of Iconaster , I. elegans , I. longimanus , and I. uchelbeluuensis n. sp., occur within the range of the photic zone (30-208 m depth) ( Fig. 6 ) and the remaining species, Iconaster vanuatuensis n. sp., from

Vanuatu, occurs in deeper water (294-300 m depth). Although this initially appears inconsistent, significant levels of light remain present at intermediate depths between 2 0 0-9 0 0 m ( Denton 1990), especially in the relatively clear water of the South Pacific.

Interpretation of biogeographic patterns in Iconaster and Glyphodiscus must be tentative given that occurrence data for each taxon’s geographic range is probably incomplete and influenced by collection bias.

The basal species of Glyphodiscus ( G. magnificus n. sp.) has been recorded in New Caledonia,

Figures

FIG. 6. — Phylogram of Iconaster + Glyphodiscus, plus outgroup taxa. Numbers with % above branches are bootstrap values (300 replicates). Single numbers below branches are Bremer support values. Lines shown in bold are ingroup taxa. Geographic and bathymetric range data shown to right of tree. Dotted line around Vanuatu indicates possible photic transmission to deeper depths (see Discussion). Abbreviation: OG, outgroup taxon. Scale bar: 5 changes.