Three new solar-powered species of the genus Phyllodesmium Ehrenberg, 1831 (Mollusca: Nudibranchia: Aeolidioidea) from the tropical Indo-Pacific, with analysis of their photosynthetic activity and notes on biology

Abstract

Three new Phyllodesmium species, Phyllodesmium lizardensis n. sp. from Lizard Island (Australia), P. lembehensis n. sp. from Sulawesi (Indonesia) and P. koehleri n. sp. from the Philippines, are described. Phyllodesmium lizardensis n. sp. and P. lembehensis n. sp. are associated with octocorals of the family Xeniidae and are similar to other Xeniidae-feeding Phyllodesmium species. Nevertheless, unique combinations of cerata morphology and colour, tooth and jaw morphology, the position of the anal papilla, as well as the special digestive glandular branching system within the cerata clearly distinguish these new species from described ones. Phyllodesmium koehleri n. sp. probably feeds on octocorals of the genera Lemnalia or Paralemnalia; it shows a cactus-like cerata morphology that is unique among Phyllodesmium species. In vivo measurements of photosynthetic activities in P. lizardensis n. sp. and P. lembehensis n. sp. indicate a symbiotic relationship with zooxanthellae at least for some days. These results are discussed in comparison to the Xeniidae-feeding species P. jakobsenae Burghardt & Wägele, 2004 and P. rudmani Burghardt & Gosliner, 2006. Histological investigation of the digestive diverticula within the cerata of all new species also suggests a relatively high efficiency of the symbiosis. © The Author 2008. Published by Oxford University Press on behalf of The Malacological Society of London, all rights reserved.