First record of eulimids on brittle stars from Spratly Islands

This study presents the first record of two eulimid species, Stilapex zebra and Pyramidelloides sp., found on the arms of the brittle star Ophiothrix (Acanthophiothrix) purpurea on Spratly Islands (Truong Sa). Previously eulimids were found on ophiuroids only in central Vietnam (Nhatrang Bay), while the current study is the first symbiotic association between eulimids and ophiuroids from another part of the South China Sea (Spratly Islands). For the first time Ophiothrix (Acanthophiothrix) purpurea was recorded as a host species for both Stilapex zebra and Pyramidelloides sp. We can suppose that Ophiothrix (Acanthophiothrix) purpurea , is a generalist symbiont with a high range of hosts (mainly soft corals). If so, this case can be seen as an interesting example of hyper-symbiosis among mobile macroinvertebrates: the brittle star is the symbiont of a soft coral, and the eulimids are the symbionts of the brittle stars.