First record of Protomystides hatsushimaensis (Annelida: Phyllodocidae) inhabiting vacant tubes of vestimentiferan tubeworms

Abstract

Background: Vestimentiferan tubeworms (Annelida: Siboglinidae) often play an important role as a foundation species in chemosynthetic ecosystems by providing microhabitats for other organisms. In the present study, we detected a new relationship between phyllodocid worms and tubes of a vestimentiferan Alaysia sp. Methods: Tubes of Alaysia sp. were collected from a hydrothermal vent field at a depth of 1052 m on the North Iheya Knoll in the Okinawa Trough on January 17, 2000. The Alaysia tubes were fixed with 4.7% neutralized formaldehyde solution and preserved in 70% ethyl alcohol. Phyllodocid worms were later obtained from empty tubes of Alaysia sp. Results: We classified the collected phyllodocid worms as Protomystides hatsushimaensis based on the morphology of specialized chaetae. They were observed in thin brownish tubes of mucous, probably secreted by P. hatsushimaensis, at approximately 30 and 50 mm from the upper openings of the tubes of Alaysia sp. Conclusions: The phyllodocid worm P. hatsushimaensis was found inside the tubes of Alaysia sp., a vestimentiferan tubeworm, collected in a hydrothermal vent field on the North Iheya Knoll in the Okinawa Trough of the western Pacific. The present study provides a new record of P. hatsushimaensis using empty vestimentiferan tubes as a microhabitat.