Ammothea hilgendorfi (Pycnogonida: Ammotheidae) Associated with a Sea-Star, Coscinasterias acutispina (Echinodermata: Asteroidea), from Sagami Bay, Japan

Abstract

Pycnogonids of the species Ammothea hilgendorfi (Bohm, 1879) were found attached to sea-stars, Coscinasterias acutispina (Stimpson, 1882), from the intertidal zone of Hayama, Sagami Bay, Japan. The sea-stars were collected throughout the year, but the pycnogonids were found only between March and August, mostly in April. The pycnogonids attached to the body surface of the sea-stars mainly by clinging to spines of the aboral and lateral sides of the arms. Developmental stages of the pycnogonids attached to the sea-stars comprised the four final juvenile stages as well as adults, but earlier juvenile stages were not found.