Additional Records of Hawaiian Platyctenea (Ctenophora)

Abstract

In a previous paper (Matthews, 1954 :282) representative samples of all orders of Ctenophora were reported for Hawaii. Of these, the platyctenids were represented by only two immature specimens of Coeloplana dubosequii collected on the reef of the Hawaii Marine Laboratory on December 31, 1952. This small, pale, yellowish-green platyctenid has not been collected since, although the alga (Hypnea nidifica) on which it was found has been periodically examined. Also, continuous examination of spines of the slate-pencil urchin, Heterocentrotes mamillatus (viz. Utinomi, 1961 :116, pI. 58, no. 9), has failed to reveal platyctenids, although Dawydoff (1938: 161) reported having collected Coeloplana weilli on this urchin in the region of Ream (Gulf of Siam, Cambodia). It is rather ironical that, quite by chance, plaryctenids were taken in 1961 on the spines of the black urchin, Echinothrix diadema, collected from the sandy bottom in about 10 m of water at the seaward edge of Waikiki reef. Again, in January, April, and May 1962, and in April 1963, platyctenids were taken on E. diadema at about the same depth, near Buoy No.8, Kaneohe Bay, Oahu.