Pontoniid shrimps from the Palau Islands

the chance to s t ay at the Palao Tropical Biological Station in the Palau Islands for the collection and ecological s tudy of decapod crus taceans in the coral reef. From the islands Kubo (1940) recorded only three species of pontoniid shr imps based on the late Professor Esaki ' s collection, since then additional records have been hard ly known. T h e authors, there-fore, t r y to reveal the pontoniid fauna of the Palau Islands and the commensal relationship of pontoniids and other mar ine invertebrates. In th is paper are reported fifteen species of pontoniids collected there, wi th the description of one new species, Periclimenaeus palauensis and six species whose occurrences have never been known from Micronesia. T h e r e are some discussions regard ing to the taxonomic interests in each species. In addition, the colour pa t te rns of some species are here made clear, and also it is of interest to note tha t one specimen of Periclimenes (Harpilius) brevicarpalis infested by a bopyrid showed the in-termedia te colour pa t te rn between male and female. Most of the species of five genera, Periclimenes, Periclimenaeus, Philarius, Coralliocaris and Jocaste were taken among the branches of madreporar ian corals, and those of the other genera, Anchistus, Paranchistus and Conchodytes were found in commensal w i th large bivalves. Almost all the mater ia ls here dealt wi th were obtained by hands when coral reefs were exposed at low tide. All the mater ia ls are deposited in the collection of the Zoological Laboratory, Facu l ty of Agr icul ture, Kyushu Univers i ty (ZLKU). T h e collections were made from following six Palau localities (Fig. 1): 1) Ngaruange l Atoll (8 ° 10 ' N, 134°39'E), the nor thern verge of the '* ' Palau Islands, separated from the main island by a long distance. T h