Sacculina leptodiae Guér.-Gan., a parasite of three different crabs

The description of Sacculina leptodiae by Guérin-Ganivet (1911) was based on specimens infesting the crab Xantho exaratus (H. M. E.). Other specimens, identified as S. leptodiae or otherwise, have been mentioned in literature, so that the synonymy may be given as follows. Sacculina leptodiae Guérin-Ganivet, 1911 Sacculina leptodiae Guérin-Ganivet, 1911. Type specimens on Xantho exaratus (H. M. E.) from Jibuti, Gulf of Aden, and from Grande Comore. Sacculina rotundata (p. p.), Boschma, 1931. Specimen on Pseudozius caystrus (Ad. & White) from Ternate. Sacculina leptodiae, Boschma, 1936. Type specimens on Xantho exaratus (H. M. E.). Sacculina leptodiae, Boschma, 1937. Type-locality fixed as Jibuti, Gulf of Aden. Sacculina leptodiae, Boschma, 1947. Specimens on Thalamita stimpsoni A. M. E. from Manoembai, Aroe Islands. The present paper is based on the examination of 7 specimens on Xantho exaratus (H. M. E.), 20 specimens on Thalamita stimpsoni A. M. E., and 13 specimens on Pseudozius caystrus (Ad. & White). It proved that there is a certain amount of variation in the shape and size of the male genital organs, in the structure of the colleteric glands, and in the size and shape of the excrescences of the external cuticle. Specimens occurring as parasites on one species of crab among each other show a corresponding degree of variation as that found when specimens from various hosts are compared. It seems therefore safe to conclude that the parasites of the three crabs, as far as they are characterized by corresponding excrescences of the external cuticle, really belong to one species. In the present paper the specimens are indicated with their provisional