Notes on some Indopacific species of the genus Sacculina

For many years the species problem in the Sacculinidae has been a matter of controversies. Kossmann's (1872) paper was of fundamental importance, because in his descriptions of a great number of new species, chiefly from the Philippine Islands, he derived the specific characters from the anatomical peculiarities as well as from the excrescences of the external cuticle. Later investigators for many years dealt with European material only, in which specific characters are far less apparent than in tropical Sacculinidae, so that their opinions concerning specific differences were often based on principles instead of on facts. This applies to the papers by Giard and Bonnier (Giard, 1886, 1887, 1888; Bonnier, 1887; Giard & Bonnier, 1887, 1890), in which the description of new species was regarded as sufficiently founded by a simple indication of the host, a procedure based on Giard's conviction of the "spécificité parasitaire", resulting from investigations on the Bopyridae. Previously, Delage (1884) had proclaimed the opinion that the specific differences in the genus Sacculina were not sufficiently founded, and many years later Smith (1906), after remarking that he had tried in vain to find specific differences in the European forms of the genus, placed all the names of the later described species in the synonymy of Sacculina carcini Thomps. Guérin-Ganivet (1911) described some new species of Sacculina based on characters of the internal anatomy; he did not investigate the excrescences of the external cuticle, which, e.g., in his species S. carpiliae and S. leptodiae, are of comparatively large size, consisting of groups of spines united on common basal parts. In one of Guérin-Ganivet's figures (1911, Pl. I fig. 7, region of the mantle opening of Sacculina leptodiae, X 50) the excrescences of the external cuticle are faintly visible, but in the