Recently, while going through the old collections of Malesian, Australian, and Pacific materials of Piperaceae in connection with the study of the New Guinea species of this family, taxonomic problems that need clearing up were encountered. These are of such a diverse nature that it is best they are discussed separately in each species and not summarized here. This paper is the first of many which will be published seriatim as work on this difficult group progresses. As implied in the title, this series does not deal with New Guinea species which are the subject matter of another series. It is hoped that these contributions will pave the way for a comprehensive revision of the family in Malesia in which more than 400 species have been described or recorded.