In this study 12 taxa are treated, belonging to four different genera of Gelidiales (i.e. Gelidiella, Gelidium, Pterocladia, and Porphyroglossum) as well as one species of Wurdemannia, a genus of unknown affinity. One new species, Gelidium amboniense, and a new forma, Gelidium latifolium forma elongatum, are described. Holotype material of Gelidium bornetii Weber-van Bosse in the Weber-van Bosse collection in Leiden can be synonymized with Gelidiella lubrica (Kützing) Feldmann & Hamel, while the original sample in the herbarium in Copenhagen only contains Gelidium pusillum (Stackhouse) Le Jolis var minusculum Weber-van Bosse. In the key to the genera and species we also include the very similar genus Ceratodictyon Zanardini (= Gelidiopsis Schmitz).