Re-assessment of the type collections of fourteen corallinalean species (Corallinales, Rhodophyta) described by W. Ishijima (1942-1960)

Many species of fossil coralline algae have been separated on the basis of only a few characters with slight or doubtful taxonomic significance. The analysis of the type material of the fossil coralline algal species is, therefore, needed in order to assess the taxonomic status and circumscription of these taxa. Wataru Ishijima has been one of the most prolific Japanese palaeontologists who worked on fossil calcareous algae from the western Pacific region. Ishijima described a large number of new taxa of fossil calcareous algae mostly belonging to the Corallinales from Eocene to Pleistocene sedimentary successions. An analysis of some Ishijima's types of Corallinales (Rhodophyta) described from 1942 to 1960, currently housed in the Institute of Geology and Paleontology, Graduate School of Science, Tohoku University, Sendai (Japan), is presented. For fourteen taxa changes were made to previously published statements of typification. Re-examination of the types from a modern perspective of coralline algal taxonomy shows that Hydrolithon taishakuensis (Ishijima) comb. nov (= Lithothamnium taishakuensis), Sporolithon kobamazimensis (Ishijima) comb. nov. (= Archaeolithothamnium kobamazimensis), Sporolithon kuboiensis (Ishijima) comb. nov. (= Archaeolithothamnium kuboiensis) and Sporolithon taiwanensis (Ishijima) comb. nov. (= Archaeolithothamnium taiwanensis) showed significant features justifying their use as species names in coralline algal taxonomy. No diagnostic characters occur in two types (L. nishiwadai, L. otsukiensis) and therefore the taxonomic disposition of these taxa remains unknown. Lithophyllum quadratum Ishijima is a heterotypic synonym of Lithophyllum incrustans Philippi. Lithoporella crassa Ishijima and Lithoporella hayasakai Ishijima are considered heterotypic synonyms of Lithophyllum prototypum (Foslie) Foslie, while Porolithon hanzawai Ishijima is a heterotypic synonym of Hydrolithon onkodes (Heydrich) Penrose and Woelkerling. Mesophyllum arakuraensis Ishijima is co-specific and has nomenclatural priority over M. contii Ishijima. However M. arakuraensis and M. contii do not show available evidence whether either might belong to Synarthrophyton instead of Mesophyllum. Lithothamnium ishizuchiensis Ishijima and L. kasedaensis Ishijima have no diagnostic features that can be used to ally them to any particular genus or species of Melobesioideae