Lithophyllum okamurae Foslie forma subplicatum Foslie, 1901b: 18 (`okamurai forma subplicata') (including Indian Ocean record) (lectotype locality: Samoa fide Woelkerling, 1993: 212).
Lithophyllum kaiseri (Heydrich) Heydrich forma subplicatum (Foslie) Foslie, 1903b: 467–468, pl. XXIV: fig. 6 (`kaiserii forma subplicata').—Foslie, 1907c: 104.— Foslie, 1907d: 188.— Hackett, 1977: 20.
Lithophyllum kotschyanum Unger forma subplicatum (Foslie) P. Silva.
Taxonomic synonym:
* Lithophyllum madagascarense Heydrich, 1902: 473–474 (type locality: near Fort-Dauphin [Taolanaro], Madagascar).—De Toni, 1905: 1796–1797.— Pilger, 1908b: 42–43, pl. 6: figs. 4–7.— Adey & Lebednik, 1967: 42.— Segonzac, 1984: table 1.
Lithophyllum kotschyanum Unger forma madagascarense (Heydrich) Foslie, 1909: 34–36 (`madagascariensis').—Foslie, 1929: 35, pl. LXV: figs. 7, 8.— Hackett, 1977: 20.
INDIAN OCEAN DISTRIBUTION: Cocos [Keeling] Islands, Comoro Islands, Diego Garcia Atoll, Laccadive Islands, Madagascar, Maldives (Male Atoll), Mauritius, Mozambique, Réunion, Seychelles (Praslin Island).
Note: The name Lithophyllum kotschyanum forma subplicatum (`subplicata') was employed invalidly by Hackett (1977: 20), who failed to cite the basionym. The binomial Lithophyllum madagascarense was listed in a paper by Hariot (1902: 472) published simultaneously with Heydrich's description. The conspecificity of L. madagascarense and L. kaiseri forma subplicatum was proposed by Foslie (1907c: 104; 1907d: 188). In transferring this forma to L. kotschyanum, Foslie (1909: 34) should have adopted the epithet subplicatum, which at infraspecific rank has priority over madagascarense. The Cocos-Keeling specimen cited by Foslie in the original description of this forma was listed by Adey & Lebednik (1967: 41) as Lithophyllum kotschyanum.