Note: Nakamura (1972: 152–153) proposed the order Ralfsiales to accommodate three families (Ralfsiaceae, Lithodermataceae, and Nemodermataceae, the latter two not reported from the Indian Ocean) with three shared characters: an Ectocarpus-type life history, discoid-type germling development, and cells containing a single parietal chloroplast without a pyrenoid. The ordinal name is not validly published because the author did not provide a Latin diagnosis and thus failed to satisfy Art. 36.2. Most workers, however, do not accept the order, usually retaining the Ralfsiaceae in the Ectocarpales. Christensen (1980: 145) assigned Ralfsia to the Scytosiphonaceae in the Scytosiphonales. Following analysis of nucleotide sequences of 18S rDNA in Analipus japonicus and Ralfsia fungiformis, Tan & Druehl (1994: 728) concluded that the Ralfsiaceae should not be included in the Ectocarpales, but declined to specify an alternative ordinal placement.
Note: J. Tanaka & Chihara (1982: 388–389) proposed the family Mesosporaceae to accommodate three genera usually placed in the Ralfsiaceae— Mesospora Weber-van Bosse (1911: 27), Hapalospongidion D. Saunders (1899: 37), and Basispora D. John & Lawson (1974: 285–289). These genera were said to share an allegedly unique combination of characters, including intercalary plurilocular reproductive organs, terminal unilocular sporangia not associated with paraphyses, and free-standing vegetative filaments. Womersley (1987: 74–75), however, gave cogent reasons for merging the three genera under the earliest name, Hapalospongidion D. Saunders (1899: 37). He retained the combined genus in the Ralfsiaceae.
Mesospora schmidtii Weber-van Bosse, 1911: 27–28 (syntype localities: various in Indonesia, including Lombok).—Weber-van Bosse, 1913a: 143–145, fig. 43, pl. II: figs. 2, 3.
Hapalospongidion schmidtii (Weber-van Bosse) P. Silva.
INDIAN OCEAN DISTRIBUTION: Indonesia.