Obituary Masami Mizutani (1930–2020) Tomoyuki KATAGIRI1 & S. Robbert GRADSTEIN2, 3

Hattoria 12: 93–115. 2021 Obituary Masami Mizutani (1930–2020) Tomoyuki KATAGIRI1 & S. Robbert GRADSTEIN2, 3 1 Hattori Botanical Laboratory, Obi 6–1–26, Nichinan, Miyazaki 889–2535, Japan 2 Albrecht von Haller Institute, Department of Systematic Botany, 37073 Göttingen, Germany 3 Muséum National d’Histoire Naturelle, Institut de Systématique, Evolution, Biodiversité, 75005 Paris, France Author for correspondence: Tomoyuki KATAGIRI, [email protected] Figure 1. Masami Mizutani in May 2012, courtesy of his family. Our colleague, Dr. Masami Mizutani, passed away on August 30, 2020 at the old age of 90. He was an excellent and unique Japanese bryologist, a specialist of Asian Lejeuneaceae who made an important contribution to hepaticology. 93 1. Early life and educational background Masami Mizutani was born on March 28 in 1930 in Tokyo City (Tokyo Metropolis), eldest son of his father Kiyoshi Mizutani, an architect of The South Manchuria Railway Co., Ltd., and his mother Kane Mizutani. Due to his father’s work, he spent his childhood from 5 to 16 years in Dalian, Liaoning Province, China. He entered Dalian No. 1 Junior High School (old education system) in April 1942. After returning to Japan, he went to Shizuoka Prefectural Hamamatsu No. 1 Junior High School (old education system) at the age of 16 in August 1946, and graduated there in March 1947. His formal education ended here. Before moving to Nichinan as a researcher at the Hattori Botanical Laboratory, Mizutani worked in various occupations including as a workman in a car factory in Osaka City. During his life in Osaka, he joined a study group on ferns and mosses and came in contact with Dr. Motoji Tagawa, a fern taxonomist at Kyoto University. Recognizing Mizutani’s passion for the study of plants, Dr. Tagawa introduced him to Dr. Sinske Hattori who undertook the supervision of Mizutani’s doctoral studies. In January 1956 he started bryological work, especially on taxonomy of liverworts, at the Hattori Botanical Laboratory with Dr. Hattori. Five years later he published his dissertation with the title “A Revision of Japanese Lejeuneaceae” (Mizutani 1961, Journal of the Hattori Botanical Laboratory No. 24), which was submitted to Tohoku University in January 1962 as his doctoral thesis. He was the first Japanese person to be awarded a D. Sci. in the field of plant sciences as a junior high school graduate under the old educational system. 2. Scientific contributions of Masami Mizutani To hepaticology, particularly Lejeuneaceae Masami Mizutani is remembered for his major contributions to the taxonomy of Asiatic liverworts, especially Lejeuneaceae. During the first years of his scientific career his work focused on miscellaneous taxa from southern Japan, including Aneuraceae and Lepidoziaceae, and the results were usually published together with Sinske Hattori. The early studies resulted in the description of a new subgenus, Lobatiriccardia, which was later raised to generic level by Tatsuwo Furuki (1991). At the end of the 1950s, Mizutani began working on the family Lejeuneaceae and subsequently dedicated his whole life to this group on which he became a world authority. In these early years, taxonomic knowledge of Lejeuneaceae was still in a state of chaos. Hundreds of species has been described by Franz Stephani in Species Hepaticarum (1898–1924), a taxonomic synthesis of the world’s liverwort species, but many of these were ill-founded or placed in the wrong genus (Gradstein 2006) and a complete revision of Stephani’s work was necessary. For Asiatic Lejeuneaceae, a first start had been made by Frans Verdoorn (1934) and Theodor Herzog and his students (e.g., Herzog 1930–1939; Eifrig 1937; Benedix 1953), but the most important contribution was made by Mizutani. In a long series of papers on Lejeuneaceae of Asia (e.g., Japan, Borneo, the Philippines, New Guinea, the Himalayas), and including revision of type specimens in the herbarium of Stephani (Geneva) and elsewhere, Mizutani laid a solid basis for our current taxonomic knowledge of the group. Hundreds of species were newly defined and illustrated, and the circumscriptions of the genera were improved. Many of Mizutani’s new taxonomic concepts have been confirmed in 94 Figure 2. Masami Mizutani at the Hattori Botanical Laboratory (Nichinan) in August 1978. Photo taken by Z. Iwatsuki. subsequent morphological and molecular studies. He was the first to show that the genera Taxilejeunea and Hygrolejeunea are ill-defined and synonyms of Lejeunea, and also found that the genus Ptychocoleus was heterogeneous and made up of two different groups of species, now called Acrolejeunea and Schiffneriolejeunea (Gradstein 1975). At the species level, he showed that Mastigolejeunea humilis is a good species and not a synonym of M. auriculata (Gradstein & Inoue 1980), and that the width of the junction of the lobule with the lobe is a useful new species character within Lopholejeunea, allowing for the easy separation of sterile material of the common L. nigricans and L. subfusca and other species (Mizutani 1979). Numerous other important new results could be mentioned here. Mizutani’s most influential paper has undoubtedly been the taxonomic revision of Japanese Lejeuneaceae (Mizutani 1961). The importance of this work goes far beyond the treatment of the taxa of Japan and stands out by presenting several new and innovative taxonomic concepts which are still valid today, including: 1. The classification of the family into subfamilies and tribes. Following Spruce (1884), 95 the genera of Lejeuneaceae had for almost a century been classified into Holostipae and Schizostipae, based on characters of the gametophyte such as underleaf morphology (undivided or bifid), stem anatomy and the width of the ventral merophyte. The two groups were by no means sharply defined by these characters, however, and consequently opinions differed as to the classification of some of the genera; some authors subdivided the family into as many as 7 different subfamilies (Schuster 1963). In a broad and careful analysis of gametophytic and sporophytic characters of the genera of Japan, Mizutani found that sporophyte characters were more stable and showed that Holostipae and Schizostipae were sharply different by seta structure (presence of 12 or 16 outer rows of cells), capsule wall thickening pattern (presence or absence of a layer of thickening on the inner wall) and number and spiral development of the elaters. He showed that Lejeuneaceae may be subdivided into 2 broad subfamilies for which he proposed the names Ptychanthoideae (＝Holostipae) and Lejeuneoideae (＝Schizostipae) (see also Mizutani 1985). The subfamily classification by Mizutani has subsequently been confirmed by molecular analysis and is still accepted today (Gradstein 2013). 2. The homology of the so-called “proximal” and “distal” hyaline papilla. The great hepaticologist Alexander W. Evans had first discovered that several genera of Lejeuneaceae, especially Cheilolejeunea, differ from other genera in the position of the hyaline papilla at the lobule apex (＝“apical tooth”), being distal to the tooth instead of proximal. However, in his Japanese Lejeuneaceae monograph Mizutani showed that the position of the hyaline papilla is always proximal. When it is distal, the apical tooth is simply the second tooth of the lobule (counted starting at the apex of the lobule) and the first one is reduced. The terms “proximal” and “distal” for the hyaline papilla, even though widely used, are thus in fact bit misleading and the term “apical tooth” ambiguous (Gradstein 1975; Renner 2012). We learned this important principle in Lejeuneaceae morphology from Mizutani. 3. The taxonomic position of Nipponolejeunea. In his Japanese Lejeuneaceae monograph Mizutani, for the first time, pointed out that Nipponolejeunea is more closely related to Jubula and Neohattoria than to the rest of the Lejeuneaceae—in spite of its Lejeuneaceae-type lobule—and created the subfamily Jubuloideae for these three genera. Unfortunately, he gave up this idea in 1985, moving Nipponolejeunea back to the Lejeuneaceae where it was subsequently considered the basalmost genus. However, molecular-phylogenetic analysis has recently confirmed that Nipponolejeunea is closer to Jubula than to Lejeuneaceae and should be removed from Lejeuneaceae (Ahonen 2006; Wilson et al. 2007). In addition to the taxonomic revisionary papers, Masami Mizutani wrote numerous papers in Japanese language, some of these containing highly original ideas that were subsequently validated by other studies. A noteworthy example is his paper on branching types in Lejeuneaceae (Mizutani 1970). Spruce and many later authors had shown that presence or absence of Radula-type innovations is an important generic character in Lejeuneaceae. Mizutani expanded this concept by the observation that leaf segmentation of innovations can be dextrorse or sinistrorse and can start at the base with a leaf or with an underleaf. He called innovations starting with a leaf “Radula-Lejeunea type innovation” and those starting with an underleaf “Radula-Jubula type innovation”. Independently, the two innovation types had been described one year earlier by Barbara Crandall-Stotler (1969), but the major taxonomic 96 implications were first demonstrated by Mizutani. Thus, he showed that Radula-Lejeunea type innovations are a distinctive feature of Ptychanthus, Tuzibeanthus, Thysananthus, Spruceanthus, Omphalanthus, Lejeunea, Harpalejeunea, etc., whereas the Radula-Jubula type innovations are characteristic of Jubula,

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