Range extension of Marchantia formosana (Marchantiaceae, Marchantiophyta), with an updated key to Marchantiaceae taxa in East Asia Author Zheng, Tian-Xiong Hattori Botanical Laboratory, 6 - 1 - 26 Obi, Nichinan, Miyazaki 889 - 2535, Japan Author Long, David G. Royal Botanic Garden Edinburgh, Inverleith Row, Edinburgh EH 3 5 LR, United Kingdom Author Shimamura, Masaki Program of Basic Biology, Graduate School of Integrated Sciences for Life, Hiroshima University, 1 - 3 - 1 Kagamiyama, Higashihiroshima, Hiroshima 739 - 8526, Japan text Phytotaxa 2023 2023-09-01 612 1 93 98 http://dx.doi.org/10.11646/phytotaxa.612.1.8 journal article 10.11646/phytotaxa.612.1.8 1179-3163 8308904 Marchantia formosana Horik., J. Sci. Hiroshima Univ., Ser. B, Div. 2, Bot. 2: 121. 1934 ( Figure 1 , 2 ) Type citation . FORMOSA , Tainan , Mt. Morrison ( Kodamayama-Tâtaka ), 18 Aug. 1932 , Y . Horikawa 9117 ( holotype , HIRO !); Taihoku , Mt. Taiheizan ( Minamoto ), 23 Aug. 1932 , Y . Horikawa 9293 ( paratype , HIRO !) ; Tainan , Mt. Arisan ( Jûjiro-Iwaiyama ), 17 Aug. 1932 , Y . Horikawa 8990 ( paratype , HIRO !); do. , 27 July 1928 , A . Noguchi 131 ( paratype , HIRO !) . Description . Thallus greyish green, prostrate, compact, 2.1–4.2 mm wide, successive dichotomies 3–10 mm apart; dark median band absent; margin entire or slightly crenulate, reddish to purplish. Epidermal pores conspicuous, 56–131 μm In dIam., bOrdered by 8 cellS; Inner OpenIng uSually pentacle-lIke, bOunded by 5–6 cellS wIth rOunded-prOtrudIng inner wall, seldom pentagonal or hexagonal. Compact ventral tissue of 16–19 cells layers in the median portion; central part brownish to purplish; sclerotic cells brownish to slightly blackish; mucilage cavities and oil-cells absent. Ventral surface green at the apex and reddish to purplish in other parts; scales extending over 30–40% of thallus width. Ventral scales in 4 rows; median scales reddish to purplish; appendage long elliptical to nearly circular (width: length = 0.58–1.02; 222–375 × 296–424 μm), reddISh tO yellOwISh, uSually wIth acute apex and margIn Irregularly tOOthed tO nearly entire. Cupule ciliate, narrowly triangular to linear, up to 7 cells high. FIGURE 1. Marchantia formosana Horik. (A) Thallus. (B–G) Appendages of median scales. (H) Cross section of air chamber. (I) Ventral median scales. (J–M) Inner opening of air pores. (N) Section of thallus. (O, P) Cupule margin. (Q, R) Female receptacles. (S–V) Scales of female receptacle. (W) Section of archegoniophore stalk. All from D. G. Long 35201 . Archegoniophore at apex of thallus; stalk up to the maximum 11–12.2 mm long, with 2 rhizoid furrows; air-cavities interrupted; receptacle 4–4.8 mm in diam., nearly symmetric, shallowly dissected into 7 lobes, with a prominent projection in central part of receptacle; lobes yellowish to brownish, spreading, usually with truncate or emarginate apex; median scales thread-like, seldom bifurcate, hyaline to yellowish; involucre not seen. Distribution: China ( Taiwan and Yunnan). Taxonomic notes : The present species, which had long been considered endemic to Taiwan , China , was originally described based on Taiwanese materials (Horikawa 1934). The present study provides the first record of this species outside the region. FIGURE 2. Appendages of median scales. [A, B from Y. Horikawa 9117 (holotype, HIRO). C from Y. Horikawa 9293 (paratype, HIRO). D–J from D. G. Long 35201 ]. Marchantia formosana is distinguished from other Marchantiaceae taxa in Asia by the following combination of mOrphOlOgIcal characterS: (1) large epIdermal pOreS (up tO Over 130 μm dIam.) bOarded by mOre cell rIngS (up tO 8), (2) star-like inner opening of air pores, (3) cupule with long cilia (up to 7 cells), (4) shallowly dissected female receptacle, (5) ciliate margin of involucre, and (6) appendages of median scales with acute apex and irregularly toothed to nearly entire margin. In China , when sterile, Marchantia formosana shares a similar appearance to M. emarginata Reinwardt, Blume & Nees (1824: 192) subsp. cuneiloba ( Stephani 1897: 98 ) Zheng & Shimamura (2022b: 145) and M. hartlessiana Stephani in Bonner (1953: 107) ( Zheng & Long 2023 ). However, M. emarginata subsp. cuneiloba differs from M. formosana in its appendages of median scales with multicellular toothed margins, and the epidermal pores usually with triangular to hexagonal inner openings. Marchantia hartlessiana is differentiated by its appendages, which have an entire or crenulate margin. This species may be also confused with Marchantia longii Zhu, Xiang & Shu in Xiang et al. (2016: 285) , a narrowly distributed taxon in Yunnan , because they share (1) a deeply lobed male receptacle, (2) a shallowly dissected female receptacle and (3) a similar thallus appearance. However, M. longii is distinct by having air pores with only polygonal inner openings, and appendage of median scales with an entire to weakly denticulate margin consisting of densely arranged cells ( Xiang et al. 2016 ). It should be noted that original specimens of M. longii were not available for the present study; thus, the characters listed above are all literature-based and may require amendment when more materials become available. However, this issue does not negate the fact that M. formosana is a well-established species. In 1989, Bischler-Causse noted that the width and length of appendages of median scales of Marchantia formosana can reached 475–520 μm and 571–600 μm, reSpectIvely. HOwever, Such rObuSt appendageS were neIther IlluStrated in the regional study of Marchantia (Lu & Huang 2017) nor observed in the holotype and paratype ( Figure 2 , A–C). In the present study, we provide a detailed illustration of this character to clarify the morphological variation in the Yunnan material ( Figure 2 ), which also supports the conclusion that our voucher specimen ( D. G. Long 35201 ) is indeed conspecific to M. formosana . Currently, Marchantia formosana has only been recorded in Taiwan and Yunnan , China . Disjunctive distribution is not rare in liverworts and hornworts, as they typically reproduce through the dispersing of spores and propagules ( Schofield & Crum 1972 ). However, some taxa that possess Taiwan-Yunnan disjunction can also be found in other adjacent regions (e.g., Apotreubia nana (Hattori & Inoue 1954: 99) Hattori & Mizutani (1966: 492) , Schistochila macrodonta Nicholson (1930: 29) , Cryptolophocolea sikkimensis ( Stephani 1922: 349 ) Bakalin & Maltseva (2022: 14) , Plagiochasma appendiculatum Lehmann & Lindenberg in Lehmann (1832: 14), Schiffneria hyalina Stephani (1894a: 1) . Wu et al. (2002) compared the bryoflora of Taiwan and the Hengduan Mountains, and concluded that taxa showing such disjunction are usually tropically distributed. Therefore, in future, it is expected that records of M. formosana will be found in regions with similar climates, such as the Sino-Himalaya s and Southwestern Japan . Specimens examined : CHINA . Yunnan Province , Fugong County , Shangpa Zheng , W bank of Nu Jiang , elevation 1270 m , 24 Aug. 2005 , D. G . Long 35201 ( E01080864 , MO6090561 ) . Additional specimens examined : CHINA . Taiwan , Nantou Co. , Lugo Township , Sitou Forest Road , elevation 1365 m , 14 Nov. 2019 , D. G . Long et al. 46467 ( E01080881 ); Yilan Co. , Wangyangshan Trial above Cueifong Lake , elevation 1930 m , 21 Nov. 2019 , D. G . Long et al. 46739 ( E01080879 ) .