Summary
The Podostemaceae of Laos are much less understood than those of adjacent Thailand. Comparative morphology using new materials, together with the latest molecular phylogenetic studies, have revealed a high diversity in subfamily Podostemoideae in Laos. This subfamily comprises five genera and 15 species. The genus Hydrobryum Endl. is enlarged, and found to be remarkably diverse in root and shoot morphology. We describe two species, H. subcylindricum sp. nov. and H. taeniatum sp. nov., with subcylindrical and ribbon-like roots, respectively; H. austrolaoticum sp. nov., H. verrucosum sp. nov. and H. subcrustaceum sp. nov. with crustose roots, and H. takakioides sp. nov. with crustose roots and elongate shoots. Diplobryum C. Cusset, comprising four species and characterised solely by the nearly 20-ribbed capsule, is polyphyletic. Two Lao and a Vietnamese species of Diplobryum are transferred to Hydrobryum: H. ramosum (C. Cusset) Koi & M. Kato comb. nov., with floating subcylindrical roots and anchoring disk-like bases, and H. vientianense (M. Kato & Fukuoka) Koi & M. Kato comb. nov. and H. minutale (C. Cusset) Koi & M. Kato comb. nov. with crustose roots. The rootless D. koyamae M. Kato & Fukuoka was recently combined as Hydrodiscus koyamae (M. Kato & Fukuoka) Koi & M. Kato. Cladopus (sect. Griffithella) pierrei (Lecomte) C. Cusset is not segregated even at a sectional rank. We also describe Polypleurum pluricostatum sp. nov., and add Hydrobryum tardhuangense M. Kato, Paracladopus chiangmaiensis M. Kato and Polypleurum schmidtianum Warm. as new records to Laos, and Polypleurum wallichii (R. Br. ex Griff.) Warm. from new localities in Laos.
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Acknowledgements
We thank T. Wongprasert, S. Suddee, N. Katayama, R. Fujinami and C. Tsutsumi for their help in the field study, Y. Hirayama for her technical assistance, and M. F. Newman who drew our attention to specimens collected from central Laos. We are also indebted to directors and curators of Herbaria C, E, K, L, P, and TI for helping us examine specimens in the herbaria or on loan. This study was supported by a Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science.
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Appendix
Appendix
Materials used in phylogenetic analysis. Species names (in bold) are followed by localities (for some materials), vouchers, and GenBank accession numbers of matK.
Cladopus austrosinensis M. Kato & Y. Kita — CH-301, AB104560b; CH-302, AB104559b. C. doianus (Koidz.) Koriba — JK-Manose, AB179656b. C. fallax C. Cusset — TL-701, AB293561c; TL-1610, AB537378d. C. fukienensis (H. C. Chao) H. C. Chao — CH-01, AB179653b. C. javanicus M. Kato & Hambali — ID-02, AB066175b. C. nymanii H. A. Möller — ID-03, AB104561b; S-01, AB104577b. C. pierrei C. Cusset — LK-117, AB610213e; LK-121, AB610214e; LK-123, AB610215e; LK-128, AB610219e; LK-132, AB610220e; LK-134, AB610221e; LK-211, AB610224e; LK-214, AB610225e; LK-221, AB610226e; LK-222, AB610227e; LK-232, AB610228e; LK-237, AB610222e; LK-241, AB610223e; LKF-103, AB537379d; LKF-109, AB610217e; LKF-118, AB537380d; LKF-120, AB610218e. C. queenslandicus (Domin) C. D. K. Cook & Rutish. — AU-01, AB038199a; H. Akiyama 16803, AB300702c. C. taiensis C. Cusset — TL-101, AB048372a. Hanseniella heterophylla C. Cusset — TL-311, AB104562b; TL-1104, AB537388d; Gaeng Tha Lad, Loei, Thailand, TPK-13, AB610229e; Gaeng Gliang, Loei, Thailand, TPK-15, AB610230e. Hydrobryum austrolaoticum Koi & M. Kato — LK-116, AB610232e; LK-122, AB610233e; LK-125, AB610234e; LKF-104, AB537417d; LKF-106, AB610231e; LKF-115, AB537418d. Hy. bifoliatum C. Cusset — TL-310, AB104564b. Hy. chiangmaiense M. Kato — TK-07, AB537389d; TL-65, AB537390d; TL-422, AB537391d; TL-423, AB048373b; TL-424, AB537392d; TL-428, AB537393d; TL-429, AB104570b; TL-801, AB537394d. Hy. floribundum Koidz. — JK-Mae, AB104571b. Hy. griffithii (Wall. ex Griff.) Tul. — CH-102, AB104568b; TL-205, AB104569b. Hy. japonicum Imamura — CH-101, AB104573b; JK-01, AB038192a; J. Murata et al. 041232, AB537396d; Tard Muey waterfall, Maetakhra National Park, Mae On, Chiang Mai, Thailand, TK-01, AB610235e; TL-415, AB537397d; TL-420, AB537398d; TL-427, AB537399d; TL-1103, AB537400b; Sapa, Vietnam, Vie-1, AB610236e. Hy. kaengsophense M. Kato — TL-312, AB104565b. Hy. khaoyaiense M. Kato — TK-09, AB537395d. Hy. koribanum Imamura ex Nakayama & Minamitani — JK-05, AB048374a. Hy. loeicum M. Kato — TL-210, AB104566b; TL-211, AB537401d. Hy. micrantherum var. crassum M. Kato — TL-57, AB038205a; TL-58, AB104574b; TL-306, AB104576b. Hy. micrantherum var. micrantherum (P. Royen) C. D. K. Cook & Rutish. — TL-62, AB104575b. Hy. phetchabunense M. Kato & Koi — TKF-01, AB537414d, TL-1102, AB537415d. Hy. puncticulatum Koidz. — JK-Yaku, AB104572b. Hy. ramosum (C. Cusset) Koi & Kato — LK-05, AB537383d; LKF-05, AB610237e. Hy. somranii M. Kato — TL-703, AB537402d; TL-704, AB537403d. Hy. subcrustaceum Koi & M. Kato — L-15, AB537408d; LK-03, AB537409d, LKF-02, AB537410d, LKF-04, AB537411d. Hy. subcylindricum Koi & M. Kato — L-09, AB537405d; L-13, AB610238e; LKF-17, AB537406d. Hy. taeniatum Koi & M. Kato — L-08, AB537404d; LK-107, AB610239e. Hy. takakioides Koi & M. Kato — L-14, AB610240e; LK-202, AB610241e; LKF-16, AB537407d. Hy. tardhuangense M. Kato — LK-113, AB610242e; TL-208, AB104567b. Hy. verrucosum Koi & M. Kato — L-07, AB537412d; L-12, AB610243e; LK-105, AB610244e; LKF-14, AB537413d. Hy. vientianense (M. Kato & Fukuoka) Koi & M. Kato — L-01, AB537384d; L-02, AB610245e; L-16, AB537385d; LK-06, AB537386d; LK-07, AB610246e; LK-08, AB537387d; TKF-02, AB537416d; Gok-tab waterfall, Loei, Thailand, TPK-26A, AB610247e; loc. cit., TPK-26B, AB610248e; Gaeng Hua Wang Hai, Loei, Thailand, TPK-28, AB610249e; Loei stream, Loei, Thailand, TPK-29, AB610250e. Hydrobryum sp. — Gaeng Songkone, Loei, Thailand, TPK-01, AB610253e. Hydrobryum sp. — Gaeng Wang Gohia, Loei, Thailand, TPK-16, AB610251e. Hydrobryum sp. — Huai Phai waterfall, Loei, Thailand, TPK-22, AB610252e. Hydrodiscus koyamae (M. Kato & Fukuoka) Koi & M. Kato — L-06, AB537381d; L-11, AB537382d; LK-104, AB610255e; LKF-13, AB610254e. Paracladopus chanthaburiensis Koi & M. Kato — TL-1533, AB293558c. Pa. chiangmaiensis M. Kato — LK-213, AB610258e; LK-220, AB610259e; LK-223, AB611703e; LKF-105, AB610256e; LKF-110, AB537419d; LKF-116, AB610257e; LKF-119, AB537420d; LKF-121, AB537421d; TL-808, AB293560c; TL-1706, AB537422d. Polypleurum elongatum (Gardner) J. B. Hall — SL-12, AB048376a. Po. erectum M. Kato — Cha Naen waterfall, Phu Wua Wildlife Sanctuary, Nong Khai, Thailand, TL-706, AB610260e. Po. insulare M. Kato & Koi — Khlong Phu waterfall, Ko Chang, Trat, Thailand, TL-1512, AB610261e. Po. longicaule M. Kato — Tharn Ngam waterfall, Udon Thani, Thailand, TL-709, AB610262e; loc. cit., TL-901, AB610263e. Po. longifolium M. Kato — Cha Naen waterfall, Phu Wua Wildlife Sanctuary, Nong Khai, Thailand, TL-707, AB610264e; loc. cit., TL-904, AB610265e. Po. longistylosum M. Kato — TL-318, AB104578b; Phoolaor waterfall, Si Sa Ket, Thailand, TL-1503, AB610266e. Po. munnarense Nagendran & Arekal — Kuriyarkutty R., Orukomban, Parambikulam Wildlife Sanctuary, Trichur, Kerala, India, A. K. Pradeep 90004, AB610267e. Po. phuwuaense M. Kato — Chet Si waterfall, Phu Wua Wildlife Sanctuary, Nong Khai, Thailand, TL-705, AB610268e. Po. pluricostatum Koi & M. Kato — LK-01, AB610269e; LK-02, AB610270e; LK-04, AB610271e; LKF-01, AB610272e; LKF-03, AB610273e; Lad Hin Tak waterfall, Phu Rua National Park, Loei, Thailand, TPK-20, AB610274e. Po. prachinburiense M. Kato & Koi — Takro waterfall, Prachinburi, Thailand, TL-1404, AB610275e; Kaeng Hin Phoeng waterfall, Khao Yai National Park, Na Dee, Prachinburi, Thailand, TL-1601-1, AB610276e; loc. cit., TL-1602, AB610277e; loc. cit., TL-1604, AB610278e. Po. schmidtianum Warm. — LK-106, AB610279e; Sato stream, Klong Sato, Bo Rai, Trat, Thailand, TKF-21, AB610463e; Saphan Hin waterfall, Trat, Thailand, TL-1303, AB610280e; loc. cit., TL-1508A, AB610281e; loc. cit., TL-1508B, AB610282e. Po. sisaketense M. Kato & Koi — Phoolaor waterfall, Kantharalak, Si Sa Ket, Thailand, TL-1502, AB610464e. Po. stylosum (Wight) J. B. Hall — Kunthipuzha, Mannarkkad, Malappuram, Kerala, India, A. K. Pradeep 90003, AB610465e; Panathur, Kasaragod, Kerala, India, KI-109, AB610466e; Cheenganni Puzha, Kannur, Kerala, India, KI-211, AB610467e; Punavoorthodu Urulanthanni, Ernakuram, Kerala, India, KI-222, AB610468e; SL-05, AB066174b. Po. wallichii (R. Br. ex Griff.) Warm. — L-03, AB610470e; LK-09, AB610471e; LK-127, AB610472e; LK-238, AB610473e; TL-55, AB038204a; Nang Rong waterfall, Khao Yai National Park, Nakhon Nayok, Thailand, TL-601, AB610469e. Po. wongprasertii M. Kato — TL-319, AB104579b. Thawatchaia trilobata M. Kato, Koi & Y. Kita — TL-419, AB104563b; Gaeng Khem, Dansai, Loei, Thailand, TPK-02, AB610474e; Gaeng Tham, Huaylad, Dansai, Loei, Thailand, TPK-04, AB610475e; Gaeng Tha Laad, Phu Ruea, Loei, Thailand, TPK-14, AB610476e. Zeylanidium lichenoides (Kurz.) Engl. — KI-37, AB104582b. Z. subulatum (Gardner) C. Cusset — Pooyam Kutty R. near Kothamanglam, Ernakuram, Kerala, India, KI-219, AB610477e; SL-01, AB038202a.
Sources: a Kita & Kato (2001), b Kita & Kato (2004), c Koi et al. (2008), d Koi & Kato (2010), e present study.
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Koi, S., Kato, M. A taxonomic study of Podostemaceae subfamily Podostemoideae of Laos with phylogenetic analyses of Cladopus, Paracladopus and Polypleurum . Kew Bull 67, 331–365 (2012). https://doi.org/10.1007/s12225-012-9399-8
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DOI: https://doi.org/10.1007/s12225-012-9399-8