Canthium obscurum W.J.de Wilde & Duyfjes, 2021

Canthium obscurum W.J.de Wilde & Duyfjes View in CoL , sp. nov. — Fig. 1 View Fig , 2 View Fig

Canthium parvifolium auct . non Roxb.: Hook.f. (1882) 135, p.p.; Pit. (1924) 298; Craib (1932) 142; Sangratt. (2013) 17.

Canthium horridum auct . non Blume: T. Chen et al. (2011) 84.

This species differs from the somewhat resembling Canthium horridum Blume in its blackish drying colour (yellow-green in C. horridum ), dry fruits 1.5–3 cm diam (1–1.5 cm diam in C. horridum ), 2–5-flowered inflorescences (only 1

1 Naturalis Biodiversity Center, section Botany, P.O. Box 9517, 2300 RA Leiden, The Netherlands;

corresponding author e-mail: b.dewilde-duyfjes@naturalis.nl

or 2 flowers in C. horridum ). From Canthium parvifolium Roxb. it differs in its large fruit, ripening yellow-green (smaller and ripening red in C. parvifolium ). — Type: Gardner & Sidisunthorn 2098 (holo BKF117727 View Materials ; iso CMU n.v.), Thailand, Northern, Chiang Rai, approximately 1 km north of Payapri Village , 20 May 1997 .

Etymology. The specific epithet obscurum (Latin, obscurus = dark) refers to the blackish drying colour of the plant.

Shrub, 1.5–4 m tall, or treelet to 6(–8) m tall, older stem with or without straight spines to 7 cm long; twigs slender, appressed hairy when young, 1–2(–2.5) mm diam; spines usually present, straight, paired, 0.5–1 cm long. Stipules hairy, long-triangular, 2–3 mm long, acute-acuminate. Leaves in distinct pairs along the twigs; petiole slender, 0.3–0.7 cm long; lamina membranous, drying blackish, (variously) sparsely hairy on both surfaces, somewhat scabrous on upper surface, (obovate-) elliptic, 2–6 by 1.5–3 cm, base (more-or-less rounded or) cu- neate, narrowed into the petiole, margin sparsely hairy, apex rounded, bluntish or acute or acute-acuminate; midvein flat, hairy on upper surface, secondary veins 2–4 on each side. Inflorescence composed of 2–5-flowers, close together on a short brachyblast. Flowers creamy-greenish, 5-merous; bud glabrous, 4–5 mm long; pedicel slender, 1–2(–3) mm long, with 2 ± saucer-shaped connate bracteoles towards the apex; ovary glabrous, broadly obconical, 1–1.5 mm long; calyx: limb c. 0.5 mm long, lobes short-triangular; corolla: tube urceolate, c. 1.5 by 1.5 mm, constricted at throat, inside with a ring of deflexed hairs, c. 1 mm long, lobes reflexed, acute-acuminate, about as long as the tube; filaments c. 0.5 mm long, anthers c. 1 mm long; style 2–3 mm long, lower thickened half densely hairy; stigma green, c. 0.7 by 0.5 mm. Fruit subglobose or shortellipsoid, 1.5–3 cm diam, sparsely scattered, close to the twigs, ripening greenish yellow, blackish when dry.

Distribution — NE Myanmar, Thailand (Northern), Laos, Vietnam, southern China.

Habitat & Ecology — An understorey shrub or treelet of upland (degraded) mixed evergreen or deciduous forest, in pine forest and in dry dipterocarp-deciduous forest, also with bamboo; granite bedrock; 900–2100 m altitude. Flowering:April to June; fruiting: May to November.

Specimens studied (all Thailand). Chiang Rai,Doi Tung, Chamchumroon et al.VC 1537 (BKF); Chiang Mai, Doi Suthep National Park , Chamchumroon et al. VC 1651 ( BKF) ; Chiang Rai, Doi Tung, Chayamarit 905 ( BKF) ; Chiang Mai, Mae Pan Waterfalls, Fukuoka T 62307 ( BKF) ; Chiang Rai, Payapri , Gardner et al. 2098 ( BKF), type ; Chiang Mai, Doi Angka, Garrett 372 ( L, P) ; Chiang Mai, Doi Chiang Dao, Garrett 1179 ( L) ; Chiang Mai, Mae Rim, Glamwaewwong 120­60 ( QBG) ; Chiang Mai, Mae Rim, Glamwaewwong 261­58 ( QBG) ; Chiang Mai, Mae Rim, Glamwaewwong 960 ( QBG) ; Chiang Mai,Ban Mae Klang Luang, Hara et al. PJ 55 ( BKF) ; Chiang Rai, Doi Tung, Iwatsuki et al. T­10969 ( BKF, L) ; Chiang Mai, Samoeng , Jatupol K. 08 283 ( QBG) ; Chiang Mai, Huai Nam Dang National Park , Karaket et al.153 ( BKF) ; Chiang Mai, Doi Chiang Dao, Kerr 6646 ( BK) ; Phayao, Doi Pha Mon Noi, La­ongsri et al. 2852 ( QBG) ; Nan, Doi Tiu , Larsen et al. 43510 ( BKF) ; Chiang Rai, Doi Tung, Maxwell 05­309 ( BKF) ; Chiang Rai,Doi Tung, Maxwell 05­332 ( QBG) ; Chiang Rai, Maxwell 06­291 ( QBG) ; Chiang Mai, Doi Sutep, Maxwell 87­757 ( BKF, L) ; Chiang Mai, Doi Sutep, Maxwell 88­635 ( BKF, L) ; Chiang Mai, Doi Sutep, Maxwell 88­982 ( BKF, L) ; Chiang Mai, Doi Mawn Angget, Maxwell 93­426 ( BKF) ; Chiang Mai, Doi Meun, Maxwell 95­327 ( BKF) ; Chiang Rai, Doi Luang National Park , Maxwell 97­485 ( BKF, L) ; Chiang Rai, Doi Luang National Park , Maxwell 98­563 ( BKF, L) ; Lampang, Jae Sawn National Park , Maxwell 96­1251 ( BKF) ; Chiang Mai, Huay Yah Dtai, Maxwell 98­638 ( BKF, L) ; Phayao, Doi Luang National Park , Muangyen 273 ( QBG) ; Chiang Mai,Pha Mawn, Murata et al. T 15637 ( BKF) ; Chiang Mai, Mae Rim, Botanic Garden, Nanakorn et al. 153 ( QBG) ; Chiang Mai, Pong Yen, Nanakorn et al. 1379 ( QBG) ; Chiang Mai, Chiang Dao, Nanakorn et al. 1864 ( QBG) ; Chiang Mai, Baan Karen Huai Phachao, Mae Tang, Nanakorn et al. 5014 ( QBG) ; Chiang Mai, Chiang Dao, Nanakorn et al. 9393 ( QBG) ; Nguanchoo 254 ( BK, QBG) ; Nan, Ban kew Num, Nguanchoo 971 ( QBG) ; Nam, Phu Ka , Niyomdham et al. 7686­1 ( BKF) ; Phayao, Doi Luang National Park , Norsaengsri 12280 ( QBG) ; Chiang Mai, Chiang Dao, Norsaengsri et al. 1470 ( QBG) ; Chiang Mai, Mae Rim, Norsaengsri et al. 9176 ( QBG) ; Chiang Rai, Doi Luang National Park , Palee 436 ( BKF, L) ; Chiang Rai, Mae Fah Luang, Phaosrichai et al. 984 ( QBG) ; Chiang Mai, Doi Intanon National Park , Phengklai et al. 6205 ( BKF) ; Chiang Mai, Doi Intanon National Park , Phengklai et al. 6793 ( BKF) ; Nan, Doi Phu Ka National Park , Phonsena et al. 7486 ( BKF, L) ; Chiang Mai, Fang, Pongamornkul 2632 ( QBG) ; Phayao, Doi Pha Tang, Pongamornkul 6164 ( QBG) ; Chiang Mai, Mae On, Pongamornkul et al. WP 406 ( QBG) ; Chiang Mai, Mom Lhong, Pongamornkul WP 95 ( QBG) ; Chiang Mai, Doi Suthep, Pongamornkul WP 331 ( QBG) ; Chiang Mai, Doi Suthep-Pui National Park , Pooma 344 ( BKF) ; Chiang Mai, Mae Sruai, Prayad 930 ( BK) ; Mae Hong Son, Pang Tawn, Put 3847 ( BK, L) ; Chiang Mai, Huai Nam Dang, Santisuk 1055 ( BKF) ; Chiang Mai, Mae Rim, Seepacha YJ 1 ( QBG) ; Chiang Mai, Doi Chang, Shimizu et al. T­20818 ( L) ; Chiang Mai, Mae Rim, Serm 48 ( QBG) ; Nan, Bo Klua , Sirimongkol et al.645 ( BKF) ; Chiang Mai,Mawn Kia, Smitinand et al. 6733 ( BKF) ; Chiang Mai, Doi Suthep, S Ø rensen et al.3068 ( BKF) ; Nan, Joon Village , Srithi 298 ( QBG) ; Nan, Ban Pong Kham , Trisonthi et al. PK 182 ( QBG) ; Chiang Rai, Doi Tung, Van de Bult 1254 ( BKF) ; Chiang Mai, Doi Suthep, Vanpruk s.n., May 1941 ( BKF) ; Chiang Mai, Ban Mae Klang Luang, Vidal et al. 6173 ( BKF) ; Chiang Mai, Ban Ang Ka Noy, Vidal et al. 6289 ( BKF, L) ; Chiang Rai, Doi Tung, Watthana 315 ( QBG) .

Notes — 1. Canthium obscurum is a common species of (sub)- montane northern Thailand, known from about 70 collections.

2. The ripe fruit when fresh is recorded as not juicy but with a spongy white endocarp, yellowish green or yellow, globose or obovate, 2–4 cm diam. The majority of the specimens dry conspicuously blackish.