Lasianthus repoeuensis Pierre ex Pit. (1924: 387)

Dang, Van-Son & Naiki, Akiyo, 2023, A revision of the genus Lasianthus Jack (Rubiaceae) from Vietnam, Phytotaxa 581 (1), pp. 1921-1935 : 1921-1935

57. Lasianthus repoeuensis Pierre ex Pit. (1924: 387) — Fig. 86 (plate), Fig. 84 (map)

Type: — CAMBODIA. Monitbus Knang Krepoeu , 800 m elev., May 1870, Pierre 1257 (holotype P! [P02285238]; isotypes A! [A00096531], P! [P03981159, P03981160]) .

Specimens examined: — VIETNAM. Southern: Kien Giang Province, Phu Quoc National Park, 405 m elev., 10 October 2019, Dang V.S., Dang 430 ( VNM); in the same location, 405 m elev., 11 October 2019, Dang V.S., Dang 430a ( VNM) .

Distribution: —Campuchia, Thailand, and Vietnam (Kien Giang).

Habitat & Ecology: —Growing in the shade of evergreen forest or the edge of the forest at 300–500 m elev. Lasianthus repoeuensis was collected from the forest habitat dominated by species Antidesma laurifolium Airy Shaw (1972: 356) , Ardisia sanguinolenta Blume (1826: 685) , Lasianthus hirsutus (Roxb.) Merr. (1952: 229) , Phyllanthus reticulatus Poir. (1804: 298) , Psychotria cambodiana Pierre ex Pit. (1924: 359) , Rauwenhoffia siamensis Scheff. (1885: 23) , Uvaria rufa Blume (1828: 13c), Strophanthus divaricatus Hook. & Arn. (1837: 199) , Erythroxylum cambodianum Pierre (1893: 282) , Croton heterocarpus Müll.Arg. (1866: 621) , Syzygium bullockii (Hance) Merr. & L.M.Perry (1938: 107) , Campylospermum striatum (Tiegh.) M.C.E.Amaral (2007: 362) , Ixora grandifolia Zoll. & Moritzi (1846: 65) , Glycosmis gracilis B.C.Stone (1985: 10) , Micromelum minutum (G.Forst.) Wight & Arn. (1834: 448) .

Phenology: —Flowering and fruiting from May to November.

Vernacular name: —Xú hưƠng nhiễu gân.

Notes: — Lasianthus repoeuensis was described in 1924 by Pierre ex Pitard (Pierre 1257). This species can easily be recognized from other species of Lasianthus in having lanceolate to oblong-elliptic leaves, secondary veins 14–16 on each side of midrib, stipules broadly triangular, bracts extremely short, hairy, calyx obconical, and fruits globose, crowned by calyx lobes.

Figures

FIGURE 84. Distribution maps of Lasianthus phamhoangii, L. pierrei, L. repoeuensis and L. rhinocerotis subsp. pedunculatus.

FIGURE 86. Lasianthus repoeuensis Pierre ex Pit. (from Dang 430, VNM): A. Branch with fruits, B. Close-up of young branch and leaves, C. Stipules, D. Abaxial leaf surfaces, E. Young fruits, F–G. Fruits.