Lasianthus helferi Hooker

Napiroon, Tiwtawat, Chayamarit, Kongkanda, Dawson, Sally, Till, Walter & Balslev, Henrik, 2020, A synopsis of Lasianthus (Lasiantheae, Rubiaceae) in Thailand and two additional new species, Phytotaxa 439 (1), pp. 1-38 : 16-17

23. Lasianthus helferi Hooker filius (1880:189). Type (lectotype designated by Deb & Gongopadhyay 1991):― MYANMAR. Andaman islands , Tennaserrim, s. d., J. W. Helfer 2921 (lectotype K000031677!; isolectotype M0198176 image!, GH00055291 image!).

T hailand: ―PENINSULAR. Ranong: Ngao waterfall, 8 July 1992, K. Larsen et al. 43224 (AAU, BKF, PSU).

Distribution: ― India, Myanmar, Thailand (Peninsular).

Ecology: ―Evergreen forest in shaded places at an elevation of 100‒ 300 m. Flowering in July.

Notes: ― Lasianthus helferi was first recorded in Thailand by Zhu (2001) and we have not found any additional specimens in any herbarium. Here, we accept this species based on the description which shows that it is different from other species. It is also accepted in the World Checklist of Selected Plant Families (http://wcsp.science.kew.org/).

Lasianthus helferi is closely related to L. verticillatus (Lour.) Merr. (1935:372) but it differs by being densely hispid on the midrib and veins abaxially and having globose, small 0.4‒0.5 cm long, drupes with 6 pyrenes, while L. verticillatus is glabrous or thinly pubescent abaxially on the leaves and has subglobose, 0.8‒1 cm long, drupes with 4‒5 pyrenes.