Literature: — Prain (1891: 210), Brandis (1906: 159), Craib (1926: 280), Tardieu-Blot (1948: 785), Fan (2006: 254, fig. 67 1 – 2), Ho (2003: 145, fig. 4512), Kress et al. (2003: 191), Gardner et al. (2007: 128, fig. and photo 255, 2015: 323, fig. and photo 491); Ma et al. (2008: 464), Hou et al. (2010: 163, fig. 7); Savinov (2014: 187).

Basionym: — Euonymus sclerocarpus Kurz (1872: 299). Kurz (1877: 250).

TYPE: — BURMA [MYANMAR]. [Bago region]: Pegu, 23 February, S. Kurz 1923 (lectotype: CAL: CAL0000007365!, designated here; isolectotypes: CAL: CAL0000007366!, CAL0000007367!, CAL0000007377!, K: K000669663!, K000669664!).

Nomenclatural notes:—The protologue of Euonymus sclerocarpus (Kurz 1872) includes a description of the species together with the type locality as “ Pegu ” (Myanmar). Kurz visited Burma (Myanmar) in 1867–1868 and 1870–1871 (Grout 2004). Six duplicates of the collection Kurz 1923 matching the protologue description and collected in Pegu, Myanmar, were found at CAL (CAL0000007365, CAL0000007366, CAL0000007367, CAL0000007377) and K (K000669663, K000669664). These specimens include the name “ Glyptopetalum sclerocarpum Kurz ” written in Kurz’s handwriting, as confirmed by checking van Steenis-Kruseman & van Steenis (1950, p. CL); this name (combination) was indicated in the protologue as provisional: “ Evonymus (Glyptopetalum) sclerocarpum ” (Kurz 1872). Though labels of these specimens do not include collection date, the two duplicates kept in K contain the date of material reception by Kew stuff from Kurz in Calcutta: 15 August 1872, which is after Kurz’s expeditions to Burma and before publication of the protologue (Kurz 1872). Therefore, these specimens are expected to have been used in the protologue.

We select the CAL specimen (barcode CAL0000007365; Fig. 1) as the lectotype since it is the only specimen bearing both fruit and inflorescence with flower buds. Other specimens (at CAL and K) are isolectotypes.

Ecology and phenology:—Evergreen, broad-leaved and mixed forests, in moist shady areas, sometimes on limestone; 100–2500 m. Flowering and fruiting all year round.

Distribution:— MYANMAR (Bago region), THAILAND (provinces: Mae Hong Son, Chiang Mai, Chiang Rai, Lamphun, Lampang, Phrae, Uttaradit, Kamphaeng Phet, Uthai Thani, Phetchabun, Chaiyaphum, Prachinburi, Chonburi, Chanthaburi), LAOS (Bolikhamsai province), CAMBODIA (Kampong Speu province), VIETNAM (provinces: Lai Chau, Cao Bang, Son La, Thai Nguyen, Thanh Hoa, Lam Dong), CHINA (Yunnan, Guangxi).

Distribution of G. sclerocarpum is presented in Fig. 2, basing exclusively on the specimens examined in our study (see Appendix). This map also includes all known specimens of G. vidalii, a species which is morphologically very close to G. sclerocarpum and not yet fully understood. The type locality of G. vidalii is Vang Vieng area in Laos (Vientiane province); the other specimens provisionally assigned here to this species are found in Chiang Rai, Nan and Kanchanaburi provinces of Thailand.

The occurrence of G. sclerocarpum in Laos was documented only recently; this record was published by Tagane et al. (2017). Only one of their specimens (Tagane et al. L1061, FOF) was cited, while the other one collected in the same location (Tagane et al. L1057, FOF) was not referred and may be identified by the authors as other species of this genus.

The current treatment appears to be the first work which confirms the presence of G. sclerocarpum in Vietnam by citing its specimens, though it was previously reported by Ho (2003) and Hou et al. (2010). Meanwhile, G. sclerocarpum is most likely widely distributed in this country, currently known in five provinces of northern Vietnam and one province of southern Vietnam.

The presence of this species in Guangxi, China (Fig. 3) is reported here for the first time.

The specimens of G. sclerocarpum from Vietnam and Guangxi of China significantly expand its known distribution range eastward. The specimen Gardner et al. 149 from Lam Dong is the most eastern one, while Nuraliev et al. G80 from Guangxi is the most eastern within China.

A number of records at the level of provinces or regions which are found in earlier works are not confirmed in our study; they can possibly be represented by some collections overlooked here. These are Phangnga province of Thailand (Hou et al. 2010) and Mandalay Region of Myanmar (Kress et al. 2003). Gardner et al. (2015) included G. sclerocarpum into their book dedicated to the Thai section of the Malay Peninsula; this is most likely based on indication of Phangnga province mentioned above. However, we were not able to locate any specimens of this species from Peninsular Thailand. The report of G. sclerocarpum from Kanchanaburi province of Thailand (Hou et al. 2010) most likely corresponds to the specimens assigned earlier to this species but here treated as G. vidalii (see also Savinov 2014). Finally, we could not match any specimen of G. sclerocarpum with the Cocos Island mentioned by Tardieu-Blot (1948), which most likely refers to the Coco Islands belonging to Myanmar.

Though G. sclerocarpum is indicated to occur in India in “Flora of China ” (Hou et al. 2010), this report is not confirmed by any other treatment, and no specimen of this species from India is available. This inconsistence may originate from the fact that the combination Glyptopetalum sclerocarpum was originally published in “Flora of British India ” (Lawson 1875); British India included the territory of modern Myanmar, where the type of this species was collected.