Rhapis humilis Blume (1836: 54)

Henderson, Andrew, 2016, A revision of Rhapis (Arecaceae), Phytotaxa 258 (2), pp. 137-152 : 143

4. Rhapis humilis Blume (1836: 54) . Lectotype (designated here):— JAPAN. No locality, no date, C. Thunberg sheet number 24385 (lectotype UPS n.v., UPS image!)

Rhapis multifida Burret (1937: 588) . Type:— CHINA. Guangxi: Chen Bien, 21 November 1935, S. Ko 56092 (holotype B, destroyed). Neotype (designated here):— CHINA. Guangxi: Loh Hoh Tsuen , Lin Yun Hsien , 1150 m, 26 May 1933, A. Steward & H. Cheo 518 (neotype A!).

Stems length and diameter not recorded. Leaf ligules acute, soon disintegrating; petioles 33.9(31.7–36.0) cm long, 3.9(2.7–5.0) mm wide at the apex; abaxial hastula usually complete, a low ridge separating petiole apex from costa; segments 18(13–28) per leaf; central segments narrowly linear, usually 1–2-veined, acuminate, the apices scarcely toothed, 34.8(31.5–40.0) cm long, 1.8(1.1–2.7) cm wide at midpoint, joined at the base, the non-split basal part 7.5(5.0– 10.5) cm; lateral segments 26.0 cm long, 1.8(0.8–2.4) cm wide at midpoint, the non-split basal part 3.6(2.5–5.3) cm; abaxial surface of segments without scales, not indumentose when first exposed. Inflorescences small to large, with the first branch almost as large as the rest of the inflorescence; prophyll and peduncular bract narrow, tubular, not or scarcely overlapping, the inflorescences exerted apically through the bracts on a curved peduncle; rachis 23.8(21.0– 26.5) cm long; rachillae filiform, usually tomentose, especially the staminate ones; proximal rachilla 8.2(6.0–10.5) cm long, 0.9(0.9–1.0) mm wide; staminate and pistillate flowers sessile; staminate and pistillate corollas with poorly developed, inturned apical lobes, these not swollen internally; filaments not recorded; fruits globose, yellow, 7.0 mm long, 7.0 mm diameter, borne on a pedicelliform pistillate corolla.

Distribution and habitat:— China (Guangxi, Guizhou, Yunnan)( Fig. 2 ) in montane forest on steep, rocky slopes at 1105(915–1250) m elevation.

Taxonomic notes:— Blume established Rhapis humilis without designating a type, and Hastings (2003) considered that lectotypification was necessary. She stated that a Thunberg collection (sheet number 24385 at UPS), comprising a leaf and partial inflorescence, matched the protologue. However, she did not designate this specimen as lectotype, and instead gave a different specimen, Thunberg s.n. from L, as the type of R. humilis . In the circumstances it seems best to designate the UPS Thunberg specimen (sheet number 24385) as lectotype of R. humilis .

Rhapis multifida is here included in synonymy. The holotype at B was destroyed, and an isotype has not been found at either IBSC, KUN, or SYS, and the type is presumed destroyed. A neotype is here designated, from the same province (Guangxi) although the original type locality has not been found on maps or gazetteers.

All specimens of Rhapis humilis cited by Hastings are from cultivated plants except Morse 380 at K, but this clearly belongs to R. robusta (and is from the type locality of that species).

Only one specimen (Feng 13462 at A) records fruit color, and is given as yellow, although cultivated plants of R. humilis have white fruits.

Hastings (2003) distinguished R. multifida from R. humilis based on leaf sheath fibers, inflorescence branching, and calyx lobing. Rhapis multifida was said to have leaf sheaths with coarse outer and fine inner fibers, inflorescences branching to 2 orders, and irregularly lobed calyces. Rhapis humilis was said to have leaf sheaths with similar fibers, inflorescences branched to 3(–4) orders, and regularly lobed calyces. However, a specimen cited by Hastings as R. multifida, Steward 518 at A (mistakenly given as 158) has all the character states of R. humilis ; and a specimen cited as R. humilis, Chow 6249 at A, has all the states of R. multifida . Although this last specimen lacks leaf sheaths, another from the same locality, Fang 2347 at A, has leaf sheaths with coarse outer and fine inner fibers. Hastings also used some inflorescence characters, but it has not been possible here to distinguish between “bracts large, thick, dark brown; rachis pale brown with pale brown tomentum” for R. multifida and “bracts of relatively medium thickness, pale brown with darker patches; rachis dark brown and bearing rusty brown tomentum” for R. humilis .

Figures

FIGURE 2. Distribution maps of Rhapis evansii, R. excelsa, R. gracilis, and R. humilis.