A revision of Rhapis (Arecaceae)
Author
Henderson, Andrew
text
Phytotaxa
2016
2016-04-28
258
2
137
152
http://dx.doi.org/10.11646/phytotaxa.258.2.3
journal article
10.11646/phytotaxa.258.2.3
1179-3163
13669842
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
.