Two new species of Indigofera L. (Leguminosae) from the Sneeuberg Centre of Floristic Endemism, Great Escarpment (Eastern and Western Cape, South Africa)
Author
Clark, V. Ralph
Institut fuer Systematische Botanik, Zollikerstrasse 107, Universitaet Zuerich, 8008 Zuerich, Switzerland & Great Escarpment Biodiversity Programme, Department of Botany, Rhodes University, Grahamstown, 6140, South Africa
Author
Schrire, Brian D.
Author
Barker, Nigel P.
Great Escarpment Biodiversity Programme, Department of Botany, Rhodes University, Grahamstown, 6140, South Africa
text
PhytoKeys
2015
2015-04-02
48
29
41
http://dx.doi.org/10.3897/phytokeys.48.4798
journal article
http://dx.doi.org/10.3897/phytokeys.48.4798
1314-2003-48-29
D0663A74B14AB200CE08FF95FFEDFF85
576276
Indigofera magnifica Schrire & V.R. Clark
sp. nov.
Figs 1
, 2
; Plate 1
Diagnostic characters.
Indigofera magnifica
is morphologically similar and most closely related to
Indigofera meyeriana
Eckl. & Zeyh., but differs in its prostrate, compact, densely matted habit (vs. laxly spreading, less dense and diffuse habit), sparsely to moderately strigose becoming reddish-maroon and glabrescent stems (vs. green-grey to canescent), fewer flowers (
+/-
3-8) per raceme (vs.>8), brighter, more vivid pink flowers (vs. paler pink), and sparsely, appressed hairy pods (vs. spreading hairy pods). The overall colour of plants of
Indigofera magnifica
is a darker green than the generally grey-green to grey appearance of
Indigofera meyeriana
.
Indigofera meyeriana
is common and widespread in the Western Cape and western Northern Cape Provinces, and also occurs on the Sneeuberg.
Type.
South Africa, Western Cape Province, 3224AA, Plaas 113: summit plateau of the Koudeveldberge, Murraysburg District, Sneeuberg.
32°10'32"S
,
24°01'41"E
, 2134 m, 9 December 2011,
Clark VR & Moholwa TT 206
(K, holotype; GRA, MO, NBG, NSW, PRE, S, isotypes).
Description.
Prostrate suffrutex
20-50 mm tall, densely to laxly matted, much branched.
Stems
slender, terete to ribbed, sparsely to moderately strigose with whitish biramous hairs, glabrescent later, reddish-maroon; stoloniferous, often rooting from nodes, arising from a woody rootstock.
Leaves
alternate, digitately trifoliolate, petiole 2-8 mm long, scattered with pearl bodies at base of leaflets.
Stipules
1-2 mm long, up to 0.5 mm wide at base, lanceolate, attenuate, falcate, often recurved at apex,
+/-
membranaceous, gland-tipped, reddish.
Stipels
absent.
Terminal leaflet
1.5-5.5 mm
x
1-3 mm, obovate, apex emarginate, truncate or rounded, base cuneate, upper surface glabrous or sparsely appressed strigose, paler than below; lower surface more densely strigose and slightly rugose; margins somewhat thickened, often appearing slightly involute, often reddish; lateral leaflets similar.
Racemes
(10)20-70 mm long, many times longer than the subtending leaf, including a peduncle of (6)11-55 mm, becoming flattened, appearing soft-tissued on drying;
+/-
3-8 flowered; bracts 0.5-1.5 mm long, lanceolate-subulate, recurved at apex, caducous.
Pedicels
0.75-1.5 mm long, becoming recurved in fruit.
Flowers
4.5-6.5 mm long.
Corolla
vivid fuchsia-pink.
Calyx
1.5-2.5 mm long, lobes triangular, 0.75-1.4 mm,
+/-
equaling the tube,
+/-
sparsely strigose appressed.
Standard
5.5-6.5 mm long, up to 5 mm wide, broadly obovate, tapering to a short claw at the base; blade sharply reflexed upwards for distal half of length; apex rounded to emarginate; dorsal surface glabrous, often with translucent, short stripes.
Wings
5-6 mm long, unguiculate, shortly clawed at base, asymmetrically obovate towards apex.
Keel petals
5-6.5 mm long, valvately connate distally, lateral spurs to 1 mm long, distal margin curving upwards to base of the keel to an obtuse apex; claws
+/-
2 mm long, broadening from the base.
Stamens
4-5 mm long, alternately long and short, the 9 fused stamens free for
+/-
1 mm distally; anthers uniform.
Ovary
densely strigilose laterally, glabrous along upper margin; stigma capitate.
Pods
(9)11-15 mm long, up to 3.5 mm wide, cylindrical, inflated, shiny, reddish-green becoming reddish-brown, sparsely strigose, explosively dehiscent with the valves twisting.
Seeds
4-6, 1.5
x
1.5 mm,
+/-
quadrate, dark green.
Figure 1.
Analytical drawings of
Indigofera magnifica
Schrire & V.R. Clark, all drawn from the type collection (
Clark VR & Moholwa TT 206
)
A
growth habit
B
stoloniferous habit
C
trifoliolate leaf with stipules
D
terminal leaflet, underside
E
flower, front view
F
bud, side view
G
calyx
H
standard petal
I
wing petal
J
keel
K
staminal sheath
L
pistil
M
infructescence
N
pod
O
dehiscent pod
P
seed. Drawings by M. Tebbs.
Plate 1.
Indigofera magnifica
Schrire & V.R. Clark, plants
in situ
on the Koudeveldberge, Sneeuberg (Western Cape Province;
Clark VR & Moholwa TT 206
)
A
inflorescence
B
fruits
C
typical prostrate growth habit
D
mountain summit habitat. Photographs by V.R. Clark.
Etymology.
The specific epithet
magnifica
is derived from the Latin adjective
magnicus
-
a
-
um
(a. splendid, magnificent) and is named for the magnificent, showy, vivid fuchsia-pink flowers.
Distribution and ecology.
Indigofera magnifica
is confined to the summit plateau of the Toorberg-Koudeveld-Meelberg in the western Sneeuberg, between 1700-2150 m. The species is occasional to abundant, found exclusively on the dolerite-derived loamy-clays and black turf soils typical of this plateau. The vegetation type is Karoo Escarpment Grassland (Gh1,
Mucina and Rutherford 2006
), typical of high altitudes in the Sneeuberg mountain complex, with the dominant grass species being
Tenaxia
(=
Merxmuellera
)
disticha
(Nees) N.P. Barker & H.P. Linder.
Indigofera magnifica
is particularly abundant on the highest parts of the plateau near the eastern and southern scarps, where it forms large colonies. It compliments a suite of several local endemics only found in the western Sneeuberg, including
Acmadenia
sp. nov.,
Erica passerinoides
(Bolus) E.G.H. Oliv.,
Euryops dentatus
B. Nord. and
Faurea recondita
Rourke & V.R. Clark (
Clark et al. 2009
,
2012
,
Rourke et al. 2013
).
Figure 2.
Known distributions of
Indigofera magnifica
Schrire & V.R. Clark (△) and
Indigofera asantasanensis
Schrire & V.R. Clark (○).
Conservation status.
While the extent of occurrence (EOO) of
Indigofera magnifica
is small (ca. 30 km2), it is common (probably>10 000 individuals) in its restricted area. There are no obvious risks from the current land-use of livestock grazing: plants do not show evidence of damage from foraging or trampling. The remote, rocky high-altitude habitat renders it relatively safe from other detrimental land-use. Already restricted to summit elevations, it is however potentially at risk from global climate change. Any potential wind farm proposals for the Toorberg-Koudeveld-Meelberg would place this species at serious risk. The category VULNERABLE (Vu D2) is thus recommended.
Further collections and localities.
South Africa, Western Cape Province (straddling the provincial boundary with the Eastern Cape Province), 3223BB & 3224AA, Farms Plaas 113, Annex Koudeveld 114, Koudvelds Hoogte 117, Annex Onder Hoogde 116: summit plateau of the Koudeveldberge and Meelberg, Graaff-Reinet and Murraysburg Districts, Sneeuberg. ca. 32°10-11'S 23°59'E, ca. 2100 m, 25 November 2006,
Clark VR & Te Water
Naude
T 335
(GRA, K).
-Western Cape Province, 3224AA, Farm Quaggas Drift 108: Toorberg summit plateau, next to stream ca. 100 m from edge of escarpment, Murraysburg District, Sneeuberg.
32°08'46"S
,
24°04'31"E
, 1780 m, December 2007,
Clark VR & Pienaar C 511
(GRA, K).