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A New Species of Pavetta (Rubiaceae) from South Africa
Stefan J. Siebert
A. P. Goossens Herbarium, School of Environmental Sciences and Development, North-West
University, Private Bag X6001, Potchefstroom 2520, South Africa.
Corresponding author: stefan.siebert@nwu.ac.za
Elizabeth Retief
National Herbarium, South African National Biodiversity Institute, Private Bag X101, Pretoria
0001, South Africa. E.Retief@sanbi.org.za
Abraham E. van Wyk
H. G. W. J. Schweickerdt Herbarium, Department of Plant Science, University of Pretoria, Pretoria
0002, South Africa. braam.vanwyk@up.ac.za
ABSTRACT. Pavetta glaucophylla Retief, S. J. Siebert
& A. E. van Wyk, a new species of the Rubiaceae
(Ixoroideae) from South Africa, is described and
illustrated. A member of Pavetta L. subg. Pavetta,it
has a restricted range and is near endemic to the
Sekhukhuneland Centre of Endemism. Hitherto P.
glaucophylla has mainly been confused with P.
zeyheri Sond., from which it differs in being a taller
plant with larger, blue-green lea ves in living
condition instead of dark green to gray-green leaves
and flowers in which the calyx lobes are 0.5–0.75 mm
long and triangular-ovate, and 1.25–2 mm long and
not triangular-lanceolate, as in P. zeyheri.
Key words: IUCN Red List, Pavetta, Rubiaceae,
Sekhukhuneland, South Africa.
The rubiaceous genus Pavetta L. belongs to
subfamily Ixoroideae, tribe Pavetteae, and comprises
ca. 400 species from the Old World tropics,
excluding Madagascar (Retief & Leistner, 2000;
Bridson, 2003). Sub-Saharan Africa is a center of
diversity for the genus, with 21 described species
known from South Africa, all restricted to the summer
rainfall area (Germishuizen et al., 2006). Although
not as diverse as it is further north in Africa, Pavetta
is the largest of the 53 genera of Rubiaceae native to
South Africa (Germishuizen et al., 2006). Members of
Pavetta are trees, shrubs, or dwarf shrubs (geoxylic
suffrutices), and the majority are, among others,
readily distinguished from most other woody Rubia-
ceae by the presence of symbiotic bacterial nodules
in the leaf blades (Bridson, 2003). The genus is
further characterized by stipules partly to completely
connate, mostly long-acuminate to awned; terminal,
umbellate inflorescences with numerous fragrant,
tetramerous flowers with secondary pollen presenta-
tion (on style), usually white, contorted corolla lobes,
and a style at least twice as long as the corolla (Retief
& Leistner, 2000). The calyx limbs of Pavetta have
four distinct lobes, and the fruit are fleshy, 2-seeded,
and indehiscent (Retief & Leistner, 2000). Even
though general floral morphology is very similar in
Pavetta, the calyx is quite variable and provides some
of the best criteria for the infrageneric classification
of the group (Bremekamp, 1929; Bridson, 2003).
In southern Africa a number of Pavetta species
with restricted range are known from recognized
centers of floristic endemism (van Wyk & Smith,
2001), for example, P. tshikondeni N. Hahn from the
Soutpansberg Centre of Endemism (Hahn, 1999) and
P. barbertonensis Bremek. from the Barberton Centre
of Endemism (Bremekamp, 1929). In this paper we
describe a new species of Pavetta near endemic to the
Sekhukhuneland Centre of Endemism in northeastern
South Africa. In the past, this species often has been
included under P. zeyheri Sond., but Siebert et al.
(2001) and von Breitenbach et al. (2001) first
recognized it as an undescribed species in the
literature. Subsequently, Schmidt et al. (2002: 642)
referred to it as a ‘‘large-leaved form’’ of P. zeyheri
that ‘‘may prove after further research to be a distinct
species.’’ Coates Palgrave (2002) also mentions the
Sekhukhuneland taxon under P. zeyheri but specu-
lates that it is probably conspecific with P. micro-
lancea K. Schum., a taxon known only from the type
specimen collected at Komatipoort in easternmost
Mpumalanga (Bridson, 2003), outside the range of the
new species. A possible link between the new species
and P. microlancea is refuted by Herman (2005),
based on the generally smaller habit, 0.3–1 m, of the
latter species, and on P. microlancea having fewer-
flowered (four to six) umbellate inflorescences, as is
doi: 10.3417/2011025 NOVON 22: 473–477. PUBLISHED ON 18 OCTOBER 2013.
also indicated by Bridson (2003). Herman (2005)
suggests that our new species, already collected as
early as 1939 (Mogg 725, PRE), has been dumped
into a taxonomic ‘‘waste bin,’’ namely P. zeyheri.
Pavetta glaucophylla Retief, S. J. Siebert & A. E.
van Wyk, sp. nov. TYPE: S outh Africa.
Mpumalanga: Sekhukhuneland, Thorncliffe
Mine, entrance rd., 1 Dec. 1997 (fl., fr.), J. E.
Burrows 6198 (holotype, PRE; isotype, BNRH).
Figure 1.
Species nova secundum morphologiam generalem Pavet-
tae zeyheri Sond. proxima, sed ab ea habitu robustiore
altioreque, foliis majoribus conspicue glaucis (46–)
72(116) 3 (7–)13(25) mm et limbo calycis usque ad
medium in lobos breviores (0.5–0.75 mm) triangulari-ovatos
(non triangulari-lanceolatos) diviso differt.
Erect, deciduous shrub or small tree, (1.5–)
2.5(3.5) m tall; young twigs glabrous; branches
thick, robust. Leaves opposite, sometimes appearing
fascicled, sessile, glabrous; lamina narrowly elliptic
to oblanceolate, (49–)72(93) 3 (8–)13(21) mm,
coriaceous, blue-green in living conditi on, apex
acute, base decurrent, margin entire; midrib on lower
surface pale and prominent; domatia absent; bacterial
nodules dotlike or elliptical, unevenly scattered in
lamina; stipules interpetiolar, limb triangular. Inflo-
rescences sub-umbellate, branched, (32–)37(44)
mm wide; primary inflorescence branches 4–6 mm;
flowers (14–)17(21) clustered on short side branch-
es 10–30 mm long; peduncles 6–8 mm; pedicels 3.5–
4.5 mm; bracts up to 2 mm, densely white silky-hairy
to almost glabrous inside; bracteoles present but
inconspicuous. Flowers (14–)17(21) per inflores-
cence; calyx 4-lobed, lobes short, triangular-ovate,
0.5–0.75 mm, glabrous, persistent in fruit, never
reflexing; corolla 4-lobed, white, tube cylindrical,
(10–)13(15) mm, lobes (15–)19(23) mm; style
slender, distally slightly thickened into an elongated
club-shaped pollen presenter, (21–)26(32) mm;
stigmatic surface confined to bidentate apex; stamens
4, arising in corolla mouth; filaments very short;
anthers exserted, dorsifixed near the base, linear to
oblong, 5–6 mm. Fruit a drupe, spherical, slightly 2-
lobed, (5–)6(8) 3 (5–)7(8) mm, black when ripe,
with 1 or 2 pyrenes.
Distribution and habitat. Pavetta glaucophylla
has been collected in the provinces of Mpumalanga
and Limpopo in South Africa (Fig. 2) on calcrete,
dolerite, dolomite, gabbro norite, magnetite, and,
rarely, shale. It is common on stony, rocky soil in
open mountain savanna (bushveld), rarely as part of
copses of woody vegetation in grassland, and has
been recorded from 500 to 1200 m. The species is
confinedtothatpartoftheCentralBushveld
Bioregion associated with the northeastern Great
Escarpment of South Africa, specifically the following
vegetation units: Sekhukhune Mountain Bushveld,
Sekhukhune Plains Bushveld, and Ohrigstad Moun-
tain Bushveld (Mucina & Rutherford, 2006). Biogeo-
graphically, it is near endemic to the Sekhukhune-
land Centre of Endemism (mainly on ultramafic
substrates), where it ranges, usually on dolomite, into
the bordering Wolkberg Centre (van Wyk & Smith,
2001).
IUCN Red List category. Pavetta glaucophylla is
assessed as of Least Concern (LC) according to IUCN
RedListcriteria(2001)duetotheextentof
occurrence, area of occupancy, and the existence of
more than 30 known populations (Siebert et al.,
2002). Pavetta glaucophylla is, however, increasingly
subjected to habitat degradation as a result of
extensive mining activities and urban expansion in
the Sekhukhuneland region.
Phenology. Flowers of Pavetta glaucophylla were
collected in early summer (November and December)
and fruits in summer and autumn (January to May).
Etymology. The epithet glaucophylla derives
from the Greek and refers to the conspicuous blue-
green foliage leaves of the species.
Vernacular names. The local Pedi use the leaves
of Pavetta glaucophylla as a vege table, and in
Northern Sotho (Sepedi) the plant is called mabudel-
alelane, with budela meaning ‘‘sour,’’ a reference to
the watercress-like taste of the leaves (from Barnard
1446, PRE). English and Afrikaans vernacular
names for the species are Sekhukhune bride’s bush
and sekhukhunebruidsbos, respectively (van Wyk et
al., 2011).
Discussion. Older herbarium collections of Pa-
vetta glaucophylla are mainly identified as P. zeyheri,
and, more particularly, the infraspecific entity is
sometimes recognized as P. zeyheri subsp. zeyheri
(Herman, 2005). The two species are superficially
rather similar owing to resemblances in gross
morphology and geographical distribution. Differenc-
es between P. glaucophylla and P. zeyheri include
the distinctly blue-green and larger, (49–)72(93) 3
(8–)13(21) mm, leaves of the former, compared to
the dull dark-green to gray-green and smaller,
(24–)38(50) 3 (7–)8(11) mm, leaves of the latter.
In P. glaucophylla the calyx limb-tube is divided at
midpoint into relatively short (0.5–0.75 mm), trian-
474 Novon
gular-ovate lobes, but in P. zeyheri the calyx limb-
tube is shorter than the lobes, with the lobes
relatively long (1.25–2 mm) and triangular-lanceolate
(for calyx limb types in southern African Pavetta, see
Bridson, 2003). Pavetta glaucophylla is also a more
robust and larger plant, (1.5–)2.5(3.5) m high, with
P. zeyheri generally slender and smaller, (1–)2(3) m
high.
Figure 1. Pavetta glaucophylla Retief, S. J. Siebert & A. E. van Wyk. —A. Flowering branch. —B. Flower. —C. Calyx. —D.
Pollen presenter with cleft stigma apically. —E. Fruiting branch. —F. Fruit. —G. Stipule. A–D, G drawn from the holotype, J.
E. Burrows 6198 (PRE); E, F from A. E. van Wyk 12367 (MO). Scale bars: A, E ¼ 10 mm; B–D, F, G ¼ 1 mm.
Volume 22, Number 4
2013
Siebert et al. 475
Pavetta (Rubiaceae) from South Africa
To a lesser extent, Pavetta glaucophylla was
previously also misidentified as P. inandensis Bremek.
and P. lanceolata Eckl. However, these latter two
species are easily distinguished by their distinctly
petiolate leaves, and the corymbose inflorescences
terminal on short branches, never paired, both the
inflorescence and its individual parts subtended by
leaf pairs (Kok et al., 1987; Bridson, 2003). The leaves
of P. glaucophylla and P. zeyheri are sessile and the
sub-umbellate inflorescences terminal on short leafless
branches, usually two per node. Moreover, P.
inandensis and P. lanceolata are characterized by
stipules with elongated apices up to 3 mm long and
domatia on the lower surface of the leaves, whereas P.
glaucophylla and P. zeyheri have broadly triangular
stipules and no domatia. Pavetta lanceolata further
differs from the new species and P. zeyheri in having
smaller flowers, corolla tube (8–)11(14) mm long,
and smaller fruit, (5–)5.5(6) 3 (4–)5(6) mm.
Pavetta inandensis also differs in having much larger
leaves, (63–)81(107) 3 (15–)20(27) mm, than P.
zeyheri, and broader inflorescences, (55–)71(100)
mm, than P. glaucophylla. Pavetta zeyheri has the
largest flowers, (10–)14(18) mm tube length, of all
the species considered here.
Paratypes. SOUTH AFRICA. Limpopo: Farm Parys, 5
Jan. 1939 (fr.), A. O. D. Mogg 725 (PRE); Schoonoord,
NNW of town, Km. 25, 22 Nov. 1959 (fl.), J. P. H. Acocks
20941 (PRE); Schoonoord, Nov. 1941, N. J. van Warmelo
89 (PRE); Farm Zoetvelden, 8 Nov. 1935 (fl.), W. G.
Barnard 144B (PRE); Penge, circular mine shaft in town, 1
Apr. 1972 (fr.), J. P. Nel 195 (PRE); Strydom Tunnel, cliff
at S entrance, 2 Feb. 1982 (fr.), A. E. van Wyk, R. Dahlgren
& P. D. F. Kok 5474 (PRU), 26 Feb. 1981 (fl.), A. E. van
Wyk 5181 (PRU); Strydom Tunnel, Farm Perkeo, next to old
tufa waterfall, 21 Aug. 1985 (fr.), F. Venter 10860 (PRU).
Mpumalanga: Roossenekal, Mapoch’s Cave rd., Km. 2.5,
14 Nov. 1997 (fl.), S. J. Siebert 22 (PRE); Thorncliffe,
entrance rd. to mine, 17 May 1997 (fr.), Plant Specialist
Group 15 (PRE); Farm Dwarsrivier, 24855 966 99 S,
3080792299 E, 17 Nov. 1998 (fl.), G. B. Deall 4174
(PRU); Roossenekal, rd. to Steelpoort, Km. 14, 13 Apr.
Figure 2. Known geographical distribution of Pavetta glaucophylla Retief, S. J. Siebert & A. E. van Wyk in South Africa.
Black dots indicate collection localities for the species as vouchered by the type and paratype collections.
476 Novon
1994 (fr.), A. E. van Wyk 12367 (MO); Roossenekal, railway
station on tar rd. to Steelpoort, Km. 11, 6 Apr. 1994 (fr.), P.
van Wyk BSA2054 (PRU); Farm Dwarsrivier, rd. to
Lydenburg, Km. 4, 17 Feb. 1987, A. E. van Wyk 8015
(MO, PRU); Stofberg, before Mapoch’s Mine, Km. 8, 17
Feb. 1987, A. E. van Wyk 8020 (PRU); Steelpoort,
Ferrochrome Holdings, rd. to factory dam, Km. 2, 12 Feb.
1998 (fr.), S. J. Siebert 297 (PRU); Roossenekal, rd. from
Mapoch’s Mine to Steelpoort, Km. 4, 11 Apr. 2000 (fr.), A.
E. van Wyk, S. J. Siebert & Y. Steenkamp 1465 (PRU).
Acknowledgments. We are grateful to Otto Leist-
ner for the Latin diagnosis, John Burrows for the type
material, Daleen Roodt for the line drawings, and
Marie
´
du Toit for the distribution map. The National
Research Foundation of South Africa and the South
African Natio nal Biodiversity Institute provide d
financial support.
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