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Taxonomy of the Genus Gibbaeum (Aizoaceae) and Clarification of the Confusion Around Gibbaeum haagei , with a New Species Gibbaeum hartmannianum

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As an introduction to a series of contributions on the genus Gibbaeum N.E.Br., a review of the current taxonomic knowledge of the genus and open problems is given. The second part clarifies the intricate taxonomic history of Gibbaeum haagei. Gibbaeum haagei Schwantes ex H. Jacobsen 1935 was invalidly published and is a synonym of G. petrense (N.E.Br.) Tischer. Gibbaeum haagei Schwantes 1938 was validly published and misidentified by Glen (1974) and subsequent authors, as the white-tomentose Gibbaeum species from the Swellendam region (Western Cape Province, South Africa). Glen wrongly treated G. haagei Schwantes 1938 as a later illegitimate homonym of the earlier G. haagei Schwantes ex H. Jacobsen 1935 nom. inval. and proposed the new species G. austricola Glen ('austricolum') nom. inval. for the white-tomentose species from the Swellendam region. This prompted Hartmann (2001) to publish G. haaglenii H. E. K. Hartmann as a replacement name which is illegitimate. Here it is shown that G. haagei Schwantes 1938 as well as G. haaglenii are synonyms of G. velutinum (L. Bolus) Schwantes. The white-tomentose species from the Swellendam region was published as G. haagei var. parviflorum L. Bolus, but is as yet without a valid name at the species level. As a new starting point, it is described here as G. hartmannianum Thiede & Niesler sp. nov.
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Haseltonia 18: 34–44. 2012 34
INTRODUCTION - TAXONOMY
OF THE GENUS GIBBAEUM
e genus Gibbaeum (Aizoaceae) was rst men-
tioned by Haworth (1821) and formally established
by N. E. Brown hundred years later (1921). In the
following year, Brown (1922) recognized ve spe-
cies in Gibbaeum which had formerly been placed
in Mesembryanthemum L. by Haworth (1821). Five
years later, Brown (1926/27) had raised the number
to twelve species of tufted leaf-succulents with more
or less ovoid to (sub-)globose bodies with equal to
very unequal leaves, a subequally 6-lobed calyx, 6-7
stigmas and locules, and fruits with valve wings and
covering membranes but without closing devices.
In the following three decades, further new species
were added, all distributed in the Little Karoo. But
the species number in Gibbaeum was also raised by
merging other genera with partly deviating char-
acters: the monotypic Argeta N.E.Br. and Imitaria
N.E.Br., the dispecic Mentocalyx N.E.Br., and some
species (including the type species), but not all spe-
cies of the small genus Rimaria N.E.Br. (Schwantes
1927, Bolus 1931, 1937, Tischer 1937, Jacobsen
1949). ese mergers were accepted by most authors.
In the period after 1950, scientists mainly at-
1e genus Gibbaeum N.E.Br. I. 2Corresponding author.
tempted to reduce redundant species names. e tax-
onomy of Gibbaeum was revised in a posthumously
published handbook by Nel (1953) and in an (un-
published) taxonomic revision by Glen (1974); the
latter constitutes the most detailed treatment of the
genus to date. Of the 37 species names published
in Gibbaeum to date, most recent authors recog-
nize roughly about the half, as follows: Nel 1953
recognized 17 spp.; Glen 1974, 15 spp.; Jacobsen
1981, 21; Chesselet and de Wet 1997, 20; Smith et
al. 1998, 16; Klak 2000, 17; Hartmann 2001, 27;
Chesselet et al. 2003, 16; and Vlok and Schutte-
Vlok 2010, about 20. ese dierent numbers of
species are partly due to dierent species concepts
(e.g., recognition of G. schwantesii Tischer as a sepa-
rate species or its inclusion in G. velutinum (L.Bolus)
Schwantes), but partly also due to dierent circum-
scriptions of Gibbaeum with regard to the inclusion
or exclusion of monotypic genera. E.g., the inclusion
of Antegibbaeum Schwantes by Nel (1953) was not
followed by other authors; Imitaria was again kept
separate by Chesselet and de Wet (1997), and the in-
clusion of the monotypic Muiria N.E.Br. (iede &
Klak in Klak 2000) is followed by Vlok and Schutte-
Vlok (2010) but not by Chesselet et al. (2003). Mo-
lecular AFLP studies of 15 populations in the G. nu-
ciforme (Haw.) Glen ex Glen & H.E.K.Hartmann-G.
Abstract: As an introduction to a series of contributions on the genus Gibbaeum N.E.Br., a review of
the current taxonomic knowledge of the genus and open problems is given. e second part claries the in-
tricate taxonomic history of Gibbaeum haagei. Gibbaeum haagei Schwantes ex H.Jacobsen 1935 was inval-
idly published and is a synonym of G. petrense (N.E.Br.) Tischer. Gibbaeum haagei Schwantes 1938 was
validly published and misidentied by Glen (1974) and subsequent authors, as the white-tomentose Gib-
baeum species from the Swellendam region (Western Cape Province, South Africa). Glen wrongly treated G.
haagei Schwantes 1938 as a later illegitimate homonym of the earlier G. haagei Schwantes ex H.Jacobsen
1935 nom. inval. and proposed the new species G. austricola Glen (‘austricolum’) nom. inval. for the white-
tomentose species from the Swellendam region. is prompted Hartmann (2001) to publish G. haaglenii
H.E.K.Hartmann as a replacement name which is illegitimate. Here it is shown that G. haagei Schwantes
1938 as well as G. haaglenii are synonyms of G. velutinum (L.Bolus) Schwantes. e white-tomentose species
from the Swellendam region was published as G. haagei var. parviorum L.Bolus, but is as yet without a valid
name at the species level. As a new starting point, it is described here as G. hartmannianum iede & Niesler
sp. nov.
Keywords: Aizoaceae - Flora of South Africa - Gibbaeum - nomenclature - quartz elds - Swellendam region
- taxonomy - Western Cape Province.
TAXONOMY OF THE GENUS GIBBAEUM (AIZOACEAE) AND CLARIFICATION
OF THE CONFUSION AROUND GIBBAEUM HAAGEI, WITH A NEW SPECIES
GIBBAEUM HARTMANNIANUM1
JOACHIM THIEDE2
Schenefelder Holt 3, 22589 Hamburg, Germany.
email: joachim_thiede@gmx.de
INGEBORG M. NIESLER
Biozentrum Klein Flottbek und Botanischer Garten,
Ohnhorststr. 18, 22609 Hamburg, Germany.
email: ingeborg.niesler@uni-hamburg.de
HASELTONIA VOL. 18. 2012 35
cryptopodium (Kensit) L.Bolus-G. pilosulum (N.E.Br.)
N.E.Br. complex (Bertram 2010) showed, albeit tax-
onomic aspects were not considered, that only one
morphologically highly variable species is involved.
e sole species novelties after the publication of
G. esterhuyseniae L.Bolus (1958) from the Stormsvlei
area, the rst species occurring completely outside of
the Little Karroo, were G. austricola (‘austricolum’)
Glen (1974), an invalid name for the white-tomen-
tose species occurring in the Swellendam region
south of the Langeberge, and G. johnstonii van
Jaarsveld & Hammer (1996), a close relative of G.
nebrownii Tischer. G. johnstonii was subsequently re-
duced to a variety of G. nebrownii (Pavelka 1998) or
placed in the synonymy of G. nebrownii (Klak 2000).
iede (2004: 57) depicted an unpublished new
species from the Swellendam region, and Vlok and
Schutte-Vlok (2010: 209) depicted a further unpub-
lished new species related to G. dispar N.E.Br.
Schwantes (1947) classied Gibbaeum together
with Muiria, Imitaria, Antegibbaeum and Didymaotus
N.E.Br. in his “Subtribus 17. Gibbaeinae Schwantes”.
Hartmann (1993), in her system based on fruit type
groups, placed Gibbaeum in the “Delosperma group”
which, in addition to Gibbaeum, includes the two
rst of the above and seven further genera. With mo-
lecular sequence data from four plastid DNA regions
(Klak et al. 2003), the position and closest relatives
of Gibbaeum remained uncertain.
Infrageneric classications for Gibbaeum based
on morphological features were provided by Wul
(1944) and Glen (1974; the new names proposed
therein are invalid). Molecular phylogenetic studies
of Gibbaeum with ITS, AFLP, and ISSR data (Ber-
tram 2007) yielded conicting trees and dendro-
grams with low support values, but conrmed with
weak support the placement of Muiria in Gibbaeum.
Geographically, Gibbaeum concentrates in the
western Little Karoo (Glen 1974), an arid intermon-
tane valley between the Swartberge in the north and
the Langeberge in the south, in the Western Cape
Province of South Africa. e species occur either in-
terspersed in a karooid subshrubby matrix vegetation
or on azonal habitats such as quartz elds or shale
banks (Schmiedel and Jürgens 1999). Most species
are endemic in the ‘Little Karoo Centre’ of ende-
mism (Hartmann 1994, van Wyk and Smith 2001).
Gibbaeum gibbosum (Haw.) N.E.Br., G. heathii
(N.E.Br.) L.Bolus and G. nuciforme extend north-
wards into the Touwsrivier-Matjiesfontein-Laings-
burg region2, ’G. austricola’ Glen (1974) nom. inval.
as well as an unpublished new species (iede 2004:
57) are endemic to the Swellendam region south of
the Langeberge (Fig. 1), and the sole extant local-
ity of G. esterhuyseniae lies just with the “Worcester-
Robertson Karoo Centre” as outlined by van Wyk
and Smith (2001).
1van Wyk and Smith (2001: 63) list these three species as (near-)
endemic in the ‘Little Karoo Centre’.
Figure 1. Landscape in the Swellendam region with undulating hills and the Langeberge in the background. e rainfall is
about twice as high as in the Little Karoo and allows wheat farming. Gibbaeum spec. nov. occurs on the quartz slope above the
midst (19. viii. 1998; photo: J. iede).
36 THIEDE & NIESLER. GIBBAEUM
Despite the great quantity of species descriptions,
taxonomic treatments, travelogues and horticultural
information gathered up to now on Gibbaeum, sev-
eral taxonomical and nomenclatural questions re-
mained unsolved. In the framework of the treatment
of Gibbaeum for the forthcoming 2nd edition of the
“Handbook of Aizoaceae” (H. E. K. Hartmann, ed.)
by the rst author, this rst contribution claries the
identity of Gibbaeum haagei Schwantes and provides
the valid species name G. hartmannianum iede &
Niesler sp. nov. for the white-tomentose Gibbaeum
species occurring south of the Langeberge.
TAXONOMIC HISTORY AND IDENTITY
OF GIBBAEUM HAAGEI
Gibbaeum haagei Schwantes ex H.Jacobsen 1935
nom. inval. Gibbaeum haagei was published by Ja-
cobsen (1935: 179) for a new species cultivated at
BG Kiel (D) as “Gibbaeum haagei Schwantes”. With
an English description only, but no Latin diagno-
sis, the name is invalid (ICBN Art. 36; McNeill et
al. 2006). Tischer (1937) indicated a close similar-
ity of G. haagei Schwantes ex H.Jacobsen 1935 nom.
inval. with G. petrense (N.E.Br.) Tischer, and later,
based on his karyological studies, Wul (1940, 1944,
1949) regarded the former as a
slightly larger tetraploid relative
of the smaller diploid G. pet-
rense. In order to provide a valid
species name against the later (!)
homonym G. haagei Schwantes
1938 (see below), Wul (1949)
published the replacement name
G. tischleri H.Wul which is
nomenclaturally superuous
since G. haagei Schwantes ex
H.Jacobsen 1935 nom. inval. is
the earlier homonym and fur-
thermore invalid. However, since
Wul provided a Latin diagnosis
for his G. tischleri, it represents
a valid new species name for G.
haagei Schwantes ex H.Jacobsen
1935 nom. inval. Gibbaeum
tischleri was not mentioned by
Nel (1953) and was placed in
the synonymy of G. petrense by
Glen (1974: 127) and Hartmann
(2001: 40).
Gibbaeum haagei Schwantes
1938. In 1938, Schwantes validly
published a very dierent new
species with unequal spreading
leaves as G. haagei with Latin
diagnosis and a detailed descrip-
tion accompanied by a black and
white photograph reproduced
here (Fig. 2). Since the earlier G.
haagei Schwantes ex H.Jacobsen
1935 was invalidly published (see
above), G. haagei Schwantes 1938
is neither a later homonym nor illegitimate. e
description of G. haagei Schwantes 1938 was repro-
duced in abbreviated form by later authors (e.g., Nel
1953, Jacobsen 1955) without adding further infor-
mation.
Glen, in his revision of Gibbaeum (1974), iden-
tied G. haagei Schwantes 1938 with the white-
tomentose Gibbaeum species occurring south of the
Langeberge in the Swellendam region, but did not
provide any argument for his identication. Appar-
ently, the publication of G. haagei var. parviorum
L.Bolus (1966), a taxon doubtless representing the
white-tomentose Gibbaeum species from the Swellen-
dam region (see below), prompted Glen to treat G.
haagei Schwantes 1938 as likewise identical with the
white-tomentose Gibbaeum species from the Swellen-
dam region.
Glen (1974: 108, 127) wrongly treated the
validly published G. haagei Schwantes 1938 as a
later illegitimate homonym of the earlier G. haagei
Schwantes ex H.Jacobsen 1935 nom. inval. despite
the fact that he correctly treated the latter as inval-
id. Consequently, the white-tomentose Gibbaeum
species from the Swellendam region was in Glens
opinion without legitimate species name which led
Figure 2. Reproduction of the photograph accompanying the description of Gibbaeum
haagei Schwantes 1938 (= Gibbaeum velutinum; from Beiträge zur Sukkulentenkunde
und -pege 1938: 90). is photograph was chosen as lectotype for the species by Hart-
mann (2001).
HASELTONIA VOL. 18. 2012 37
him to publish the new species G. austricola (‘austri-
colum’), but this name remained invalid since Glen’s
revision never had been validly published. Neverthe-
less, G. austricola is currently used in the literature
(e.g., Frandsen 1998) and in the horticultural trade
as if it were valid.
Hartmann (2001: 38) followed Glen and conse-
quently treated G. haagei Schwantes 1938 as an il-
legitimate later homonym of G. haagei Schwantes
ex H.Jacobsen 1935 nom. inval. and identical with
G. austricola Glen nom. inval. In order to provide a
valid species name, she published the replacement
name G. haaglenii H.E.K.Hartmann for G. haagei
Schwantes 1938 and selected the photograph accom-
panying the protologue of the latter (Fig. 2) as lecto-
type (Hartmann 2001: 38).
However, the treatment of G. haagei Schwantes
1938 by Glen (1974) and Hartmann (2001) must be
rejected due to nomenclatural as well as taxonomi-
cal misconceptions. ICBN Art. 53.1 (McNeill et al.
2006) states that a name constitutes a later illegiti-
mate homonym only when an identical earlier name
based on a dierent type was validly published for a
taxon of the same rank. Since G. haagei Schwantes
ex H.Jacobsen 1935 was invalidly published, G.
haagei Schwantes 1938 does not represent an invalid
later homonym, but is in fact a valid new name, as
mentioned above. Consequently, the description of
G. austricola by Glen (1974) and the replacement
name G. haaglenii by Hartmann (2001) were both
nomenclaturally superuous, as was already noted
for the latter by Eggli and Zappi (2002: 6).
Gibbaeum haagei Schwantes 1938 var. par-
viorum L.Bolus. In 1966, Bolus validly pub-
lished G. haagei var. parviorum as the rst name
for the white-tomentose Gibbaeum-species from
the Swellendam region, based on the specimen van
Breda # 1754/62 (BOL!) from that region. Bolus did
not state whether she identied G. haagei Schwantes
1938 with the white-tomentose species from the
Swellendam region, and did not provide a diagnosis
for her new variety. Glen (1974: 109) noted that the
chosen epithet (parviorum = small-owered) is mis-
leading since the owers are somewhat larger than
those of G. haagei Schwantes 1938.
e identity of Gibbaeum haagei Schwantes
1938. In contrast to Glen (1974) and Hartmann
(2001), it is shown here that G. haagei Schwantes
1938 represents a synonym of G. velutinum (L.Bolus)
Schwantes and is not identical with the white-to-
mentose species from the Swellendam region, based
on the following evidence:
a) e Botanical Garden of Kiel University re-
ceived the plant on which G. haagei Schwantes
1938 was based from the Haage nursery (Erfurt,
D) without locality (Schwantes 1938). Exactly the
same plant was used for anatomical-karyological
studies by Wul (1940, 1944) who worked at that
time at the Botanical Institute and Garden in Kiel
(D), together with Schwantes and Jacobsen. Wul
(1940) at rst listed the plant as G. “spec. nov. cfr.
velutinum” and later (Wul 1944: 167) as “G. spec.
nov.” diering from G. velutinum in its more com-
pact growth, while both species share the same
type of hairs which are unbranched or forked once
at the tip and exhibit transverse ridges (the hairs of
G. austricola’ are very dierent, see below). Wul
(1944: 167) added that the plant grows at the “Tou-
wsriver” in the Little Karoo and was imported from
W. Triebner at Windhoek, and was at that time at
the disposal of Schwantes for its description. ese
data are certainly erroneous: From Touwsrivier, only
G. gibbosum is known, and Wilhelm Triebner (1883-
1957) lived in Windhoek and only collected and sent
plants from the former South West Africa, the today
Namibia (Schwantes 1959, Gunn and Codd 1981).
Later, Wul (1949: 55) stated that his “G. spec. nov.
(1944: 167) much resembled G. velutinum in habit,
that it was published as G. haagei Schwantes already
back in 1938, and that the plant was lost during
World War II.
b) In the original diagnosis, Schwantes (1938:
90) describes the leaf color of his G. haagei as blu-
ish green (“bläulich grün”) which matches cultivated
plants of ‘G. haagei’ (Fig. 3) and G. velutinum (Fig.
4), whereas the dense tomentum in ‘G. austricola’ is
Figure 3. is old cultivated plant of unknown origin labeled
Gibbaeum haagei’ (= Gibbaeum velutinum) matches the lecto-
type photograph (Fig. 2) very well (Bot. Inst. Cologne, 1. vi.
1998, photo: J. iede).
Figure 4. Gibbaeum velutinum is rather variable in its leaf
shape and size. is plant, owering in cultivation, has much
longer and narrower leaves than that shown in Fig. 3 (HBG;
Anonymous s.n., ex Barrydale; 14. iv. 2003, photo: J. iede).
38 THIEDE & NIESLER. GIBBAEUM
whitish or grayish-white (Figs. 5–9) but not bluish-
green.
c) In the original photograph of G. haagei (Fig.
2), the leaves are distinctly divergent-spreading as is
typical of G. velutinum (Figs. 3−4), whereas leaves
of ‘G. austricola’ are nearly upright and connivent
when no new leaf pair is formed and slightly spread-
ing only when a new leaf pair or owers are formed
(Figs. 5−7).
d) e rst specimen of the white-tomentose spe-
cies occurring south of the Langeberge (= ’G. aus-
tricola’) was collected in 1943 (Otzen s.n., BOL!),
i.e., ve years after the publication of G. haagei
Schwantes 1938. Neither Schwantes nor Jacobsen
nor even Nel (1953: 25-33) became aware of the
existence of any species of Gibbaeum south of the
Langeberge. e rst printed record of a Gibbaeum
species occurring in the wider Swellendam region
was the publication of the green-leaved G. esterhuy-
seniae from the Stormsvlei area by Bolus in 1958;
the oldest specimens of that species were collected in
1940 (Glen 1974: 78).
e) Plants labeled as ‘G. haagei‘ are still in culti-
vation and also oered commercially. Several old
plants studied (Bot. Gard. Kiel 1994; Bot. Inst. Univ.
Cologne 1998, Fig. 3) proved to be a G. velutinum
variant with short and broad leaves (cf. a) match-
ing the lectotype picture of G. haagei (Fig. 2) very
well. ese plants might represent propagations of
the original material at the Haage nursery where no
material of G. haagei is extant (Fa. Haage, Erfurt
[D], pers. comm. to JT). e hairs of these G. haagei
plants match those of G. haagei and G. velutinum as
described by Wul (1944).
TAXONOMIC SUMMARY
1.) Gibbaeum haagei Schwantes ex H.Jacobsen
1935 nom. inval. is a synonym of G. petrense
(N.E.Br.) Tischer, as was already pointed out by
Glen (1974: 130) and Hartmann (2001: 40).
Gibbaeum petrense (N.E.Br.) Tischer, Kakteen
und andere Sukkulenten 1937: 151 (1937) Ar-
geta petrensis N.E.Br., Gard. Chron. ser. 3, 82: 114
(1927). Type: Muir 3622 (K).
= G. haagei Schwantes ex H.Jacobsen, Succ. Pl.
179 (1935), nom. inval. G. tischleri H.Wul, Suk-
kulentenkunde 3, 55 (1949). Type (lecto, designat-
ed by Hartmann 2001: 40): g. on p. 55 in Wul
(1949).
2.) Gibbaeum haagei Schwantes 1938 as well as G.
haaglenii H.E.K.Hartmann nom. illeg. are synonyms
of G. velutinum:
Gibbaeum velutinum (L.Bolus) Schwantes, Z.
Sukkulentenkunde 3, 106 (1927) Mesembryanthe-
mum velutinum L.Bolus, Ann. Bolus Herb. 3: 124
(1922) Mentocalyx velutina (L.Bolus) Schwantes,
Monatsschr. Deutsch. Kakteen-Ges. 1: 17 (1929).
Type (holo): Anonymous s.n. in BOL 15195 (BOL!).
= G. haagei Schwantes, Beitr. Sukkulentenk. Suk-
kulentenpege 1938: 89 (1938) non Schwantes ex
H.Jacobsen, Succ. Pl. 179 (1935), nom. inval. G.
haaglenii H.E.K.Hartmann, Handb. Aizoaceae F-Z:
38 (2001), nom. illeg. (Art. 52.1). Type (lecto, se-
lected by Hartmann l.c.): g. on p. 89 in Schwantes
1938 (reproduced here as Fig. 2.). Synon. nov.
3.) e white-tomentose species from the
Swellendam region was validly published as G.
haagei var. parviorum L.Bolus (1966), but is as yet
without valid binomial on species level, since G. aus-
tricola (‘austricolum’) Glen nom. inval. (1974) was
never validly published. Combining G. haagei va r.
parviorum to species level would result in a mislead-
ing epithet, since the owers of several Gibbaeum-
species (e.g., G. petrense) are much smaller. To avoid
further confusion, a new starting point is made here
in describing the white-tomentose species from the
Swellendam region under a new name as G. hart-
mannianum spec. nov.
GIBBAEUM HARTMANNIANUM SP. NOV.
Gibbaeum hartmannianum iede & Niesler sp.
nov., sect. Mentocalyx (N.E.Br.) Glen ex P.V. Heath
(Figs. 5–9).
= Gibbaeum austricola (‘austricolum’) Glen, Rev.
Gibbaeinae 105 (1974), nom. inval. Type (holo):
Glen 714 (BOL!). Synon. nov.
= Gibbaeum haagei var. parviorum L.Bolus, J.
S. Afr. Bot. 32: 128 (1966). Type (holo): van Breda
1754/62 (BOL!). Synon. nov.
Type: Western Cape, 3420 (Riversdale): Between
Malgas and Infanta (–BC) (exact locality deposited
with type material), on quartz eld, 20. viii. 1998,
iede et al. 110200. (Holotype: BOL.).
Similar to G. album N.E.Br. in its dense white
tomentum; dierent in its longer leaves subequal to
clearly unequal in size and with ssure straight, and
in its owers rose to magenta with elevated ovary
roof.
Description: Perennial leaf-succulent nano-
chamaephyte, with short taproot up to 1 cm diam.,
with brous roots, with (3−)5–20(−50+) branches
with mostly 2 or only 1 leaf pair(s), forming dense
clumps 5−10(–25+) cm diam. Leaves decussate,
hemispherical, ovoid or ellipsoid, rarely subtrigo-
nous; subequal to unequal in size, longer leaf about
1.0−1.4 times longer than lesser leaf; the larger
(14−)20–50(−60) × (6−)12–22(−27) mm, somewhat
to distinctly elongated dorsally to a “chin”; the lesser
(11−)17–35(−42) × (5−)10–17(−22) mm, lower part
of larger and lesser leaf ± semi-globose in transection,
without keel, keel mostly increasingly distinct to-
wards apex, leaves of a pair nearly upright and conni-
vent when no new leaf pairs or owers are formed, or
slightly to distinctly spreading (up to about a right
angle) when new leaf pairs or owers are formed. In-
dumentum dense, of unicellular almost straight hairs
branched irregularly antler-like 2 or 3 times, hair
branches intertwining, plants appearing white to
HASELTONIA VOL. 18. 2012 39
Figure 5. Gibbaeum hartmannianum: Shoot, leaves, buds, ower, ower details and fruits (Schmiedel # 109788). Scale: 1 mm
(plate: I. Niesler).
Figure 6. Gibbaeum hartmannianum (iede et al. # 110200) at its type locality among quartz pebbles: plants of average size,
forming clumps with densely arranged shoots with mostly two leaf pairs (20. viii. 1998; photo: J. iede).
5 6
Figure 7. Gibbaeum hartmannianum (iede et al. # 110200) at its type locality among quartz pebbles: small plant with buds just
before anthesis (20. viii. 1998; photo: J. iede).
40 THIEDE & NIESLER. GIBBAEUM
whitish-greyish or whitish-greenish. Flowers terminal,
solitary, bractless, pink to magenta, 22–30 mm diam.
Pedicel exserted for ca. 10–15 mm, compressed par-
allel to ssure and strongly keeled, keel continuing
into outer sepals. Sepals 6, strongly unequal, the
two outer larger, parallel to ssure, ± linear, 10–15 ×
5–6 mm, up to 5 mm thick, elongated for 7–8 mm,
strongly keeled dorsally and thus trigonous, remain-
ing upright in anthesis, the smaller trigonous, 5–7 ×
3–4 mm, with membranous margins, only slightly
thickened, dorsally keeled in upper part. Petals (pet-
aloid staminodes) 40–75, biseriate, 10–20 × up to
1.9 mm, pink to magenta, color lighter towards base
and at margins thus appearing ± striped; staminodes
liform, 0–50, 2.5–8.5 mm, whitish. Stamens 70–
160, 2−3-seriate, laments 2–6 mm, whitish, anthers
and pollen light yellow. Styles (stylodia) and stigmas
6−7, subulate, 2.5–4.0 mm. Ovary roof elevated for
about 1.5 mm. Capsule 6-locular, locules with cov-
ering membranes, 6–7 mm diam., ca. 4 mm deep,
valves with raised and recurved rims. Seeds pale red-
brown, 600–835 × 375–520 × 300–420 µm, with a
180–250 µm funicle, surface pattern mostly of ir-
regular tessellate elements irregularly arranged, or ab-
sent in patches; pattern on funicle of rectangular to
irregular elements in irregular rows.
Further material studied (paratypes; cult. =
cultivated plants): Glen 659, 666, 714, 804 (BOL),
Hartmann 30404, 34498, 34501 (HBG & cult.),
Schmiedel 109788, 109798 (cult.), iede et al.
110198 (BOL & cult.), van Breda s.n. (BOL).
Distribution, ecology, vegetation and climate:
Western Cape Province, 3420 (Riversdale): (–AA, –
AB, –AC, –AD, –BA, –BC); Swellendam region,
rocky slopes overlying clayey sand, mainly in quartz
elds, often on hilltops (cf. Fig. 1). e distribu-
tion area of G. hartmannianum spans over an area
of about 60 × 35 km. At least thirteen localities are
known eight of which have been studied during the
last fteen years.
Schmiedel and Mucina (2006) published a sepa-
rate Delospermo asperuli-Gibbaeetum haaglenii asso-
ciation restricted to quartz elds in the Swellendam
region, characterized by Drosanthemum asperulum
(Salm-Dyck) Schwantes (as Delosperma asperulum
(Salm-Dyck) L.Bolus, see Klak 2003, Klak et al.
2003, Wagner and Schröder 2009), Gibbaeum hart-
mannianum (as G. haaglenii), and the grass Pentas-
chistis eriostoma (Nees) Stapf. e Delospermo asper-
uli-Gibbaeetum haaglenii association has a very high
plant cover (19 %) compared to quartz eld commu-
nities in the Little Karoo and occurs on moderate to
steep slopes covered with medium-sized quartz-de-
bris (6−20 cm) and on shallow soils (< 20 cm) with
a very low soil pH (Schmiedel and Mucina 2006).
Due to the direct inuence of the Indian Ocean,
the annual precipitation (at Riversdale) is 459 mm
which is almost twice as high as in the Little Karoo
(Schmiedel and Mucina 2006).
Conservation status: Vlok and Raimondo
(2006) list G. hartmannianum (as G. haaglenii) as
Endangered (EN): Only some small, severely frag-
mented subpopulations remained after most of its
habitat has been transformed for wheat cultivation,
and the decline due to grazing and trampling by cat-
tle and ostriches continues.
Phenology: Flowering specimens were collected
in April (out of season) and on 31. Aug. and 21. Oct.
Plants at the type locality were in bud on 20. Aug.
1998 (Fig. 7). In cultivation on the Northern hemi-
sphere (Germany), G. hartmannianum owers from
mid of March to mid of June (iede, unpubl.).
Illustrations: Smith et al., Mesembs of the
World: 107 (1998), Jaarsveld and Pienaar, Aizoaceae.
Mittagsblumen Südafrikas: 111 (2004; both as G.
haagei var. parviorum), Klak et al., Nature 427: 64
(2003), Hecktheuer, Mesembs - mehr als nur Lithops:
38 (2003; both as G. haaglenii).
Etymology: We take pleasure in dedicating this
new species to Heidrun (‘Heidi’) E. K. Hartmann
on occasion of her 70th birthday in August 2012 to
commemorate her outstanding contributions to the
taxonomy and systematics of the Aizoaceae culminat-
ing in her 2-volume Handbook of Aizoaceae.
RELATIONSHIPS
Glen (1974) and Hartmann (2001) compared G.
hartmannianum (as G. austricola and G. haaglenii)
with G. album N.E.Br., to which it is supercially
similar in its dense white tomentum, but otherwise
very dierent (data for the latter in parentheses):
leaves 14-60 mm and subequal to clearly unequal
(vs. 15-21 mm and subequal), ssure straight (vs.
oblique), and owers rose to magenta with elevated
ovary roof (vs. white or rarely rose with at ovary
roof).
Based on the former genus Mentocalyx, Wul
(1944: 167) established G. subsection Mentocalyx
(N.E.Br.) Wul which included four species (G. ve-
lutinum, G. schwantesii, G. spec. nov. [= G. haagei
Schwantes 1938], and G. pachypodium (Kensit)
L.Bolus) with large, unequal leaves with chin-like
projection at the end, and all with a tetraploid
chromosome number of 2n = 36. Glen (1974: 71)
shifted Mentocalyx to sectional rank and excluded
Figure 8. Gibbaeum hartmannianum (iede et al. # 110200).
Field collected plants before potting showing the root system:
many brous roots emerge from a taproot up to 1 cm Ø (24.
viii. 1998; scale: 1 cm, photo: J. iede).
HASELTONIA VOL. 18. 2012 41
G. pachypodium which is very dierent in its sub-
shrubby (not clump-forming) habit, its subequal to
nearly equal and nearly rounded, long and upright
leaves (nearly) without chin-like projection, and its
very long pedicels. Glen’s new combination (1974:
71) remained invalid and was validated by Heath
(1993) as Gibbaeum sect. Mentocalyx (N.E.Br.)
[Glen ex] P.V.Heath which is circumscribed here to
include four species (see key below) with the fol-
lowing characteristics: leaves of a pair mostly clearly
unequal in length (partly subequal in G. hartman-
nianum), keeled, mostly trigonous in transection
(partly hemispherical in G. hartmannianum), mostly
with ± clearly developed chin-like projection espe-
cially at apex of longer leaf, ovary roof convex and
elevated, and sepals strongly unequal with the outer
two elongated, dorsally keeled and thus trigonous
(cf. Fig. 5). Gibbaeum schwantesii and G. velutinum
are tetraploids with 2n = 36 (Wul 1944, Vos 1951);
the chromosome numbers of G. esterhuyseniae and
G. hartmannianum are unknown. e four species
of sect. Mentocalyx can be dierentiated with the fol-
lowing articial key:
1 Leaves dull green, without indumentum (Stormsvlei area) ...........................G. esterhuyseniae
- Leaves whitish or greenish to grayish- or bluish-green, with ±
dense indumentum (Western Little Karoo or Swellendam region) .................................. 2
2 Leaves with densely interwoven white to grayish-white tomentum;
larger leaf about 1.0 to 1.4 times longer than lesser leaf;
hairs irregularly antler-like, forked up to 3 times, without transversal ridges;
roots brous, main root up to 1 cm diam. (Swellendam region) ............... G. hartmannianum
- Leaves with lax, not interwoven tomentum, greenish or grayish- to bluish-green;
larger leaf about 1.2 to 2.3 times longer than lesser leaf;
hairs unbranched or forked at tip, with transversal ridges;
with thick woody rootstock (Western Little Karoo) .......................................................... 3
3 Leaves ± broadly triangular, ± horizontally compressed, about 3−7 cm,
longer leaf with ± expressed chin or hook;
owers pink to pale magenta, 20−35 mm diam. ................................................. G. velutinum
- Leaves narrowly triangular, laterally compressed, about 6 to >10 cm,
longer leaf with almost axe-like, hooked upper end;
owers white, 30−50 mm diam. .................................................................... G. schwantesii
Figure 9. Gibbaeum hartmannianum (iede et al. # 110200): at its type locality, the species occurs in monospecic mass
stands on a quartz eld (20. viii. 1998; photo: J. iede).
42 THIEDE & NIESLER. GIBBAEUM
Gibbaeum sect. Mentocalyx (N.E.Br.) Glen
ex P.V.Heath, Calyx 4(1): 27 (1993) Mentoca-
lyx N.E.Br., Gard. Chron. ser. 3, 81: 251 (1927)
Gibbaeum subsect. Mentocalyx (N.E.Br.) Wul, Bot.
Archiv. 45: 167 (1944) Gibbaeum sect. Mento-
calyx (N.E.Br.) Glen, Rev. Gibbaeinae: 71 (1974)
nom. inval. Type: Mentocalyx muirii N.E.Br. ( G.
schwantesii Tischer).
Gibbaeum velutinum (L.Bolus) Schwantes (Figs.
2−4) is common on the southern fringe of the west-
ern Little Karroo just north of the Langeberge from
Barrydale to Muiskraal and is also reported from
Sandkraal. Schmiedel and Mucina (2006) described
an association Gibbaeetum velutini where the low
Gibbaeum plants grow among a higher layer of mega-
chamaephytes and phanerophytes on poorly weath-
ered shale bands with or without quartz cover, often
between dense stands of renosterbos (Elytropappus
rhinocerotis Less.), and on shallow acid soils (pH <6)
with high stone content.
Gibbaeum velutinum is rather variable in its leaf
shape and size ranging from plants with long and
narrow leaves (Fig. 4) to plants with short and thick
leaves (Figs. 2, 3); the latter prompted Glen (1974)
to misinterpret “G. haagei” as the white-tomentose
species occurring south of the Langeberge (“G. aus-
tricola”). Flowers are pink to pale magenta, white-
owered plants are known only from cultivation.
Gibbaeum schwantesii Tischer (Fig. 10) is
known only from two localities with loose quartz
covering within the area of G. velutinum. Glen
(1974) included G. schwantesii in G. velutinum de-
spite its separate position in his dendrogram based
on numerical character analysis. Here, G. schwante-
sii is kept separate following Hartmann (2001) and
Vlok and Schutte-Vlok (2010). It diers from G. ve-
lutinum mainly in its longer and narrower, laterally
compressed leaves and larger and white owers.
Gibbaeum esterhuyseniae L.Bolus (Fig. 11) was
discovered by E. Esterhuysen near Stormsvlei and
is documented by four collections at BOL(!) made
by Esterhuysen and udichum between 1940 and
1951. e species could not be recollected despite
considerable eorts and was considered extinct,
but was rediscovered recently on one locality by P.
Bruyns and B. Bayer (Bruyns # 6968; Fig. 11) where
it is threatened by land development (Hilton-Taylor
1998).
ACKNOWLEDGMENTS
Plant material was collected under a permit is-
sued to J.T. by Cape Nature Conservation (Cape
Town), which is gratefully acknowledged. Further
plant material was made available by H.E.K. Hart-
mann, U. Schmiedel (both Hamburg) and P.V.
Bruyns (Cape Town). T. Trinder-Smith and P. Ches-
selet (Cape Town) made specimens available at BOL
and NBG, respectively. H.F. Glen (Pretoria) kindly
permitted the use of data from his unpublished the-
sis, S. Schmidt (Hamburg) carried out leaf measure-
ments, and L. Berka (CZ) sent a copy of remote lit-
erature. Many thanks also to H. Zimmer (Köln) and
Figure 10. Gibbaeum schwantesii: cultivated owering plant with its typical long and very narrow leaves and large white owers
(HBG; Hartmann # 8730; 14. iv. 2003, photo: J. iede).
HASELTONIA VOL. 18. 2012 43
K. Baumgärtner (Hamburg) for carefully keeping the
living collections.
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Chapter
Taxonomic synopsis of the genus Gibbaeum N.E.Br. with synonymy, description, distribution map, notes, infraganeric taxa, key to the species, and treatment of the recognized species (with 10 colour photographs): G. album N.E.Br., G. angulipes (L.Bolus) N.E.Br., G. dispar N.E.Br., G. esterhuyseniae L.Bolus, G. geminum N.E.Br., G. gibbosum (Haw.) N.E.Br., G. hartmannianum Thiede & Niesler, G. heathii (N.E.Br.) L.Bolus, G. hortenseae (N.E.Br.) Thiede & Klak, G. ihlenfeldtii Thiede spec. nov., G. nebrownii Tischer, G. nuciforme (Haw.) Glen & H.E.K.Hartmann, G. pachypodium (Kensit) L.Bolus, G. petrense (N.E.Br.) Tischer, G. pubescens (Haw.) N.E.Br., G. schwantesii Tischer, G. shandii N.E.Br., G. velutinum (L.Bolus) Schwantes
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