A recircumscription of Jacobsenia (Aizoaceae): Re-instating Drosanthemopsis, with two new quartz-endemics from Namaqualand, South Africa and sinking Knersia *
Author
Klak, C.
Author
Hanáček, P.
Author
Bruyns, P. V.
text
South African Journal of Botany
2018
2018-05-31
116
10
67
81
http://dx.doi.org/10.1016/j.sajb.2018.02.402
journal article
10.1016/j.sajb.2018.02.402
1727-9321
14036691
2.
Drosanthemopsis bella
Klak
,
sp. nov.
Type:
South Africa
,
Northern Cape
,
Hondeklipbaai
(3017): farm
Leeuvlei near Spioenkop
, (− DA),
140 m
,
26 Sept. 2013
,
Klak
2309
(
BOL
,
holo
.;
K
,
iso
)
.
Low, sprawling, succulent perennial shrub
30–50 mm
high,
300– 400 mm
diam., spreading branches
150–200 mm
long, stems woody, distinct long and short shoots present, internodes brown, to
25 mm
long, young internodes covered with papillae, visible as white dots in dried material, becoming smooth with age.
Leaves
fresh green to dirty green and reddish suffused, boat-shaped to club-shaped, top flat, keels indistinct, spreading widely, leaf-pairs isophyllous to slightly anisophyllous, basally shortly fused, sheath c.
4 mm
long, free parts
11–18 mm
long,
8–10 mm
broad and thick, keel inconspicuous; epidermis with large bladder cells with thickened outer walls, cells
0.2–0.3 mm
diam., ± circular to polygonal, bladder cells with flat top covered with tiny protrusions on their surface (
Fig. 5C
). Flowers solitary, terminal, petaloid staminodes pink becoming white towards the centre or white throughout, filamentous staminodes absent or very few, filaments white,
30–40 mm
diam., pedicels
6–14 mm
long; sepals 6, succulent, two larger and opposite, the remaining ones smaller.
Fruit
a hygrochastic capsule, old capsules grey, capsule as seen from above ±circular,
7–9 mm
diam., top flat with rims raised, lower part funnel-shaped; locules 6; borderline between expanding keels and expanding sheet ±distinct, keels broad and only slightly diverging; covering membranes thin and without any additional closing devices, ±covering the locule, small closing bodies infrequently formed, valve wings broad.
Seeds
with testa translucent to ochre, almost smooth, c. 0.7 ×
0.5 mm
.
Distribution and ecology:
Drosanthemopsis bella
is known from a single population near Garies in southern Namaqualand (Map 6). The plants grow in heavy loam over weathered shales in otherwise almost bare patches of quartz-gravel. Flowering takes place between August and September.
Diagnostic characters
: Fruit and epidermal features (see diagnostic characters for
D. kwaganapensis
) clearly place
D. bella
within
Drosanthemopsis
. Only
D. vaginata
and
D. bella
form low
cushions or mounds (
Fig. 1B&C
), whereas the other two species are erect shrublets. In contrast to
D. vaginata
, which has grey leaves, the leaves are light green with a red tinge in
D. bella
. The diameter of the epidermal cells is smaller in
D. vaginata
than in
D. bella
(
Table 1
).
Etymology
The epithet
“
bella
” is derived from the Latin meaning pretty and alludes to the showy flowers.
Conservation status
The species is known only from one location where the population covers a total area (Area of Occupancy; AOO) of less than 1 ha. The total number of plants is estimated at between 200 and 300. The area is grazed by small livestock (mainly sheep), but the plants did not appear to be affected by this. According to IUCN 3.1 criteria (
IUCN, 2001
) the species is classified as VU D1.
Additional specimens examined:
South Africa
.
NORTHERN CAPE
:
3017 (Hondeklipbaai):
30 km
W of Garies, farm Soutfontein 436, N of Outeep river, (−DA),
Helme 8058
(NBG).