A new species of Linderniella
(Linderniaceae) from central Malagasy
granitic inselbergs
Roger Lala Andriamiarisoa, Marina N. Rabarimanarivo & Stefan Porembski
Abstract
ANDRIAMIARISOA, R.L., M.N. RABARIMANARIVO & S. POREMBSKI (2023). A new species of Linderniella (Linderniaceae) from central
Malagasy granitic inselbergs. Candollea 78: 11 – 15. In English, English and French abstracts. DOI: http://dx.doi.org/10.15553/c2023v781a2
A rupicolous, resurrection, inselberg specialist plant is newly described and illustrated. Linderniella porembskii Andriamiar.
& Rabarim. (Linderniaceae) is restricted to central Malagasy granitic inselbergs in the Amoron’i Mania Region. It differs
from the other Malagasy species of the genus by its habit with dense and richly branched stems, decumbent to erect, and
by being glabrous to glabrescent and having obovoid-acuminate capsule. A detailed description of the species is provided,
accompanied by illustrations and an identification key to the Malagasy species of the genus. The new species is assessed
as “Endangered” using to IUCN Red List Categories.
Résumé
ANDRIAMIARISOA, R.L., M.N. RABARIMANARIVO & S. POREMBSKI (2023). Une nouvelle espèce de Linderniella (Linderniaceae) des
inselbergs granitiques du centre de Madagascar. Candollea 78: 11–15. En anglais, résumés anglais et français. DOI: http://dx.doi.org/10.15553/c2023v781a2
Une plante rupicole, reviviscente, spécialistes des inselbergs est nouvellement décrite et illustrée. Linderniella porembskii
Andriamiar. & Rabarim. (Linderniaceae) est restreinte aux inselbergs granitiques du centre de Madagascar, dans la Région
d’Amoron’i Mania. Elle se distingue des autres espèces malgaches du genre par son port herbacé avec des tiges richement
ramifiées et touffues, décombantes et dressées, des plantes glabres à glabrescentes et sa capsule obovoïde-acuminée. Une
description détaillée de l’espèce est fournie, accompagnée d’illustrations et d’une clé d’identification des espèces malgaches
du genre. La nouvelle espèce est considérée comme “En danger” selon les Catégories de la Liste rouge de l’UICN.
Keywords
LINDERNIACEAE – Linderniella – Madagascar – Inselberg – New species – Resurrection plant
Addresses of the authors:
ALR, MNR: Missouri Botanical Garden, P. O. Box 3391, Antananarivo 101, Madagascar. E-mail: roger.andriamiarisoa@mobot.mg
SP: University of Rostock, Institute of Biosciences, Department of Botany, Wismarsche Str. 44 – 45, D – 18051 Rostock, Germany.
Submitted on August 3, 2021. Accepted on January 19, 2023.
ISSN : 0373-2967 – Online ISSN : 2235-3658 – Candollea 78(1) : 11 – 15 (2023)
First published online on March 28, 2023.
© CONSERVATOIRE ET JARDIN BOTANIQUES DE GENÈVE 2023
12 – A new species of Linderniella (Linderniaceae) from Madagascar
Candollea 78, 2023
Introduction
Taxonomy
Linderniella Eb. Fisch. et al. (Linderniaceae) was newly
described based on a molecular phylogenetic analysis (Fischer
et al., 2013) and currently includes 16 species formerly treated
in the genus Lindernia All. (APD, 2023). Linderniella comprises small and delicate plants, mainly rupicolous annuals,
with the following distinctive characters: plants with rosettes
or elongated stems, leaves opposite, veins palmate, flowers with
2 fertile adaxial stamens and 2 abaxial stamens usually reduced
to staminodes, rarely fertile, seed surface with rounded pits or
bothrospermous seeds (Fischer et al., 2013).
The genus in Madagascar was revised under Lindernia
by Fischer (1995) and comprises three species currently
accepted in Linderniella: L. cerastioides (Bonati) Eb. Fisch. et
al., L. horombensis (Eb. Fisch.) Eb. Fisch. et al., and L. pygmaea
(Bonati) Eb. Fisch. et al. These species are strictly confined to
granitic inselbergs and appear to be desiccation-tolerant plants
(Rabarimanarivo et al., 2019; Madagascar Catalogue,
2023).
During botanical inventories in 2015 and 2016 on the
inselbergs of central Madagascar carried out by the authors
and collaborators, three collections of Linderniella were collected at two different sites. A morphological comparison of
these collections has shown that they differ from the hitherto
documented species from Madagascar and they represent a
new species which is described and illustrated below.
Linderniella porembskii Andriamiar. & Rabarim., sp. nov.
(Fig. 1, 2).
Key to the species of Linderniella from
Madagascar
Plants up to 8.5 cm high, glabrous; basal leaves > 12 mm
long; corolla up to 15 mm long; pedicel up to 20 mm long
................................................................. L. cerastioides
1a. Plants up to 4.5 cm high, pubescent, rarely glabrous to
glabrescent; basal leaves generally < 12 mm long (rarely
reaching 14 mm in L. porembskii); corolla up to 8 mm
long; pedicel up to 8(– 10) mm long ............................. 2
1.
2.
Stems up to 2.5 cm long; leaves and calyx not foveate; leaf
blades acuminate at apex with margin sparsely dentate;
capsule up to 9 – 10 mm long ...................... L. pygmaea
2a. Stems 2.5 – 4.5 cm long; leaves and calyx foveate; leaf
blades acute to obtuse at apex with margin entire; capsule
up to 6 mm long .......................................................... 3
3.
Plants fairly pubescent; stems usually single, erect from a
basal rosette; basal leaves 6 – 7 × 1.7 mm; pedicels 4 – 5 mm
long; capsule acuminate-attenuate ......... L. horombensis
3a. Plants glabrous to glabrescent; stems dense and
richly branched, decumbent to erect; basal leaves
9 – 14 × 1.5 – 2.5 mm; pedicels 5 – 8(– 10) mm long; capsule
obovate-acuminate ................................. L. porembskii
Holotypus: Madagascar. Reg. Amoron’i Mania [Prov.
Fianarantsoa]: Ambositra, Ambalamanakana, Réserve
Ankazomivady, inselberg côté droit de la route RN 7 vers
Fianarantsoa, 20°46'22"S 47 °10'51"E, 1706 m, 9.III.2016,
fl. & fr., Rabarimanarivo, Porembski, Giebelmann & Werner
741 (TAN!; iso-: MO [MO-2894736]!).
Linderniella porembskii Andriamiar. & Rabarim. can be
distinguished from the most similar L. horombensis (Eb. Fisch.)
Eb. Fisch. et al. by its habit with dense and richly branched
stems, decumbent to erect (vs. stems usually single, erect from
a basal rosette), plants glabrous to glabrescent (vs. pubescent),
and its capsules obovate-acuminate (vs. acuminate-attenuate).
Resurrection herbs, up to 4.5 cm high, tufted, decumbent
to erect, glabrous to glabrescent. Stems somewhat succulent,
4-angled, glabrous to glabrescent (with sparse, short, stiff
trichomes), highly branched from the base; young branches
green (in vivo), adult branches brown to red (in vivo); lowest
internode (from base to first node) about 1.5 cm long. Leaves
somewhat succulent, densely foveate, glabrous to glabrescent,
sometimes with sparse and short stiff white hairs at the
margin, shortly petiolate; basal leaves 4 – 12 forming a rosette,
spathulate, 9 – 14 × 1.5 – 2.5 mm, apex obtuse; upper leaves,
opposite, lanceolate to obovate, 3.5 – 4 × 1 – 2 mm, sessile, base
gradually tapering, apex acute to obtuse, sometimes slightly
mucronate and reddish apically, margin entire, glabrous or
sparsely pubescent with minute short stiff white hairs, veins
palmate, obscurely visible abaxially, inconspicuous adaxially.
Flowers solitary in the upper leaf axils, pedicellate, erect; pedicels 5 – 8 mm long, accrescent (up to 10 mm in fruit); calyx
foveate, somewhat succulent, green with red lobe margins (in
vivo), 3.4 – 4 mm long, glabrous, with 5 lobes up to 1 mm long,
persistent in fruit; corolla white or light purple with purple
shading on the throat, 8 mm long, tube 3.5 mm long, upper
lip bifid, lower lip 3-lobed with sinuate margins; stamens 4,
the abaxial pair reduced with curved and geniculate filaments
0.6 × 0.09 mm, anthers 0.2 mm long, the adaxial pair with
straight filaments 0.7 × 0.25 mm long, anthers 0.5 mm long;
pistil 4 mm long, style 3 mm long, stigma bilobed. Mature
capsule distinctly longer than calyx lobes, obovoid acuminate,
6 mm long, dehiscent into two valves when dried or mature.
Seeds bothrospermous, 0.6 mm long.
Etymology. – The species is named in honor of Prof. Dr.
Stefan Porembski, who has studied inselbergs globally and
made important contributions to our knowledge, understanding, and conservation of these unique ecosystems. He
published many articles dealing with these subjects, including
A new species of Linderniella (Linderniaceae) from Madagascar – 13
Candollea 78, 2023
0.6 mm
L
K
2 mm
A
F
1 mm
0.4 mm
E
2 mm
D
2 mm
F
G
0.4 mm
H
2 mm
I
J
2 mm
B
C
1 mm
Fig. 1. – Linderniella porembskii Andriamiar. & Rabarim. A. Habit; B. Distal leaf; C. Basal leaf; D. Sepal; E. Corolla (open); F. Staminode;
G. Stamens; H. Pistil; I – K. Fruits; L. Seed.
[Rabarimanarivo et al. 741, TAN] [Drawings: R.L. Andriamiarisoa]
14 – A new species of Linderniella (Linderniaceae) from Madagascar
Candollea 78, 2023
Notes. – Linderniella porembskii resembles L. horombensis
and L. pygmaea in general habit but it can be distinguished
from both species by its dense and richly branched stems,
which are decumbent to erect, by its glabrous calyx and its
obovate-acuminate capsules (vs. erect, usually single stems
arising from a basal rosette, pubescent calyx, and acuminate-attenuate capsules in L. pygmaea and L. horombensis).
Linderniella porembskii and L. horombensis have foveate leaves
and calyces, entire leaf margin, abaxial stamens and anthers
reduced to staminodes. They can also be distinguished by the
basal leaf size, pedicel length, and the plant pubescence of
plants.
Fig. 2. – Linderniella porembskii Andriamiar. & Rabarim.
[Rabarimanarivo et al. 741] [Photo: S. Giebelmann]
some that advocate for urgent protection of this neglected
habitat (Porembski et al., 2016). He also participated in the
collection of the type in 2016.
Distribution and ecology. – Linderniella porembskii is known
from three granitic inselbergs in central Madagascar, at midelevations of c. 1500 – 1700 m (Madagascar Catalogue,
2023). It is restricted to rock outcrops. The species appears to
be a resurrection plant growing in mats dominated by monocotyledonous, small patch-forming on open rock and shallow
depressions.
Conservation status. – Linderniella porembskii is known
from three recent collections made between 2015 and 2016.
These three collections represent two subpopulations occurring
outside the protected area network and are highly threatened
by ongoing degradation or destruction of its habitat due to
fire, quarrying, grazing, trampling by people overharvesting
other plants (medicinal, ornamental, useful plants), adjacent
farming, and climate change (Porembski et al., 2016). The
species has both an estimated Extent of Occurrence [EOO]
and a minimum Area of Occupancy [AOO] of 12 km² falling
within the limits for “Endangered” status under criterion
B2. With respect to the most plausible threat of fire, the two
known subpopulations represent two locations sensu IUCN
(2012). In addition, it is inferred that the ongoing loss of its
habitat induces a decline in its AOO, EOO, the extent and the
quality of its habitat, the number of subpopulations, and the
number of mature individuals. Based on available information,
L. porembskii is preliminary assessed as “Endangered” [EN B1a
b(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v)] according to IUCN Red List
Categories and Criteria (IUCN, 2012).
Specimens examined. – Madagascar. Reg. Amoron’i Mania [Prov.
Fianarantsoa]: Ivato, Faliarivo Anjoman’Ankona, Bemanta, inselberg côté E
de la route RN 35, à env. 13 km d’Ivato vers Ambatofinandrahana, 20°40'46"S
47 °07 '49"E, 1673 m, 14.XII.2015, fl., Rabarimanarivo et al. 615 (MO, TAN);
ibid. loco, inselberg côté gauche de la route RN 35, sur la route vers le camp
de Bemanta, 20°40'33"S 47 °07 '28"E, 1582 m, 8.III.2016, fl., Rabarimanarivo
et al. 719 (MO, TAN).
Acknowledgements
The authors are grateful to the Malagasy National Herbarium
(TAN), which is affiliated to the Zoology and Botanical Park
of Tsimbazaza, for providing collection material to compare
with allied taxa; the Malagasy Government [Ministère de
l’Environnement et du Développement Durable] for issuing
research permits no 317/15/MEEMF/SG/DGF/DAPT/SCBT
of December 7, 2015 and no 317/16/MEEMF/SG/DGF/
DAPT/SCBT of December 7, 2016, to conduct field work
and plant collecting. We thank Sylvie Andriambololonera for
leading the inventories of inselbergs in central Madagascar and
for improving an earlier version of this manuscript and Sophie
Giebelmann for the photograph of living plants. Thanks are
extended to Eberhard Fischer and Pete Phillipson for their
careful review of this article.
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