Journal of Threatened Taxa |
www.threatenedtaxa.org | 26 March 2021 | 13(3): 18054–18058
ISSN 0974-7907 (Online) | ISSN 0974-7893
(Print)
https://doi.org/10.11609/jott.4801.13.3.18054-18058
#4801 | Received 07 January 2019 | Final
received 17 November 2020 | Finally accepted 29 January 2021
Revisiting the taxonomy of Strobilanthes lawsonii
and S. pushpangadanii (Acanthaceae),
two endemic taxa of Western Ghats, India
Blessy Cherian 1, K.M. Prabhukumar 2, R. Jagadeesan
3, V.V. Naveen Kumar 4 & Indira Balachandran 5
1–5 Centre for Medicinal Plants
Research (CMPR), Arya Vaidya Sala, Kottakkal,
Malappuram, Kerala 676503, India.
2 Present address: Plant
Diversity, Systematics & Herbarium Division, CSIR-National Botanical
Research Institute, Rana Pratap Marg, Lucknow, Uttat
Pradesh 226001, India.
1 blessysmiles@gmail.com, 2 prabhu.krishna@nbri.res.in
(corresponding author), 3 vishnuviru22@gmail.com, 4 naveenkumar2389@gmail.com,
5 indirapa@hotmail.com
Editor: N.P. Balakrishnan, Coimbatore,
Tamil Nadu, India. Date of publication: 26 March
2021 (online & print)
Citation: Cherian, B., K.M. Prabhukumar, R. Jagadeesan,
V.V.N. Kumar & I. Balachandran (2021). Revisiting the taxonomy of Strobilanthes
lawsonii and S. pushpangadanii
(Acanthaceae), two endemic taxa of Western Ghats,
India. Journal of
Threatened Taxa 13(3): 18054–18058. https://doi.org/10.11609/jott.4801.13.3.18054-18058
Copyright: © Cherian et al. 2021. Creative Commons Attribution
4.0 International License. JoTT allows unrestricted use, reproduction, and
distribution of this article in any medium by providing adequate credit to the
author(s) and the source of publication.
Funding: None.
Competing interests: The authors
declare no competing interests.
Acknowledgements: The authors express sincere
gratitude to authorities of Arya Vaidya Sala, Kottakkal
for their support and Tata Trusts, Mumbai for financial assistance. Thanks are also due to Dr.
Mark Carine, The Natural History Museum, United Kingdom and Dr. E.S. Santhosh Kumar, JNTBGRI, Thiruvanathapuram
for their comment on the identity S. gamblei
and S. pushpangadanii respectively; Dr. Maya C. Nair, Govt. Victoria College, Palakkad, P.M. Binu Prakash, CMPR for their help in the field. Department of Kerala Forest is also
thankfully acknowledged for the permission granted to enter the forest.
Strobilanthes Blume (1826), the second largest
genus in the family Acanthaceae Juss.
(1789), consists of 400 species restricted to the hilly regions of tropical
Asia (Wood 1998; Augustine 2018). In
India, it is represented by 160–170 species from the mountains of peninsular
India and the Himalaya of northeastern and northwestern India.
In peninsular India, 65 taxa are recorded so far with many new recent
additions (Gamble 1924; Venu 2006; Josekutty et al. 2016, 2017, 2018; Sasidharan
et al. 2016; Augustine et al. 2017; Biju et al. 2017; Augustine 2018). Clarke (1885) enumerated 146 species of Strobilanthes in the Flora of British
India. In southern India and Sri Lanka,
the genus is represented by 65 species, of which most are endemics (Carine
& Scotland 2002).
EIght years of explorations in the
southern region of the Western Ghats has resulted in the documentation and
collection of many endemic Strobilanthes
species. Among them, materials collected
from Nelliyampathy forests (CMPR 8707, 9589) and Muthikulam forests (CMPR 9879) of Palakkad District, Kerala
did not key out their identity exactly.
After detailed taxonomic studies with the perusal of relevant literature
(Clarke 1885; Gamble 1924; Santhoshkumar et al. 2002;
Venu & Daniel 2003; Carine et al. 2004; Venu 2006) revealed their identity as S. pushpangadanii E.S.S. Kumar et al. (2002: 73), S.
gamblei Carine et al. (2004: 5), and
S. lawsonii Gamble (1923: 374)
respectively.
Since 1923, many subsequent
researchers recorded the distribution of S. lawsonii
from different localities of Kerala in their floristic reports (Ramachandarn & Nair 1980; Sasidharan
2004, 2013). But our herbarium survey
revealed that the materials so far identified as S. lawsonii
are either S. gamblei or S. pushpangadanii.
Hence our present collection is a rediscovery of S. lawsonii after Gamble’s collection in 1884, after a
lapse of 133 years.
Based on the evidence of the live
collection of S. gamblei and S. pushpangadanii from Nelliyampathy
forests of Palakkad, we reinstate S. pushpangadanii
as a distinct species, with the most notable morphological differences from
S. lawsonii (Table 1) being partially fused
corolla lobes, exserted stamens, and glabrous style. The latter species, S. gamblei
has been recently reinstated by Pradeep et al. (2020).
Strobilanthes lawsonii Gamble Bull. Misc. Inform. Kew
1923: 374. 1923. (Image 1, Figure 1)
Type: Tamil Nadu. Nilgiri Distr., 6000ft., Nov. 1883, Gamble 13387
(lectotype: K!)
=Phlebophyllum
lawsonii (Gamble) Bremek.,
Verh. Acad. Wet. afd. Natuurk. Sect. 2, 41: 169. 1944.
Type: Same as S. lawsonii.
Erect shrubs. Stem quadrangular with dense tawny coloured
short simple hairs; young branches are similar to that of its main axis. Leaves opposite-decussate, petiolate; petiole
2.3–3.8 cm long, pubescence as same as in stem.
Lamina 8.7–14.8 × 3.0–6.2 cm long, ovate, apex long acuminate, decurrent
at base, margin entire, abaxial surface covered with dense tawny-coloured woolly
indumentum, adaxial surface glabrous; venation
reticulated; nerves 9–11 pairs, arcuate, parallel with invisible reticulations,
prominent on both surfaces while less in adaxial surface comparatively. Inflorescence spike, axillary and terminal,
simple or branched, 1–3 branches, narrowly cylindrical, 26–70 × 3.5–5 mm,
interrupted; peduncle 1.0–1.5 cm long, densely covered with tawny tomentose indumentum.
Bract single, 4.5–4.8 ×1.5–1.6 mm long, shorter than calyx, ovate,
green, apex acuminate, margin entire, adaxial surface and margins with dense
tawny woolly indumentum. Bracteole 2,
ca. 3.5mm long. Flower 2–2.2 cm long,
blue, covered with soft tawny hairs, sessile.
Calyx 5-lobed, unequal, 2 or 3 lobes are larger than the rest, 5.6–6.5
mm long, lobes lanceolate, acuminate or acute at apex, margin entire, adaxial
surface covered with simple white delicate hairs, abaxial surface densely
covered with tawny indumentum, similar to that of bract. Corolla 5-lobed, equal, overlapping, 5.5-5.7
× ca. 0.5 mm long, ovate to broadly triangular, round or rarely acute at apex,
margins almost entire, blue, throat campanulate, outer surface with soft tawny tomentose indumentum; tube 14.0–15.5 mm long, ventricose, outer surface with soft tawny hairs. Stamens 2, equal, included; filaments 10–10.2
mm long, sparsely white hairs at base; anthers ca 1.8mm long, dithecous, dorsifixed. Ovary 2-celled, superior, on a prominent
disc, ca. 1.5mm long, oblong, glabrous. Style ca.
9.5mm long, pubescent; stigma 2.5mm long with sparsely white hairs. Capsule 14–15 mm long, elliptic to narrowly
obovate, glabrous.
Seeds 2.2–4.5 mm long.
Phenology: October–June.
Distribution and Ecology: Found
in thick rainforest undergrowth and shades of open grassland in the evergreen
forest. The distribution of the species
is strictly restricted to Tamil Nadu and Kerala (based on present collection)
region of Western Ghats.
Additional specimens examined: India:
Tamil Nadu. Nilgiri Dist., 6000ft. alt., xi.1883,
Gamble, 13387 (BM!); Kerala. Palakkad District, Way to Elival
Hills, 12.xi.2016, K.M. Prabhukumar & Binu Prakash, 9879 (CMPR!).
Reinstatement of S. pushpangadanii: In the protologue of Strobilanthes lawsonii,
Gamble (1923) cites four materials, two from Sispara
Ghat of Nilgiri Hills
(Gamble 13387, 14252), one each from Thamracheri Ghat of Wayanad (Barber 5686) and Travancore hills (Bourdillon 42), however, the collection from Wayanad and
Travancore hills is now considered representing two distinct species S. gamblei and S. pushpangadanii,
respectively.
Carine et al. (2004) did an
excellent revision of Strobilanthes kunthiana group in peninsular India with an
understanding morphological comparison chart to distinguish the members among
the group. As per the protologue, hand
drawing of flower on the type specimen (Gamble 13387; lectotype designated by
Carine et al. (2004) and Isolectotype) and the
present collection from Muthikulam Hills (9879), it
is very clear that, S. lawsonii is
distinct from S. gamblei and S. pushpangadanii by means of its equally divided
corolla lobes. But during the
revisionary work of Strobilanthes in
peninsular India, Venu (2006) synonymised S. gamblei and S. pushpangadanii
under S. lawsonii with commenting “S.
lawsonii looks very similar and stands between
S. pushpangadanii and S. gamblei”. But he completely ignored the most notable
morphological feature of this group, fusion of corolla lobes, exsertion of stamens, and pubescence nature of style. Based on the evidence of live collections and
strong distinguishing characters between the taxa, status of S. pushpangadanii as a distinct species (Table 1 &
Image 2). The latter species, S. gamblei
(Image 3) has been recently reinstated by Pradeep et al. (2020).
Special notes: Augustine
(2018) used a few photographs of the above discussed taxa provided by PKM with
due acknowledgment.
Strobilanthes pushpangadanii E.S.S. Kumar, Jabbar & A.E.S. Khan, Rheedea
12: 73. 2002. (Image 2).
Type: India. Kerala. Thiruvanthapuram district, Mankayam
hills, E.S.S. Kumar 14722 (Holotype: TBGT; Isotype: MH, CALI!)
Flowering & Fruiting:
August–March.
Distribution and Ecology: Margins
of evergreen forest and open grasslands in Kerala. Carine (2004) noted that the distribution of
the species is strictly restricted to Thiruvananthapuram and Idukki districts
of southern Kerala, but our field surveys reveal that the occurrence of the
species extends up to the Palakkad gap.
Additional specimens examined:
14722 (CALI!, Isotype), India, Kerala, Thiruvananthapuram District, Mankayam Hills, 800m, 20.x.1992, coll. E.S. Santosh Kumar;
14030 (CALI!), Idukki District, Vellimala, 1,700m,
20.viii.1994, coll. Augustine; 11157 (CALI!), Thiruvananthapuram District, Ponmudi, Barnes s.n (K!); 5936
(KFRI!), Chemingi, c. 900m, 24.i.1992, coll. Mohanan; Thrissur District, Sholayar,
25.x.1992, coll. N. Sasidharan; 9879 (CMPR), Palakkad
District, Nelliyampathy, Minnampara,
12.xi.2016, coll. K.M. Prabhukumar & Binu Prakash.
Key to the species
1a. Two
partially fused corolla lobes, stamens exserted,
style glabrous ...……………........................…..………
2
1b. Corolla lobes divided equally, stamens
included, style pubescent …………...........................…… S. lawsonii
2a. Leaves
with up to 9cm long petiole and acuminate apex, margins entire, spikes
uninterrupted, up to 6.5cm long, peduncle long, 2.3–6.5 cm long, corolla light
pink ……...……………………..…………… S. gamblei
2b. Leaves
shortly petiolate up to 2cm long, apex short candidate-acuminate, margins
denticulate or crenate-serrate, spikes interrupted, up to 10cm long, peduncle
short, 1–1.5 cm long, corolla light pink with dark purple venation
………………..………………........ ……………..………. S. pushpangadanii
Table 1. Comparison of
morphological features of Strobilanthes lawsonii, S. gamblei,
and S. pushpangadanii
|
Character |
S. gamblei |
S. pushpangadanii |
S. lawsonii |
|
Young stem |
quadrangular |
cylindrical |
quadrangular |
|
Petiole length |
3−9 cm |
1.5−2 cm |
2.3−3.8 cm |
|
Leaf size |
5.5–15 × 2–6 cm |
3.2–12 × 1–4.5 cm |
8.7−14.8 × 3.0−6.2 cm |
|
Leaf apex |
long acuminate |
caudate - acuminate |
long acuminate |
|
Leaf margin |
entire |
denticulate |
entire |
|
Leaf abaxial surface |
densely covered with cream or
tawny-colored woolly indumentum |
abaxial soft silky texture due
to the presence of dense tawny indumentum |
abaxial surface covered with
dense tawny-colored woolly indumentum |
|
Leaf adaxial surface |
glabrous |
coriaceous, glabrous
or sparsely pilose above |
glabrous |
|
Nerves (pairs) |
6–11 |
7–13 |
9−11 |
|
Inflorescence type |
interrupted |
uninterrupted |
interrupted |
|
Inflorescence dimension |
4–15 × 0.2–0.4 mm |
5.5–6.2 × 0.5–0.8 mm |
26–70 × 3.5–5 mm |
|
Peduncle length |
1–1.5 cm long |
2.3–6.5 cm long |
1–1.5 cm long |
|
Bracts |
glandular golden brown woolly
indumentum outside |
glandular golden brown woolly
indumentum outside |
adaxial surface and margins
with dense tawny woolly indumentum |
|
Bracteole |
tawny woolly indumentum
abaxially |
golden brown woolly tomentose abaxially |
tawny woolly indumentum
abaxially |
|
Calyx length |
7.7–10.2 mm long |
4–6 ×1−1.5 mm long |
5.6−6.5 mm long |
|
Calyx |
glabrous or rarely hairy
with tawny tomentose |
dense tawny tomentose
abaxially and adaxial glabrous |
adaxial surface covered with
simple white delicate hairs, abaxial surface densely covered with tawny
indumentum |
|
Corolla |
light pink; 1.5–1.8 cm
long, hairy |
light pink with dark purple
venation, 1.5–1.9 cm long, hairy |
blue, outer surface with soft
tawny tomentose indumentum |
|
Corolla tube |
1.1–1.3 cm long |
1.0–1.2 cm long, |
1.4–1.6 cm long |
|
Corolla lobes |
unequal, bi-lipped |
unequal, bi-lipped |
equal |
|
Stamens |
exserted |
exserted |
inserted |
|
Filament |
8.5 –11 mm long |
ca. 2.2 cm |
10-10.2 mm long |
|
Style |
glabrous |
glabrous |
pubescent |
For
figure & images - - click here
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