Research Article
Print
Research Article
Sonerila nairii (Melastomataceae) – a new species from the southern Western Ghats, India
expand article infoSoumya Murugan, Maya C. Nair§
‡ Environmental Resources Research Centre, Peroorkkada, Thiruvananthapuram, Kerala, India
§ University of Calicut, Palakkad Kerala, India
Open Access

Abstract

The new species Sonerila nairii (Melastomataceae) is here described from Pothumala of the Nelliampathy hill ranges of Western Ghats of Kerala, India. Morphologically it most closely resembles Sonerila erecta and Sonerila pulneyensis from which differs by the form of the stem, leaves, peduncle, pedicel, inflorescence, pubescence of the stem, leaves and hypanthium, and by the form of stamens and stigma.

Keywords

Sonerila, Kerala, Nelliampathy, Palakkad, Western Ghats, India, critically endangered

Introduction

The genus Sonerila Roxb. (Melastomataceae) consists of erect or creeping and rhizomatous terrestrial low epiphytic herbs or semi-woody shrubs, occasionally acaulescent with a distribution in tropical Asia (Clausing and Renner 2001). The genus is classified under the tribe Sonerileae (Triana 1866) and is clearly delineated from other genera in having trimerous flowers and mostly uniparous scorpioid cymes (Sunil et al. 2014).

In Hooker’s Flora of British India, Clarke (1879) recognised 43 species and Gamble (1919) recognised 13 species of Sonerila. Lundin (1998) made an extensive documentation of Melastomataceae with special emphasis on Sonerila of South India. Lundin and Nordenstam (2009) considered the genus to have about 175 species distributed from Sri Lanka and India to the Indo-Pacific. As per recent assessment by considering the works published after Gamble’s 1919 treatment, the genus is represented by 52 species in India and Western Ghats has the highest species diversity with about 35 species (Nayar 1976, Giri and Nayar 1985, 1986a,b, 1987, Prakash and Mehrotra 1988, Gopalan and Henry 1989, Giri et al. 1992, Ravikumar 1999, Murugan and Manickam 2002, Josephine et al. 2003, Lundin and Nordenstam 2009, Murugesan and Balasubramaniam 2011, Narayanan et al. 2013, 2014a, b, Deepthikumary and Pandurangan 2014, Sunil et al. 2014, Narayanan et al. 2015).

During the field exploration in the Kollengode range of Nemmara forest division, an interesting Sonerila was collected from the Pothumala region of Nelliampathy hills of Palakkad district during October 2015, at an altitude of about 1140–1160 m. Critical analysis of the specimen and comparison with protologues and digital images of herbarium specimens of the closely allied species, Sonerila erecta Jack (Barcode id: K000867797) and Sonerila pulneyensis Gamble (Barcode id: K00867655) deposited at Kew Herbarium revealed its distinctiveness from these and other allied species. Therefore this taxon is here described as the new species S. nairii.

Description of the new species

Sonerila nairii Soumya & Maya, sp. nov.

Figs 1, 2

Diagnosis

The new species is distinguished from S. erecta and S. pulneyensis by the decumbent unbranched stem, absence of a distinct peduncle, the cymose 1–2 flowered terminal inflorescence and by the anthers which are half the length of filament. (Sonerila erecta and S. pulneyensis have branched stem, a distinct peduncle, inflorescence consisting of more than 2 flowers in a cyme and anther having same the length of the filament.)

Type

INDIA. Kerala: Palakkad district, Pothumala, Nelliampathy hills, 10°30'09.6"N; 76°42'16.5"E, 1160 m 18 Oct 2015, Soumya M. & Maya C. Nair 1185 (Holotype CALI!, isotypes MH!, ERRCH!, GVCH!)

Description

Decumbent, unbranched, delicate, succulent herbs attaining 6–10 cm height; the lower portion more or less trailing and bear perennating buds, while the upper portion curves upward and grows erectly. Stem translucent, fleshy, subterete with scattered multicellular and glandular trichomes which form a dense hairy nodal ring. Leaves opposite, fleshy, petiole 0.5–1.5 cm, adaxially grooved, with glandular trichomes; lamina ovate, 1.3–2.5 × 1–1.5 cm, base obtuse, green with pink tinge below, upper surface densely hirsute (0.08–0.09 × 0.03–0.06 cm), lower surface with scattered glandular trichomes (0.02–0.03 cm × 0.03–0.04 cm), margins finely serrate, acute at apex, prominently 3-nerved a pair of nerve obscurely seen near the margin. Inflorescence terminal, unbranched, condensed, a 1–2- flowered cyme. Peduncle more or less absent. Flowers 3-merous, pedicel 0.5–0.7 cm with few glandular trichomes, shorter than hypanthium, light green. Hypanthium 0.8–0.9 cm long, campanulate with scattered glandular trichomes, light green. Calyx lobes 3, 0.15–0.2 cm long, triangular, non-caducous, with sporadic glandular trichomes and pink tinge. Petals 3, 0.8–0.7 × 0.5 cm–0.45 cm orbicular-obovate, acuminate at apex with 3–4 glandular trichomes on the midrib of the abaxial side. Stamens 3; filaments 0.4–0.42 cm long, glabrous, white; anthers yellow, 0.2–0.22 cm, cordate at base, glabrous. Style 0.8–0.9 cm long, curved, deep pink towards the tip, stigma capitate, glabrous. Capsule campanulate, 0.8–0.9 cm long and 0.45 cm wide with occasional glandular trichomes, green. Seeds many, 0.07× 0.02 cm, minutely tuberculed, brown.

Phenology

October–December.

Etymology

The specific epithet honours Dr. P.K.K. Nair (1930-), eminent scientist, renowned as father of Indian palynology and founder director of the Environmental Resources Research Centre (ERRC), Thiruvananthapuram.

Distribution and ecology

Sonerila nairii grows at altitudes of 1140–1160 m in shady rock surfaces within moist loose soils and under the evergreen canopies along the Pothumala hill tract of Nelliampathy hills. In these habitats, S. nairii grows close association with crustose lichens. The new species seems to prefer more or less moist lithophytic habitats in contrast to S. erecta and S. pulneyensis which grow in evergreen and riparian forests respectively. The distribution of the three taxa has been summarized in Fig. 3.

Figure 1.

Sonerila nairii A Habit B Single flower and flower bud C Calyx D Petal-Adaxial side E Petal-Abaxial side F Stamen G Gynoecium H Ovary TS I Flower LS J Seed (from Soumya. M & Maya. C. Nair 1185) Illustration by Soumya. M.

Figure 2.

Sonerila nairii A Habitat B Habit C Single flower and flower bud D Calyx E Petal-Adaxial side F Stamen G Gynoecium H Ovary TS I Flower LS J Seed (from Soumya. M & Maya. C. Nair 1185) Photos by Soumya. M & Maya. C. Nair.

Figure 3.

Map showing the distribution of Sonerila nairii sp. nov., Sonerila erecta Jack and Sonerila pulneyensis Gamble.

Conservation status

Two populations comprising only a few individuals (5–10) of the species were recorded growing within a distance (50 meters) of each other. Apart from the type locality, the species has yet to be found anywhere else. Because the number of mature individuals is less than 50 and the species has a very restricted area of occupancy, we assign the species, the status of Critically endangered using IUCN Strategies and criteria (IUCN 2014).

Additional specimens examined

(Paratypes). INDIA. Kerala: Palakkad district, Pothumala, Nelliampathy hills, 1 Nov 2015 Soumya M. & Maya C. Nair 1187 (ERRCH!) (Environmental Resources Research Centre Herbarium), 5 Nov 2015 Maya C. Nair & Soumya M. 98 (GVCH!) 12 Nov 2015 Maya C. Nair & Soumya M. 99 (GVCH!) (Government Victoria College Herbarium)

Discussion

Sonerila nairii differs from S. erecta by having an unbranched decumbent stem, leaf margins with pink tinge; by the absence of a peduncle, a condensed, cymose, 1–2-flowered, terminal inflorescence. The anthers are half the length of the filaments and the stigma is capitate. From S. pulneyensis Gamble it differs in having decumbent and sparse glandular trichomes on the stem and pedicel, dimorphic hairs on the leaves, by the absence of a distinct peduncle; by the terminal inflorescence of 1-2 flowers borne in a condensed cyme. The hypanthium is green-coloured and the anthers are half the length of the filaments. Further differences between S. nairii, S. erecta and S. pulneyensis are given in Table 1.

Taxonomic delineation of Sonerila nairii from S. erecta and S. pulneyensis.

Taxonomic traits Sonerila nairii sp. nov. S. erecta S. pulneyensis
Habitat Shady rocks within evergreen forest Evergreen forests Riparian forests in high altitudes
Stem Decumbent, sub-terete succulent, unbranched with sparse glandular trichomes Erect, 4-angled, slender, branched with sparse glandular trichomes Creeping, sub-succulent, branched, glabrous
Nodal region Glandular trichomes arranged in a nodal ring Not prominent Absent
Leaf Petiole 0.5–1.5 cm long, angular, sparsely with glandular hairs; lamina slightly coriaceous, ovate, 1.3–2.5 × 1 –1.5 cm, prominently 3-nerved, an additional pair of nerve obscurely seen near the margin Petiole 0.4–1.5 cm long; lamina membraneous, narrowly elliptical to ovate, 1–2.5 × 0.4–1.6 cm, Secondary veins 2–3 pairs Petiole 0.5–1.5 cm; lamina coriaceous, ovate 1- nerved, 2–5 × 1–3 cm
Nature of hairs on leaf lamina Dimorphic hairs present,
densely hirsute above and with sparse glandular trichomes below
Dimorphic hairs present, densely hirsute above and with sparse glandular trichomes below Absent
Leaf margin Narrowly serrate with pink tinge Serrate without pink tinge Broadly serrate with pink tinge
Postion of Inflorescence Terminal Terminal Axillary or terminal
Inflorescence Usually 1-2 flowered compressed terminal cyme Inflorescences occurs at the end of branches, in 1-5 (up to 11-flowered) terminal scorpioid cymes. Axillary or terminal 5- flowered umbellate cyme
Peduncle More or less absent Up to 2cm, with sparse glandular hairs 3–4cm long, glabrous
Pedicel Pedicel 0.5–0.7cm with sparse glandular trichomes shorter than hypanthium Pedicel 0.2–0.7cm with sparse glandular trichomes, shorter than hypanthium Pedicel 1cm long, glabrous, length equalling hypanthium
Hypanthium Light green with sparse glandular trichomes Green with sparse glandular trichomes Pink, glabrous
Petals Petals pink to purple, broadly ovate, slightly clawed on either side,4–5 glandular trichomes on the mid rib below, tip acuminate Petals pink to purple oblong-elliptic sparse glandular trichomes on the mid rib below, tip acute to acuminate Petals rose, elliptic, glabrous,tip apiculate.
Stamen Anthers half the length of filaments Anthers as long as filaments Anthers as long as filaments
Stigma Capitate Three lobed Capitate
Capsule Tubular, 3-sided with sparse glandular trichomes Tubular, 3-sided with sparse glandular trichomes Campanulate, glabrous

Acknowledgements

The senior author wishes to acknowledge the Kerala State Council for Science Technology and Environment (KSCSTE), Government of Kerala for their financial support by way of its Fellowship in Taxonomy. The authors are thankful to Dr Sasidharan N. (KFRI) and Dr Shaju T (JNTBGRI) for their input into confirming the novelty of Sonerila nairii. The authors appreciate the assistance and advice of Dr(s) G. Achuthan Nair, (Senior Scientist, ERRC) and P.K. Shaji (Scientist and Research Coordinator, ERRC). Maya C. Nair would like to thank the Director of Collegiate Education, Government of Kerala and Principal, Government Victoria College, Palakkad for their support and encouragement.

References

  • Clarke CB (1879) Sonerila. In: Hooker JD. The Flora of British India. L. Reeve & co., London, 2: 529–540.
  • Clausing G, Renner SS (2001) Molecular phylogenetics of Melastomataceae and Memecylaceae: Implications for character evolution. American Journal of Botany 88: 486–498. doi: 10.2307/2657114
  • Deepthikumary KP, Pandurangan AG (2014) A new species of Sonerila (Melastomataceae) from the Western Ghats of Kerala, India. Taprobanica 6: 72–75. doi: 10.4038/tapro.v6i2.7229
  • Gamble JS (1919) Sonerila In: The Flora of the Presidency of Madras. Adlard & Son Limited, London, 3: 497–500.
  • Giri GS, Nayar MP (1985) A new species of Sonerila Roxb. (Melastomataceae) from India. Blumea 31: 235–237
  • Giri GS, Nayar MP (1986a) A new species of Sonerila (Melastomataceae) from India. Journal of Japanese Botany 61: 344–348.
  • Giri GS, Nayar MP (1986b) A new species and notes on two species of Sonerila Roxb. (Melastomataceae) from South India. Bulletin of Botanical Survey of India 26: 174–180
  • Giri GS, Nayar MP (1987) A new species of Sonerila Roxb. (Melastomataceae) from southern India. Bulletin of Botanical Survey of India 27: 86–89.
  • Giri GS, Pramanik A, Chowdhery HJ (1992) A new species of Sonerila Roxb. (Melastomataceae) from Arunachal Pradesh, India. Indian Journal of Forestry 15: 95–96.
  • Gopalan R, Henry AN (1989) A new Sonerila Roxb. (Melastomataceae) from southern India. Journal of the Bombay Natural History Society 86: 82–83.
  • Josephine MM, Manickam VS, Murugan C, Sundaresan V, Jothi GJ (2003) Sonerila longipetiolata, a new species of Melastomataceae from Tamil Nadu, India. Journal of Bombay Natural History Society 100: 81–83.
  • Lundin R (1998) Studies in Melastomataceae with special emphasis on the Ceylonese and South Indian Sonerila species. Licentiatavhandling, Stockholmsuniversitet, 1–94.
  • Lundin R, Nordenstam B (2009) Two new species of Sonerila (Melastomataceae) from South India. Novon 19: 76–79. doi: 10.3417/2004198
  • Murugan C, Manickam VS (2002) New species of Memecylon and Sonerila (Melastomataceae) from southern Western Ghats of India. Journal of Economic and Taxononomic Botany 25: 509–513.
  • Murugesan M, Balasubramaniam V (2011) A new species of Sonerila (Melastomataceae) from the Western Ghats, India. Taprobanica 3: 93–95. doi: 10.4038/tapro.v3i2.3965
  • Narayanan RMK, Mini V, Shaju T, Sujana KA, Joseph JP, Sivadasan M, Alfarhan AH (2013) A new species of Sonerila Roxb. (Melastomataceae) from Kerala, India. Phytotaxa 110: 55–60. doi: 10.11646/phytotaxa.110.1.5
  • Narayanan RMK, Sunil CN, Nandakumar M, Shaju T, Mini V, Satheesh KT, Balakrishnan V (2014a) Sonerila raghaviana sp. nov. (Melastomataceae), a new species from southern Western Ghats of Karnataka, India. International Journal of Advanced Research 2: 772–777.
  • Narayanan RMK, Nandakumar MK, Prajeesh P, Sujana KA, Sunil CN, T Shaju (2014b) A New Species of Sonerila Roxb. (Melastomataceae) from Kerala, India. Annals of Plant Sciences 11: 863–868.
  • Narayanan RMK, Sivadasan M, Sunil CN, Nandakumar MK, Shaju T, Alfarhan AH, Tamimi AA (2015) Sonerila gadgiliana, a new scapigerous species of Melastomataceae from India. Bangladesh Journal of Plant Taxonomy 22(1): 9–15. doi: 10.3329/bjpt.V22i1.23861
  • Nayar MP (1976) A new species of Sonerila (Melastomataceae) from Kerala, S. India. Journal of Bombay Natural History Society 71: 632–633.
  • Prakash V, Mehrotra BN (1988) A new species of Sonerila Roxb. (Melastomataceae) from Meghalaya, India. Candollea 43: 143–145.
  • Ravikumar K (1999) Novelties from High Wavy Mountains, Southern Western Ghats, Theni District, Tamil Nadu, India. Rheedea 9: 55–75.
  • Sunil CN, Naveen Kumar VV, Rajeev TS (2014) Sonerila sreenarayaniana (Melastomataceae), a new species from Kerala, India. International Journal of Advanced Research 2: 701–704 doi: 10.2307/3392180
  • Triana JJ (1866) Dispositio Melastomacearum. Bulletin du Congres international de botanique et d’horticulture 1865: 457–461.