Murdannia saddlepeakensis M.V.Ramana & Nandikar, 2013

Ramana, M. Venkat, Nandikar, Mayur, Gurav, R. V., Johny Kumar Tagore, & M. Sanjappa,, 2013, Murdannia saddlepeakensis (Commelinaceae) - a new species from Andaman and Nicobar Islands, India, PhytoKeys 20, pp. 9-15 : 10-14

Murdannia saddlepeakensis M.V.Ramana & Nandikar sp. nov. Figs 1 , 2

Type.

India. North Andaman: Saddle Peak National Park, open scrub forests ( Fig. 1-A ), 13°09'N, 93°01'E, at 508 m, 18 November 2011, M.V.Ramana 0550 (holotype: CAL; isotypes: US, BSI, SUK, PBL).

Description.

Erect, 40-60 cm high, glabrous perennial with a basal rosette of leaves ( Fig. 1-B ); roots fibrous, 2-4 cm long and 2 mm in diam. Leaves rosette, sheaths 0.5-1 cm long, lamina narrowly linear, 20-60 cm long, 0.4-0.8 cm wide, apex acuminate, base rounded merged into the sheath, margins entire; cauline leaves with sheaths 0.2-2 cm long, glabrous, narrowly lanceolate to linear, 1-25 cm long, 0.2-0.5 mm wide, base rounded, apex acute to acuminate, glabrous, margin entire, often scabrid; flowering shoot terminal in the basal rosette, erect, 20-40 cm long, unbranched or rarely branched from apically reduced cauline leaves (a bract). Inflorescence terminal and axillary (from uppermost foliaceous bract) of peduncled cincinni ( Fig. 2-B ); peduncles 2-7 cm long, glabrous, cincinni to 2 cm long, few flowered, bracteoles 5 mm long, caducous. Flowers bisexual ( Fig. 1-C ; Fig. 2-C, D ), c. 1.5 cm wide, opening 1230-1600 hr; pedicels (2-) 3-5 mm long (not declinate in capsule); sepals elliptic to oblong elliptic, 5-6 mm long, pale white to green; petals ovate to obovate, lilac to pale lavender; stamens 2 ( Fig. 2E ), filaments densely bearded, (3-) 4 mm long, anthers elliptic, c. 1 mm long; staminodes 3 ( Fig. 2G ), antepetalous with glabrous to sparsely bearded filaments, antherodes tri-lobed, yellow; one rudimentary stamen, antisepalous ( Fig. 2F ) with densely bearded filament ending with sterile knob; ovary glabrous; style recurved towards staminodes, (3-)4 mm long; stigma simple. Capsule subglobose, 4-5 mm long, 3 mm wide, locules 1-seeded. Seeds ( Fig. 2J, K ) elliptic or rarely ovoid, 2.5 -5 mm long, 1.5-3 mm wide, testa scorbiculate on all surfaces, the depressions often partially uniting on the dorsal surface, forming a little larger, irregular depressions, dark brown, hilum linear or oblong-linear, embryotega dorsal-semidorsal, farinose sparsely in all depressions and around the embryotega.

Distribution.

Murdannia saddlepeakensis is so far only known from Saddle Peak National Park, North Andaman Islands, India.

Ecology.

It grows in an open scrub forest in rocky situations at an elevation of 508 m. The common associates are Sonerila andamanensis Stapf & King (Melastomataceae), Ophiorrhiza mungos L.(Rubiaceae) and Gomphostemma javanicum (Blume)Benth. (Lamiaceae). It was observed flowering and fruiting from October to February.

Etymology. Murdannia saddlepeakensis is named after the type locality Saddle Peak National Park. It is the highest peak of the entire archipelago, reaching an altitude of 732 m.

Conservation status.

Murdannia saddlepeakensis was collected only once from the Saddle Peak National Park (North Andaman Islands). At this site c. 25 individuals in an open scrub forest in rocky situations were observed and hence it is assumed to be rare. However, larger part of the National Park is unexplored due to human inaccessibility. Therefore, the species can be accessed as "Data Deficient" (DD), using the criteria of IUCN (2001).

Discussion.

Murdannia saddlepeakensis belongs to the group Terminatae G. Brückn. (173: 1830) [Inflorescence terminal, many-flowered, the main shoot and lateral flowering shoots few to several, shortened, completely tufted]. In India, series Terminatae is represented by eight species viz. Murdannia dimorpha G. Brückn., Murdannia divergens (C.B. Clarke) G. Brückn., Murdannia hookeri (C.B. Clarke) G. Brückn., Murdannia japonica (Thunb.) Faden, Murdannia gigantea (Vahl) G. Brückn., Murdannia loriformis (Hassk.) R.S. Rao & Kammathy, Murdannia nudiflora (L.) Brenan and Murdannia simplex (Vahl) Brenan (modified after Brückn. 1930). The first four species have more than two seeds per locule and rest four have two seeds per locule while Murdannia saddlepeakensis has single seed per locule.

Murdannia saddlepeakensis closely resembles Murdannia simplex but can be easily distinguished by its narrow linear leaves, terminal flowering shoot in the basal rosette, glabrous leaf sheaths, single seeded locule, elliptic seed with scorbiculate surface. In addition, Murdannia saddlepeakensis is restricted to northern Andaman Island whereas Murdannia simplex is much more wide spread in Tropical Africa and Asia. Murdannia gigantea with a terminal flowering shoot also is similar to Murdannia saddlepeakensis but differs in having thick, fibrous roots, broad leaves, three stamens and seeds with dorsal embryotega. Murdannia saddlepeakensis can also be mistaken for the widespread Murdannia loriformis in general. However, the presence of erect, terminal flowering shoot and scorbiculate, single seeded locule along with anthesis by noon supports its distinctness.

Pandey and Diwakar (2008) recorded five species of Murdannia from Andaman & Nicobar Islands namely Murdannia crocea (Griff.) Faden subsp. crocea, M. gigantea (Vahl) G. Brückn., M. nudiflora (L.) Brenan, M. spirata (L.) G. Brückn. and Murdannia vaginata (L.) G. Brückn.The occurrence of Murdannia crocea (Griff.) Faden subsp. crocea from Andaman seems to be erroneous as the screening of herbarium specimens at Kew have revealed that Murdannia crocea subsp. crocea is known only from Myanmar, Tenasserim [Herb. Helfer 5497 (K!)]. No one has reported this species till from India after Helfer’s collection. A key for the species of the genus Murdannia in Andaman and Nicobar Islands and closely related taxa of the new species is given below to facilitate identification(modified after Faden 2000).

1	Plants with basal rosette leaves	2
-	Plants without basal rosette leaves	5
2	Rosette leaves 0.4-0.8 cm wide; capsule subglobose; locule one seeded	Murdannia saddlepeakensis
-	Rosette leaves (0.5-) 0.8-1.5 cm wide; capsule ovoid to ellipsoid; locule two seeded	3
3	Flowering shoots terminal in the rosette; seeds ovoid to ellipsoid, 2.5-4 × 2-2.5 mm, hilum linear	Murdannia gigantea
-	Flowering shoots lateral in the rosette; seeds ovoid to obovoid, 1.6-2 × 1.5 mm, hilum linear to oblong	4
4	Pedicels 3-5 mm long; seeds 1.5-2 mm long; flowers 12-15 mm wide, opening after noon	Murdannia simplex
-	Pedicels 2-3 mm long; seeds 1.4-1.8 mm long; flowers 9-12 mm wide, fading by noon	Murdannia loriformis
5	Leaves subtending inflorescence bract-like; capsule globose; locule one seeded	Murdannia vaginata
-	Leaves not subtending inflorescence bract-like; capsule ovoid to obovoid or elliptic; locule more than 2 seeded	6
6	Leaves linear-lanceolate to linear-oblong; seeds 2 per locule	Murdannia nudiflora
-	Leaves lanceolate to ovate; seeds 3-7 per locule	Murdannia spirata

Figures

Figure 1. Murdannia saddlepeakensis A Habitat (a view of Saddle Peak National Park) B Habit C Flower, ventral view.

Figure 2. Murdannia saddlepeakensis A Habit B Inflorescence C Flower, ventral view D Flower, lateral view E Stamen F Rudimentary stamen G Staminode H Pistil I Capsule J Seed, lateral view K Seed, ventral view. All from M V Ramana 0550. Drawn by Mayur Nandikar