Pandanus martinianus Nadaf & Zanan, 2012

Zanan, Rahul L. & Nadaf, Altafhusain B., 2012, Pandanus martinianus (Pandanaceae), a new endemic species from northeastern India, Phytotaxa 73 (1), pp. 1-7 : 2-6

Pandanus martinianus Nadaf & Zanan , sp. nov. Figs. 2 , 3 , 4B .

Differs from Pandanus unguifer by its ellipsoid syncarp (vs. globular in P. unguifer ), 6–7 x 10–12 cm (vs. 7–10 x 7–10 cm), with 140–160 drupes arranged in rows (vs. 90–110 randomly distributed drupes), and a style bifid in upper 2/3 of syncarp and unlobed in lower 1/3 style (vs. unlobed and bifid style).

Typus:— INDIA. Arunachal Pradesh: West Siang District, foothill of Along , 294 m, 28 ° 10’16”N, 94 ° 46’37”E, 29 September 2010 (fr.), Zanan 65 (holotype CAL!; isotypes G [ G00368627 ]!, K!) .

Small shrub, 1–3 feet tall with slender decumbent stem, 1.5–2.5 cm in diam., smooth, branched from the base; prop roots present at the base of trunk. Leaves on the distal part of branches, coriaceous, linear, 80–120 cm long, 3–4 cm wide in the middle, abruptly attenuate in its distal 1/10, ending by a subulate tip 3–4 cm long, auricles lacking, adaxial leaf surface dark green and abaxial surface pale green, longitudinal and transverse veins visible on both surfaces; leaf margins and abaxial mid vein spiny with sharp prickles, yellow, proximal prickles thick becoming thinner in the distal end; marginal prickles appear at 5–7 cm from the base of leaf and extending towards apex, prickles on margin at the base of leaves 1–3 mm long, 0.4–1.5 cm apart (8–10 spines per 10 cm), on midrib 2–2.5 mm long and 1–1.5 cm apart, in the middle part of the leaf prickles 1–2 mm long, 0.3–1 cm apart (10–12 spines per 10 cm), on midrib 1–1.5 mm long 1–3 cm apart (3–4 spines per 10 cm) and crowded towards apex. Infructescence terminal, a solitary ellipsoid syncarp, 10–12 cm long, 6–7 cm wide; peduncle straight, 10–16 cm long, 1–1.5 cm across, trigonous, veins on bract visible, bearing 7–8 pale yellow bracts armed with prickles; drupes 140–160 per syncarp, arranged in rows, connate in the syncarp, drupes 2.7–3.2 cm long, 1.5–2 cm wide, hexagonal, pileus conical, superior portion free, 0.7–1 cm high, smooth; style curved, bifid and unlobed, 2–3 mm long, upper 2/3 portion of syncarp with bifid styles and lower 1/3 portion with unlobed styles; single style per drupe in the centre of the conical pileus, 1.5–3 mm long, bony, brown; endocarp cone-shaped, inner side smooth and shiny, apex flat with a conic projection extending to the style base, 0.8–1 cm long in the center of drupe, 0.4–0.6 cm wide at middle part, 0.1–0.15 cm thick; mesocarp fibrous, superior mesocarp narrow and compact, 0.3–0.5 cm long, inferior mesocarp thick and fibrous, 1.2–1.4 cm long; single seed per locule, seed locule conical, 0.6–0.8 cm long. Staminate inflorescence and flower unknown.

Distribution, phenology and ecology: — Pandanus martinianus is found in open forests in the foothills of West Siang District of Arunachal Pradesh and Dhimaji and Golaghat District of Assam ( Fig. 1 ). It is fruiting from June to September.

Etymology: —The species is named in honour of Dr. Martin W. Callmander (Missouri Botanical Garden and Conservatoire et Jardin botaniques de la Ville de Genève) for his contributions to the knowledge of the family Pandanaceae , especially in Madagascar and New Caledonia and for his tireless support in the current revision of the Indian screw pines.

Discussion:— The new species closely resembles P. unguifer in having a single small syncarp with small leaves abruptly attenuated in the distal part. P. martinianus can be distinguished from P. unguifer in having ellipsoid syncarp (vs. globular in P. unguifer , see Fig. 4A ), 6–7 x 10–12 cm (vs. 7–10 x 7–10 cm), with 140–160 drupes arranged in rows (vs. 90–110 randomly distributed drupes), with style bifid in upper 2/3 of syncarp and unlobed in lower 1/3 style (vs. unlobed and bifid style) ( Fig. 3 ) (see also Hooker 1878: tab. 6347). A comparative account of the morphology of both species is presented in Table 1. Furthermore, both species are geographically separated from each other. P. martinianus is found in Assam and Arunachal Pradesh in open forest whereas P. unguifer is endemic to West Bengal and Sikkim states of India and Bhutan ( Noltie 1994) in dense forests (see Fig. 1 ). P. martinianus can also be compared to some extent to P. urophyllus and P. tonkinensis in having leaves tapering gradually towards the tip and ending in a subulate apex but can be easily recognized when fruiting. Pandanus urophyllus has a narrow sub-cylindric syncarp, c. 8 x 13 cm with up to 160 drupes, with irregularly bifid style, endocarp in lower 1/3, thick, ellipsoid. ( Fig. 5A ). Pandanus tonkinensis has a globular syncarp, c. 5 cm in diam. with c. 70 drupes ( Fig. 5B ) ( Stone 1983a, 1983b). Several collections from Peninsular Malaysia (Pahang, Perak) have been determinated as P. unguifer in the K herbarium. These collections were previously gathered under the name P. bicornis Ridley (1904: 49) . It is possible that the latter is in fact a synonym of P.unguifer with its globular syncarp and leaves tapering gradually towards the tip and ending in a subulate apex. This synonymy would extend P. unguifer ’s range to the south. A revision of the family in Peninsular Malaysia by H. Beentje at K will hopefully solve this question.

Pandanus martinianus is placed in Pandanus subg. Rykia ( Vriese 1854: 268) Stone (1974: 489) following the infrageneric classification of Stone, for having leaf apex with unarmed ventral plates; drupes crowed with free carpel and acute or bifid style and stigmas on ventral side of style.

Additional specimens examined (paratypes):— INDIA. Assam: Dhimaji District, Dhimaji , 107 m, 27 ° 28’22”N, 94 ° 32’31”E, 29 September 2010 (fr.), Zanan 66 ( BSI!) ; Golaghat District, Kaziranga National park , 28 km west of wild grass rest house, 150 m, 26 ° 35’ N, 93 ° 27’ E, 13 January 1994 (ster.), Namdapha Rainforest project s. n. ( E [ E00567766 ]!) .

Conservation status:— Pandanus martinianus has an extent of occurrence (EOO) of c. 350 km ², an area of occupancy (AOO) of 135 km ² and comprises up to 11 known subpopulations, three of which are found in a protected area (Arunachal Pradesh) (calculation following Callmander et al. 2007). Pandanus martinianus should be considered as Endangered [EN B1ab(i, ii, iii) + B2ab(i, ii, iii)] according to IUCN Red List Categories and Criteria ( IUCN 2001).

Figures

FIGURE 1. Details of localities of Pandanus martinianus Nadaf & Zanan from North Eastern States of India.

FIGURE 2. Pandanus martinianus Nadaf & Zanan. A. Adaxial and abaxial leaf surface at basal position; B. Abaxial leaf surface at middle position; C. Abaxial leaf surface at apical position; D. Entire syncarp; E. Drupe with unlobed style; F. Drupe with bifid style; G–H. Drupes in longitudinal section showing the mesocarp and endocarp. A–H: Zanan 65, holotype CAL; drawing: R. Zanan.

FIGURE 3. Pandanus martinianus Nadaf & Zanan. A. Habit; B. Syncarp with a focus on stigmas in frame. A, B: Zanan 65; photographs: R. Zanan.

FIGURE 4. Detail of syncarps. A: Pandanus unguifer Hook. f.; B: Pandanus martinianus Nadaf & Zanan. A: Zanan 35; B: Zanan 65; photographs: R. Zanan.

FIGURE 5. Detail of syncarps. A. Pandanus urophyllus Hance; B. Pandanus tonkinensis Martelli ex B.C. Stone. A: Regalado & al. 1955; B: Regalado et al. 1861; photographs: C. Davidson.