Pandanus halmaherensis Callm. & A. P. Keim. The 2015, spec. nova
Creators: name: Callmander, Martin W.
name: Keim, Ary P.
name: Buerki, Sven
name: Phillipson, Peter B.
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Pandanales
Pandanaceae
Pandanus
Pandanus halmaherensis

description: Pandanus halmaherensis Callm. & A. P. Keim, spec. nova
(Fig. 2 E-F, 4 C, 8).
Typus: INDONESIA. Prov. North Maluku [Halmahera Isl.]: Central, Weda Bay, along the road to Bukit Limber, 00°31’13”N 127°59’56”E, 600 m, 27.I.2013, Callmander, Haris & Mahroji 1078 (holo-: G [G00341587]!; iso-: BO!, L!, MO-6465087!, MO-6465088!, MO-6465089!, MO-6124975 carpo!).
Haec species a congeneris infructescentia pendente solitaria ingente atque drupis pileo rubro prismatico-conico non profunde bullato in stigma spinescens desinente munitis distinguitur.
Tall tree to 10-20 m tall, trunk 15-25 cm in diam., with a large cone of proproots, 1-2(-5) m long, 6-7 cm in diam. Leaves linear-attenuate, mostly (180-)220-250 (-300) cm long, 5-8 cm wide, apex gradually attenuate; sub-coriaceous to coriaceous, paler green abaxially shiny axially (especially when dry); longitudinal veins visible on both surfaces; marginal prickles borne 7-11(-15) cm above base to apex, antrorse, 1.5-2.5 mm long in the lower third, (1-) 3-10 mm apart, (0.5-) 1-2 mm long in the mid-third, 2-5 mm apart, to 0.5-1 mm long in the distal third, 0.2-0.5 (-1) mm apart, subappressed to apressed in the distal third; midrib unarmed in the lower third, prickles <0.5 mm long towards the apex, irregularly spaced but mostly 1-2 mm apart; prickles absent on apical ventral pleats; sheath (7 -) 11 (- 17) cm long, (7 -) 9 - 10 cm wide at apex, (8-)12-14(-19) cm at base. Infructescence terminal, pendant, red to purple, the solitary syncarp ovoid, (25-) 30-35 cm long, 11-15 cm wide, peduncle (45-) 50-80 cm long, c. 3 cm thick at apex, bearing foliaceous bracts, the proximal ones c. 60 cm long, the distal one 13 cm long, crowded at peduncle apex, spreading open at maturity. Drupes very numerous, crowded, (30-) 35-40 mm long, 4-5 mm wide, 4-5 mm thick, 1-celled, 5-7-angled, linear, pileus prismatic-conic, 8-10 mm long, shiny, shallowly bullate. Stigma one, c. 6-8 mm long, spinescent, deflected toward the syncarp apex: stigmatic groove ventral (adaxial), running along the whole length of the stigma and extending in a groove on distal part of the pileus. Endocarp bony, basal, c. 8 mm long, flat at apex, lateral walls> 1 mm thick; proximal mesocarp 2-4 mm long, fibrous, distal mesocarp 15-25 mm long, sparsely fibrous, chambered, seed locule c. 5 × 3 mm, ellipsoid. Staminate inflorescence unkown.
Distribution and ecology. – Pandanus halmaherensis is found at low to mid elevations (160-700 m) in primary and disturbed evergreen tropical forests. It grows on slopes and in open areas. The species is only known from the eastern and central part of Halmahera (Fig. 4C).
Conservation status. – With an EOO of 178 km 2, an AOO of 45 km 2, and 4 subpopulations, none of which are situated within the protected area network, Pandanus halmaherensis is assigned a preliminary status of “Endangered” [EN B1ab(iii)+2ab(iii)] based on the IUCN Red List Categories and Criteria (IUCN, 2012). The conservation status is based on the currently available information on the geographical distribution of the species, and is justified because the extent of suitable habitat is expected to decrease in the coming years. However our remarks about the current inadequate knowledge of the flora of Halmahera and the possible establishment of conservation offset sites under P. beguinii above are applicable to P. halmaherensis.
Notes. – Pandanus halmaherensis is notable in having a large and massive pendant infructescence and drupes with a prismatic-conic shallowly bullate pileus with a spinescent stigma, unlike any other known species of the genus. Our new species can, however, be compared to P. sarasinorum Warb., endemic to Sulawesi (see STONE [1974b] for a complete description of this species). The two species share a similar habit (tall trees with long aerial proproots) and syncarps (very numerous and crowded cylindric drupes). Pandanus halmaherensis can nevertheless be easily distinguished by the larger dimensions of its leaves (mostly 220-250 × 5-8 cm vs. c. 150 × 4 cm in P. sarasinorum), much larger drupes (mostly 35-40 × 4-5 mm vs. 12-20 × 2-3 mm) and most notably by its larger (30-35 × 11-15 cm) solitary, ovoid syncarps (vs. an inflorescence with multiple, cylindrical syncarps, each 16-17 × 3-6 cm). This new species seems to be morphologically isolated within the genus and would only fit into Pandanus sect. Rykiopsis B. C. Stone (STONE, 1974a). However, the latter section was defined based on the multiple syncarps of its type species P. sarasinorum.
Paratypi. – INDONESIA. Prov. North Maluku [Halmahera Isl.]: Central Halmahera, Weda Bay, Sake West, 00°29’39”N 127°57’44”E, 218 m, 19.VI.2013, Bangun, Mahroji & Fabanyo 843 (BO, G, L, MO-6486427, MO-3762979 carpo); East Halmahera, Weda Bay, SE of Tofu Blewen camp, 00°47’55”N 128°02’06”E, 480 m, 3.II.2013, Callmander, Fabanyo & Mahroji 1114 (BO, G, K, L, MO-6451256, MO-6451257, MO-6451258, MO-6149145 carpo); East Halmahera, Weda Bay, Kao Rahai, 00°41’54”N 128°01’02”E, 693 m, 26.II.2013, Fabanyo et al. 58 (BO, G, L, MO-6199115, MO-6451255, MO-6451254 carpo); Central Halmahera, Weda Bay, 00°31’44”N 127°54’22”E, 163 m, 11.IV.2013, Gushilman, Lasut & Fabanyo 560 (BO, G, L, MO-6472415, MO-6472416, MO-6398426 carpo).
description: Published as part of Callmander, Martin W., Keim, Ary P., Buerki, Sven & Phillipson, Peter B., 2015, The genus Pandanus Parkinson (Pandanaceae) on Halmahera Island (Moluccas, Indonesia) with descriptions of three new species and a key to the species on the island, pp. 179-195 in Candollea 70 (2) on page 193, DOI: 10.15553/c2015v702a2, http://zenodo.org/record/5720986