Pandanus beguinii Callm. & A. P. Keim, 2015

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, Candollea 70 (2), pp. 179-195 : 182-187

Pandanus beguinii Callm. & A. P. Keim , spec. nova

( Fig. 3 A-C, 4A , 5 ).

Typus: INDONESIA. Prov. North Maluku [Halmahera Isl.]: Central , Weda Bay , near Weda Bay , 00°28’38”N 127°59’38”E, 26 m, 30.I.2013, Callmander, Haris, Lasut & Mahroji 1088 (holo-: G [ G00341586 ]! ; iso-: BO!, L!, MO-6465094 !, MO-6465095 !) .

Haec species a congeneris habitu gracili, syncarpo parvo terminali erecto drupas truncatas in turriculam obscuram conicam lateraliter concavam stigma minutum laterale bicornutum gerentem desinente atque inflorescentia staminata ex spica solitaria constante distinguitur.

Shrub to 3 m tall, monocaulous; stem c. 3 cm in diam., with few proproots at the base. Leaves spirally arranged, linear, mostly (50-) 70-110 cm long, (4-) 5-8 cm wide in the middle, but gradually narrowing to 2-3 cm wide and more deeply folded in the lower third above the broader sheath, apex abruptly attenuate with a short acumen (3-10 mm), chartaceous; longitudinal veins visible and prominent on both surfaces; marginal prickles borne 3-4 cm above base to apex, antrorse, 0.4-1 mm long in the lower third, 0.5-1 mm apart, 0.7-1 mm long in the mid-third, 4-7 mm apart, to 0.5-1 mm long in the distal third, 0.5-1.5 mm apart, subappressed to appressed in the distal third; midrib unarmed, except the distal 7-13 cm with prickles> 1.5 mm long towards the apex, irregularly spaced but mostly 1-5 mm apart; sometimes sparsely armed on apical ventral pleats; sheath (2.5-) 4-4.5 cm long, (2-) 3-4 cm wide at apex, (3-) 4-6 cm at base. Infructescence terminal, erect, green-orange when immature becoming red at maturity, the solitary syncarp ellipsoid, 10-15 cm long, 5-6 cm wide, peduncle short and slender, c. 11 cm long, c. 1 cm thick at apex, bearing multiple foliaceous bracts, crowded at peduncle apex, partly covering the syncarp, the proximal ones c. 45 cm long, the distal one 15 cm long. Drupes 400-500, 13- 15 mm long, 5-7 mm wide, 4-5 mm thick, 1-celled, (4-)6-angled, ovoid, truncate, pileus short, truncate, 2-3 mm long, with a flat to slightly concave dark coloured turret, bearing a lateral minute bicornate stigma, c. 0.5 mm wide. Endocarp bony, median, c. 5 mm long, circular, lateral walls> 0.5 mm thick; proximal mesocarp c. 2-3 mm long, fibrous, distal mesocarp c. 4-5 mm long, fibrous, chambered, seed locule c. 4 mm, spherical. Staminate inflorescence c. 30 cm long with a single terminal spike on a fleshy peduncle, c. 20 cm, covered with c. 9 caniculate foliaceous yellow bracts, distal ones c. 25 × 3.5 cm; proximal ones 8 × 1 cm; spike brown, short cylindric, mostly 11 cm long, 2 cm in diam., composed of crowded and congested flowers, formed by 4-12 briefly basally connate stamens; stamens c. 3 mm long; with a dilated basal column, c. 2 × 0.5 mm, the single anther born on a minute filament, c. 0.3 mm long; anther c. 1 × 0.3 mm, apiculate; apiculus c. 0.1 mm long.

Etymology. – This new species honours Victor E. Beguin (1886-1943) who collected this species nine times during his visits to Halmahera in 1921 and 1922 among the 50 collections of Pandanaceae gathered from the island.

Distribution and ecology. – Pandanus beguinii is mostly found at lower elevations (30-600 m) in primary and disturbed evergreen tropical forest. It grows on slopes and in open areas, where individuals are scattered and discrete. The species is known from the northern, eastern and central regions of Halmahera ( Fig. 4A ).

Conservation status. – With an EOO of 1625 km 2, an AOO of 54 km 2, and 5 subpopulations, none of which are situated within the North Maluku protected area network, P. beguinii is assigned a preliminary status of “Endangered” [EN B1ab(iii)+2ab(iii)] based on the IUCN Red List Categories and Criteria ( IUCN, 2012) (calculation following CALLMANDER et al., 2007). Four of the known subpopulations of P. beguinii have been recorded on or near WBN’s CoW, and we assume that some or all of them will be impacted by the proposed mining operations or associated environmental degradation. The current status of the subpopulation sampled by Beguin in northern Halmahera nearly a hundred years ago is unknown, but it occurs in an area that appears to be already somewhat degraded as judged by available satellite imagery. 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. Nevertheless, Halmahera is botanically poorly known and new subpopulations may occur in currently unexplored areas. If new sub-populations are discovered, the estimated AOO and EOO for the species would increase, and reassessment of the conservation status of the species may result in a lower category of threat. Furthermore the establishment of conservation offset sites to mitigate mining and associated impacts that encompass natural subpopulations of the species would decrease the level of threat to the species.

Notes. – Pandanus beguinii can easily be distinguished by its small, slender habit, its small, terminal, erect syncarp of truncate drupes topped by a dark turret with a flat to concave apex, bearing a lateral minute bicornuate stigma, and its singlespiked staminate inflorescence ( Fig. 3 A-C, 5). The new species is a member of the morphologically well-defined Pandanus sect. Maysops H. St. John , that is characterized by “cephalia resembling an ear of maize, with flat-topped drupes” ( JEBB, 1992: 116). This section, distributed throughout the Malesian region from the Moluccas to Papua New Guinea, is also present in the Bismarck Archipelago, the Solomon Islands and northern Queensland in Australian ( STONE, 1992). Within this section, P. beguinii is similar to P. kosteri B. C. Stone in being miniature in all parts compared to all other species of the section, which develop into relatively robust trees. Pandanus beguinii can nevertheless be easily distinguished by its broader leaves, mostly 5-8 cm wide across the middle (vs. 2.5-3.7 cm in P. kosteri ), its larger syncarp (10-15 × 5-6 cm vs. 6.5 × 3.5 cm), its simple staminate inflorescence with yellow bracts (vs. a compound inflorescence comprised of 6-7 spikes with red bracts) and its staminate flowers with their stamens shortly basally connate (vs. fused, i.e. forming a phalange) (see STONE, 1987: 436, Fig. 5 ).

Paratypi. – INDONESIA. Prov. North Maluku [Halmahera Isl.]: Loleo Poeloe [ Loypoloy ] Rao , 13.X.1921, Beguin 1819 ( BO) ; ibid. loc., 30 m, 14.X.1921, Beguin 1822 ( BO) ; ibid. loc., 40 m, 15.X.1921, Beguin 1825 ( BO) ; Soa Tobaroe , 60 m, 24.VI.1922, Beguin 2044 ( BO) ; ibid. loc., 60 m, 28.VI.1922, Beguin 2067 ( BO) ; ibid. loc., 29.VI.1922, Beguin 2069 ( BO, L [ L1195381 ]) ; ibid. loc., 29.VI.1922, Beguin 2071 ( BO) ; ibid. loc., 60 m, 29.VI.1922, Beguin 2071 ( BO) ; ibid. loc., 29.VI.1922, Beguin 2107 ( L [ L1195381 ]) ; ibid.loc., 6.VIII.1922, Beguin, 2167 ( BO) ; Central Halmahera, Weda Bay , on the road to Bukit Limber , 00°31’01”N 127°59’41”E, 600 m, 15.IV.2013, Bidault et al. 1089 ( BO, G, L, MO) ; Weda Bay, Sagea Lagoon , 00°29’35”N 128°04’16”E, 29.I. 2013, 15 m, Callmander et al. 1086 ( BO, G, L, MO-6465090 ) ; East Halmahera, Weda Bay , Pinto , 00°38’10”N 128°09’05”E, 340 m, 1.II.2013, Callmander et al. 1090 ( BO, G) ; East Halmahera, Weda Bay , Kao Rahai , 00°40’22”N 127°58’31”E, 366 m, 9.XII.2012, Merello et al. 3539 A ( BO, L, MO-6444045 , MO-6444047 ) .

Figures

Fig. 3. – Field pictures of Halmahera Pandanus Parkinson species. A, C. Pandanus beguinii Callm. & A. P. Keim (pistillate plant); B. Pandanus beguinii Callm. & A. P. Keim (staminate plant); D. Pandanus dubius Spreng.;E, F. Pandanus halmaherensis Callm. & A. P. Keim; G, H. Pandanus papuanus Solms; I. Pandanus kaernbachii Warb. [photo taken in Seram]; J. Pandanus conoideus Lam. [Photos: A: M. Merello; B-G: M. Callmander; H, J: P. Phillipson; I: A. Keim]

Fig. 4. –Distribution map of the three endemic new species of Halmahera.A. Pandanus beguinii Callm. & A. P. Keim; B. Pandanus benstoneoides Callm., Buerki & Phillipson;C. Pandanus halmaherensis Callm. & A. P. Keim.

Fig. 5. – Pandanus beguinii Callm. & A. P. Keim. A. Tip of a leaf; B. Syncarp on peduncle; C. Basal section of a leaf; D. Side view of a drupe; E. Top view of the pileus; F. Cross section of a drupe. [A-G: Callmander, Haris, Lasut & Mahroji 1088, G] [Drawing: R. L. Andriamiarisoa]