Pandanus letocartiorum Callm. & Buerki

Callmander, Martin W. & Buerki, Sven, 2013, Notes on New Caledonian Pandanaceae: identity and typifications of Pandanus decumbens (Brongn.) Solms and Pandanus reticulatus Vieill., with the new species Pandanus letocartiorum Callm. & Buerki, Candollea 68 (1), pp. 51-60 : 57-59

Pandanus letocartiorum Callm. & Buerki , spec. nova ( Fig.1 , 5 , 6 ).

Typus: NEW CALEDONIA: Tchamba , Napoé , 20°59’51”S 165°18’58”E 15 m, 29.IX. 2009, fr., Munzinger & al. 5889 (holo-: P [ P02604869 , P02604870 carpo]!; iso-: G [G0036 8574]!, MO!, NOU!, P!).

Haec species inter congeneros novacaledonicos habitu arbusculae erectae pauciramosae usque ad 6 m altae, syncarpio oblongo-ellipsoideo plerumque 9-13 × 6-8 cm atque drupa 2-2.8 × 2-3.5 cm cicatricibus pallide brunneisbrevibus parallelispilei atrobrunnei ex apice ad latus patentitbus notata distinguitur.

Erect and little-branched small treelet, 2-4(-6) m tall, 3-5 cm in diam.; prop roots slender, rather many, forming an open cone up to 4 m high. Leaves linear-attenuate, (80-)90- 150(-190) cm long, (1.4-) 2-2.5 cm wide, apex abruptly attenuate on the ca. 5 distal cm, somehow acute; dry leaves thin but firm coriaceous, abaxial face dark green, adaxial paler green in vivo; longitudinal veins visible on both surfaces, evident toward leaf apex; marginal prickles borne from 4-8 cm above base to apex, antrorse, 0.5-1 mm long in the lower third, mostly 1-4 mm apart, up to 0.5 mm long in the mid third, 1-2 mm apart, mostly> 0.5 mm long in the distal third, 0.5-1 mm apart; midrib near base unarmed up to about the middle; near the middle with prickles ca. 0.5 mm long, 1.5-5 mm apart; near apex, with prickles similar to those of marginal margins; distal ventral pleats sometimes prickly, with minute appressed prickles. Infructescence terminal, the solitary syncarp oblongellipsoid, mostly 9-13 cm long, 6-8 cm wide, on a peduncle about 10-13 cm long, at apex 15 mm thick; lower bracts foliaceous; upper bracts navicular. Drupes ca. 80, connate in the mature syncarp, ca. 2.0- 2.8 cm long, 2-3.5 cm wide, 0.8- 1.3 cm thick, (2-)4-7(-10)-celled, 5-6-angled, obovoid compressed, truncate; pileus convex, 1/4 to 1/5 superior portion free, low convex to subconcave at apex; pileus dark brown, with short parallel light brown scars spreading from the apex on its side. Stigma 4-7, 1.5-2.5 mm wide, erect to oblique, or plane on apical phalanges and strongly antrorsely deflected on basal phalanges. Endocarp supramedian, dense, to 10 mm long; proximal mesocarp to 12 mm long, fibrous-fleshy mesocarp fibromedullar, distal mesocarp up to 5 mm long. Seed locule to 7 mm long. Staminate flower unknown.

Etymology. – This new species is named in honour of Irène and Daniel Letocart who have a great interest in the New Caledonian flora and accompanied the authors to several places on the Island. Along with Jérôme Munzinger and Pete Lowry, they organized a memorable tour around the island in 2009 where we collected the type specimen in the Tchamba valley, their home region in northeastern New Caledonia.

Distribution and ecology. – Pandanus letocartiorum is known in lowland dense humid forest between 30-600 m on grauwacks, schist and serpentine ( Fig. 1 ).

Conservation status. – With an EOO of 768 km 2, an AOO of 45 km 2, and 3 subpopulations, one of which is situated within a protected area (Aoupinié), Pandanus letocartiorum is assigned a preliminary status of Endangered (EN B1ab [iii]; B2ab [iii]) based on the IUCN Red List Categories and Criteria ( IUCN, 2001).

Notes. – Several collections with rather small leaves and syncarps have been determined by H. St. John and B. C. Stone as P. neocaledonicus . Now that the taxonomy of this species and P. decumbens and P. reticulatus has been clarified (see above), it has become obvious that these collections pertain to a different undescribed species. Pandanus letocartiorum is the third species known in New Caledonia with fruit less than 15 cm in length, the two other species being P. decumbens and P. reticulatus . Pandanus letocartiorum can be easily distinguished from P. reticulatus , described above, by its leaves, generally smaller and narrower (mostly 90-150 cm long and 2-2.5 cm wide vs 75-80 cm long, and 1.2-1.4 cm wide in P. reticulatus ); its larger syncarp (9-13 cm long and 6-8 cm wide vs ca. 5.5 cm long and ca. 2.5 wide); and the number and orientation of the stigmas (4-7 and erect to oblique, vs solitary and plane) ( Fig. 5 , 6 ). The new species is morphologically closer to P. decumbens , both species having similar sized leaves and syncarp. Nevertheless, P. letocartiorum can be distinguished by its habit (erect and little-branched small treelet to 6 m tall vs slender-stemmed branched or not shrub with the stem usually decumbent in P. decumbens ); numbers of drupe per syncarp (ca. 80 vs ca. 100-180 in P. decumbens ), longer and wider (ca. 2.0- 2.8 cm long and 2-3.5 cm wide vs 1.5-2.5 cm long, 1-2 cm wide) and the short parallel light brown scars spreading from the apex on the side of the dark brown pileus (vs absent).

Paratypi. – Vallée de l’Amoa , [20°56’26”S 165°13’24”E], ca. 100 m, 14.I.1963, fr., MacKee 9989 ( BISH, P [ P02095733 ]); Houaïlou , Hô , [21°10’36”S 165°31’12”E], 50 m, 29.IV.1973, y. fr., MacKee 26656 ( G, NOU [ NOU048339 , NOU048471 ], P [ P0209 5734 , carpo]); Touho , Ponandou , [20°49’12”S 165°13’45”E], 30- 100 m, 15.V.1973, fr., MacKee 26721 ( G, FI, K, MO, NOU [ NOU048 475 ], P [ P02139395 , carpo], PH); Ponérihouen , Pente E Mt. Aoupinié , [21°10’36”S 165°18’30”E], 600 m, 16.V.1973, fr., MacKee 26750 ( G, NOU [ NOU048338 , NOU048472 , NOU048473 ], P [ P02095731 , carpo], PH); Ponérihouen , Mt. Aoupinié , [21°10’46”S 165°18’12”E], 700 m, 18.VIII.1981, fr., MacKee 39467 ( G, NOU [ NOU048474 ], P [ P02095729 ], PH); Inédete , [20°52’17”S 165°06’49”E], ca. 500 m, 25.VI.1969, fr., Veillon 1962 ( BISH, NOU [ NOU04 8477 , NOU048 476 ], P [ P02095726 , P02095727 , carpo]).

Figures

Fig. 1. – Distributions of Pandanus Parkinson species in New Caledonia showing ultramafic (light grey) and serpentine (dark grey) soils: Pandanus decumbens (Brongn.) Solms (solid dots), Pandanus reticulatus Vieill. (stars) and Pandanus letocartiorum Callm. & Buerki (squares).

Fig. 5. – Pandanus letocartiorum Callm. & Buerki. A. Leaf; B. Syncarp; C. Drupe; D. Longitudinal section of a drupe showing the endocarp (black) and the seed locules; E. Detail of stigmas. [Munzinger & al. 5889, P] [Drawing: C. Chatelain]

Fig. 6. – Pandanus letocartiorum Callm. & Buerki. A. Habit with detail of stigmas (framed); B. Syncarp. [Munzinger & al. 5889, P] [Photos: P. P. Lowry]