Pandanus reticulatus Vieill.

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 : 56-57

Pandanus reticulatus Vieill.

in Ann. Sci. Nat., Bot. ser. 4, 16: 52. 1862 ( Fig. 1 , 3B , 4 ).

Neotypus (designated here): NEW CALEDONIA: Réserve botanique de Nodéla , flan du massif du Mé Moya, 21°26’07”S 165°20’05”E, 500 m, 19.II.2011, fr., Callmander & al. 981 ( P [ P00700916 ]!; iso-, BISH!, BM!, FI!, G [G00368275]!, K!, MO!, NOU [NOU054165]!, P [P007 00915]!, PH!).

Understory erect shrub to 3 m tall, with slender weak, sometimes leaning, stem, and a few branches; prop roots few, but up to 1 m long; leaf crowns dense. Leaves linear-attenuate, (50-)75-80(-90) cm long, 1.2-1.5 cm wide, attenuate or but slightly acuminate toward apex; subcoriacous in the proximal half part, chartaceous in the distal half, discolour, dark green to brown abaxially, pale green adaxially when dried; longitudinal veins visible on both surfaces; marginal prickels borne 2-2.5 cm above base to apex, antrorse, 1 mm long, 4-7 mm apart in the proximal third, ca. 1 mm, 2-5 mm apart in the mid third, 0.5-1 mm long, 1-2 mm apart in the distal third, more appressed towards the apex; midrib near base unarmed to beyond the middle, after with sparse, remote prickles similar to those adjacent to margins, ca. 0.5 mm long; apical ventral pleats with a few antrorse prickles, unequally dispersed, often mostly or only on one (usually the left) side, lacking on extreme tip. Infructescence solitary, terminal, the syncarp oblong-ovoid, ca. 2.5-3 × 5-6 cm, on short erect, peduncle about 8 cm long, 4-5 mm thick. Drupes ca. 90-110, 10- 15 mm long, 5-10 mm wide, 7-10 mm wide, mostly l-celled, very rarely 2-celled, 5-6-angled, with smooth sides; pileus 3 mm long, crowned by the antrorsely excentric inclined stigma. Stigma unique, rounded reniform, 1-1.5 mm wide. Proximal mesocarp fibrous, 3-4.5 mm long, distal mesocarp fibrous, 2-4 mm long; endocarp sub-median or median, about 5 mm long, the walls ca. 1 mm thick. Seed locule 3 mm long. Staminate inflorescence to ca. 20 cm long; proximal bracts foliaceous-tipped; distal bract ca. 3 × 15 cm and decrescent, margins and midrib finely ciliate, serrulate-prickly, navicularovate in outline; spikes about 5-6, short sub-cylindric, ca. 25- 50 mm long, terminal spike longer, ca. 7-8 cm, merged at base with adjacent lateral spike, composed of crowded phalanges of stamens. Stemanophore sub-peltate, the column, ca. 2 mm in length, with a deep inverse-conic depression in the distal part, the margins bearing the stamens radially. Stamens about 13-18 per stemanophore, the filament 0.75-1 mm long; a short filamentous pendiculus intervening between filament and anther, the pendiculus 0.1-0.2 mm long. Anther oblong, acuminate, ca. 1 mm long, with an apiculus ca. 0.35 mm long, dorsally set with raphidophorus cells, at apex subentire; connective dorsally and distally with a few raphidophorus cells.

Distribution and ecology. – Pandanus reticulatus is known from lowland dense humid forest in northeastern and southern New Caledonia between 300-700 m on schist and serpentine ( Fig. 1 ).

Conservation status. – With an EOO of 6979 km 2, an AOO of 90 km 2, and 6 subpopulations, one of which is situated within the protected area network (Barrage Yaté, Haute Yaté, Rivière Bleue, Pic du Grand Kaori), P. reticulatus is assigned a preliminary status of Vulnerable (VU B1ab [iii]; B2ab [iii]) based on the IUCN Red List Categories and Criteria ( IUCN, 2001).

Notes. – Pandanus reticulatus was described by VIEILLARD (1864) very succinctly. This species was considered by MARTELLI (1914) and STONE (1972) to be synonym of P. decumbens , whereas ST. JOHN (1989: 25) treated it as a “species dubia”. BRONGNIART (1875: 286) noted the close resemblance but underlined the morphological distinction by emphasising Vieillard’s description: “drupe petite, serrées, subtetragones, couronées par le stigmate persistant, uniloculaire”, whereas P. decumbens holds larger drupes with several stigmas in one row. No type material has been located, nor was any referred to by MARTELLI (1914), St. JOHN (1989) or Stone (pers. comm.), therefore a neotype is required to be designated. No collections are known to exist that Vieillard might have seen. Nevertheless , the species has been collected many times in the last 65 years before our visit to New Caledonia in 2011, but only one has a mature syncarp (MacKee 42975). During our visit we were able to locate a large population of P. reticulatus in Nodéla , on the slopes of the Mé Moya massif. This collection (Callmander & al. 981), which is accompanied by extensive field information and photographs and comprises multiple duplicates, is chosen as the neotype. The species is now described in detail above for the first time based on this collection. The species is unique among the New Caledonian taxa in having a unicarpellate drupe with a reniform stigma ( Fig. 3B , 4 ). It can be easily recognized in the field by its slender habit usually with prop roots up to 1 m tall, its narrow leaves (ca. 12-15 mm wide) and tiny oblong ovoid syncarp (ca. 2.5 × 5.5 cm) with unicarpellate drupes ( Fig. 3B ).

Additional material examined. – NEW CALEDONIA: Riv. Blanche , Moi de Mai , [22°07’19”S 166°38’34”E], 300 m, 23.VI.1951, st., Baumann-Bodenheim 14099 ( P [ P02077341 ]); Dawenia , versant SW du Mont Colnett, 20°32’25”S 164°41’12”E, 575 m, 14.XI.2010, fr., Callmander & al. 877 ( G, NOU, P [ P00700842 ]); Réserve botanique de la Fausse Yaté , 22°11’05’’S 166°54’14’’E, 300-500 m, 9.X.2007, st. fl., Dagostini 1463 ( NOU [ NOU031137 ]); Riv. Bleue , [22°06’11”S 166°37’60”E], 200 m, 22.II.1951, st., Guillaumin & Baumann-Bodenheim 10906 ( P [ P02077341 ]); Yaté , [20°09’21”S 166°53’48”E], 300 m, 29.XII.1985, fr., MacKee 42975 ( G, NOU [ NOU006188 ], P [ P02139400 ], PH [ PH00072777 , PH00072778 , PH00072779 ]); Haute Rivière des Pirogues : Forêt Faux Bon Secours , [22°10’02”S 166°41’ 33”E], 300 m, 12.I.1986, st., MacKee 42995 ( NOU [ NOU048442 ], P [ P02139389 ], PH [ PH00072771 ]); Pic du Grand Kaori , 22°17’19”S 166°53’48”E, 235 m, 9.X.2009, fr., Munzinger & al. 5978 ( NOU); Hills above Riv. Bleue , [22°06’11”S 166°37’60”E], 27.VIII.1971, st., Stone 10551 ( PH [ PH00072773 ]); Ouégoa , bassin SW de la Tendé, [20°25’ 22”S 164°29’39”E], 22.VII.1973, fr., Veillon 2990 ( NOU [ NOU048440 , NOU048441 ], PH [ PH00072770 ]); Riv. Bleue , [22°011”S 166°37’60”E], 13.VI.1985, fr., Veillon 5910 ( NOU [ NOU048446 ], PH [ PH00072775 ]); Riv. Bleue , [22°06’11”S 166°37’ 60”E], 200-250 m, 29.I.1986, fr., Veillon 5948 ( NOU [ NOU048447 , NOU048448 ], PH [ PH0072772 ]); Mt Rembaï , [21°34’47”S 165°49’ 59”E], ca. 670 m, 17.XI.1989, st. fl., Veillon 7227 ( NOU [ NOU04 8439 ], P [ P02139405 ]).

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. 3. – Syncarp with detail of stigmas (framed). A. Pandanus decumbens (Brongn.) Solms; B. Pandanus reticulatus Vieill. [A: Callmander & al. 979, MO; B: Callmander & al. 981, P] [Photos: P. P. Lowry]

Fig. 4. – Pandanus reticulatus Vieill. A. Longitudinal section of a drupe showing the endocarp (black) and the seed locules; B. Detail of stigmas; C. Syncarp. [Callmander & al. 981, G] [Drawing: C. Chatelain]