Arisaema brinchangense Y.W. Low, Scherberich & Gusman, 2016

Low, Yee Wen, Scherberich, David & Gusman, Guy, 2016, Arisaema brinchangense Y. W. Low, Scherberich & Gusman (Araceae), a new threatened species endemic to the Cameron Highlands (Peninsular Malaysia), Candollea 71 (1), pp. 83-89 : 85-88

Arisaema brinchangense Y.W. Low, Scherberich & Gusman , spec. nova ( Fig. 1 ; 2A, B ).

Typus: MALAYSIA. Pahang (Peninsular Malaysia): Cameron Highlands, Mt. Brinchang , beside road leading towards the observation tower, c. 2000 m, 10.XI.2012, Low & Low-Edwin LYW 520 (holo-: SING [ SING0166277 including spirit material, SING0202906 ]!; iso-: BR!, G!, KLU!, LYJB!) .

A r isa ema br inchangense Y.W. Lo w, Sche rbe r ich & Gusman is morphologically close to A. anomalum Hemsl. but differs by having spathe-tube mouth margin straight and hardly recurved (not auriculate) (vs. strongly recurved (auriculate) in A. anomalum ), and a distinctive white or pale cream coloured marking somewhat resembling a trident (with 3-6 pointed tips) around the mid-portion of the spathe-limb (vs. 9-10 longitudinal stripes parallel along the spathe-tube).

Terrestrial perennial evergreen herb, to 40(-60) cm tall. Rhizome to 7 cm long and 0.7-1.7 cm wide, carmine; roots numerous, 1-3 mm wide, cream to apricot. Pseudostem absent. Cataphylls to 3, c. 1-9 cm long, carmine with longitudinal darker stripes. Leaf 1(-2). Petiole cylindrical, c. 19-29 cm long, c. 3-5 mm wide at the base, dull carmine to claret, without any markings. Leaf blade trifoliolate; leaflets glossy apple green on both sides, paler below, membranaceous; apex acuminate ending in an arista about 0.7-1 cm long; base cuneate to obtuse; margin entire; midrib prominent and glabrous on both sides; secondary veins 9-12 pairs, making an angle of 30-50° with the midrib and joining to form a distinct marginal vein, slightly sunken and glabrous on upper side, slightly raised to prominent and glabrous on lower side; marginal vein approximately 2-5 mm from margin; tertiary venation flat on both sides. Central leaflet elliptic-ovate, 9-17 cm long, 3-6.6 cm wide, petiolulate; petiolule c. 1.8-2.7 cm long; blade symmetrical. Lateral leaflets ovate to elliptic-ovate, 10.5-15.7 cm long, 3.5-5 cm wide, petiolulate; petiolule c. 0.5-1.8 cm long; blade asymmetrical. Inflorescence overtopping the leaves. Peduncle 23.5-35 cm long, similar in colour to petiole from the base upwards, fading gradually to white towards the inflorescence. Spathe-tube cylindrical or slightly funnel-shaped, 3.7-5.5 cm long, 0.4-0.9 cm wide at base, widening to 1-2.5 cm at the mouth, green to pale dull green with a thick white band on outer and inner dorsal side, white-waxy outside, white at base; mouth-margins straight and hardly recurved (not auriculate). Spathe-limb horizontal, lanceolate, c. 4.5-6.5 cm long and 1.3-2.5 cm wide, similar in colour to the tube, but darker. Spathe-tip caudate, ending with a thread c. 0.5-1.3 cm long. Spadix-appendix c. 3-4.8 cm long, c. 2-3.2 cm exserted from the tube, but not exceeding the spathe-limb, sessile, protruding portion bent forward to slightly down-curved, blunt at apex, 2-4 mm wide at base tapering gradually towards the apex, green to carmine, glabrous above the fertile portion or with a few upcurved neuters. Spadix fertile zone male or bisexual. Male fertile zone cylindrical, c. 4.2 cm long and c. 3-4 mm across; synandria loosely arranged, pale pink to carmine, 4-6-androus, thecae dehiscent by an elongated pore, borne on a pale pink to carmine stalk, pollen white. Female fertile zone c. 2.5 cm long and c. 3-4 mm across; pistils densely arranged; ovaries ovoid, vivid green, c. 2.5-4 mm wide, with a whitish stigma on a short green style.

Etymology. – The species epithet refers to Mount Brinchang (2031 m), where the type specimen was collected.

Distribution and Habitat. – Arisaema brinchangense is so far known only from around the summit of Mount Brinchang, Cameron Highlands ( Fig. 3 ) where it grows in the montane forest c. 2000 m on moist forest floor covered with thick organic litter under deep to semi-shaded condition.

Phenology. – This species has been collected in flower in September and November. However, this may not necessary reflect a clear flowering period as climate of Cameron Highlands is quite constant throughout the year. Fruiting period unknown.

Conservation status. – Arisaema brinchangense is so far known only from the Cameron Highlands where recent discoveries were mostly around the summit of Mount Brinchang, protected within the Batu Gangan Permanent Forest Reserve. Otherwise, no further recent observations were made elsewhere apart from the two historical collections at a much lower elevation around Sungai Bertam near the golf course. The extent of occurrence (EOO) of the species is estimated to be 0.010 km 2, whereas its area of occupancy (AOO) is estimated to be 8 km 2. Major conservation concern for the species is habitat loss due to exploitation for agriculture and floriculture industries that have increased tremendously since its inception during the colonial times in the early 20th century. Illegal land clearing for farming activities is a major concern as local authority estimated about 6000 ha of land were encroached illegally (New Straits Times, 2014). Arisaema brinchangense should thus be assigned a preliminary conservation status of “Critically Endangered” [CR B1ab(iii,iv)+2ab(iii,iv)]. This preliminary conservation status would require reassessment as more botanical surveys in Peninsular Malaysia are being carried out under the “Flora of Peninsular Malaysia programme”.

Notes. – Arisaema brinchangense is an evergreen species that has rhizomatous underground stem with roots generally growing out from all over the rhizome. Besides that, it also has (i) leaves and inflorescences emerging separately from the rhizome each wrapped in their own cataphylls; (ii) new leaves emerge when old leaves are still present; (iii) spadix-appendix slightly exserted from the spathe-tube; (iv) neuters present above the fertile portion of the spadix; and (v) free flowering. All these characters possessed by A. brinchangense placed it in Arisaema sect. Anomalum as defined by Gusman & Gusman (2006). At present, there are five species of Arisaema sect. Anomalum recorded for Peninsular Malaysia, namely Arisaema anomalum , A. brinchangense , A. filiforme , A. scortechinii , and A. wrayi , of which all have strongly recurved (auriculate) spathe-tube mouth margin except A. brinchangense .

note pollen accumulated at the base of the tube.

[Low & Low-Edwin LYW 520, SING] [Photos: Y.W. Low]

Arisaema brinchangense differs from A. anomalum in having straight and hardly recurved (not auriculate) spathe-tube mouth margin, and distinctive white to pale cream coloured marking somewhat resembling a trident (with 3-6 pointed tips) around the mid-portion of the spathe-limb ( Fig. 2A, B ). In contrast, A. anomalum has strongly recurved (auriculate) spathe-tube mouth margin, and 9-10 longitudinal stripes parallel along the spathe-tube ( Fig. 2C, D ). Besides that, these two taxa also differ in a suite of morphological characters largely observed in inflorescence that distinguishes them apart (see Table 1 ). It is important to note that these two taxa are difficult to tell apart in the field or on herbarium sheet when they are sterile.

Paratypi. – MALAYSIA. Pahang (Peninsular Malaysia): Cameron Highlands, around the Green Cow Tavern (following van Steenis-Kruseman, 1950), XI.1939 - I.1940, fl., Batten Pooll s.n. ( SING [2 sheets]); Cameron Highlands , Sg. Uruil, below golf course, 1463 m [4800 ft], 2.IX.1956, fl., Burkill HMB 820 ( SING) .

Figures

Fig. 1. – Arisaema brinchangense Y.W. Low, Scherberich & Gusman. A. Habit;B. Details of the lower leaf blade surface; C. Rhizome showing numerous offsets and fleshy white roots, inflorescence artificially removed; D. Front view of an inflorescence showing spathe-limb with distinctive white trident marking (with three pointed tips) and spadix-appendix slight bent forward; E. Spathe-tube of a male inflorescence artificially removed to show the male spadix fertile zone,

Fig. 2. − Inflorescences of Arisaema brinchangense Y.W. Low, Scherberich & Gusman (A-B) and A. anomalum Hemsl. (C-D). A. Side view of the inflorescence showing straight and hardly recurved spathe-tube mouth margin; B. Dorsal view of the inflorescence showing distinct white to pale cream coloured trident marking (with three pointed tips) on the spathe-limb; C. Side view of an inflorescence showing strongly recurved (auriculate) spathe-tube mouth margin; D. Dorsal view of the inflorescence showing white to pale cream coloured narrow parallel stripes along the spathe-limb. [Photos:D. Scherberich]

Fig. 3. – Distribution of Arisaema brinchangense Y.W. Low, Scherberich & Gusman (black circle) in Peninsular Malaysia.