Gastrodia cajanoae Barcelona & Pelser, 2016

Pelser, Pieter B., Doble, Kim John S., O’Byrne, Peter, Ormerod, Paul & Barcelona, Julie F., 2016, Gastrodia cajanoae (Orchidaceae: Epidendroideae: Gastrodieae), a new species from the Philippines, Phytotaxa 266 (1), pp. 53-56 : 53-55

Gastrodia cajanoae Barcelona & Pelser , sp. nov. ( Fig. 1A–I )

Type:— PHILIPPINES. Negros: Negros Occidental, Northern Negros Natural Park , Victorias City, Barangay Gawahon , Gawahon EcoPark , 6 Dec. 2015, Plaga & Alcala 1 (holotype: PNH!) .

Diagnosis:— Gastrodia cajanoae differs from G. spathulata in having petals that are narrowly lanceolate, lack a dilated apex, and are adnate to the calyx tube for two-thirds of their length, and in the ridges on the lip, which extend onto the acuminate apex.

Terrestrial holomycotrophic herbs, c. 11–30 cm tall, glabrous. Rhizome not observed. Stem 1.5–2.0 mm wide at base, c. 1.0 mm wide at apex, 50–150 mm long, brown. Scale leaves appressed to stem, basal ones caducous, c. 5, narrowly ovate, 5–7 mm long, apex long acuminate and slightly patent, brown. Inflorescence racemose, few-flowered. Peduncle 3.5–4.5 cm. Flowers campanulate, slightly curved, resupinate, erect or patent, (2–)3–5(–8), in some plants only slightly opening; sepals white, base slightly darker and sometimes with a pink suffusion; petals pinkish-brown; labellum white, slightly darker at apex; column white; ovary brown with paler ridges. Bracts narrowly ovate, 5–6 mm long, apex long acuminate. Pedicel 5–8 mm long, not markedly elongating when fruit develops. Ovary conical, 3.0–4.0 × 1.5–2.5 mm, 6-ridged. Calyx 13–22 × 5–18 mm wide (at apex), sepals connate; free apical part of dorsal sepal 3.5–7.0 mm long, slightly verrucose, apex obtuse; lateral sepals connate almost to their apex, fused to dorsal sepal for 10.0–13.0 mm, slightly verrucose, apex obtuse, sinus between free apical parts 1.5–2.5 mm. Petals narrowly lanceolate, 9.0–12.0 × 1.0– 1.5 mm, enclosed within the calyx tube and fused to it for 5.0–9.0 mm, free apical part 3.0–4.0 mm, initially incurved, otherwise porrect, apex acute. Labellum enclosed within calyx, adnate to apex of column foot with two white round calli on the claw at the apex of the column foot, simple, 6–9 × 2–3 mm, epichile narrowly ovate, boat-shaped, with two central longitudinal ridges that extend onto the acuminate lip apex as a thickened median band, base rounded, apex acuminate and slightly undulate. Column broadly winged towards apex, c. 4–7 × 2–3 mm, ventral surface with numerous white papillae, c. 1 mm long tooth-like projections on both sides of the apex, apex round; operculum hemispherical, c. 1 mm diameter; pollinia not observed. Fruits erect, fusiform, c. 20.0 × 4.5 mm, greenish brown with dark stripes.

Diagnostic characters:— Gastrodia cajanoae and G. spathulata differ from G. javanica ( Fig. 1J ) and G. verrucosa ( Fig. 1K ) and all other known Gastrodia species in having petals that separate from the inner wall of the calyx well before their apex and that are considerably shorter than the calyx tube ( Fig. 1C, D, F ). Most other Gastrodia species have flowers with petals longer than the calyx tube (e.g., Fig. 1J, K ). Petals of these species are fused with the sepals into a perianth tube. Only their apical portions are free, and they emerge from the perianth tube. In G. effusa Ong & O’Byrne (2012: 11) , sepals and petals are fused only basally, but this differs from the arrangement in G. cajanoae . Gastrodia cajanoae is most similar to G. spathulata from Borneo but can be distinguished from this species by petals fused to the calyx tube for 5–9 mm (not 1–2 mm), narrowly lanceolate and entirely glabrous (not linear with a dilated fimbriate tip; Carr 1935). In G. cajanoae the upper surface of the lip has two longitudinal ridges that extend onto the acuminate lip apex where they form a thickened median band ( Fig. 1G ); in G. spathulata these ridges terminate as a short bilobed keel about two-thirds of the way along the lip ( Carr 1935).

Plants observed in the Mountain Province in Luzon are different from those encountered in Mindanao and Negros in being taller (up to c. 30 cm vs. c. 16 cm) and having larger flowers (calyx up to 22 mm long vs. 15 mm) that open more widely (calyx up to 18 mm wide at apex vs. 6 mm; Fig. 1B, H ). These plants are otherwise similar in floral dimensions, shapes and colour, and we therefore consider them conspecific.

Etymology:— Named in honour of Ms. Mary Ann O. Cajano (CAHUP, University of the Philippines —Los Baños), a great friend and colleague who passed away in the morning of the discovery of this new species in Negros Occidental.

Distribution and habitat:— This species is widespread in Mindanao where it was photographed in Bukidnon Prov. (Mt. Kitanglad Range Natural Park) and North Cotabato Prov. (Mt. Apo Natural Park; Nickrent et al. 2006 onwards). It is also found in Negros Occidental (Northern Negros Natural Park) in Negros and the forests of Lias, Barlig, Mountain Province in Luzon. Gastrodia cajanoae grows among leaf litter in tropical rain forest at 550–1400 m.

Conservation:— The conservation status of G. cajanoae is here assessed as of Least Concern (LC; IUCN 2014). Although Philippine tropical rainforest habitats are severely threatened by, amongst others, conversion to other land uses, illegal logging, and slash-and-burn agriculture, G. cajanoae appears to be widespread in the Philippines and was found in three areas with protected status. It might have escaped discovery thus far, due to its small size, lack of leaves and white flowers.

Figures

FIGURE 1. A–I. Gastrodia cajanoae.A. Habit of flowering plant. B. Side view of flower from Mindanao; yellow scale = 1 cm. C. Front view of flower showing apex of petals, which can be seen to separate partway along the calyx. D. Side view of flower, perianth partially removed to show labellum, column, and apical part of petal, the last showing narrow lanceolate shape. E. Infructescence. F. Section of flower with petal. G. Labellum. H. Side view of flower from Luzon; yellow scale = 1 cm. I. Ventral view of column and dorsal view of base of labellum. J. Gastrodia javanica, ventral view of flower showing attachment of petals. K. Gastrodia verrucosa, side view of flower, perianth partially removed to show labellum, column and apical portion of petal. Additional photos are available from the PhytoImages website (Nickrent et al. 2006 onwards).