ANOTHER NEW SPECIES OF RAFFLESIA ( RAFFLESIACEAE ) FROM LUZON , PHILIPPINES : R . LEONARDI

A new species of Philippine Rafflesia is described. Rafflesia leonardi is the eighth species of Rafflesia described from the Philippines and the fourth species from Luzon Island. It most closely resembles R. lobata and R. manillana in perigone colour and wart ornamentations and in the wide aperture relative to diaphragm diameter. It is, however, different from both of these and other Philippine Rafflesia species in its flower size and disk that lacks or has rudimentary processes.

Mature buds to 16 cm diameter.Basal cupule c. 3.5 cm high, c. 7.5 cm wide.Bracts (or bud scales) in three imbricate whorls, outermost smallest, c. 3 by 4 cm, largest innermost ones to 12 by 8 cm.Flowers (25.5-)28-34 cm diam.when fully expanded, 13.8-18 cm high, male and female flowers similar in size and shape.Perigone tube 9-11 cm long.Perigone lobes 5 (or 6), orbicular to broadly orbicular, 7.5-13 by 11-13.5 cm, base slightly auriculate, reddish orange, becoming darker with age, margins entire to irregularly sinuate, tan to pale yellow, warts prominent on the upper surface, mostly elliptic or roundish, larger warts interspersed with tiny ones, powdery white when fresh, becoming concolorous with background with age.Diaphragm 14-18(-22) cm diam., 2.5-3 cm wide from aperture rim to base of perigone lobe, 3-10 mm thick at base, becoming thinner towards the aperture, background concolorous with perigone, outer surface with shallow indentations from the perigone warts when the flower was in bud stage, marked with roundish tan coloured warts, some of which are elevated on mamilla, surrounded by tiny tan coloured speckles, windows absent; aperture 10.5-12.5(-19)cm diam., rim maroon in colour.Disk 7-8 cm diam., c. 1.2-1.3cm thick midway between the margin and the point where the disk joins the column, nearly flat to slightly dome-shaped with a slightly raised margin, tan centrally, purplish maroon towards the periphery, devoid of or with few, rudimentary processes, margin irregularly and shallowly incised or crenulate, corona smooth, sparsely and minutely pubescent, cream-colored in bud; processes when present, up to 10, often tuberculate, sometimes pointed, up to 5 mm long, very seldom longer, dark maroon; column 3-5 cm from the base of cupule to the upper surface of disk; neck of column c. 3 mm long, c. 4.5 mm wide; annulus c. 1 cm wide, c. 9 cm diam., smooth, glabrous, whitish in the inner part, darker in the outer part.Ramenta dimorphic, to 2 mm long, those toward the base of perigone tube filiform, dense, those inside diaphragm stout, branched or cleaved apically, tips darker.Male flower without vestigial ovary; anthers 20 (or 21), semi-globular, c. 3 mm diam., deeply immersed in anther sulci that are 8-9 mm long and c. 5 mm wide.Female flower as big as the male, without vestigial anthers, ovary c. 1.2 cm tall, 6 cm wide, lunate.
Etymology -This beautiful Rafflesia species is named after Mr. Leonardo L. Co.With his enormous knowledge of the Philippine flora, Leonard (to colleagues and friends) has been a mentor to the first author and many other students of Philippine botany.He spent most of his prolific botanical career in Luzon's Sierra Madre Mountain Range where R. leonardi is found.
Habitat & Ecology -Logged-over lowland dipterocarp forests at 270-300 m asl, thus far the lowest elevation for Rafflesia populations in the Philippines.Rafflesia leonardi usually grows along river and stream banks on thin soil and rocky substrate and among trees that have exposed roots and form buttresses.A total of six populations were found in the area.Tetrastigma cf.loheri (Barcelona et al. 3356, PNH, US) was identified as the host plant.On one host plant a total of ten buds and four developing fruits were observed, although usually fewer flowers per host plant seem to be produced.Rafflesia leonardi not only forms flowers on the exposed roots of its host, but also blooms along the aerial portions of the host liana (Plate 1a), some buds reaching a height of c. 10 m above the ground.In the Philippines, three other species, R. lobata, R. manillana, and R. speciosa exhibit this aerial habit.Rafflesia leonardi is sympatric with R. manillana, known from Luzon, Samar, and Leyte.At one site for instance, a population of R. leonardi is located less than 10 m from a population of R. manillana.Populations of both Rafflesia species in the Cagayan area rely on Tetrastigma cf.loheri as a host.Other species of Tetrastigma appeared to be absent from the areas where Rafflesia populations have been found.Tetrastigma loheri was also reported as the host of R. mira of Compostela Valley in Mindanao.Common canopy trees in the area are Dillenia philippinensis, Dipterocarpus validus, Pterospermum niveum, Shorea contorta, S. palosapis, and Terminalia foetidissima.The understory layer is composed of Astronia spp., Ficus spp., Leea congesta, Leptonychia banahaensis, Saurauia klemmei, and Syzygium curranii.Rattans and Freycinetia spp.also abound.The herbaceous layer consists of the angiosperm genera Begonia, Cyrtandra, and Donax cannaeformis, and the fern genera Asplenium, Microsorum, Pleocnemia, and Tectaria.
Morphological affinities -Rafflesia leonardi is similar in habit to R. lobata, R. manillana, and R. speciosa in that it blooms from both the roots and aerial portions of the host.It is further similar to R. lobata and R. manillana in perigone colour (different hues of reddish orange) and the shape and density of the perigone warts, but mostly in the relatively wide diaphragm opening, which is much narrower in all other Rafflesia species.The diaphragm is reminiscent of R. speciosa.The colour and morphology of the ramenta are very similar to those of R. banahawensis, which are maroon, variably branched, and stouter and more densely clustered in the diaphragm than in the perigone tube.The white spots or windows inside the perigone tube and diaphragm, typical in both R. lobata and R. manillana, are absent in R. leonardi.Rafflesia leonardi differs from all other Philippine Rafflesia species in the overall size of the open flower which is intermediate between the small-sized R. baletei, R. banahawensis, R. lobata, and R. manillana, and the medium-sized R. mira and R. speciosa.It is also different in characters of the disk, which is nearly flat to slightly dome-shaped and devoid of or with few processes, somewhat resembling the disk of R. rochussenii from Indonesia.
Conservation -The presence of two species of Rafflesia in the Cagayan area, the only case of sympatry in Rafflesia ever recorded in the Philippines, supports previous studies emphasizing the uniquely high yet poorly understood biological diversity in this part of the Sierra Madre mountain range (Danielsen et al. 1994;Co et al. 2006).This discovery strengthens proposals for the establishment of a Protected Area system currently being initiated by CAVAPPED and partner Peoples' Organizations (POs), Non-governmental Organizations (NGOs) and Local Government Units (LGUs).The dipterocarp forests in this portion of northern Luzon, although logged-over, are still in good condition.Small-scale rattan gathering by the local community was observed.Timber poaching for premium hardwood, such as narra (Pterocarpus indicus), was also evident.Slash-and-burn (kaingin) seems to be the most significant threat to Rafflesia populations in Cagayan.Although currently there are only a few small kaingin patches in adjacent areas, we predict that its impact will increase as these patches become larger and more numerous with the growing population in the area.