Rafflesia leonardi Barcelona & Pelser (2008: 223–228)

Tobias, Adriane B., Thorogood, Chris J. & Malabrigo Jr, Pastor L., 2023, The reinstatement of Rafflesia banaoana (Rafflesiaceae), and implications for assessing species diversity and conservation requirements of the world's largest flowers, Phytotaxa 612 (2), pp. 201-216 : 207-209

2. Rafflesia leonardi Barcelona & Pelser (2008: 223–228) . Fig. 5

urn:lsid:ipni.org:names:77091703–1

Type: — Philippines, Luzon island, Cagayan Province, Gattaran Municipality, Barangay Bolos Point , Sitio Kanapawan , 370 m, May 2007, Barcelona et al. 3355 (holotype: PNH!, isotype: PUH, US, L)

Description:— Endophytic holoparasite. Mature bud 16 cm diameter, pale yellowish-pink. Cupule c. 3.5 cm high, 7.5 cm wide. Bracts dark brown to black, in a set of 3 imbricate whorls, outermost smallest, c. 3 cm by 4 cm, innermost largest, 12 cm by 8 cm. Flowers (25.5–)28–34(50) cm diameter when fully expanded, 13.8–18 cm high. Perigone tube geniculate, 9–11 cm long. Perigone lobes 5 (or 6), 7.5–13 cm by 11–13.5 cm, 6–7 mm thick, reddish-orange in color becoming darker with age, apex recurved, orbicular to broadly orbicular, basally imbricate to widely-spaced, with margins entire to irregularly sinuate, covered with conspicuous, elliptic to orbicular warts, larger ones interspersed with minute warts, whitish when fresh, becoming concolorous with background with age. Diaphragm 14–18 (–22) cm diameter, 2.5–3 cm wide from aperture rim to base of perigone lobe, 3–10 mm thick at base, background concolorous with perigone; outer surface covered with tan-colored warts, each set in a reddishindentation, in a matrix dense, minute warts of the same color. Diaphragm Aperture 10–12.5(–19) cm diameter, rim maroon in color. Windows absent. Ramenta reddish-orange, up to 2 mm, sub-filiform to tuberculate, with few lobed ramenta in the lower perigone tube, shallowly and deeply-bilobed and multi-lobed with few merged ramenta in the middle perigone tube, multi-lobed, merged and fence-like ramenta in the upper perigone tube and near the diaphragm aperture. Disk 7–8 cm diameter, c. 1.2–1.3 cm thick, dull yellow to reddish-orange, paler in the center becoming darker with age, almost flat, upper with waxy bloom (not shiny), rim not extended, margin glabrous, devoid of processes or processes few and rudimentary, under surface of male flower pale cream, with inconspicuous bristles and minute brown dots; female flower undersurface and margin cream throughout, devoid of bristles. Processes normally absent, when present shallowly conical. Male flower similar in size to the female, without vestigial ovary, anthers 20–21, 3–4.5 mm diameter, irregularly globose, immersed in anther sulci 8–9 mm long and c. 5 mm wide; neck of the column 1 cm height, 4 cm diameter; lamella 20, 3–3.5 mm long from the neck margin; annulus structure not observed. Female flower without vestigial anthers, neck of the column 5 mm height, 4.5–5 cm diameter, margin lobed; interior annulus structure smaller than the disk, 8 cm in diameter, pale ochre in color, surface and margin hispidulous, with broad grooves 1–1.5 cm long, 5–6 mm wide; exterior annulus structure 1–1.5 cm from the edge of the interior annulus structure, concolorous with the disk’s upper surface, glabrous; ovary 6 cm wide, 1.2 cm height, narrowly-lunate, not acutely angled. Fruit and seeds not observed.

Distribution and habitat: — Rafflesia leonardi is endemic to Luzon Island. It is recorded in tropical moist lowland forests of Sierra Madre Mountain Range particularly in the Province of Cagayan and Aurora (See Figs. 4e‒g ). It grows close to rivers and streambanks in all localities. Flowers bloom both on ground and on aerial vines of Tetrastigma loheri Gagnep (1910:210) . Barcelona et al. (2008) documented R. leonardi at elevations of 270– 300 m. In Aurora Province, the species occurs at 250–480 m elev.

Phenology: — The type specimens of R. leonardi (Barcelona et al. 3354 and Barcelona et al. 3355) were collected on 29 May 2008. However, no mature buds or senesced flowers were observed when ABT visited the site on 16 April 2019, or by all authors in March, 2022. It was later observed in flower from May to August 2022 in Aurora Province, with an apparent peak from June to July. Fruiting was observed.

Provisional conservation status: — Critically Endangered C2b. Rafflesia leonardi was known from only six sites in Cagayan Province prior to this study. Additional localities in Aurora Province were observed by the staff of Amro-River Protected Landscape (ARPL) on 11 May 2020 and in Calabgan Watershed Forest Reserve (CWFR) on 11–16 June 2020. The expanded distribution of R. leonardi makes its EOO and AOO larger, which are estimated at 1024 km 2 and 20 km 2, respectively. However, its subpopulation in Cagayan was last seen in 2015 before the typhoon Ompong devastated the province in 2018 (S. Aresta, pers. comm.). This equates to a 98% reduction in EOO and 20% in AOO. Moreover, it appears to be locally rare with flowers usually fewer than 50 in each subpopulation, and the number of individuals fluctuating markedly.

Additional specimens examined: — PHILIPPINES: LUZON, Aurora Province, Amro-River Protected Landscape , Dilasag Municipality, 270 m elev., 13 August 2022, Tobias 2022-1, male flower bud (LBC!).

Figures

FIGURE 4. Habitat of Rafflesia banaoana and R. leonardi. A. Overlooking view of mountains in Banao Protected Landscape (BPL). B. Mature flower of R. banaoana (~43 cm across) in Mt. Magadgad. C. Habitat of R. banaoana in Mt. Mapga. D. R. banaoana with the park rangers of BPL. E. Habitat of R. leonardi in Calabgan Watershed Forest Reserve (CWFR) with the locals and staff of the protected area. F. Flower buds of R. leonardi in CWFR. G. Habitat of R. leonardi in Amro River Protected Landscape. H. Vegetation in the type locality of R. leonardi in Mt. Rabuaran, Sitio Kanapawan, Barangay Bolos Point.—Photos by A.B.Tobias

FIGURE 5. Rafflesia leonardi. A1. Mature flower bud. A2. Dissected male flower bud. B1. Flower found in Calabagan Watershed Forest Reserve. B2. Flower found in Amro River Protected Landscape. C. Dissected female flower showing the characters of the processes, disk column, annulus structure and ovary. D. Enlarged view of the column of female flower showing short hairs on the surface of annulus interior. E1. Annulus structure of male flower showing white hairs on the surface of the annulus interior. E2. Disk under-surface of male flower. F1. View from above the disk of male flower bud. F2. Disk of mature flower. Photo credits: A1, A2, C, D, E1, E2, F1, F2— A.B.Tobias; B1—E.Agbayani; B2.—M.Aguan