Rafflesia speciosa Barcelona and Fernando

In 2002 a Rafflesia was seen blooming on the island of Panay, Antique Province, Sibalom Natural Park (SNP) near the town of Sibalom. Sightings were also reported from the adjacent town of San Remegio and nearby barangays at the Antique-Iloilo border. Up to this point in time, two species of Rafflesia had been described from the Philippine islands: R. manillana, originally named Teschemacher in 1842 from a population on the island of Leyte (Basey), and R. schadenbergiana described by Göppert in 1885 from Mindanao (Mt. Apo). The name R. manillana now applies only to the Samar species whereas all the Rafflesia from Luzon that were thought to be conspecific with it are now referred to as R. lagascae (Barcelona et al. 2009). These two species are easily distinguished from each other because R. manillana has a smal (15-20 cm diameter) flower whereas R. schadenbergiana has a large flower (80 cm diam.). So what was the identity of the Rafflesia from Panay Island that was discovered by members of The Antique Outdoors (TAO), a conservation group in the province of Antique, Panay Island? They contacted Dr. Julie Barcelona, a botanist with the Philippine National Herbarium (PNH) who together with Dr. Edwino S.Fernando named this new species Rafflesia speciosa (Barcelona and Fernando 2002). The photographs shown below were taken by Albert Mamora, Julie Barcelona and members of TAO.

Since it discovery, additional field work has shown that Rafflesia speciosa is present in numerous populations of the Central Panay Mountain Range. Furthermore, the species is also known from the Kanlaon volcano on Northern Negros Island (Barcelona et al. 2009). This distribution pattern is unusual for Philippine Rafflesia where most species are confined to single islands. That said, these two islands were contiguous during the late Pleistocene when sea levels were lower. A conservation genetic study using microsatellites was conducted on nine populations of R. speciosa (Pelser et al. 2018). The populations on Panay have higher genetic variation than on Negros and it appears that the Guimaras Strait between the islands has imposed a barrier to gene flow between the island populations. Because of the unique genetic diversity contained within these separate populations, they are significant from a conservation standpoint and legal protection was proposed.

References

Barcelona JF, Fernando ES. 2002. A new species of Rafflesia (Rafflesiaceae) from Panay Island, Philippines. Kew Bulletin 57:647-651.

Barcelona JF, Pelser PB, Balete DS, Co LL. 2009. Taxonomy, ecology, and conservation status of Philippine Rafflesia (Rafflesiaceae). Blumea 54:77-93.

Pelser PB, Nickrent DL, Barcelona JF. 2018. A conservation genetic study of Rafflesia speciosa (Rafflesiaceae, Philippines): patterns of genetic diversity and differentiation within and between islands. Blumea 63:93-101.

Albert Mamora Jr. posing with the flower of Rafflesia speciosa.

Albert Mamora and friend near the plants. Note the bamboo exclosure placed around some of the buds.

Close-up of the flower buds and an open flower in the background.

A fully opened flower and one that is senescing to the right.

Julie Barcelona (center) and two members of The Antique Outdoors group posing with the flower of Rafflesia speciosa.

Julie Barcelona (for scale!) with a flower bud of R. speciosa.

Close-up of the flower bud of R. specios

A senescent flower of R. speciosa. Hopefully there will be some fruit production in these populations.

A fully opened flower of Rafflesia speciosa. Fantastic! Julie notes that the markings on the perigone lobes look like Rice Crispies!

Valderrama municipality, Antique Province, Panay Island, Philippines. 11.0000, 122.1333. Photo by Leonard Co.

Valderrama municipality, Antique Province, Panay Island, Philippines. 11.0000, 122.1333. Photo by Leonard Co

Last updated: 12-Apr-19 / dln