New aromatic flower Ridsdalea philippinensis discovered in El Nido


By Sharleen Gabriel

A new species of the Ridsdalea flowing plant was discovered at a karst forest in El Nido, Palawan.

“We came across it while resting on the summit of Taraw Cliff during one of our hikes to document the different karst flora of El Nido,” said Rene Alfred Anton Bustamante, the main author of the paper “A new Philippine species of Ridsdalea (Rubiaceae, Ixoroideae) from karst vegetation in Palawan.” The paper has already been accepted for publication in Blumea, an international journal devoted to the biodiversity, evolution, and biogeography of plants, as of January 17, 2022.

“The strong perfume of the blooms drew our attention to the species” Bustamante added.

In the report, Bustamante of the Philippine Taxonomic Initiative (PTI), and Dr. Pieter B. Pelser of the University of Canterbury named the new Ridsdaleaspecies, Ridsdalea philippinensis which endemic to El Nido and the Philippines' seventh known Ridsdalea species. R. philippinensis is the only Malesian Ridsdalea species with a corolla with a distinctly inflated apex, a feature shared by R. sootopensis and R. thailandica from Laos and Thailand, respectively. Among other characteristics, R. philippinensis differs from both of these species as its flowers are smaller and its anthers do not emerge from the corolla tube.

Ridsdaleaspecies, Ridsdalea philippinensis

According to studies, karst landscapes account for 11.7 percent of the country's total land area. Karst landscapes, which emerge from the dissolving of soluble rocks, mostly consisting of calcium carbonate, are regarded as some of the most stunning, picturesque places. Additionally, Palawan’s karst areas are home to numerous endemic flora and fauna. However, despite their status as biodiversity hotspots, karst ecosystems have received very little attention in terms of research.

During the National Research Council of the Philippines (NRCP) Biological Sciences Division's Scientific Session, wildlife specialist and multi-award-winning scientist Arvin C. Diesmos stated that “quite a large portion of is still unknown to science.” He also mentioned that, due to the low emphasis and restricted funding allocated to this field of study, only a small number of biologists are trained or interested in exploring karst fauna.

Restificar et al. (2006) estimate that the land area covered by karst formations is approximately 12 percent. However, the inaccessibility of the karst terrains makes it difficult to conduct field study on these areas. For this reason, Clements et al. (2006) and Tang et al. (2011) believe the species diversity of karst landscapes is likely to be underestimated. Thus, a number of research expeditions across Palawan, including the karst forest where the Ridsdalea was discovered, had been conducted by the PTI. One of the organization’s initiatives is to conduct larger and more comprehensive investigations of karst biodiversity, as numerous novel species await discovery.

“The discovery of this new species shows how special, but poorly known the karst ecosystems of the Philippines are and, therefore, how important it is to protect them.” Pelser said.

Ridsdalea is a genus of plants in the Rubiaceae family native to Asia; it was named in honor of Dr. Colin Ridsdalea. The unintentional finding of Ridsdalea philippinensis resulted in the discovery of the island's second Ridsdalea species. The first author, J. T. Pereira & K. M. Wong, discovered the first undocumented species of Ridsdalea near the peak of Taraw Cliff in Barangay Buena Suerte.