CRITICALLY ENDANGERED "LOST" RATTAN REDISCOVERED IN DAVAO DE ORO

By: Dr. Pieter Pelser

Calamus vinosus, a Critically Endangered rattan rediscovered in Mt. Candalaga, Davao de Oro.

A plant photography expedition in the forests of the Mt. Candalaga Range in Maragusan, Davao de Oro, has led to the remarkable rediscovery of one of the Philippines' rarest and most enigmatic palms, Calamus vinosus, a critically endangered rattan species that had not been documented in the wild for more than a century.

From 26 November to 4 December 2024, Dr. Julie F. Barcelona and Dr. Pieter B. Pelser (School of Biological Sciences, University of Canterbury and Philippine Eagle Foundation), together with Mr. Guiller S. Opiso (Philippine Eagle Foundation), conducted plant photo-documentation fieldwork in the Mt. Candalaga Range. The project aimed to improve our understanding of the habitat of the Philippine Eagle while also documenting the rich plant diversity of Davao de Oro Province.

Dr. Pieter B. Pelser documents the rediscovered Calamus vinosus in Mt. Candalaga.

The fieldwork forms part of an ongoing collaboration between the University of Canterbury and the Philippine Eagle Foundation, combining biodiversity research and conservation efforts in one of the country's most important forest landscapes.

Plant identifications were carried out both during and after the expedition, with valuable assistance from the Co's Digital Flora of the Philippines (CDFP) citizen science community. The work resulted in an impressive collection of 2,271 photographs documenting 236 plant species, all of which are now freely available through the CDFP website (www.philippineplants.org). Many of these species had never before been reported from Davao de Oro Province, significantly expanding knowledge of the region's flora.

Dr. Pieter B. Pelser, Dr. Julie F. Barcelona, Guiller S. Opiso, and Maragusan forest guards during the Mt. Candalaga expedition.

Among the most exciting discoveries was the identification of Calamus vinosus by palm expert Mr. Jiro Adorador of the University of the Philippines Los Baños.

"This is an amazing find. I never thought that this species would ever be encountered again in the wild," said Adorador.

Calamus vinosus is a Philippine endemic species classified as Critically Endangered. While approximately 40 species of the rattan genus Calamus are known from the Philippines, C. vinosus is unique in having striking wine-red fruits, making it unlike any other Philippine rattan.

Calamus vinosus, distinguished by its striking wine-red fruits.

Prior to this discovery, the species was known only from a single collection from 1912 on Mt. Urdaneta in Agusan del Norte. For more than 110 years, no additional records had been made, leaving uncertainty about whether the species still survived in the wild.

The rediscovery of Calamus vinosus highlights both the extraordinary biological richness and the conservation importance of the Mt. Candalaga Range. It also serves as a powerful reminder of how much remains to be learned about the forests of Mindanao and the species they support.

The forests of Mt. Candalaga, a refuge for rare and threatened species.

This remarkable finding underscores the urgent need to protect the remaining forests of the Mt. Candalaga Range. These ecosystems are not only vital habitat for the Critically Endangered Philippine Eagle and Rafflesia mira, but also refuge for rare and poorly known plant species that may occur nowhere else on Earth.

As discoveries like this continue to emerge, Mt. Candalaga Range stands as a testament to the Philippines' globally significant biodiversity and the importance of sustained research, collaboration, and conservation to ensure that these natural treasures are not lost.

Dr. Pieter B. Pelser and Dr. Julie F. Barcelona with PEF’s Guiller S. Opiso, Kristian James Suetos, Japheth Richa, and forest guards of SUMPAW and LABATA.