Rafflesia verrucosa Balete, Pelser, Nickrent and Barcelona

This Rafflesia species is named for the abundant warts that cover the perigone lobes and diaphragm. 

This species was named in the following publication:

Balete D. S., P. B. Pelser, D. L. Nickrent, and J. F. Barcelona. 2010. Rafflesia verrucosa (Rafflesiaceae), a new species of small-flowered Rafflesia from Mindanao, Philippines. Phytotaxa 10: 49-57. A pdf of the article can be obtained HERE.

While conducting small mammal surveys on the southeastern slopes of Mt. Kampalili in Davao Oriental Province of Mindanao Island, Danny Balete noticed a small-flowered Rafflesia along one of the high elevation trails.  This mammologist (honorary botanist), whose eyes are trained to notice details at ground level, had already discovered two other species: R. aurantia and R. baletei. The parasitic plant community is fortunate that Danny saw this flower, for indeed he seems preadapted to finding new Philippine species of Rafflesia!

And what a new species it is!  For anyone with even cursory experience with Philippine Rafflesia, this one is obviously quite different from anything previously described.  The photos below will do better than words to illustrate the assemblage of unusual and unique morphological features presented by this species, but here are the highlights:
Rafflesia verrucosa is presently known only from the type locality, a montane forest between 1350 and 1550 m elevation.  This is unusually high, for most Rafflesia species occur in lowland or lower montane forests.  This area is undergoing disturbance from human activities such as forest clearing for cultivation of abaca (Musa textilis) or cutting of rattan palms for food.  The area is currently not under protection or a management plan.  As stated in Balete et al. (2010):

 "We strongly support efforts by local people (e.g. Taocanga Tribal Council Association), environmental organizations (e.g. Philippine Eagle Foundation) and concerned government agencies (e.g. Department of Environment and Natural Resources and the Department of Tourism Region XI) to place certain portions of Mt. Kampalili under protected area and ancestral domain management."

Rafflesia verrucosa flower

Rafflesia verrucosa flower, top view.  Note the densely packed warts all over the perigone lobes and diaphragm.

Rafflesia verrucosa flower

Rafflesia verrucosa flower, showing a bit of the lower surface of the perigone lobe.  Note the dark, hardened tissue is flaking off leaving a pitted surface.

Rafflesia verrucosa diaphragm

Rafflesia verrucosa flower (fixed material).  Close-up of the diaphragm showing how the warts go all the way to the aperature opening.  This photo also shows the laminar plates that make up the processes on the top surface of the disk.

Rafflesia verrucosa upper perigone peeling

Rafflesia verrucosa flower, beginning to senesce.  The warts on the upper perigone surface have turned black and are abscising, leaving a schlerenchymatous layer which is persistent on the fruit.

Rafflesia verrucosa lower perigone peeling

Rafflesia verrucosa (fixed material), closer view of the lower perigone surface as the hardened layer is beginning to flake off.

Rafflesia verrucosa lower perigone peeled and pitted

Rafflesia verrucosa (fixed material), closer view of the lower perigone surface, after the hardened layer has fallen off, leaving a pitted surface on the sclerenchymatous inner layer.

Rafflesia verrucosa flower opened

Rafflesia verrucosa flower (fixed material) cut open showing the disk borne on a short column.  The disk has a wide, raised margin and many anastomosing laminar plates make up the processes. The lower portion of the disk is covered with acicular hairs. Surrounding the disk is a doughnut-shaped, shallowly rugose annulus. Ramenta project inward toward the annulus from the perigone tube.

Rafflesia verrucosa anthers

Rafflesia verrucosa (fixed material), disk removed an turned upside down to expose the numerous anthers on its underside.

Rafflesia verrucosa flower LS

Rafflesia verrucosa flower (fixed material) in longitudinal section showing the presence of both anthers and ovules, thus the flower is bisexual.

Last updated: 27-July-16 / dln