Exceptionally species-rich assemblages of modern larger benthic foraminifera from nearshore reefs in northern Palawan (Philippines)

Symbiont-bearing larger benthic foraminifera (LBF) are ubiquitous components of tropical and subtropical carbonate-rich shallow-water habitats and contribute substantially to coral reef accretion and stability. More than 60 species of LBF are currently described from the Indo-Pacific Ocean with the Philippines being recently identified as their potential center of maximum species richness.

The Palawan archipelago, also known as the “last ecological frontier” of the Philippines and a hotspot of biodiversity, attracts a growing number of tourists due to its comparatively intact marine environments and picturesque landscapes. Here, we document and illustrate the species-rich fauna of modern LBF from shallow nearshore habitats in northern Palawan. Sampling covered the northernmost part of Palawan's South China and Sulu Sea coasts including the Calamian Islands group. A total of 24 samples were taken from fore-reef slopes, inter-reef areas, a back-reef, seagrass leaves with a nearby mangrove swamp, and a WW2 shipwreck at depths between 0 to 25 m. We recorded a total of 44 LBF morphospecies, a number that is among the highest reported so far. Heterostegina depressa and Calcarina mayori were identified as the most widely distributed taxa in the study area. We further describe Peneroplis hoheneggeri nov. sp. as a new species of Peneroplis de Montfort. The newly described peneroplid is characterized by single rows of large pits and was previously also documented from Micronesia. Our survey supports the designation of northern Palawan as an exceptionally biodiverse ecoregion with high priority for marine conservation efforts.