High localised diversity of Halimeda (Chlorophyta: Bryopsidales) in a tropical marine park from Pahang, Malaysia

Abstract

The chlorophyte genus Halimeda is common in tropical waters but gaps still exist in the understanding of the biogeographical distributions of its species in Southeast Asia, particularly in Malaysia. During a study into the ecological functioning of reefs in a marine park (the Sembilang–Seri Buat group of islands, Pahang, Malaysia) along the eastern coast of Peninsular Malaysia, a previously unreported community of sand-dwelling Halimeda was discovered on a shallow reef flat (water depths of 1-2 m). We randomly collected 63 individuals and identified them using defining morphological and anatomical characteristics. The collection consisted of Halimeda borneensis, H. discoidea, H. macroloba, H. opuntia, and H. taenicola. Halimeda borneensis was the most collected (52 individual explants) in our study site. We report that H. taenicola is a new record for the eastern coast of Peninsular Malaysia, which is also a first biogeographical report of this species for the area spanning the Gulf of Thailand and towards the coastal areas to the east of Singapore. This study together with past records on Halimeda in the immediate surroundings show a total of six Halimeda species in the area, a localised coastal diversity uncommon to this part of the South China Sea.