AN EXAMINATION OF SPECIES WITHIN THE GENUS SURIRELLA FROM THE MALILI LAKES, SULAWESI ISLAND, INDONESIA, WITH DESCRIPTIONS OF 11 NEW TAXA

Abstract

With 35 taxa reported by Hustedt (1942a), the genus Surirella (Turpin) is one of the most taxonomically rich and important genera in the Malili Lakes, a system of five ancient lakes located on the island of Sulawesi, Indonesia. We examine in detail the taxonomy of diatoms within the genus Surirella from the Malili Lakes. We also statistically evaluate valve morphology and relationships among taxa, and describe 11 new taxa. Results show Surirella taxa clustered according to unique combinations of morphological characteristics. Individuals within clusters often shared common valve shape, torsion, and presence of siliceous features including spines, spinules, and novel structures such as siliceous tendrils and tubular processes along the median area. We demonstrate that the siliceous tendrils of Surirella sublinearis and its varieties, and S. tenacis are used for attachment to substrata and further postulate that the evolutionary development of attachment features contributes to the substantial diversity of Surirella taxa in this ancient lake system.