Accurate species delimitation and identification are an important first step in protecting biodiversity and environmental monitoring. Accordingly, alpha taxonomy and biogeography are critical pieces of baseline information for identifying the basic units of conservation. The four clades of C. malayensis differ by 5–10% in their net COI sequence divergence, which is comparable to that reported in the tropical, eastern-Pacific Chthamalus species (Wares 2001; Pitombo and Burton 2007) which has been attributed to recent radiation within the genus (Wares et al. 2009), but the high plasticity of chthamalid barnacles poses severe hurdles to field identifications.