Plectostoma turriforme (van Benthem Jutting, 1952)

Plectostoma turriforme, Plectostoma sciaphilum, and Plectostoma senex are three very similar species than occur in the four lenticular easternmost limestone hills in Peninsular Malaysia (Figure 18A). These four hills, namely, Bukit Panching, Bukit Charas, Bukit Sagu, and Bukit Tenggek are located along a 15 km longitudinal transect. Plectostoma turriforme occurs at the two former sites and Plectostoma senex at the two latter sites. Plectostoma sciaphilum occurs sympatrically withPlectostoma turriforme in Bukit Panching. These four hills (and thus the three species) are among the most isolated limestone outcrops in Peninsular Malaysia.