A new molecular cladistic study of 42 species (including Mastopoma scabrifolium) in 25 genera of Sematophyllaceae in Peninsular Malaysia and Singapore has revealed the non-monophyly of the genus Mastopoma. Mastopoma scabrifolium was shown in a MP phylogenetic tree based on rbcL sequences to be forming a separate clade with Acanthorrhynchium papillatum. A transfer of this species to Acanthorrhynchium is proposed. Acanthorrhynchium scabrifolium (Broth. in Moell.) B.C. Tan & Chang Ying is a new combination.