A Opisthostoma ballorum Vermeulen, 1991 ME 9002 Gunung Kapor B Opisthostoma brachyacrum brachyacrum Thompson, 1978 ME 0353 Gunung Batu C Opisthostoma brachyacrum lambi (Vermeulen, 1991) ME 9003 Gunung Kapor D Opisthostoma cryptodon Vermeulen, 1991 ME 9084 Gunung Doya.

 
 
  Part of: bin Marzuki ME, Liew T-S, Mohd-Azlan J (2021) Land snails and slugs of Bau limestone hills, Sarawak (Malaysia, Borneo), with the descriptions of 13 new species. ZooKeys 1035: 1-113. https://doi.org/10.3897/zookeys.1035.60843