This zip compressed file contains the first batch of proposals approved during the ICTV Executive Committee meeting (EC50) in July, 2018 in Washington DC, and ratified by the ICTV membership in October, 2018. This represents release number 33, 2018a of the Master Species List. A second ratification of proposals approved during EC50 was held in February, 2019. This was release number 34, 2018b of the Master Species List.