antiprismo-

https://doi.org/10.1351/goldbook.A00404
An affix used in names to denote eight atoms bound into a rectangular antiprism.
Sources:
Blue Book, p. 464 (http://www.acdlabs.com/iupac/nomenclature/)
Red Book, 3rd ed., p. 245 (https://doi.org/10.1515/pac-2014-0718)