Tracheal terminal cells in ivy¹⁷⁸¹ mutants are moderately to severely pruned with multiple convoluted lumens, compared to wild-type. These mutants also exhibit a terminal cell gas-filling defect that typically affects only new or distal portions of sub-cellular tubes. The tip-clearance defects are variable, with some mutant termina cells more severely affected than others, even within the same mosaic animal.