ALS of 1st to 3rd instars of Australomimetus spinosus and Australomimetus djuka. A–C. A. spinosus. D–F. A. djuka. A, D. Boxed regions, magnified in insets, show putative 2° MaA tartipore primordia. Unlabeled arrows indicate the four PI spigots present in 1st instars (two T-A, two non-T-A); note increased PI spigot numbers in later instars. B, E. Unlabeled arrows indicate the two PI tartipores present in 2nd instars; note increased PI tartipore numbers in later instars. A, C, E, F. Left ALS. B, D. Right ALS (image flipped). 1°, 1° MaA spigot; 2°, 2° MaA spigot; T, 2° MaA tartipore. All scale bars 20 µm. See also Abbreviations and terminology (‘Spinning apparatus abbreviations’) and Results (Convention 3 in ‘Conventions applied…’).