Fig. 3.

Reconstruction of the pattern of abdominal-A loss within the major clades of arthropods and their correlation with a reduction in posterior segmentation. a Phylogenetic relationships of arthropods based on previous data [101, 104–106]. Arthropod taxa from at least two subphyla that have been identified as missing abd-A and contain reduced posterior body morphologies. b–d. Illustrations of arthropod taxa with reduced posterior segmentation and reported missing abdominal-A. b Sacculina carcini naupli (left; ventral view, oriented anterior up) and cypris (right; lateral view, oriented anterior up) (adapted from [107]). c Tetranychus urticae; lateral view, oriented anterior left. d Endeis spinosa; dorsal view, oriented anterior left (adapted from [108]). Scale bar in B = 5 cm, C = 0.125 mm, and D = 1 mm