The abnormal wing structure observed in tsh^ae-1 mutants is a result of fusion of the proximal wing hinge to thoracic pleural structures found near the base of the wing. The fusion occurs between the proximal ventral radius in the wing hinge and the pleural wing process region of the thorax. The thoracic pleural wing process and the proximal ventral radius act to anchor the wing into a held-out position during flight or for wing posturing during courtship. In addition, within the same general area, the yellow club structure is either missing or fused to the proximal ventral radius and pleural wing process in the mutant. No other defects are observed for the rest of the pleural structures or the notum. In tsh^ae-1 flies, the ventral surfaces of the halteres do not have a hinge-like folding as in the wild-type, but appear to have a continuous layer of cuticle from just below the ventral pedicellar sensilla to the thorax, within the area of the haltere sclerite. Since the metathoracic bristle group is detected, this limits the affected area of the haltere to between the haltere sclerite and the ventral pedicellar sensilla. Thus, a fairly subtle structural defect of the cuticle prevents the mutants from folding their wings back into a resting position and causes the halteres to droop. Heterozygotes for tsh^ae-1 and tsh^8.1 show the characteristic abnormal wing and haltere posture, as found in tsh^ae-1 mutants, but the phenotypes also include a number of other thoracic and wing-hinge defects, much like those observed with tsh⁸. In heterozygotes for tsh^ae-1 and tsh^8.1, it appears that, within the mesopleural plate, the pre-alar apophysis is pushed anteriorly towards the vertical cleft. The cuticle of the mesopleural plate on the posterior side of the vertical cleft appears to be forced into the vertical cleft or under the mesopleural plate. There is also a buckling of the cuticle in the suture between the notopleurite and the mesopleural plate.

Wings spread, balancers drooping. Overlaps wild type. RK3.