Trunk region. A–D Morphology of the trunk region (thick lines) A conical (S. tremula) B cylindrical (S. tavina) C bell-shaped (S. tremuloida) D wineglass-shaped (S. longipes) E Presence of a distinct anal pseudosegment (thick line; S. oblonga) F Presence of a posteriodorsal saccate appendage (thick line; S. arcifera) G, H Longitudinal striae on the dorsal trunk G present (S. tavina) H absent (S. pectinata) I–L Location of the internal organs I occupy entire trunk region (S. oblonga) J occupy middle and caudal trunk regions, oesophagus only structure in the anterior trunk (S. pectinata) K occupy middle trunk region, cloaca ends anteriorly to the lateral antennae (S. grimpei) L stomach and ovary each occupy separate sides of the trunk (S. longipes). Drawings modified from B, G Rousselet (1902) F Rougier and Pourriot (2006). Scale bar: 50 µm.