Fig. 4

Details of a single zooid of Stephanella hina. a View of the lophophore with the horseshoe-shaped tentacle arrangement and the epistome protruding over the mouth opening. Note the orange tinge of the epistome. b Lateral view of the lophophoral base, showing the evident coloration of the epistome as well as the pharynx. Note the intertentacular membrane on the outer side of the lophophore. c Lateral view through the transparent ectocyst showing parts of the digestive tract as well as retractor muscle strands traversing the visceral coelom. d View from the basal side of the lophophore and the intertentacular membrane extending from the lophophoral base towards the outer area of the tentacles. Abbreviations: cae – caecum, en . endocyst, ep – epistome, int – intestine, itm – intertentacular membrane, l – lophophore, ph – pharynx, rm – retractor muscle, t – tentacle, ts – tentacle sheath