Figure 7

Myoanatomy of Loxosomatoides sirindhornae. (a). General overview showing an adult on the right side with its muscular stalk and less muscular calyx. On the left side a small bud and a stalk without calyx are seen. (b) Lateral view of the tentacle crown with tentacle muscles and the atrial sphincter on the right. The intestinal sphincter is shown on the left side below the rectum. (c) Detail of the longitudinal muscles of the stalk, which is slightly bent in the specimen. At the right upper border the esophageal muscles are visible. (d) Detail of the 'star structure' in the calyx just below the stomach, somewhat above the end of the stalk. (e) Detail of the sphincter at the cuticular diaphragm of the stalk. A few small muscle fibres (asterisk) run from the sphincter towards the lateral musculature of the stalk. (f) Detail of the esophageal musculature showing conspicuous ring musculature and a few longitudinal muscles attaching to the upper end of the pharynx. (g) Detail of the anal sphincter opening into the atrium with retracted tentacles visible. Somewhat below, the intestinal sphincter is shown. (h) Frontal section of the calyx showing the esophageal retractors originating at the proximal bodywall and inserting at the upper broad end of the eosphagus. (i) Frontal section through the tentacle membrane and the contracted atrial sphincter. Abbreviations: ansp - anal sphincter, asp - atrial sphincter, cut - cuticle, em - esophageal musculature, er - esophageal retractors, erm - esophageal ring musculature, es - esophagus, isp - intestinal sphincter, itm - inner tentacle muscle, lsm - longitudinal stalk musculature, ltm - lateral tentacle muscle, rec - rectum, rt - retracted tentacles, ss -'star structure', ssp - stalk sphincter, sto - stomach, tm - tentacle musculature, tmb - tentacle membrane.