Fig. 2

CLSM of phalloidin stained muscle of Diuronotus aspetos. Anterior of the specimen is pointing left for a, b and j–p, and dorsal is pointing at the top for d–i. a–n Muscles in green, nuclei in cyan a Ventral view of the maximum intensity projection (MIP) of the whole specimen. b Dorsal MIP of the pharynx. c Dorsal MIP of the posterior specimen. d–i CLSM virtual transverse section of various parts of the specimen: d head, e posterior part of the pharynx, f anterior of the trunk, g posterior of the trunk, h post-anal region of the trunk, i and furca before bifurcation of the tubes. j Dorsal MIP of a sub-stack showing details on the head musculature. k Dorsal MIP of a sub-stack showing details of the furca separation. l Ventral MIP of a sub-stack showing details of the semicircular musculature. m Single section showing details of the inner pharynx. n Dorsal MIP of a substack showing details of the helicoidal musculature. o and p, isosurface reconstruction of the pharynx. o Dorsal view, p ventral view. ag adhesive gland, agn adhesive gland nucleus, aps anterior pharyngeal sphincter, cmag circular muscle of the adhesive gland, dlm dorsal longitudinal muscle, dvlm dorsal projection of the ventral longitudinal muscle, dvm dorso-ventral muscle, hdm head diagonal muscle, hm helicoidal muscles, lplm lateral pharyngeal longitudinal muscle, lvlm Lateral extension of the ventral longitudinal muscle, mn myocyte nuclei, mvlm medial projection of the ventral longitudinal muscle, pcm pharyngeal circular muscle, pddm pharyngeal dorsal diagonal muscle, pdm posterior diagonal muscle, pdlm pharyngeal dorsal longitudinal muscle, ph pharynx, pps posterior pharyngeal sphincter, pt primary tube, rpm radial pharyngeal muscles, scm semi-circular muscle, st secondary tube, tdm tube diagonal muscle, vlm ventral longitudinal muscle, vllm ventro-lateral longitudinal muscle, vlm ventral longitudinal muscle