Figure 3
From: Ringiculid bubble snails recovered as the sister group to sea slugs (Nudipleura)
Morphological comparison of euthyneuran bubble snails.
(a–c) Microanatomy of Ringicula doliaris with emphasis on head and nervous system. (a) 3D reconstruction of entire animal, anterodorsal view. Broken line indicates separation of headshield into head and mantle parts. (b) Central nervous system, oblique right view, highlighting lack of connection between nerves N1 and N2 (grey dotted line). Head (green) and mantle (purple) are innervated by cerebral and pleural (or parietal) nerves, respectively. (c) Schematic drawing of central nervous system, orientation as in (a). Hypothetical course of visceral loop is shown as yellow line. (d–i). Ringiculidae (Ringiculoidea). (d) Schematic drawing of head-hoot, mantle and shell. Green areas denote head with cerebral innervation and purple area represents mantle innervated by pleural or parietal nerves. (e–i) Shells of sequenced specimens: (e) Ringiculoides kurilensis, (f) Microglyphis japonica, (g) Ringiculopsis foveolata, (h) Ringicula doliaris and (i) ‘Microglyphis’ sp. (j,k) Acteonoidea. (j) Schematic drawing. Cream area denotes expanded margins of foot or parapodia. (k) Shell of a representative species, Punctacteon teramachii. (l–o) Euopisthobranchia. (l) Schematic drawing and shells of (m) Cylichnium ancillarioides, (n) Acteocina gordonis and (o) Toledonia sp. Scale bars: 200 μm for 3D reconstruction; 1 mm for shells. Abbreviations: DGL, defensive gland, seen transparency in (j,l); EY, eye; FT, foot; G1, supraintestinal ganglion; G2, visceral ganglion; GB, buccal ganglia; GCP, cerebropleural ganglia; GO, osphradial ganglion; GP, pedal ganglia; MO, mouth; MS, mantle shield; N1, osphradial nerve; N2, visceral nerve; NC, cerebral nerves and innervated area; NP, pedal nerves; NPL, pleural or parietal nerves; OC, oocytes; SI, siphon; VS, visceral sac with internal organs.
