Fig. 3

Musculature, digestive gland diverticula, cnidosac entrance and cnidopore in different Fionidae species (CLSM). A Diaphoreolis viridis, 3D-reconstruction of musculature of ceratal distal part. B Cuthonella concinna, optical longitudinal section, digestive gland diverticula showing intact nematocysts in digestive gland lumen (white arrowheads), the brightness/contrast is enhanced to make nematocysts visible among mollusc tissues. C Cuthonella concinna, optical longitudinal section, cnidosac entrance showing intact nematocysts in digestive gland lumen (white arrowheads), the brightness/contrast is excessive to make nematocysts visible among mollusc tissues. D Eubranchus odhneri, optical longitudinal section, cnidosac entrance, white dotted lines indicate cnidophages with NCs. E Cuthona nana, optical longitudinal section, cnidopore with invagination of epidermal layer closely adjacent to cnidophages (borders are indicated with white arrows), white dotted lines indicate cnidophages, yellow dotted lines indicate NCs layer. F Cuthona nana, optical longitudinal section, discharged cnidosac, cnidopore with ejected cnidophages containing nematocysts (borders are indicated with white arrows). G Catriona columbiana, optical longitudinal section, cnidopore with invagination of epidermal layer closely adjacent to cnidophages (borders are indicated with white arrows). H Zelentia pustulata, optical longitudinal section, cnidopore. I Eubranchus odhneri, optical longitudinal section, cnidopore with ejected cnidophages containing nematocysts, white dotted lines indicate cnidophages with NCs. cmb circular musculature of body, cnph cnidophage, cns cnidosac, cp cnidopore, cs cellules speciale, dg digestive gland, dgc digestive gland cells, ep epithelium, hc haemocoel cell with chitinous spindles, he haemocoel, lmb longitudinal musculature of body, lmc longitudinal musculature of cnidosac, lu lumen, mb body musculature, mc cnidosac musculature, nc NCs, ncl NCs layer within cnidophage, nu nucleus, seg subepidermal mucus gland, sph muscular sphincter of cnidosac. Scale bars: 20 µm