FIGURE 4 in Spionidae (Annelida) from shallow waters around the British Islands: an identification guide for the NMBAQC Scheme with an overview of spionid morphology and biology

FIGURE 4. Spionid adult morphology. Nuchal organs; palps missing in A–C. A, Spiophanes sp., anterior end, dorsal view, bell-shaped prostomium with extended fronto-lateral edges, and nuchal organs as long straight longitudinal ciliary bands; notice that prostomium not extending posteriorly as a caruncle. B, Spio sp., anterior end, dorsal view, anterior J-shaped metamers of nuchal organs. C, Prionospio sp., anterior end, fronto-dorsal view, U-shaped nuchal organs, ear-like structure formed by fusion of posterior dorsal part of peristomium and notopodial postchaetal lamella of segment 1, and everted proboscis. D, Spio cf. filicornis, middle segments, dorsal view, paired oval nuchal metamers. E, Laonice sp., middle segments, dorsal view, posterior part of long low caruncle sided by U-shaped nuchal organs. F, Dispio sp., middle segments, dorsal view, nuchal metamers and various dorsal ciliation. ea—ear-like structure; lo—lateral ciliated organ; nt—nototroch; nu—nuchal organ; pa—palp scar; pb—proboscis; pe—peristomium; pr—prostomium; tc—intersegmental transverse ciliation. Scales: A, C, F—100 µm. B, D—50 µm. E—30 µm.