Isocirrus tropicus (Monro, 1928). A) Body, anterior part, lateral view, B) cephalic plaque and first two chaetigers, lateral view, C) everted proboscis, D) anal funnel, lateral view, E) dorsal margin of cephalic plaque, F) manubriavicular uncini from 5th chaetiger, G) anal plaque, posterior view, H) mid-ventral whitish ridge starting in chaetiger 7. Scale bars: A) 3 mm, B) 2 mm, C) 1 mm, D) 1.3 mm, E) 1.8 mm, F) 400x magnification, G) 0.5 mm, H) 1.5 mm. Arrows in A pointed to lateral notches of cephalic plaque. In B, arrows pointed to crenulated margin of cephalic plaque.