Characters;"M. adunca sp. n.";"M. arctica Detinova, 1985";"M. californiensis Green, 1991";"M. capensis (Day, 1961)";"M. cristata Treadwell, 1923";"M. cuculligera Ehlers, 1887";Characters;"M. decorata Grube, 1877**";"M. glabra Knox & Cameron, 1971";"M. glebifex Grube, 1860";"M. gorgonensis Monro, 1933";"M. malmgreni McIntosh, 1885***";"M. marsupialis Grube, 1878";Characters;"M. meridionalis (Chamberlin, 1919)";"M. monilata Fauchald, 1972";"M. philippinensis Treadwell, 1931";"M. pigmentata (Imajima & Shiraki, 1982)";"M. sarsi Malmgren, 1865";"M. theodori Augener, 1926" "Type locality";"Southwest of Macao";Arctic;"Southern California";"South Africa";California;"Gulf of Mexico" "Collar on chaetiger 1";No;No;"Yes, limited ventral side";No;No;"Yes, limited ventral side" Pigmentation;absent;?;?;"Head of living worm flecked with brown";"Anterior segments with dark brown pigment";"Nuchal groove with brown pigment spot?" "Shape of nuchal grooves";"Strongly curved anteriorly, J-shaped";"Short, slightly curved";"Slightly curved";J-shaped;"Short and divergent anteriorly";"slightly curved" "Posterior cephalic rim";Low;Pocket-like;Pocket-like;Pocket-like;Pocket-like;Pocket-like "Dorsal glandular band on chaetiger 5";Absent;?;Absent;Absent;"Sixth chaetiger with an anterior dorsal flange*";"Dorsal glandular band" "Prostomial palpode";"Bluntly rounded";Spade-like;"Rounded to semi-triangular";"Broadly spatulate";Hemispherical;"Bluntly rounded" "Border of anal plate";"Laterally notched";"Laterally notched";"Laterally notched";"Laterally notched";"Laterally notched";"Laterally notched" "Ventral part of anal rim";"Smooth to slightly crenulate";Smooth;"Slightly crenulate";Crenulated;"Slightly crenate";"Smooth to slightly crenulate" "Type locality";Congo;"Port Phillip Bay, Australia";French;"Gorgona Island, Colombia";"Strait of Gibraltar";Philippines "Collar on chaetiger 1";No;"Ventrally; inconspicuous";No;No;No;No Pigmentation;?;?;"No pigmentation";?;?;"2 eye spots on peristomium" "Shape of nuchal grooves";?;"Faintly J-shaped";"Short and arched";"Boldly curved";?;"Slightly curved" "Posterior cephalic rim";?;Pocket-like;Pocket-like;Pocket-like;Low;Pocket-like "Dorsal glandular band on chaetiger 5";?;Absent;Absent;;?;Absent "Prostomial palpode";?;Prow-like;Spade-like;"Bluntly rounded";?;Spade-like "Border of anal plate";?;"Laterally notched";"Laterally notched";"Complete, no notches";?;"Complete, no notches" "Ventral part of anal rim";?;Smooth;Crenulated;Smooth;?;Smooth "Type locality";"Between Galapagos Islands and Peru";"Middle America Trench";"Darvel Bay";"Kashima Sea";Sweden;"Queen Charlotte Sound, New Zealand" "Collar on chaetiger 1";No;Yes;No;No;No;Yes Pigmentation;"Living worm with dark pigment areas on anterior body";"Without distinct color patterns";?;"Anterior body with brown spots";"Anterior end with black-brown pigmentation, but smaller individuals may be missing";? "Shape of nuchal grooves";"Short, curved";"Short, curved";"Short, curved";"Short, curved in a semicircle";"Short, slightly curved";J-shaped "Posterior cephalic rim";?;Pocket-like;Pocket-like;Low;Pocket-like;Pocket-like "Dorsal glandular band on chaetiger 5";Absent;Absent;?;Absent;"Crescentic glandular band, but not always present";? "Prostomial palpode";"Narrow and pointed";"Broudly rounded";Spade-like;"Broudly rounded";Spade-like;"Broadly spatulate" "Border of anal plate";?;"Laterally notched";"Laterally notched";"Laterally notched";"Laterally notched";"Laterally notched" "Ventral part of anal rim";?;Crenulated;Smooth;Smooth;"Smooth to slightly crenulated";Crenulated