Key to all known species of Metachromadora (Metachromadoroides)

1 Male without ventromedian precloacal supplements ....................................................2

1’ Male with ventromedian precloacal supplements ........................................................ 3

2 Anterior non striated end equal to 2 amphid lengths ...................................................... ................................................................ M. (M.) vulgaris Timm 1961 (Bay of Bengal)

2’ Anterior non striated end equal to 1 amphid length ..... M. (M.) zaixsi sp. n. (Patagonia)

3 Cephalic setae absent .......................... M. (M.) complexa Timm 1961 (Bay of Bengal)

3’ Cephalic setae present. .................. M. (M.) pulvinata Wieser & Hopper 1967 (Florida) .................................................................... M. (M.) remanei Gerlach 1951 (North Sea)