Four closely related taxa in the genus Bostrychia (B. tenella, B. binderi, B. binderi f. terrestris and B. flagellifera) are investigated and re-assessed using multivariate analyses. Continuous variation was found in all but one of the characters measured and the complex is resolved as a single species, B. tenella (J. V. Lamouroux) J. Agardh, with a new subspecies flagellifera (Post) R. J. King et Puttock comb. et stat. nov.