Microcotyle rubrum is a species of monogenean, parasitic on the gills of a marine fish.

It was described from the gills of the tigertooth croaker Otolithes ruber (Sciaenidae) from Karachi coast off Pakistan.

[1] Microcotyle rubrum has the general morphology of all species of Microcotyle, with a symmetrical lanceolate body, comprising an anterior part which contains most organs and a posterior part called the haptor.

The reproductive organs include an anterior tubular and fork-like genital atrium, armed with numerous spines, a medio-dorsal vagina, a single long and tubular ovary and 56 testes which are posterior to the ovary and scattered in middle region.

[1] The tigertooth croaker Otolithes ruber (Sciaenidae) is the type-host and only recorded host.