Comparison of type material of Trichodorus aerequalis Allen, 1957 and of T. sparsus Szczygiel, 1968 showed that these species can be distinguished by the spicules being setose in the latter and smooth in the former species, and by the shape of the male tail. The difference in arrangement of the ventral cervical pores in the male, which is suggested by the original descriptions, is non-existent. No clear-cut differences were found between females. Variation in these two species appears to be greater than in other Trichodorus species. A population from Plymouth, South England, shows aberrant characters: smooth, almost straight spicules; females with only one pair of lateral cuticular pores. This population is considered to represent a separate species, here described as T. hooperi.