This paper provides new information about five species of Aporcelaimellus sensu lato from Sri Lanka (formerly Ceylon) studied by Loos in two contributions published in 1945 and 1949, and whose corresponding material is deposited in part at the University of California (Riverside). Aporcelaimellus insignis is re-described on the basis of the type material. Aporcelaimellus loosi sp. n. is described on the basis of two females and characterised by its body length of 1.52-1.71 mm, lip region offset by constriction and 15.015.5 μ m in diam., odontostyle 18.5-19.0 μ m long and with aperture occupying about two-thirds its length, neck 450-467 μ m long, pharyngeal expansion 234-246 μ m long or occupying 52-53% of total neck length, uterus short and simple, V = 55-56, female tail short and rounded (23 μm, c = 67-74, c = 0.6), and male unknown. One female of A. tropicus perfectly fits those forming part of the type population. Aporcelaimellus mamillatus is described in detail and transferred to the genus Aporcelinus. One female of Makatinus minor is also described and compared with type material of this species. Measurements and illustrations, including line drawings and/or LM pictures, are given for the five species.