Two new species of the family Desmodoridae are described from the upper continental slope of New Zealand, Southwest Pacific, and the genera Spirinia, Chromaspirina and Perspiria are revised. Spirinia verecunda sp. nov. is characterised by a short, stout body, cuticle covered in minute, hair-like structures, unispiral amphideal aperture and cryptospiral amphideal fovea, buccal cavity with small dorsal tooth and minute subventral teeth, eight oblong glands surrounding anterior portion of pharynx, large sperm cells, spicules with weak capitulum, and the absence of precloacal supplements. Stygodesmodora confusa sp. nov. is characterised by a relatively short body, spiral amphids with 1.2–1.4 turns, cephalic setae situated at or slightly posterior to mid-level of amphid, and males with four precloacal supplements consisting of short setae on wide bases. Like other species of the genus, S. confusa sp. nov. is characterised by an annulated head region, but in some specimens the cuticle annulations are restricted to the dorsal and ventral sides of the head. S. confusa sp. nov. shows similarities with species of other desmodorid genera (i.e., Echinodesmodora, Bolbonema), but can be differentiated from them by the presence of an annulated head region and amphideal plates. The genera Spirinia, Chromaspirina and Perspiria have very similar morphologies and differ mainly in the size and structure of the buccal cavity (Spirinia vs Chromaspirina) or the shape of the tail and placement of the amphids relative to the cuticle annulations (Spirinia vs Perspiria); their diagnoses are clarified and some nomenclatural changes are proposed to eliminate overlap in the definitions of these genera.