Approximately 8,900 species of the staphylinid beetle subfamily Pselaphinae have been described, based on adults, but the larvae of only 18 species and 14 genera have been described in sufficient detail for systematic study. The larva of Pselaphophus atriventris (Westwood) (Staphylinidae: Pselaphinae: Pselaphini) is described herein based on a series collected in a pasture habitat in New Zealand. Larvae are distinguished from other described larvae of pselaphines based on the following combination of characters: antennal segment two bearing two trifid setiform sensoria and labrum with irregularly arranged short spines and setiferous tubercles. It is most similar to the larva of Pselaphus heisei Herbst, sharing the following characters: antenna with two subapical branched sensoria, femora tuberculate, and tibiae with ventral row of minute teeth in proximal one third. P. atriventris is introduced to New Zealand and may be widespread in the country in open habitats. Seasonal data indicate that the species is univoltine. Larvae were found during late September–November (early summer), whereas adults are found year-round, but they were most abundant June–December. A list of the described immature stages of Pselaphinae is included.