The small waterstriders of the subfamily Trepobatinae have radiated extensively on New Guinea and surrounding archipelagos. The present contribution is the fifth in a series of reports dealing with this endemic fauna, and presents taxonomic and distributional addenda to our previous tribal level treatments. The following new species are described: Ciliometra setosa from southern Papua New Guinea, Ciliometra waigeo from Waigeo and Batanta Islands, Ciliometra minajerwi from southern Irian Jaya, Stygiobates iweka from southern Irian Jaya, Stygiobates mubi from southern Papua New Guinea, Stygiobates rajana from Waigeo and Gam Islands, Calyptobates kopi from southern Irian Jaya, and Calyptobates kamoro from southern Irian Jaya. The previously unknown male of Iobates somare Polhemus & Polhemus is also described, and new distribution records are provided for the following taxa based on recent collections in northern New Guinea and the Raja Ampat Islands: Iobates affinis (Esaki), Metrobatopsis flavonotatus Esaki, Stygiobates iriana Polhemus & Polhemus, Pseudohalobates inobonto Polhemus & Polhemus, Stenobates australicus Polhemus & Polhemus, Stenobates fakfak Polhemus & Polhemus, Stenobates kamojo Polhemus & Polhemus and Rheumatometroides sele Polhemus & Polhemus. New distribution records are also provided for the following species occurring outside the New Guinea region, based on recent collections in Southeast Asia: Calyptobates samarinda Polhemus & Polhemus from Sumba, and Naboandelus signatus Distant from southern Vietnam. Revised keys are presented for the New Guinea species of Ciliometra, Stygiobates, Iobates and Cryptobates, accompanied by updated distribution maps and illustrations of key characters.