Eight new species of ground beetles of the lebiine genus Dolichoctis Schmidt-Goebel, 1846, from New Guinea and the island of Seram are described: D. bisetosiceps from Goodenough Island off the southeast coast of Papua New Guinea; D. ivimkae, D. ocularis, D. latibasis, D. aterrima, and D. cylindripennis from eastern and northern Papua New Guinea; D. lackneri from central Papua Indonesia; and D. mehli from Seram. All species belong to the subgenus Spinidolichoctis Baehr, 1999, which is characterized by the dentate or spinose apex of the elytra and the absence of the anterior marginal seta of the pronotum. This subgenus mainly occurs in the Papuan Region with a few species recorded from the southern Oriental Region and from northeastern Australia. For the new species, differential diagnoses are provided that distinguish them from related or similarly shaped species. A complete new key is provided for the subgenus Spinidolichoctis. Some thoughts on evolution and biogeography of the genus Dolichoctis in New Guinea are outlined.