Two species of parasitic copepods are described from the common cloacal cavity of the algal-bearing (photosymbiotic) compound ascidian, Didemnum molle (Herdman), occurring in Okinawa, Japan. They are a new form of Lichomolgidae (Poecilostomatoida), Lobomolgus okinawaensis new genus, new species, and a new species of Notodelphyidae (Cyclopoida), Doroixys capillosus. The new genus Lobomolgus is unique among the lichomolgid genera in having in the female a pair of long, dorsolateral processes on each of the last two somites of the metasome. It is also characteristic in having in the female a highly reduced endopod (a small lobe tipped with one seta) on leg 4 and bearing an armature of III, 5 (not II,I,5) on the last exopodal segment of leg 4. Doroixys capillosus, new species, can be distinguished from its congeners by the possession of: 1) a 6-segmented antennule, 2) a mandibular endopod with 5 setae, 3) a maxilliped tipped with 6 setae, 4) a 2-segmented endopod on leg 3, and 5) a cephalosome with rounded posterolateral corners (due to the lack of processes).