Callionymus boucheti sp. nov. from northern New Ireland Province, Papua New Guinea, is described on the basis of seven specimens collected with dredges and trawls in about 72-193 m depth between northeastern New Hanover and off Kavieng. The new species is characterised within Margaretichthys subgen. nov. by a short head (3.5-3.7 in standard length); eye large (2.5-3.0 in head length); preopercular spine with a short, straight main tip, 5-7 curved serrae on its dorsal margin and a strong antrorse spine at its base, ventral margin smooth, slightly convex; first dorsal fin in male much higher than second dorsal fin, in female as high as second dorsal fin, with 4 spines, first spine with a long filament (male) or without a filament (female); second dorsal-fin distally straight, with 9 unbranched rays (last divided at base); anal fin with 8 unbranched rays (last divided at base); 21-23 pectoral-fin rays; caudal fin elongate, much longer in male than in female, nearly symmetrical (upper rays not much shorter than lower rays); no dark blotch near pectoral-fin base; first dorsal fin in male dark grey, anteriorly with oblique white streaks, posteriorly with white spots, in female also with a black blotch distally near third spine; anal fin distally black, margin of black area straight, black area wider in male than in female; caudal fin in male with 18-22 vertical streaks (in female with 8-11 vertical streaks); pelvic fin pale, without spots. The new species is compared with similar species. A key to the five species of Margaretichthys subgen. nov. is presented.