Crassantenna mimorostrata is an aetideid calanoid copepod known after female (3.1-3.3 mm in length) off New Zealand, from bathyal depths, most likely benthopelagic species.
Female. (Description after Bradford (1969b) with modifications). Total length 3.1-3.3 mm. Rostrum present as a very small point. Cephalothorax about 3 times longer than abdomen. Th5 posterior corners upturned backwards. A1 reaching Th3. Re A2 more slender than Ri A2, Re1 A2 with 2 setae, Re2 A2 with 2 setae. Md palp base without setae, Ri1 Md with 1, Ri2 Md with 4 setae. Second and third Mx1 internal lobes with 4 setae each, gnathobase with one of posterior setae rudimentary. Re P1 with external spine on each segment.
The species was found at depth 1234-1697 m and presumed to be benthopelagic (Bradford and Jillett, 1980).
Pacific Ocean: continental slope off north-east of New Zealand (Bradford, 1969b).
Type locality: 34°38'S 174°36'E.
Species absent in the collections of the Zoological Institute, Russian Academy of Sciences, St. Petersburg.