Abstract
Calanopia tulina sp. nov., a new pontellid copepod, is described from plankton samples collected in Saudi Arabian waters of the Red Sea. The female of the new species differs from other congeners in having the genital operculum located posteroventrally on the genital compound somite and by a slightly asymmetrical leg 5, in which the right leg is slightly shorter than the left one. The male is distinguished by: (1) the presence of a distinct notch on the medial margin of the right prosomal corner; (2) the structure of leg 5, in which the second exopodal segment of the left leg has one medially directed spine and two large laterally directed and curved serrated spines distally; and (3) the first exopodal segment of the right leg has a very small rounded-tip thumb located at the mid-length. The new species is most similar to Calanopia media described from the Red Sea. The presence of the new species in night collection may be due to the diel vertical migration behavior that is known for some species of this genus.