Two new species of spionids are described from the Caribbean Sea, Malacoceros cariacoensis n. sp. from Venezuela and Rhynchospio harrisae n. sp. from Guana in the Virgin Islands, British Virgin Island. Malacoceros cariacoensis n. sp. can be differentiated by the shape of the prostomium, which has two short frontal horns and the posterior portion laterally prolonged into a faintly demarcated, double-looped nuchal organ, extending to the base of setiger 2, a reduction in the size of setiger 1, the absence of body pigmentation, and the number of apical teeth on the hooded hooks. Rhynchospio harrisae n. sp. differs from other species of the genus in that the peristomium is moderately developed with low lateral wings, and the anterior notopodial setae are arranged in two rows with a superior tuft of capillaries. A key to Malacoceros species worldwide is provided.