Two new species of spionids from the genera Apoprionospio Foster, 1969 and Prionospio Malmgren, 1867 (Annelida: Spionidae) from the Colombian Caribbean.

Two species of genera Apoprionospio and Prionospio are described from the Colombian Caribbean. Apoprionospio sanguarensis sp. nov. and Prionospio gabriellae sp. nov. are new to science. Apoprionospio sanguarensis sp. nov. is distinguished from the three previously described Apoprionospio species by having the smallest body size, triangular prostomium, three pairs of eyes, the branchial pairs 1-3 are cirriform, wrinkled, the anterior notochaetae arranged from chaetiger 2 onwards arranged in three rows, and all hooded hooks lack secondary hoods. Prionospio gabriellae sp. nov. is distinguished from all Prionospio species with five branchial pairs by having dorsal crests across the dorsum on chaetigers 16-25. Closely related species are P. heterobranchia Moore, 1907 and P. caribensis Delgado-Blas, 2014 and Prionospio gabriellae sp. nov. differs from both species in that it has a small medial peak in the dorsal region of prostomium, the first neuropodial lamellae is very small, the shaped of branchial pairs 2 and 3 are cirriform, neuropodial postchaetal lamellae on chaetiger 2 is square, all chaetae of chaetiger 1 are arranged in a row. We propose raising the status of Apoprionospio dayi japonica Imajima, 1989 to the species level as A. japonica Imajima, 1989. A key and a table detailing the most relevant characters of Apoprionospio species and a key to all species of Prionospio with five pairs of branchiae are provided.