Ophiothrix synoecina new species (Echinodermata: Ophiuroidea) from the Caribbean coast of Colombia

A new species, Ophiothrix synoecina, is described and figured. O. synoecina differs from its Caribbean congeners in spination of disk and arms and in its color pattern. The disk of O. synoecina bears short, stout stumps, the arm spines are flattened and uniform denticulated. Some individuals are dark blue-grey, others have banded arms. O. synoecina is an obligate associate of the regular sea urchin Echinometra lucunter (L.) in the area of Santa Marta on the Caribbean coast of Colombia. The rock-boring echinometrid E. lucunter inhabits heavily exposed areas of rocky shores. O. synoecina lives in the boreholes excavated by the sea urchin, spending its life under the echinoid.