A new laomediid genus, Strianassa gen. nov., is established to accommodate a new eastern Pacific species of mud-shrimp, Strianassa lerayi sp. nov. The holotype and single specimen of the new species was collected on a shallow subtidal flat at Isla Afuerita, Canales de Afuera, Coiba Archipelago, Panama. Strianassa gen. nov. appears to be most closely related to Axianassa Schmitt, 1924 and Heteroaxianassa Sakai, 2016, differing from both of them by the dorsal surface of the rostrum armed with teeth; the third maxilliped with an exopod and a set of setobranchs; and the epipodal complex of the fourth pereiopod including a small podobranch. In addition, Axianassa ngochoae Anker, 2010 and Heteroaxianassa heardi (Anker, 2011) are recorded for the first time from New Caledonia and Papua New Guinea, respectively, representing minor extensions of their previously known distributional ranges. The validity of Heteroaxianassa is discussed.