We describe Alvinocaris komaii, new species, from hydrothermal fields at the Eastern Lau Spreading Center (ELSC). Adults of this species are distinguished in the field from other alvinocaridids at the ELSC by their larger size and orange-white carapace. Additionally, they appear to preferentially inhabit mussel beds composed of Bathymodiolus brevior. Alvinocaris komaii differs from all known species in the genus by a distinctive deep notch mesially on the telson and accessory spinules on the dactyli of the third to fifth pereopods arranged in 2 rows. A suite of morphological characters separates A. komaii from other alvinocaridids. We analyze the degree of morphological variation in A. komaii and discuss affinities of the Pacific species of Alvinocaris. Molecular data from the mitochondrial COI gene is used to compliment this description, and a key to the species of the family Alvinocarididae is included with locality information.