Callichirus garthi is a valid species, distinct from C-seilacheri (Decapoda: Axiidea: Callianassidae)

Callichirus garthi from the southeastern Pacific has long been considered as a junior synonym of Callichirus seilacheri from the eastern tropical Pacific. The present study is based on a detailed comparison between both taxa collected along the coast of Chile and the Pacific coast of Central America, including type material of C. garthi and topotypic material of C. garthi and C. seilacheri. This reveals that C. garthi is a valid species, with a suite of morphological features that allow it to be separated from C. seilacheri. Callichirus garthi can primarily be distinguished from C. seilacheri by closely set eyestalks; the proximal margin of the terminal antennular segment exceeding the proximal margin of the last antennal segment with the dorsal margins of both the basal and intermediate antennular segment setose; the merus of the larger cheliped armed with a rough semicircular lobe over the anterior ventral margin and the ischium curved downwards without ornamentation on the ventral margin. On the basis of the present study, we therefore resurrect C. garthi as a valid species for the Chilean and Peruvian populations.http://zoobank.org/urn:lsid:zoobank.org:pub:6FB68C22-5C87-4331-8FCA-CC8994034F3C