Integrative taxonomy reveals hidden species within the western Atlantic Callichirus major s. l. (Decapoda, Axiidea, Callichiridae)

Abstract

The ghost shrimp Callichirus major (Say, 1818) is widely distributed in the Atlantic Ocean from [~]23{degrees}N to [~]26{degrees}S, and has also been reported from the tropical eastern Pacific. Evidence has been accumulating over many years that C. major is actually a species complex. Yet, the name C. major is widely and frequently used in many kinds of research. The current lack of clarity in the use of the name C. major has resulted in nomenclatural instability, but also in unreliability and miscommunication of the available ecological and distributional information. Existing morphological and molecular evidence is reviewed and new evidence presented for the specimens from the southern localities previously assigned to C. major s. l. actually being a new species. That new species is herein described based on morphological and molecular evidence. Additionally, a neotype is selected for C. major in order to settle the defining characters of C. major s. str. and, therefore, ensuring the correct use of this name.