A new eusocial species of snapping shrimp, Synalpheus idelisae n. sp. (Decapoda, Alpheidae), with a review of caste differentiation in eusocial shrimp

(Decapoda, Alpheidae), with a review of caste differentiation in eusocial shrimp. Zoosystema 48 (20): 623-638, DOI: 10.5252/zoosystema2026v48a20 ABSTRACT Snapping shrimp in the genus Synalpheus Spence Bate, 1888 are the only marine organisms known to exhibit eusociality, a social structure characterized by colony-living and a reproductive division of labor.

Here we describe a new species of eusocial sponge-dwelling snapping shrimp, Synalpheus idelisae n. sp., based on material collected from Puerto Rico and the Dominican Republic. Phylogenetic analyses (based on mitochondrial 16S and COI loci) and morphological traits place S. idelisae n. sp. within the Synalpheus rathbunae CoutiÈre, 1909 species complex, which includes several other eusocial species. Synalpheus idelisae n. sp. can be distinguished from its close relatives by the shape of the anterodorsal spine on the major chela, the morphology of the pleura, and the number of setal combs on the fifth pereopod.