Synalpheus

Synalpheus is a genus of snapping shrimp of the family Alpheidae, presently containing more than 100 species; new ones are described on a regular basis, and the exact number even of described species is disputed.

Zuzalpheus

The genus Zuzalpheus was established for S. gambarelloides, S. brooksi, and their closest relatives, which contain several notably eusocial species. While these do seem to form a clade, it is not fully resolved whether or not they are indeed the sister taxon of all the remaining Synalpheus.

However, a detailed cladistic study of morphological characters found well marked differences between the proposed two genera and concluded that the supposed species groups around S. biunguiculatus/S. coutierei, S. brevicarpus and S. neomeris are neither clearly defined nor, as it seems, monophyletic, while the group separated in Zuzalpheus was clearly distinct in characters of the minor first walking legs (pereiopods), and usually distinct in some others; in all Synalpheus sensu stricto checked to date, the transverse setal comb on the back of the minor first pereopod dactyl is missing, and the carpus is plump (about as wide as it is long or slightly wider) and small (not longer than half the length of the palm).