SPENCE, H.R.*; KNOWLTON, R.E.; MERCHANT, H.C.; Univ. of Massachusetts; George Washington Univ.; George Washington Univ.: A comparison of cryptic species of Alpheus (snapping shrimp) from North Carolina and Florida

Differentiating cryptic species of snapping shrimp (Alpheidae), despite their ubiquity and acoustic fame, is fraught with misidentifications and ambiguity. Much of this confusion is due to previous reliance on preserved specimens for morphological descriptions, and consequent omission of color and other information lost through preservation. In this research, live shrimp were studied to determine any differing developmental, behavioral, ecological and further morphological features that could be used to identify species and provide insight into their ecological roles. The two principal species examined were Alpheus heterochaelis Say, collected from Beaufort, North Carolina, and Alpheus angulosus McClure, collected from Jacksonville, Florida. The main new morphological difference found between A. heterochaelis and A. angulosus was color and length of the (second) antennal flagellum. The extended pattern of larval development, more typical of alpheids, was demonstrated by A. angulosus, in contrast to the abbreviated development of A. heterochaelis. Snapping frequency was not found to differ between the two populations. Sheltering behavior differed between species, with A. angulosus (from Florida) found under oyster shells more often than A. heterochaelis (from North Carolina). Paired interactive behavior experiments indicated that females spent more time than males occupying the shelter, regardless of species; in female-female pairings of same sized individuals, A. angulosus exhibited dominance over A. heterochaelis. The close morphological similarities of these two alpheid species, as well as A. estuariensis and others, underlines the importance of examining live animals to identify and differentiate them.