Populational Evidence Supports a Monogomous Mating System in Five Species of Snapping Shrimps of the Genus (Caridea: Alpheidae).

The objective of this study was to verify if populations of the snapping shrimps , , , and from Pernambuco, northeastern Brazil, are monogamous based on population data. If these species are monogamous, then the populations must exhibit: 1) higher frequency of individuals living in pairs; 2) non-random population distribution, , pairs are found more often than expected by chance alone; 3) males paired with females regardless of their reproductive condition; 4) sexual dimorphism regarding body size and chelipeds weaponry little pronounced among paired individuals and 5) size-assortative pairing. Our samplings were carried out in August 2015, February and August 2016 and February 2017, in the intertidal zone, during low spring tides. We captured a total of 2,276 specimens: 300 of , 393 of , 374 of , 403 of and 806 of . The key population parameters (indicators 1, 2, 3, 4, 5 above) for the four species strongly suggest that all four undergo monogomous mating. Although our frequency distribution demonstrated a higher tendency to find solitary individuals in and , the other studied features agree with the occurrence of monogamy in those populations. Lastly, the sexual differences observed in the chelipeds and the existence of solitary egg-carrying females indicated that monogamy in the five species is not rigid, , heterosexual pairing may not last long, due to possible competition between males for females or refuge.