Synalpheus williamsi Ríos & Duffy, 1999

Hultgren, Kristin M., Iii, Kenneth S Macdonald & Duffy, Emmett, 2011, Sponge-dwelling snapping shrimps (Alpheidae: Synalpheus) of Barbados, West Indies, with a description of a new eusocial species, Zootaxa 2834, pp. 1-16 : 14

Synalpheus williamsi Ríos & Duffy, 1999

Material examined. Barbados: 1 non-ovigerous individual, 1 ovigerous female ( VIMS 08BR7501–2), Cement Factory, from Hymeniacidon caerulea . 1 ovigerous female ( VIMS 08BR1412), Spawnee Reef, host unknown (in rubble with H. caerulea ). 5 non-ovigerous individuals, 2 ovigerous females ( VIMS 08BR502–3, 08BR1101, 08BR1103, 08BR1301, 08BR2401), Spawnee Reef, from H. caerulea . 1 non-ovigerous individual ( VIMS 08BR1702), Spawnee Reef, host unknown (in rubble with H. caerulea ). Largest ovigerous female, CL 3.44 mm, largest non-ovigerous individual, CL 2.85 mm.

Color. The body color of S. williamsi ranged from almost colorless to dull orange, with distal portion of the major chela brilliant orange; ovaries were green, embryos bright orange-yellow.

Hosts and ecology. In Barbados, S. williamsi appears to be a specialist in the sponge Hymeniacidon caerulea , as is the case in Belize and Jamaica (Macdonald et al. 2006; Ríos & Duffy 2007; Macdonald et al. 2009). Although some individuals were found in loose rubble or on the surface of other sponges embedded in rubble, the rubble always contained H. caerulea .

Distribution. Jamaica ( Macdonald et al. 2009); Curaçao (Hultgren et al. 2010); Belize (Macdonald et al. 2006; Ríos & Duffy 2007); Barbados (this study).

Remarks. Synalpheus williamsi can be distinguished from other species of Synalpheus inhabiting the sponge Hymeniacidon caerulea by the number of spines on the uropod (3–6 fixed marginal teeth anterior to the moveable spine, vs. 1 fixed tooth in S. thele ) or the relative length of the basicerite and scaphocerite spines (basicerite <75% length of scaphocerite in S. williamsi , basicerite>75% length of scaphocerite in S. ul).