Synalpheus barahonensis Armstrong, 1949 (Figs. 5, 6)

Material examined: Pernambuco — Continental Shelf off Recife: 2 M, 27.ii.2018, 8°13′33.0′′S 34°37′40.3′′W, 50.6 m depth, DZ / UFRGS 7066 (genetic voucher, GenBank access PV273119) ; 1 F, same data as DZ/ UFRGS 7066, in sponge, MOUFPE 21870 .

Description: Armstrong (1949).

Distribution: Dominican Republic, Panama, Brazil (Pernambuco) (Armstrong, 1949; Duffy 1992; this study).

Ecology: In association with the coral Agaricia agaricites Linnaeus, 1758, and in coral rubble (Armstrong, 1949; Duffy 1992); 50.6 m (Dardeau 1984; De Grave & Anker 2017; this study). Sampled at continental shelf off Recife (DZ/UFRGS 7066; MOUFPE 21870) in association with unidentified sponges.

Remarks: Synalpheus barahonensis is characterized by the presence of four articles in the carpus of the second pair of pereiopods (Fig. 5F), the basicerite unarmed dorsally, and a ventrolateral spine almost equal in length to the distolateral tooth of the scaphocerite (Fig. 5A; Armstrong, 1949, Fig. 7). Additional characters include the tip of the ultimate article of the third maxilliped bearing a series of setae (Fig. 6D) [vs. a set of spiniform setae, as in most Synalpheus species (Ríos & Duffy, 2007; Anker et al. 2012)], and the second to fifth pleurae of males tapering to a sharp point ventrally (Armstrong, 1949; Dardeau 1984). The species is considered rare (De Grave & Anker 2017) and remains poorly understood in terms of biological aspects. This study represents the first record of S. barahonensis in the southwestern Atlantic, and provides the initial data on its depth range (50.6 m), and offers the first 16S gene sequence information for the species.