Synalpheus belizensis Anker & Tóth, 2008 (Figs. 7, 8)

Material examined: Pernambuco — Continental Shelf off Recife: 1 F, 27.ii.2018, 8°13′33.0′′S 34°37′40.3′′W, 50.6 m depth, in sponge, DZ / UFRGS 7051 ; Fernando de Noronha: 1 F, Ponta da Sapata, 30.vi.2022, 03º51.892′S 32º27.965’W, 11.0 m depth, in sponge, DZ / UFRGS 7041 .

Description: Anker & Tóth (2008).

Distribution: Belize, Jamaica, Curaçao, Barbados and Brazil (Fernando de Noronha and Pernambuco) (Anker & Tóth, 2008; Macdonald et al. 2009; Hultgren et al. 2010, 2011; this study).

Ecology: Often in association with sponges (e.g., Xestospongia sp.) or coral rubble with sponges (Anker & Tóth, 2008; Hultgren et al. 2010); records of co-occurrence in the same host sponge with individuals of the S. paraneptunus complex ( S. bocas Anker & Tóth, 2008, and S. duffyi Anker & Tóth, 2008) (Macdonald et al. 2009); in heterosexual pairs; 12– 50.6 m (Anker & Tóth, 2008; this study). The material analyzed (DZ/UFRGS 7041, 7051) was found in unidentified sponges.

Remarks: Synalpheus belizensis belongs to the S. paraneptunus complex, which also includes S. bocas, S. brevidactylus Anker & Tóth, 2008, S. duffyi, S. microneptunus Hultgren, Macdonald & Duffy, 2011, S. maxillispinus, S. paraneptunus, and S. riosi Anker & Tóth, 2008 (Anker & Pachelle 2014). The species is characterized by a rostrum and orbital teeth subequal in length, proximally broadened and tapering distally; the stylocerite surpassing the distal margin of the first antennular segment; the presence of a scaphocerite blade (Fig. 7A); the carpus of the second pereiopod having five articles, the first approximately four times as long as the second (Fig. 7F) (Anker & Tóth, 2008). Additional distinguishing characters include the fixed and movable fingers of the minor chela excavated on the cutting edge, with the dorsal surface of the dactylus with scattered gambarelloid setae (Figs. 7D, E); the distal tip of the third maxilliped bearing a set of spiniform setae (Fig. 8D), and the uropodal exopod armed with a distolateral tooth (Fig. 8C) (Anker & Tóth, 2008; Anker et al. 2012). Anker & Tóth (2008) initially stated that the scaphocerite blade is absent in S. belizensis . However, their figures 12A and B, illustrate its presence, which is also mentioned in other sections of the text. Interestingly, the male paratype of the species differs from the holotype by having longer orbital teeth, by the absence of scaphocerite blade on the left side, but a small blade on the right side and by the slightly longer second antennular segment (Anker & Tóth, 2008). Hultgren et al. (2010) documented additional variations in scaphocerite blade development, ranging from 50% to 80% of the scaphocerite lateral spine’s length. The following variations were observed in our material: one individual (1 F, DZ/UFRGS 7041) has the dactylus of the major chela as long as the fixed finger, and a slightly longer distodorsal spine (Figs. 7B, C) (vs. dactylus of the major chela subequal to fixed finger and a shorter distodorsal spine; see Anker & Tóth, 2008, figs. 11A–C); another individual (1 F, DZ/UFRGS 7051) has slightly longer rostrum and orbital hoods (vs. not produced rostrum and orbital hoods), major chela fingers squared (vs. rounded/pointed major chela fingers), and distodorsal region of the major chela with a very short and rounded tubercle (vs. distodorsal region of the major chela with a sharp and directed anteriorly spine) (see Anker & Tóth, 2008, figs. 12A, B, and 11A–C). These variations were identified by Anker & Tóth (2008) as intraspecific, but further sampling and molecular analyses are necessary to determine the full extent of morphological variability within the species. This study represents the first record of S. belizensis in the southwestern Atlantic and extends its known bathymetric distribution from 12 m (Anker & Tóth, 2008) to 50.6 m.