Salmoneus karenae sp. nov.

(Figs. 1–3)

Type material. Holotype: non-ovigerous specimen (cl 5.7 mm), USNM 1720638, USA, Texas, Flower Garden Banks National Marine Sanctuary, East Flower Garden Bank, 27.898 -93.599, II2402 cruise, recovered debris (TABS buoy), depth: 84.9 m, leg. U.S. Navy saturation diver team and UHD-82 ROV + M/V Island Intervention crew, 30.07.2024 [SIMDBC _ 01084].

Description. Carapace conspicuously domed, glabrous, without post-rostral tubercle (Fig. 1A). Rostrum moderately long, reaching distal margin of first article of antennular peduncle, broadly triangular in dorsal view, as long as wide at base, with acute tip, without mid-dorsal carina; lateral margins shallowly concave; ventral margin with small subdistal tooth (Fig. 1A–C). Orbital teeth well developed, subacute, demarcating ventral angle of postorbital concavity; anterolateral suture present; pterygostomial angle broadly rounded; cardiac notch rather small (Fig. 1A–C).

Pleon glabrous; pleura of first to fourth pleonites rounded posteroventrally; fifth pleuron posteroventrally produced as subacute tooth; sixth pleonite with trace of suture posteroventrally and acutely triangular projection flanking base of telson; preanal plate rounded (Fig. 1D).

Telson subrectangular, gently tapering distally, about 2.6 times as long as proximal width; dorsal surface with two pairs of short but stout spiniform setae located at about 0.5 and 0.7–0.8 telson length, respectively; posterior margin with shallow median notch furnished with three short plumose setae and two pairs of stout spiniform setae, lateral much longer than mesial (Fig. 1E).

Eyes completely exposed in dorsal and lateral views; cornea somewhat reduced, terminal, at least some ommatidia dissociated; anteromesial margin not protruding, unarmed (Fig. 1B, C). Each epistomial sclerite with short, stout, subacute process.

Antennular peduncle relatively stout; dorsally visible portion of first article somewhat longer than broad; stylocerite with subacute tip, latter by far surpassing distal margin of first article and almost reaching mid-length of second article; second article stout, slightly wider than long; third article shorter than second article; lateral antennular flagellum biramous, fused portion composed of three subdivisions, shorter ramus well developed, with at least seven groups of aesthetascs (Fig. 1B, C). Antenna with basicerite moderately stout, its distoventral margin armed with subacute tooth; scaphocerite ovate, reaching or slightly overreaching distal end of antennular peduncle, distolateral tooth not reaching beyond broadly rounded, somewhat protruding distal margin of blade, lateral margin straight; carpocerite short, not reaching mid-length of scaphocerite; flagellum slightly thickened proximally (Fig. 1B, C).

Mouthparts as illustrated (Fig. 1F–K). Mandible with distal margin of incisor process furnished with five larger teeth ventrally and 10 or so smaller teeth dorsally (Fig. 1F, G). Maxillule and maxilla typical for genus (Fig. 1H, I). First maxilliped with endopod (palp) subdivided (Fig. 1J). Second maxilliped typical for genus, with large epipod (Fig. 1K). Third maxilliped slender, pediform; coxa with strap-like epipod and squarish-rounded lateral plate; antepenultimate article slender, about eight times as long as maximal width; penultimate article slightly less than 0.4 length of antepenultimate article, slightly widening distally; ultimate article about 2.5 times as long as penultimate article, apex armed with four spiniform setae; exopod slender, reaching distal margin of antepenultimate article; arthrobranch well developed, multilamellate (Fig. 1L, M).

Chelipeds (= first pereiopods) very unequal in size and asymmetrical in shape (Fig. 2A–G; see also Fig. 3). Major cheliped robust, carried flexed under body when not in use; ischium approximately 3.2 times as long as maximal width, armed with three spiniform setae on ventrolateral surface; merus about 1.5 times as long as ischium, slightly swollen, ventromesial margin slightly convex, ventrolateral surface flattened; carpus short, cup-shaped, with blunt squarish lobe distomesially; chela moderately swollen, as long as basis, ischium and merus lengths combined, palm 2.2 times as long as wide, with deep channel proximally, ventral surface depressed; fingers about 0.8 times as long as palm, not particularly twisted, with crossing fingertips, not gaping when closed, cutting edge of pollex and dactylus armed with 13–14 small rounded to subtriangular teeth of similar size (Fig. 2A–D). Minor cheliped much smaller and weaker than major cheliped, rather stout; ischium about 3.5 times as long as wide, armed with three spiniform setae on ventrodistal surface; merus somewhat longer than ischium; carpus much shorter than merus, cup-shaped, widening distally; chela with palm noticeably longer than fingers; cutting edges of fingers armed with minute, widely spaced teeth: five on pollex (evenly distributed, except for proximal fourth) and two on dactylus (in distal third) (Fig. 2E–G).

Second pereiopod slender; ischium about six times as long as wide, armed with three stout spiniform setae on ventrolateral surface; merus slender, 1.5 times as long as ischium; carpus longer than merus, with five subarticles, proximal by far longest, subequal to combined length of others; chela much longer than distal-most carpal subarticle, fingers subequal in length, slightly longer than palm, with tufts of simple setae (Fig. 2H).

Third pereiopod slender; ischium about four times as long as wide, with two spiniform setae on ventrolateral surface; merus about twice as long as ischium, about eight times as long as wide; carpus noticeably more slender than merus, about 0.8 length of merus, with stiff seta on distoventral margin; propodus subequal to carpus in length, ventral margin armed with four unevenly distributed spiniform setae, distoventral margin with one pair of long spiniform setae flanking dactylar base; dactylus simple, moderately slender, slightly curved, about 0.4 times as long as propodus (Fig. 2I, J). Fourth pereiopod very similar to third; ischium with one spiniform seta on ventrolateral surface; ventral margin of propodus armed with three spiniform setae, distoventral margin with one pair of long spiniform setae flanking dactylar base (Fig. 2K). Fifth pereiopod longer than third and fourth; ischium unarmed; merus and carpus subequal in length, merus about nine times as long as wide; propodus longer than carpus, with four short spiniform setae on ventromesial margin, one pair of longer spiniform setae on distoventral margin flanking dactylar base, and six transverse-oblique rows of grooming microserrulate setae, latter distally increasing in length, in distal half; dactylus about 0.35 length of propodus, similar to that of third or fourth pereiopod (Fig. 2L, M).

Second pleopod with appendix masculina exceeding appendix interna by fourth of its length, furnished with spiniform setae on apex and along margins (Fig. 2N, O). Uropod with lateral lobe of protopod ending in small tooth; exopod ovate, distolateral margin with small triangular tooth and slender spiniform seta, diaeresis complete, with blunt lobe adjacent to spiniform seta; endopod equal in length to exopod, narrowly ovate (Fig. 1N).

Gill/exopod formula typical for genus.

Colour in life. Body and appendages uniform pale orange; cornea brownish (Fig. 3).

Etymology. The new species is named for our friend and colleague, Karen Reed (Museum Support Center, Smithsonian Institution), for her excellent management of the USNM invertebrate collection and continuous support to visiting taxonomists (including the first and second authors of the present study).

Distribution. Western Atlantic: presently known only from the type locality, East Flower Garden Bank, off Texas, USA.

Remarks. Salmoneus karenae sp. nov. is the second-known species of Salmoneus with the eyes completely exposed dorsally (Fig. 1B), a very untypical condition in the family Alpheidae (Anker et al. 2006).Within Salmoneus, only S. hispaniolensis Anker, 2010 from the Caribbean Sea has similarly exposed, unprotected eyes (cf. Anker 2010: fig. 1a), whereas several other species present partly exposed eyes, in which a large portion of the cornea is exposed dorsally with most of the remaining eyestalk being covered by the base of the orbital teeth and rostrum, as seen, for example, in S. cavicolus Felder & Manning, 1986, S. pusillus Anker & Marin, 2006, S. alpheophilus Anker & Marin, 2006 (species complex) and S. rostratus Barnard, 1962 (species complex) (cf. Felder & Manning 1986: fig. 4b; Anker & Marin 2006: figs. 10b, 12b, 14a; see also Ashrafi et al. 2025). The conspicuously domed carapace is another diagnostic feature of S. karenae sp. nov., however, not being exclusive to the new species as a dorsally inflated carapace is also characteristic for S. babai Miyake & Miya, 1966 and the peculiar S. pinguis Komai & Anker, 2012 (cf. Miyake & Miya 1966: fig. 1B; Komai & Anker 2012: fig. 1).

Based on its overall morphology, S. karenae sp. nov. seems to be most closely related to S. hispaniolensis, a rare species presently known only from the holotype collected in very shallow water (less than 2 m) on the southern coast of the Dominican Republic (Anker 2010). However, S. karenae sp. nov. differs from S. hispaniolensis by (1) the strongly domed carapace, which is not dorsally inflated in S. hispaniolensis; (2) the much stouter major and minor cheliped, with proportional differences in the merus and carpus being particularly obvious; (3) the much longer accessory ramus of the lateral antennular flagellum; (4) the presence of a shallow notch on the posterior margin of the telson, which is straight in S. hispaniolensis; and (5) the pale orange colour of the body and appendages, which are whitish with a pale tinge in S. hispaniolensis (cf. Figs. 1A, C, E, 2A–G, 3; Anker 2010: figs. 1, 2).

All other species of Salmoneus present in the western Atlantic seem to be more distantly related to S. karenae sp. nov., differing from the new species by the dorsally not inflated carapace and at least partly (in most cases completely) concealed eyes. This includes the only western Atlantic species with the dorsally partly exposed eyes, S. cavicolus, which further differs from S. karenae sp. nov. by the much longer rostrum, slenderer antennular peduncles, several features on the chelipeds, as well as whitish (not pale orange) colour (cf. Felder & Manning 1986; Anker & Scioli 2025). The somewhat enigmatic western Atlantic taxon originally described as S. armatus Anker, 2010 and later tentatively transferred to Triacanthoneus Anker, 2010 (Anker 2020b) also has partly exposed eyes. This species was recently shown to represent a genetically distinct salmoneoid lineage, only distantly related to two species of Triacanthoneus (Ashrafi et al. 2025); it can be easily separated from S. karenae sp. nov. by the dorsally not inflated carapace and the presence of a single mid-dorsal tooth in epigastric position.

To enable a fast genetic identification of the new species, a barcoding segment of the COI gene sequence is deposited in GenBank (see below). Since the molecular analysis of Ashrafi et al. (2025) was based on four genes, the position of S. karenae sp. nov. within the salmoneoid clade cannot be resolved with a single, fast evolving (= rapidly saturating), mitochondrial marker (COI). Therefore, a more exhaustive molecular analysis of S. karenae sp. nov., i.e., with additional genes (which is beyond the scope of the present study), will be necessary, optimally with inclusion of S. hispaniolensis and Triacanthoneus, in order to better define the phylogenetic position and taxonomic placement of S. karenae sp. nov.

GenBank accession number: PX452307 [COI].