Salmoneus manningi, Anker & Scioli, 2025

Salmoneus manningi sp. nov.

( Figs. 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 , 4a–d View FIGURE 4 )

Salmoneus cavicolus Felder & Manning 1986: 503 View in CoL (part.), figs. 4g –i, 5j, k, 6g [not S. cavicolus Felder & Manning 1986 View in CoL ].

Type material. Holotype: ovig. specimen (cl 8.6 mm), FLMNH UF 68690 , USA, Florida, St. Lucie County, Indian River Lagoon, Fort Pierce , seagrass sandbar off A1 A Causeway, no coordinates, suction pump, leg. D.L. Felder et al., 24.07.1995 . Paratypes: USA, Florida, St. Lucie County, Indian River Lagoon: 1 non-ovig. specimen (cl 5.3 mm), FLMNH UF 68682 , sta. FP-86-1, Fort Pierce , on southern A1A Causeway between Fort Pierce and Fort Pierce Beach, north side of causeway, east of bridge, 27°27.7’N, 80°18.7’W, sandflat separated from causeway by shallow (1.3 m) channel, flat with some seagrass, exposed at low tide, suction pump, leg. R. B. Manning, D.L. Felder & W.D. Lee, 11.08.1986 GoogleMaps ; 1 ovig. specimen (cl 8.8 mm), 1 non-ovig. specimen (cl 7.5 mm), MNHN-IU-2024-1940, sta. FP-86-2, Fort Pierce, southern A1A Causeway between Fort Pierce and Fort Pierce Beach , north side of causeway, east of bridge, 27°27.7’N, 80°18.7’W, sandflat separated from causeway by shallow (1.3 m) channel, flat with some seagrass, exposed at low tide, suction pump, in burrow of Lysiosquilla scabricauda , leg. R. B. Manning, D.L. Felder & W.D. Lee, 11.08.1986 GoogleMaps ; 1 non-ovig. specimen (cl 4.8 mm), FLMNH UF 68683 , sta. FP-86-4, Fort Pierce, southern A1A Causeway between Fort Pierce and Fort Pierce Beach , north side of causeway, east of bridge, 27°27.7’N, 80°18.7’W, sandflat separated from causeway by shallow (1.3 m) channel, flat with some seagrass, exposed at low tide, suction pump, leg. R. B. Manning & D.L. Felder, 12.08.1986 GoogleMaps ; 1 ovig. specimen (cl 8.3 mm), FLMNH UF 68685 , sta. FP-86-7, Fort Pierce, southern A1A Causeway between Fort Pierce and Fort Pierce Beach , north side of causeway, east of bridge, 27°27.7’N, 80°18.7’W, sandflat separated from causeway by shallow (1.3 m) channel, flat with some seagrass, exposed at low tide, suction pump, leg. R. B. Manning, D.L. Felder & W.D. Lee, 14.08.1986 GoogleMaps ; 1 non-ovig. specimen (cl 5.2 mm), FLMNH UF 68686 , sta. FP-86-3, Fort Pierce, southern A1A Causeway between Fort Pierce and Fort Pierce Beach , north side of causeway, east of bridge, 27°27.7’N, 80°18.7’W, sandflat separated from causeway by shallow (1.3 m) channel, flat with some seagrass, exposed at low tide, suction pump, in burrow of L. scabricauda , leg. R. B. Manning & D.L. Felder, 12.08.1986 GoogleMaps ; 1 non-ovig. specimen (cl 5.6 mm), FLMNH UF 68687 , sta. FP-86-3, same collection data as for previous specimen GoogleMaps ; 1 non-ovig. specimen (cl 7.0 mm), FLMNH UF 68688 , Fort Pierce , flat south of A1A Causeway bridge marina, no coordinates, suction pump, in stomatopod burrow, leg. D.L. Felder, 22.07.1993 ; 2 non-ovig. specimens (cl 4.8, 6.9 mm), FLMNH UF 68684 , sta. FP-87-11, northern side of Fort Pierce Inlet, Dynamite Point , 27°28.3’N, 80°17.8’W, suction pump, leg. D.L. Felder & W.D. Lee, 14.08.1987 GoogleMaps ; 1 non-ovig. specimen (cl 5.7 mm), USNM 1740903 About USNM , sta. FP-89-1, Fort Pierce Inlet, northern side of Causeway Island , east of bridge, 27°27.7’N, 80°18.7’W, sandflat separated by shallow (1.3 m) channel, flat with some seagrass, exposed at low tide, suction pump, leg. R. B. Manning & R. Brown, 08.08.1989 GoogleMaps ; 1 ovig. specimen (cl 8.6 mm), MNHN-IU-2024-1941, Fort Pierce , south of A1 A Causeway bridge, flat, public marina, suction pump, leg. D.L. Felder, 25.07.2003 .

Additional material examined. USA, Florida, St. Lucie County, Indian River Lagoon. 1 non-ovig. specimen (cl 6.3 mm), FLMNH UF 68689 , “Causeway Inlet”, no coordinates, suction pump, leg. D.L. Felder, 04.06.1993; 1 non-ovig. specimen (cl 5.3 mm), USNM 228055 About USNM , sta. FP-85-4, southern side of Fort Pierce Inlet , north of A1 A Causeway between Fort Pierce and Fort Pierce Beach, east of bridge over Intracoastal Waterway, no coordinates, small sandflat exposed at low tide, separated from causeway by narrow channel (1–2 m deep), suction pump, leg. R. B. Manning & D.L. Felder, 23.07.1985 [larger “male” paratype of S. cavicolus ( Fig. 3 View FIGURE 3 , see below)] .

Description. Relatively large-sized species of Salmoneus . Carapace ( Figs. 1a, b View FIGURE 1 , 3a, b View FIGURE 3 ) smooth, glabrous, without setae; antero-lateral suture present; pterygostomial angle broadly rounded; cardiac notch deep. Rostrum ( Figs. 1a, b View FIGURE 1 , 3a–c View FIGURE 3 ) elongate triangular in dorsal view, pointing straight-forward or slightly descendent in lateral view, as long as wide at base (measured between orbital notches) to slightly longer than wide (at most 1.3 times as long as wide); tip acute, reaching or almost reaching mid-length of second article of antennular peduncle; lateral margins broadly concave; dorsal rostral carina and post-rostral tubercle absent; ventral carina unarmed or armed with minute tooth subdistally. Orbital teeth ( Figs. 1a, b View FIGURE 1 , 3a–c View FIGURE 3 ) small, sharp, less than 0.2 of rostrum length, subtriangular, extending slightly beyond eyes.

Eyes ( Figs. 1a, b View FIGURE 1 , 3a–c, f View FIGURE 3 ) largely concealed dorsally, partly exposed laterally; cornea distinctly reduced, with pale pigmentation; anterodorsal margin with small blunt tubercle. Epistomial sclerites each armed with strong acute process ( Fig. 3g View FIGURE 3 ).

Pleon ( Figs. 1c View FIGURE 1 , 3d View FIGURE 3 ) glabrous, without setae; pleura of first to third pleonite rounded antero- and posteroventrally; fourth and fifth subacutely or acutely produced posteroventrally, each forming small tooth; sixth pleonite not particularly elongate, with acute subtriangular projection flanking telson on posterior margin and small suture near posteroventral angle; preanal plate broadly rounded, depressed medially.

Telson ( Figs. 1d, e View FIGURE 1 , 3e View FIGURE 3 ) moderately slender, subrectangular, tapering distally, about 2.6–2.8 times as long as proximal width; dorsal surface armed with two pairs of small spiniform setae situated at about 0.5–0.55 and 0.7–0.75 telson length, respectively, both pairs distinctly removed from lateral margin; posterior margin shallowly emarginated centrally, with two pairs of elongate spiniform setae of subequal length and two pairs of plumose setae of similar length between them.

Antennular peduncle ( Figs. 1a, b View FIGURE 1 , 3a, b, f View FIGURE 3 ) moderately robust; stylocerite stout, with acute tip reaching or overreaching mid-length of second article; ventromesial carina with anteriorly directed tooth ( Figs. 1f View FIGURE 1 , 3f, g View FIGURE 3 ); second article about 1.3 times as long as wide; lateral antennular flagellum with fused portion composed of three subdivisions; shorter free ramus with at least four poorly demarcated subdivisions with groups of aesthetascs. Antenna ( Figs. 1a, b View FIGURE 1 , 3a, b View FIGURE 3 ) with basicerite stout, armed with large, sharp tooth on distoventral margin; scaphocerite shorter than antennular peduncle, relatively broad, about 2.3 times as long as maximal width; distolateral tooth small, not reaching anterior margin of blade; carpocerite short, reaching half-length of scaphocerite but not middle of second article of antennular peduncle; flagellum long, somewhat thickened proximally.

Mouthparts typical for genus. Third maxilliped ( Figs. 1g, h, i View FIGURE 1 , 3h View FIGURE 3 ) slender; coxa with strap-like epipod (mastigobranch) and prominent lateral plate, latter rounded dorsally and with small blunt lobe posteriorly; antepenultimate article about 2.7 times as long as penultimate article, moderately setose; penultimate article about four times as long as wide; ultimate article twice as long as penultimate article, tapering distally, with two short spiniform setae, one apical and one subapical; exopod well developed, almost reaching end of antepenultimate article; arthrobranch somewhat enlarged.

First pereiopods = chelipeds ( Figs. 2 View FIGURE 2 , 3i–m View FIGURE 3 ) very different in size, asymmetrical in shape. Major cheliped ( Figs. 2a–c View FIGURE 2 , 3i–l View FIGURE 3 ) moderately robust, carried folded at rest; ischium armed with small spiniform seta on ventrolateral surface; merus elongate, slightly swollen, about 4.5 times as long as maximal (mid-length) width, depressed ventrally, unarmed; carpus vase-shaped, distally much wider, somewhat curved, unarmed; chela moderately swollen, subcylindrical, longer than merus and ischium combined; palm as long as merus, about twice as long as maximal width, smooth; fingers about 0.8 length of palm, subequal in length, not gaping when closed, slightly twisted mesially; pollex proximally with low blunt process; fingertips strongly curved, crossing subapically; cutting edges of pollex and dactylus with about 10–16 subtriangular teeth, proximal-most and distal-most teeth smaller. Minor cheliped ( Figs. 2d View FIGURE 2 , 3m View FIGURE 3 ) significantly smaller and weaker than major cheliped, moderately slender; ischium armed with small spiniform seta on ventrolateral surface; merus slightly longer than ischium, somewhat convex dorsally, about 4.2 times as long as maximal width; carpus slender, about 0.8 length of merus, subcylindrical, widening distally; chela about 0.9 of carpus length; fingers slightly shorter than palm, simple, with unarmed cutting edges.

Second pereiopod ( Figs. 1j View FIGURE 1 , 3n View FIGURE 3 ) slender; ischium elongate, about five times as long as wide, with small spiniform seta on ventrolateral surface; merus 1.4 times as long as ischium; carpus slender, with five subarticles, first almost as long as combined length of remaining four, approximate length ratio of carpal subarticles: 4: 1: 1: 0.9: 1.6. Third pereiopod ( Figs. 1k View FIGURE 1 , 3o View FIGURE 3 ) moderately slender; ischium armed with two small spiniform setae on ventrolateral surface; merus about 1.8 times as long as ischium, about 5.3 times as long as maximal width; carpus distinctly more slender than merus, about 0.6 length of merus, distoventral margin with slender spiniform seta (propodus 1.4 length of carpus, ventral margin armed with two widely spaced fine spiniform setae, distoventral margin adjacent to propodo-dactylar articulation with additional pair of slender spiniform setae; dactylus slender, gently curved, simple, about 0.4 length of propodus. Fourth pereiopod ( Fig. 1l View FIGURE 1 ) generally similar to third pereiopod; ischium armed with two small spiniform setae on ventrolateral surface; propodus 1.6 length of carpus. Fifth pereiopod ( Figs. 1m View FIGURE 1 , 3p View FIGURE 3 ) longer and not noticeably slenderer than third and fourth pereiopods, ischium with or without small spiniform seta; merus six times as long as wide; carpus 0.6–0.75 length of merus; propodus 1.5 times length of merus and 1.7 length of carpus, ventromesial margin with 1–2 minute spiniform setae, distoventral margin adjacent to propodo-dactylar articulation with one pair of spiniform setae (propodal cleaning brush well developed, composed of numerous transverse rows of micro-serrulate setae occupying distal third of article; dactylus slender, simple, slightly more than 0.3 length of propodus, similar to that of third and fourth pereiopods.

Second pleopod with appendix masculina slightly shorter than appendix interna ( Fig. 1n View FIGURE 1 ), neither exceeding distal margin of endopod; appendix masculina furnished with slender spiniform setae along inner (mesial) margin and on apex. Uropod ( Figs. 1o View FIGURE 1 , 3e View FIGURE 3 ) with lateral lobe of protopod distally produced as acute tooth; exopod moderately broad, ovate, with small distolateral tooth adjacent to stout spiniform seta; diaeresis sinuous, with blunt, subtriangular tooth near distolateral spiniform seta; endopod as long as exopod, slightly narrower.

Variation. Of the 15 type and non-type specimens of S. manningi examined, only six possess a minute subdistal tooth on the ventral margin of the rostrum, which is unarmed in nine others (cf. Figs. 1a, p View FIGURE 1 , 3c View FIGURE 3 ). Nine specimens have a minute spine on the ventral margin of the ischium of the fifth pereopod; in six remaining specimens, this spine is absent (cf. Figs. 1m, q View FIGURE 1 , 3p View FIGURE 3 ). In the latter case, the presence or absence of the spine may be influenced by development, as generally smaller individuals (cl 4.8–7.0 mm) have the ischial spine, whereas larger ones (cl 6.3–8.3 mm) usually lack it.

Colour pattern. Overall whitish, somewhat opaque, with pale yellowish tinge in ovigerous individuals; chelipeds ivory white; eyes pale orange to brownish; ovary red orange; eggs orange yellow ( Fig. 4a–d View FIGURE 4 ).

Etymology. The new species honours the late Dr. Raymond B. Manning (1934–2000), a well-known carcinologist and a specialist of both Stomatopoda and Decapoda , who contributed to the collection of a large part of the herein reported material and worked extensively at the Smithsonian Marine Station at Fort Pierce and in the Indian River Lagoon region.

Distribution. Western Atlantic: presently known only from the vicinity of the Fort Pierce inlet to the Indian River Lagoon estuary, on the Atlantic coast of Florida, USA.

Ecology. Salmoneus manningi sp. nov. inhabits intertidal and shallow subtidal sandflats, typically with seagrass meadows. Four individuals of the new species were collected from the spacious burrows of the burrowing mantis shrimp, Lysiosquilla scabricauda ( Lamarck, 1818) , with one further specimen collected from a “stomatopod burrow”. Therefore, S. manningi sp. nov. may well be an obligate infaunal associate of L. scabricauda , although collection of additional specimens with their hosts is needed to confirm this hypothesis.

Remarks. Salmoneus manningi sp. nov. has been previously confused with S. cavicolus , although the two species present a series of morphological differences and may not be closely related. Felder & Manning (1986) observed several differences between the “female” (ovigerous) holotype of S. cavicolus (cl 3.2 mm) and the two “male” (non-ovigerous) paratypes and provided some illustrations of the larger (cl 5.3 mm) and smaller (cl 2.5 mm) paratypes. The most obvious differences between the holotype and larger paratype of S. cavicolus are in the frontal region and proportions and armature of the articles of the fifth pereiopod (cf. Felder & Manning 1986: figs. 4b, g, 6f, g; see also below). In addition, the distodorsal surface of the carpus of the third and fourth pereiopods of the holotype of S. cavicolus presented a small “spongy mass” ( Felder & Manning 1986: fig. 6e), which was not observed in the paratypes. The holotype and paratypes of S. manningi sp. nov. are clearly conspecific with the larger paratype of S. cavicolus , presenting the same differences with the holotype of S. cavicolus . Therefore, the larger paratype of S. cavicolus (USNM 228055) is herein reassigned to S. manningi sp. nov. ( Fig. 3 View FIGURE 3 ). However, because of its former paratype status, this specimen is left as a non-type specimen of the new species. The identity of the smaller paratype of S. cavicolus (USNM 228055), which has some similarities with S. carvachoi Anker, 2007 , will be discussed elsewhere.

Salmoneus manningi sp. nov. can be easily separated from S. cavicolus by the proportions of the rostrum, which is as long as wide at the base to slightly longer than wide (at most 1.2 times as long as wide) (vs. almost twice as long as wide in S. cavicolus ); the absence of a rostral carina (vs. present in S. cavicolus ); the noticeably reduced eye cornea (vs. only slightly smaller than in most other species of the genus, in S. cavicolus ); the stylocerite reaching to or beyond the mid-length of the second article of the antennular peduncle (vs. not overreaching one-third of its length in S. cavicolus ); the second article of the antennular peduncle stout, 1.1–1.5 times as long as wide (vs. more slender and elongate, 1.8–2.5times as long as wide in S. cavicolus ); the antennal scaphocerite with the distolateral tooth smaller, not reaching the distal margin of the blade (vs. with a more prominent distolateral tooth, reaching or overreaching the distal margin of the blade in S. cavicolus ); the fifth pereiopod ischium sometimes with a small spiniform seta (vs. always unarmed in S. cavicolus ); and the fifth pereiopod carpus about 0.6–0.75 times as long as propodus (vs. subequal or equal in length to the propodus in S. cavicolus ) (cf. Figs. 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 ; Felder & Manning 1986: figs. 4–6). Notably, none of the comparative specimens of S. cavicolus has the “spongy mass” on the third and fourth pereopods as described for the holotype of this species, suggesting that this may be a variable character or that the holotype is an aberrant individual in this regard.

In the Indian River Lagoon, S. manningi sp. nov. appears to be largely syntopical with S. cavicolus , which is similar in the general appearance and whitish colour ( Fig. 4e, f View FIGURE 4 ). As mentioned above, two individuals of S. manningi sp. nov. were found in association with the mantis shrimp Lysiosquilla scabricauda , whereas at least three specimens of S. cavicolus were extracted from the burrows of the snapping shrimp Alpheus floridanus Kingsley, 1878 , suggesting a possible ecological separation between these two sympatric species. At least three other western Atlantic species of Salmoneus are known as infaunal associates of snapping shrimps and ghost shrimps, probably with a high degree of host specificity ( Anker 2007, 2010, 2020; see also below).

Anker & Marin (2006) tentatively placed S. cavicolus in their informal and likely non-monophyletic S. gracilipes Miya, 1972 group. The only other western Atlantic species with at least some diagnostic characters of the S. gracilipes group is S. hispaniolensis Anker, 2010 , which differs from S. manningi sp. nov. by the largely exposed eyes (vs. concealed in the new species), more prominent orbital teeth, and the posterior margin of the telson with mesial spiniform setae distinctly longer than lateral ones (vs. subequal in the new species) (cf. Figs 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 ; Anker 2010: fig. 1).

Among other western Atlantic species of Salmoneus , only S. degravei Anker, 2010 shares some important morphological characters with S. manningi sp. nov., especially in the general shape of the frontal region. However, S. degravei can be immediately distinguished from S. manningi sp. nov. by the greatly reduced orbital teeth and notches, and most importantly, by the greatly enlarged minor cheliped (cf. Anker 2010: figs. 7, 9). In addition, S. degravei is an associate of the callichirid ghost-shrimp Neocallichirus grandimana ( Gibbes, 1850) , and not of lysiosquillid stomatopods, as is the case of the new species. The frontal region of S. manningi sp. nov. is also similar to those of the eastern Atlantic S. erasimorum Dworschak, Anker & Abed-Navandi, 2000 , S. caboverdensis Dworschak, Anker & Abed-Navandi, 2000 and the species currently known as Deioneus sandizelli Dworschak, Anker & Abed-Navandi, 2000 ; however, these three taxa differ from the new species by numerous other characters, including the enlarged minor chelipeds (cf. Dworschak et al. 2000). Noteworthy is that S. manningi sp. nov., S. degravei , S. erasimorum , S. caboverdensis and D. sandizelli are all inquilines of burrows of fossorial crustaceans, in the case of the new species, of stomatopods.

All other species of Salmoneus known from the western, central and eastern Atlantic, as well as from the eastern Pacific, seem to be more distantly related to S. manningi sp. nov., at least based on the overall combination of their morphological features (cf. Schmitt 1936; Manning & Chace 1990; Holthuis 1990; Dworschak et al. 2000; Anker 2007, 2010, 2011, 2019, 2020; Anker & Lazarus 2015; D’Udekem d’Acoz et al. 2021).