Salmoneus inconspicuus, Anker, 2020

Anker, Arthur, 2020, Two new species and new records in the alpheid shrimp genera Salmoneus Holthuis 1955 and Deioneus Dworschak, Anker & Abed-Navandi, 2000 in theAtlantic Ocean (Malacostraca: Decapoda), Zootaxa 4786 (3), pp. 345-368 : 346-352

publication ID	https://doi.org/ 10.11646/zootaxa.4786.3.2
publication LSID	lsid:zoobank.org:pub:4A85C28E-DAD1-45F7-908A-93D0CE93867A
persistent identifier	https://treatment.plazi.org/id/03AE878D-FFEA-FFE3-FF37-FCC16D6EFA0D
treatment provided by	Plazi
scientific name	Salmoneus inconspicuus
status	sp. nov.

Treatment

Salmoneus inconspicuus View in CoL sp. nov.

Figs. 1–4 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4

Salmoneus teres View in CoL — Anker 2007: 32 View Cited Treatment , figs. 5, 8a [not S. teres Manning & Chace, 1990 View in CoL ].

Type material. Holotype: ovigerous specimen (cl 4.5 mm) MZUSP 34069 View Materials , Panama, Caribbean coast, Guna Yala, San Blas Islands, Isla Diablo (near Cartí), rubble flat near coral reef, under large pieces of rubble, depth: 1–2 m, leg. A. Anker, 23.05.2007 [fcn 07-179]; paratype: ovigerous specimen (cl 3.4 mm), OUMNH. ZC. 2015-08-0027, Panama, Caribbean coast, near Portobelo, silt-sand with coral rubble, depth: 8 m, leg. A. Anker, 21.07.2007 [fcn 07-197].

Additional material. 1 ovigerous specimen (cl 4.4 mm), OUMNH. ZC. 2015-08-0028, Cuba, Isla de la Juventud, 21°35.10’N, 83°10.20’W, coral reef, rubble, depth: 11 m, leg. M. Johnson and undergraduate students of University of Hull , 28.vi.2014 [fcn S168]; 1 non-ovigerous specimen (cl 4.4 mm), USNM 1171231 View Materials , Bermuda, no further collection data, 1949 GoogleMaps .

Description. Small-sized (cl 3.4–4.5 mm) alpheid shrimp with not particularly slender or compressed body. Carapace mostly glabrous, pitted, usually with few scarce setae ( Fig. 1a, b View FIGURE 1 ). Rostrum well developed, broadly subtriangular, about as long as wide at base to somewhat longer than wide, acute distally, greatly overreaching distal margin of first article of antennular peduncle, reaching or almost reaching to mid-length of second article, lateral margins feebly convex proximally; rostral or mid-dorsal carina not discernable to very faintly marked ( Fig. 1a, b, i View FIGURE 1 ). Orbital teeth well developed, sharp distally, directed slightly mesially in dorsal view, anteriorly in lateral view ( Fig. 1a, b, i View FIGURE 1 ). Pterygostomial region broadly rounded; anterolateral suture present ( Fig. 1b View FIGURE 1 ); cardiac notch well developed. Each epistomial sclerite with small acute process.

Pleon with first to fourth pleura broadly rounded to slightly angular; fifth pleuron with posteroventral margin produced into acute, posteriorly directed tooth; sixth pleonite with short suture but without articulated flap, posterior margin produced into short subacute tooth flanking telson; preanal plate produced into distally acute, sometimes bifid, tooth ( Fig. 1c, d View FIGURE 1 ). Telson moderately slender, subrectangular, tapering distally, almost 2.5 times as long as maximal (proximal) width; dorsal surface with two pairs of stout cuspidate setae both inserted at some distance from lateral margin, first pair at about telson mid-length or slightly posterior to it, second pair at about 0.7 of telson length; posterior margin with minute median notch flanked by two pairs of long robust plumose setae, and two pairs of stout spiniform setae, mesial ones much stouter and about 1.3–1.4 times longer than lateral ones ( Fig. 1e, f View FIGURE 1 ).

Eyes completely or almost completely concealed in dorsal view, most-anterior portion typically exposed in lateral view; cornea moderately developed; anteromesial margin of eyestalk not protruding or armed with tubercle ( Fig. 1a, b, i View FIGURE 1 ).

Antennular peduncle very stout; stylocerite elongate, not particularly slender, with sharp tip almost reaching distal margin of second article; ventromesial carina with small anteriorly directed tooth; second article squareshaped, slightly wider than long in dorsal view; lateral antennular flagellum with very short fused portion, consisting of three discernable subdivisions, and well-developed secondary ramus, latter with four or so groups of long aesthetascs; mesial antennular flagellum much stouter than lateral ( Fig. 1a, b View FIGURE 1 ). Antenna with basicerite stout, armed with robust subacute tooth on its distoventral margin; scaphocerite ovate in general shape, not reaching end of antennular peduncle, with straight to slightly convex lateral margin and very broad blade, latter convex anteriorly and reaching far beyond sharp distolateral tooth; carpocerite short, cylindrical, reaching to about mid-length of scaphocerite ( Fig. 1a, b View FIGURE 1 ).

Mouthparts not dissected, typical for genus in external observation. Third maxilliped slender, pediform; coxa with somewhat elongate, ear-shaped lateral plate; antepenultimate article slender, slightly flattened ventrolaterally; penultimate article about 3.2 times as long as wide; ultimate article with numerous rows of short serrulate setae and some longer simple setae, tip with blunt corneous point and stout subapical spiniform seta; arthrobranch well developed ( Fig. 2a, b View FIGURE 2 ).

First pereiopods (chelipeds) very asymmetrical in shape and dissimilar in size, carried flexed when not in use. Major cheliped moderately enlarged, slender; ischium flattened ventrolaterally, with robust cuspidate seta; merus slender, more than six times as long as proximal width, widening distally, smooth, distodorsal and distomesial margins rounded, ventrolateral surface deeply depressed distally; carpus short, cup-shaped, with distal margin protrud- ing ventromesially, forming stout subacute process; chela subcylindrical, flattened on ventromesial surface, with palm smooth, much longer than fingers; fingers not gaping when closed, not twisted, subequal in length, strongly crossing distally, with evenly serrated cutting edges; both dactylus and pollex with about 11–12 rounded to subtriangular teeth on cutting edge, extending for most of finger length, except for curved distal-most portion ( Fig. 3 View FIGURE 3 a–c). Minor cheliped substantially smaller and slenderer than major cheliped; ischium armed with one or (typically) two cuspidate setae on ventrolateral surface; merus slightly longer than ischium, not swollen or widening distally, smooth, unarmed, slightly depressed ventrally; carpus about 0.9 times as long as merus, cylindrical, slightly widening distally; chela slightly longer than carpus, simple, with palm longer than fingers, smooth; fingers somewhat gaping when closed, subequal in length, crossing distally, fingertips minutely bidentate, remaining cutting edges unarmed ( Fig. 3d, e View FIGURE 3 ).

Second pereiopod slender; ischium with one small cuspidate seta on ventrolateral surface, situated in proximal third; merus as long as ischium; carpus with five subdivisions, first almost as long as four others combined, with ratio approximately equal to 4.0/1.0/0.8/1.0/1.6; chela slightly longer than distal-most carpal subdivision, simple ( Fig. 2c View FIGURE 2 ). Third pereiopod moderately slender; ischium with one or two cuspidate seta(e) on ventrolateral surface; merus slightly more than five times as long as wide, unarmed; carpus 0.8 times length of merus, noticeably more slender, with one spiniform seta on distoventral margin; propodus as long as carpus, with three widely spaced spiniform setae on ventral margin, in addition to one pair of spiniform setae (one of them much longer) near dactylar base; dactylus reaching almost half-length of propodus, slender, conical, simple, smoothly curving distally ( Fig. 2d, e View FIGURE 2 ). Fourth pereiopod slightly more slender than third pereiopod; ischium with one cuspidate seta on ventrolateral surface; merus about six times as long as wide; carpus 0.7 times length of merus, much more slender than merus, with one spiniform seta distoventrally; propodus distinctly longer than carpus, with three widely spaced spiniform setae on ventral surface, distoventral margin adjacent to dactylus with additional pair of longer spiniform setae; dactylus about 0.4 times length of propodus, similar to that of third pereiopod ( Fig. 2f View FIGURE 2 ). Fifth pereiopod noticeably more slender compared to third and fourth pereiopod; ischium unarmed; merus more than seven times as long as wide, unarmed; carpus noticeably more slender than merus, almost as long as merus, unarmed distoventrally; propodus long, slender, 1.3 times as long as carpus, with at least eight rows of progressively longer serrulate setae forming cleaning brush on distal ventrolateral surface, ventral and ventromesial margin with few small spiniform setae, in addition to one pair of longer spiniform setae near dactylar base (visible only in mesial view); dactylus about 0.4 times length of propodus, similar to that of third and fourth pereiopods, however, slightly less curved ( Fig. 2g, h View FIGURE 2 ).

Second pleopod with appendix masculina almost as long as appendix interna, furnished with numerous long stiff setae, as illustrated ( Fig. 1g View FIGURE 1 ). Uropod with lateral lobe of protopod ending in subacute tooth; exopod narrowly oval-shaped with fairly small blunt distolateral tooth and short distolateral spiniform seta; diaeresis sinuous, with broad subtriangular tooth just mesial to spiniform seta; endopod as long as exopod, narrowly oval-shaped without specific features ( Fig. 1h View FIGURE 1 ).

Gill formula typical for genus.

Colouration. Semitransparent-whitish, sometimes with straw-yellow tinge; ovaries or fresh eggs yellow ( Fig. 4 View FIGURE 4 ).

Variation. Anker (2007: fig. 5a) illustrated a very slight rostral carina in the Guadeloupe specimen reported as S. teres . Such a carina is not noticeable in the Panamanian type specimens (holotype and paratype) and is barely visible in the Cuban specimen. The ischial armature of the pereipods varies somewhat between the specimens, but is generally relatively consistent. For instance, the holotype and the Cuban specimen have what appears to be the most complete sets of cuspidate setae on the pereiopodal ischia for this species, i.e. one cuspidate seta on the major cheliped (MP1) ischium, two on the minor cheliped (mP1) ischium, one on the second pereiopod (P2) ischium, two (holotype) or three (Cuban specimen) on the third pereiopod (P3) ischium, one (holotype) or two (Cuban specimen) on the fourth pereiopod (P4) ischium, and none on the P5 ischium. The paratype has a small cuspidate seta on the MP1 ischium, but (exceptionally) no such seta on the mP1 ischium; the P2 and P4 ischium each have one cuspidate seta and the P3 ischium has two cuspidate setae. In the specimen from Guadeloupe illustrated by Anker (2007: fig. 5, as S. teres ), the MP1, mP1, P2 and P3 ischium each had only one cuspidate seta. Thus the pereiopodal ischial armature of S. inconspicuus sp. nov. may be summarised as following: MP1 (1), mP1 (0–2, typically: 2), P2 (1), P3 (1–3, typically: 2), P4 (1–2, typically: 1), P5 (0).

Type locality. San Blas Islands , Panama .

Distribution. Western Atlantic: Panama (San Blas Islands, Portobelo), Cuba (Isla de la Juventud), French Antilles ( Guadeloupe) and possibly Bermuda (see below).

Ecology. Rubble-rich sand flats near coral reefs, under coral rubble on sand or silt, at depth range of 1– 11 m.

Etymology. From the Latin adjective inconspicuus , for inconspicuous or unremarkable, referring to the new species’ ordinary appearance, i.e. not displaying any striking characters in its morphology or colouration.

Remarks. Salmoneus inconspicuus sp. nov. was previously reported from the Caribbean Sea under the name S. teres Manning & Chace, 1990 , on the basis of on a single non-ovigerous specimen from Guadeloupe, French Antilles ( Anker 2007). The present reassignment of the Guadeloupe specimen to the new species thus restricts the distribution of S. teres to Ascension Island, central Atlantic. In fact, S. teres presently remains only known from the holotype specimen (USNM 221889), which was found in a tide-pool. The two species are closely related, but can be separated by the shape of the rostrum and the armature of the major cheliped and the third and fourth pereiopods. In S. inconspicuus sp. nov., only the base of the rostrum is slightly (if at all) convex, whilst in S. teres , the entire lateral margin is broadly convex (cf. Fig. 1a, i View FIGURE 1 and Manning & Chace 1990: fig. 10b). In S. inconspicuus sp. nov., the major cheliped ischium is armed with a stout cuspidate seta on the ventrolateral surface, whereas in S. teres , it is unarmed (cf. Fig. 3 b View FIGURE 3 and Manning & Chace 1990: fig. 10n). A direct comparison of the minor chelipeds is presently impossible as the minor cheliped was missing in the holotype of S. teres . However, since the ischial armature, if present, typically occurs on both chelipeds in Salmoneus (A. Anker, pers. obs.), the presence of two strong cuspidate setae on the minor cheliped ischium of the new species ( Fig. 3d View FIGURE 3 ) may be an additional feature distinguishing these two taxa. Furthermore, in the holotype of S. inconspicuus sp. nov., the ischia of the third and fourth pereiopods are armed with two or one stout cuspidate seta on the ventrolateral surface, respectively, whereas in S. teres , the ischia of these appendages are unarmed (cf. Fig. 2d, f View FIGURE 2 and Manning & Chace 1990: fig. 10q, r). All these differences appear to be significant and are now, with the new Caribbean material, considered to be of specific importance, despite some variation in the pereiopod armature seen in S. inconspicuus sp. nov. (see above).

Salmoneus inconspicuus sp. nov. can be separated from all other western Atlantic species of Salmoneus by at least three, and usually more, morphological characters. For instance, the new species differs from S. arubae ( Schmitt, 1936) by the presence of a small notch on the posterior margin of the telson (absent in S. arubae ); the more slender third pereiopod, with a proportionally longer and more slender dactylus (vs. the much stouter third pereiopod, with a robust dactylus, in S. arubae ); the second pereiopod ischium much longer and armed with cuspidate setae (vs. distinctly shorter and unarmed in S. arubae ); and the much shorter stylocerite, not reaching the distal margin of the second article of the antennular peduncle (vs. overreaching this margin in S. arubae ) (cf. Schmitt 1936: pl. 12, fig. 2). It must also be noted that the material identified and reported as S. arubae by Holthuis (1990) needs to be restudied.

Salmoneus inconspicuus sp. nov. can be easily separated from all species characterised by the enlarged or partly enlarged minor cheliped, including the western Atlantic S. camaroncito Anker, 2010 (see below) and especially S. degravei Anker, 2010 , or from species of the S. ortmanni ( Rankin, 1898) complex, characterised by the swollen and ventrally excavated merus and carpus of the major cheliped (cf. Anker 2007, 2010a). The new species differs from the two American species bearing a dorsal depression on the carapace, such as the western Atlantic S. depressus Anker, 2011 , from all species with partly exposed eyes, such as S. cavicolus Felder & Manning, 1986 , S. hispaniolensis Anker, 2010 , and S. armatus Anker, 2010 , this last one also differing by the presence of a strong tooth on the mid-dorsal line of the carapace ( Felder & Manning 1986; Anker 2010 a, 2011). Salmoneus inconspicuus sp. nov. also differs from the closely related S. setosus Manning & Chace, 1990 (see below) and S. rocas Anker, 2007 , by the general shape of the rostrum and orbital teeth, and the presence of cuspidate setae on the ischia of the major and minor chelipeds, and specifically from S. setosus by the absence of very conspicuous, thick, erect setae on the carapace, pleon and telson (cf. Manning & Chace 1990; Anker 2007).

The single specimen from Bermuda (USNM 1171231), collected in 1949 and not in the best condition, is tentatively assigned to S. inconspicuus sp. nov., since in most important morphological aspects it corresponds well to the Caribbean material. Most importantly, this specimen possesses cuspidate setae on the ischia of the major and minor chelipeds, as well as on the ischia of the second and third pereiopods, as does, for instance, the holotype of S. inconspicuus sp. nov. (see above).