Salmoneus armatus Anker 2010, sp. nov.
Creators: name: Anker, Arthur
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Alpheidae
Salmoneus
Salmoneus armatus

description: Salmoneus armatus sp. nov.   
(Figs. 3, 4, 14a)  
 Type material. Holotype: non-breeding specimen (cl 3.8 mm, tl 11.7 mm), USNM 1124209, Panama, Caribbean coast, Isla Grande, southern shore, 100 m east of western-most point, under rock on muddy sand, 0.5 m depth, leg. A. Anker, 21.IV.2006 [fcn 06-400].   
 Additional material examined. Non-breeding specimen (cl 3.9 mm, tl 12.0 mm), USNM 1124210, Panama, Caribbean coast, Bocas del Toro, Isla Popa, station 704, leg. S. Williams et al., 10.IV.2000 [fcn 08- 024].   
 Description. Carapace glabrous, without conspicuous setae; mid-dorsal line with low forwardly directed tooth posterior to rostrum base (Figs. 3a–c). Rostrum triangular in dorsal view, about 1.5 times as long as broad at base, reaching past mid-length of second segment of antennular peduncle, tip acute (Figs. 3a–b); lateral margins shallowly concave; ventral margin armed with minute acute subapical tooth (Figs. 3b–c); rostral carina non-distinct. Orbital teeth well developed, acute (Figs. 3a–c). Pterygostomial margin not protruding anteriorly, rounded (Fig. 3b). Eyes partly exposed in dorsal and lateral views (Figs. 3a–c); cornea somewhat reduced; anteromesial margin of eyestalk with blunt dorsal angle (Fig. 3b).   
Antennule with stylocerite reaching beyond mid-length of second peduncular segment, with acute tip; ventromesial carina of first segment with small sharp tooth (Fig. 3d); second segment not elongate, as long as wide (Fig. 3a); lateral flagellum bifurcating at second/third segment, secondary ramus well developed, with several groups of aesthetascs (Fig. 3b, c). Antenna with basicerite bearing small subacute distoventral tooth (Fig. 3b); scaphocerite broadly ovate, with acute distolateral tooth and broad blade, latter with convex, slightly angular anterior margin (Fig. 3a); carpocerite short, not reaching mid-length of scaphocerite.  
Third maxilliped (Fig. 3e) with rounded lateral plate (Fig. 3f); ultimate segment tapering, tip with short subapical spine and apical corneous tip (Fig. 3g).  
Chelipeds asymmetrical in shape, very unequal in size (Fig. 4a, d). Major cheliped slender, not greatly enlarged (Figs. 4a–c); ischium with one larger and two smaller spines proximally on ventrolateral surface; merus not inflated, slightly flattened ventrally; carpus elongate, vase-shaped; chela slender, with fingers slightly longer than palm; palm smooth, without conspicuous grooves or other sculpture; fingers slender, straight except for curved crossing tips, cutting edges serrated, with at least 10 irregular, more or less spaced teeth (Fig. 4c). Minor cheliped (Figs. 4d–e) with ischium slightly shorter than merus, armed with two spines on ventrolateral margin; carpus about 0.75 merus length, cylindrical, widening distally; chela simple, smooth, with fingers shorter than palm, cutting edges unarmed (Fig. 4e).  
Second pereiopod (Fig. 4f) slender; ischium bearing two spines on ventrolateral surface; merus longer than ischium; carpus five-segmented, first segment being slightly shorter than remaining four segments combined. Third pereiopod (Fig. 4g) slender; ischium bearing three ventrolateral spines; merus about sixseven times as long as wide; carpus more slender than merus, with stiff distoventral seta; propodus with three small ventral spinules and pair of longer and stouter distal spinules; dactylus simple, conical, moderately slender, slightly less than half of propodus length. Fourth pereiopod similar to third. Fifth pereiopod with ischium unarmed; propodus with setal brush distally.  
First to fourth pleura rounded; fifth pleuron forming blunt angle posteroventrally (Fig. 3i); sixth pleurite without articulated plate, subacute posteroventrally; preanal plate subtriangular, rounded posteriorly (Fig. 3j). Telson (Fig. 3l) about 2.5 times as long as proximal width, tapering posteriorly, with two pairs of dorsal spines situated first at telson mid-length, second at 0.75 telson length; posterior margin with small triangular median notch, fringed by two pairs of thick plumose setae in central portion, and two pairs of stouter spines at distolateral angle, lateral being somewhat shorter than mesial.  
Second pleopod with appendix masculina slightly longer than appendix interna, furnished with stout setae apically (Fig. 3h). Uropod (Fig. 3k) with narrow exopod and endopod; diaeresis sinuous; distolateral tooth very small, adjacent distolateral spine fairly long and stout.  
Gill/exopod formula typical for genus (see under previous species).  
 Size. Holotype: cl 3.8 mm, tl 11.7 mm; non-type specimen: cl 3.9 mm, tl 12.0 mm.   
 Colour in life. Semitransparent whitish; gonads yellow (Fig. 14a).   
 Etymology. Named armatus (Latin for armed) in reference to the low, anteriorly directed tooth on the mid-dorsal line of the carapace.   
 Type locality. Isla Grande, Panama.   
 Distribution. Presently known only from the Caribbean coast of Panama (Isla Grande, Bocas del Toro).   
 Ecology. Sandy-silty bottom with silt-covered coral rubble and rocks; the holotype specimen was collected under rock/rubble piece at a depth of 0.5 m.   
 Variation. In the non-type specimen from Bocas del Toro, which is missing both chelipeds, the dorsal tooth on the midline of the carapace is somewhat less conspicuous. Nevertheless this crest ends in a low, anteriorly directed tooth – the key diagnostic feature of S. armatus sp. nov. (Fig. 3m). A slight variation also exists in the length of the dorsal and posterior spines on the telson.   
 Remarks. Salmoneus armatus sp. nov., like the previous species, belongs to the S. gracilipes species group, but can be easily separated from all other species of this group by the presence of a strong, anteriorly directed, subacute tooth on the mid-dorsal line of the carapace, a feature unique not only within the S. gracilipes group, but also within the genus Salmoneus (for comparison see Miya 1972; Felder & Manning 1986; De Grave 2004; Anker & Marin 2006). Morphologically closest species appears to be the abovedescribed S. hispaniolensis sp. nov., which differs from S. armatus sp. nov. in the absence of the median tooth on the carapace, but also in the better developed corneas and the straight posterior margin of the telson (vs. bearing a small central notch in S. armatus sp. nov., cf. Fig. 3l). The new species is more distantly related to S. cavicolus and some of the Indo-West Pacific species.
description: Published as part of Anker, Arthur, 2010, The shrimp genus Salmoneus Holthuis, 1955 (Crustacea, Decapoda, Alpheidae) in the tropical western Atlantic, with description of five new species *, pp. 177-205 in Zootaxa 2372 (1) on pages 181-183, DOI: 10.11646/zootaxa.2372.1.18, http://zenodo.org/record/5306815