Salmoneus komaii, Anker, Arthur, 2011

Anker, Arthur, 2011, Three new species of the alpheid shrimp genus Salmoneus Holthuis, 1955 (Crustacea, Decapoda) from the tropical western Pacific, Zootaxa 2839, pp. 67-84 : 73-76

publication ID	https://doi.org/ 10.5281/zenodo.208086
DOI	https://doi.org/10.5281/zenodo.6194231
persistent identifier	https://treatment.plazi.org/id/03E41126-FF95-0A4B-EE88-1B7BFC18F828
treatment provided by	Plazi
scientific name	Salmoneus komaii
status	sp. nov.

Treatment

Salmoneus komaii View in CoL n. sp.

( Figs. 5–7 View FIGURE 5 View FIGURE 7 )

Type material. Mariana Islands, Guam. Holotype: ovigerous specimen (CL 4.0 mm), FLMNH UF Arthropoda 28065, west coast of Guam, south of Orote Point, Barracuda Rock, sand/silt, under rocks, depth less than 10 m, scuba diving, coll. Y. Fujita & T. Naruse, proc. A. Anker, 14 June 2010 [fcn GUOK-0257].

Description. Medium-sized species of Salmoneus (CL of holotype 4.0 mm). Carapace slightly domed, finely pitted, especially dorsally, sparsely covered with short stubby setae; anterolateral region with distinct suture ( Fig. 5 View FIGURE 5 A, B); cardiac notch deep. Rostrum moderately long, distinctly over-reaching distal margin of first article of antennular peduncle, subtriangular, as wide as long at base, slightly descendant in lateral view, without distinct medio-dorsal carina; lateral margins slightly concave; tip acute, slightly curved upwards in lateral view; ventral margin with minute subapical tooth ( Fig. 5 View FIGURE 5 A–C). Orbital teeth small compared to rostrum, subtriangular, acute distally, directed anteromesially ( Fig. 5 View FIGURE 5 A, B). Pterygostomial angle broadly rounded ( Fig. 5 View FIGURE 5 B).

Pleura of first four abdominal somites rounded posteroventrally; fifth pleuron with subacute slightly projecting posteroventral angle; sixth somite without distinct articulated plate, with barely visible suture only; preanal plate rounded. Telson rather slender, widest at base, distally tapering; dorsal surface with two pairs of spiniform setae inserted at some distance from lateral margin, at about 0.4 and 0.7 telson length, respectively; posterior margin about half as long as anterior margin, truncate, with inconspicuous, very shallow median emargination, and two pairs of long spiniform setae, mesial slightly shorter than lateral; margin between mesial spiniform setae furnished with one pair of plumose setae ( Fig. 5 View FIGURE 5 D).

Eyes partly concealed in dorsal view, anterior-most portion visible in both dorsal and lateral view; cornea beanshaped; anterolateral margin somewhat angular, protruding anteriorly, forming a small bump ( Fig. 1 View FIGURE 1 A, B, E). Epistomial sclerites with subacute processes.

Antennular peduncles stout, with second article slightly wider than long; stylocerite with subacute tip almost reaching distal margin of second article; ventromesial carina with small, anteriorly directed tooth; lateral flagellum biramous, fused portion very short; accessory ramus with at least five tufts of aesthetascs ( Fig. 5 View FIGURE 5 A, B). Antenna with basicerite ending in stout tooth distoventrally; scaphocerite ovate, with broad, anteriorly rounded blade reaching well beyond acute distolateral tooth, latter almost reaching end of antennular peduncle; carpocerite very short, barely reaching half-length of scaphocerite ( Fig. 1 View FIGURE 1 A, B, F).

Mouthparts typical for genus. Third maxilliped slender; coxa with rounded lateral plate above mastigobranch; penultimate article more than three times as long as wide, slightly widening distally, with two transverse rows of sparse serrulate setae on mesial side; ultimate article furnished with transverse rows of thick serrulate setae mesially, tapering distally, apical region with corneous tip and two short subapical spiniform setae; arthrobranch well developed ( Fig. 5 View FIGURE 5 G–J).

Chelipeds unequal in size, asymmetrical in shape, minor cheliped about 0.7 length of major cheliped, more slender, with much smaller and shorter chela (Figs. 6A, E, 7); both chelipeds folded under cephalothorax when not in use. Major cheliped elongate, slender; ischium distally widening, with two small spiniform setae on ventrolateral surface; merus about four times as long as wide, smooth, depressed distoventrally, ventral margin somewhat convex; carpus vase-shaped, elongate, about 0.6 length of merus, ventrally slightly depressed, distally widening (Fig.

6A, B); chela somewhat compressed, smooth, ventral margin strongly concave at pollex base; fingers distinctly longer than palm, with tips strongly curved and crossing; cutting edge of dactylus with three widely spaced, very strong, subacute teeth and one much smaller distal tooth; space between large teeth slightly convex, finely striated; cutting edge of pollex without teeth, except for single, relatively small subdistal tooth near crossing with dactylus (Figs. 6A–C, 7B). Minor cheliped less robust than major cheliped, with chela less swollen and with much shorter fingers; ischium with strong spiniform seta on ventrolateral surface; merus about four times as long as wide, smooth, depressed ventrally; carpus cup-shaped, distally widening (Fig. 6D, E); chela smooth, simple, with fingers stout, about 0.8 length of palm; cutting edges serrated with three broadly rounded interdigitating teeth; tips moderately curved, not strongly crossing (Fig. 6F).

Second pereiopod slender; ischium with spiniform seta on ventrolateral surface; merus about the same length as ischium; carpus five-articulated, ratio of carpal articles (from proximal to distal) equal to: 6: 1: 1: 1.5: 2; chela simple, slightly longer than most-distal carpal article ( Fig. 5 View FIGURE 5 K). Third pereiopod slender, compressed; ischium with two spiniform setae on ventrolateral surface; merus about six times as long as wide, unarmed; carpus much more slender than merus, about 0.9 merus length, with slender seta distoventrally; propodus with five spiniform setae along ventral margin and one pair of stouter and longer distal spiniform setae adjacent to dactylus; dactylus about 0.4 propodus length, simple, moderately slender, gradually curving distally, with setae at about 0.7 dactylar length ( Fig. 5 View FIGURE 5 L, M). Fourth pereiopod similar to third pereiopod. Fifth pereiopod slender, slightly longer than third pereiopod; ischium unarmed; propodus with well-developed setal brush distolaterally.

Male second pleopod with appendix masculina shorter than appendix interna, apex and distomesial margin furnished with stiff setae ( Fig. 5 View FIGURE 5 N). Uropod with lateral lobe of protopod bearing subacute tooth; endopod and exopod narrowly ovoid; diaeresis sinuous, with blunt distolateral tooth adjacent to slender spiniform seta ( Fig. 5 View FIGURE 5 O). Gillexopod formula typical for genus.

Colour in life: semitransparent, hyaline-whitish, with bright yellow freshly-laid eggs ( Fig. 7 View FIGURE 7 ).

Etymology. Named after Dr. Tomoyuki Komai (Chiba Museum and Institute, Chiba, Japan) for his numerous contributions to the taxonomy of various groups of Decapoda .

Ecology. Sand flat with burrows, sparse rocks and rubble, depth less than 10 m; under rocks and rubble.

Type locality. Barracuda Rock, Guam, Mariana Islands, northwestern Pacific Ocean.

Distribution. Presently known only from west coast of Guam (Orote Peninsula).

Remarks. Salmoneus komaii n. sp. shares with S. paulayi n. sp. the presence of an enlarged minor cheliped; therefore, it can also be assigned to the S. jarli species group (see above). It can be separated from most previously described species of Salmoneus by the presence of only three strong, widely spaced teeth on the cutting edge of the dactylus of the major chela, the cutting edge of the pollex apparently remaining unarmed (Fig. 6C). In the vast majority of previously described species of Salmoneus , the armature of the major chela fingers consists of numerous continuous teeth (serrations) along the entire cutting edge (e.g. Banner & Banner 1973, 1981; Anker 2003a, 2003b; Anker & Marin 2006; Komai 2009; Anker 2010). The only exceptions are S. rostratus Barnard, 1962 , which has a few large continuous teeth proximally ( Anker & Marin 2006); S. jarli , which has no teeth at all ( Holthuis 1951); and S. sketi , in which the teeth are spaced ( Fransen, 1991) in a way similar to that of S. komaii n. sp. However, S. komaii n. sp. can be easily distinguished from S. sketi in a number of morphological features, including a differently shaped frontal margin of the carapace (orbital teeth + rostrum); the slightly more slender second and third pereiopods; and the teeth on the fingers of the major chela being significantly larger and also less numerous (3 in S. komaii n. sp. vs. 4–6 in S. sketi ). In addition, S. sketi is a marine cave-associated species known only from the Adriatic Sea in the eastern Atlantic.

In the above-described S. paulayi n. sp., the teeth on the dactylar cutting edge are separated by broadly rounded, finely striated, lamellar convexities ( Fig. 2 View FIGURE 2 F), which are only indicated in S. komaii n. sp. (Fig. 6C). In S. komaii n. sp., the eyes are partly exposed dorsally and have an angular anterolateral margin; in contrast, the eyes are concealed in S. paulayi n. sp. and their anterolateral margin is rounded (cf. Fig. 5 View FIGURE 5 A, E). The penultimate article of the third maxilliped is furnished with fewer setal rows in S. komaii n. sp. compared to S. paulayi n. sp. (cf. Fig. 1 View FIGURE 1 I, 5I). The two species also differ in the shape of the rostrum, which is somewhat narrower at base and more produced distally in S. komaii n. sp. (cf. Fig. 1 View FIGURE 1 A, 5A). Finally, S. komaii n. sp. can be distinguished from S. paulayi n. sp. by the presence of spiniform seta(e) on the ischia of the second and third pereiopods ( Fig. 5 View FIGURE 5 K, L); these setae are absent in S. paulayi n. sp. ( Fig. 3 View FIGURE 3 A, B).