Salmoneus nhatrangensis, Marin, 2006
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publication ID |
https://doi.org/ 10.5281/zenodo.13245424 |
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persistent identifier |
https://treatment.plazi.org/id/03AB572D-FFE5-FFB3-FF53-FEB0FEFEDF06 |
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treatment provided by |
Felipe |
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scientific name |
Salmoneus nhatrangensis |
| status |
sp. nov. |
Salmoneus nhatrangensis View in CoL , new species
( Figs. 1-3 View Fig View Fig View Fig )
Material examined. – Holotype, non-ovigerous specimen (CL 3.4, TL 10.2)( ZMMU Ma 5438), South China Sea , Vietnam, Nhatrang Bay, Tre Island, on sand, under stone, depth 8-10 m, SCUBA, coll. I. Marin, 29 Sep.2003.
Description. – Carapace slightly setose, with small rounded depressions or pits, appearing somewhat granular, laterally with shallow oblique depression and slight suture starting from lateral margin proximal to base of antenna ( Figs. 1 View Fig , 2b View Fig ). Rostrum moderately long, not reaching distal margin of first segment of antennular peduncle ( Fig. 2a View Fig ), broader than long at base; lateral margins distinctly convex proximally ( Fig. 2a View Fig ); rostral carina moderately developed, reaching slightly beyond level of eyes posteriorly ( Fig. 2a View Fig ). Extra-corneal teeth acute, directed towards apex of rostrum; notch between rostrum base and extra-corneal teeth deep ( Fig. 2a View Fig ). Pterygostomial angle rounded. Eyes without tubercle, completely covered by carapace, not visible in dorsal view, anterior portion visible in lateral view ( Fig. 2b View Fig ). Epistomial sclerite with small, subacute process. Ocellar beak small.
Antennular peduncle stout, second segment shorter than first and third; ventromesial carina of first segment with acute tooth; stylocerite reaching to, but not exceeding distal margin of second segment, distally subacute ( Fig. 2a View Fig ); lateral flagellum biramous, with shorter ramus situated at firstsecond segment. Antenna with basicerite bearing strong ventrolateral tooth ( Fig. 2b View Fig ); scaphocerite relatively broad, anterior margin of blade strongly convex, exceeding distolateral tooth; carpocerite short, reaching to about 3/4 length of scaphocerite ( Fig. 2b View Fig ).
Mouthparts typical for genus. Mandible with incisor process bearing seven teeth, third and fourth largest. Maxillule with bilobed palp, lower lobe with one seta, upper lobe unarmed. Second maxilliped with rounded epipod. Third maxilliped slender ( Fig. 2c View Fig ); lateral plate blunt, ear-shaped ( Fig. 2e View Fig ); ultimate segment distally tapering, bearing two subapical spines ( Fig. 2d View Fig ), tip subacute; arthrobranch normally developed.
First pereiopods (chelipeds) very asymmetrical, unequal ( Figs. 2f View Fig , 3 View Fig ), carried flexed ventrally in life, mesially when preserved ( Fig. 1 View Fig ); major cheliped robust; ischium short, without spines; merus elongate, distally widening, ventrally depressed, rounded distal lobes; carpus short, cup-shaped, constricted, distally with several more or less pronounced lobes ( Fig. 3a, c View Fig ); chela subcylindrical, with ratio fingerspalm about 3/5; palm proximoventrally with complex deep groove ( Fig. 3b, c View Fig ), dorsal surface with elongate depression ( Fig. 3a View Fig ); pollex proximolaterally with massive blunt lobe ( Fig. 3c, d View Fig ), cutting edge with 10 rounded regularly spaced, rounded teeth, tip strongly curved; dactylus with cutting edge bearing nine teeth (one apparently broken), tip strongly curved ( Fig. 3d View Fig ); tips crossing when fingers closed ( Fig. 3a View Fig ). Minor cheliped slender; ischium slightly elongate, about half length of merus; carpus slightly shorter than merus, cylindrical; chela simple, not particularly enlarged, fingers as long as palm, cutting edges unarmed ( Fig. 2f View Fig ).
Second pereiopod slender; ischium about 3/4 length of merus; carpus with five segments with ratio approximately equal to 4/1/0.7/0.7/1.4; chela simple, fingers slightly longer than palm ( Fig. 2g View Fig ). Third pereiopod slender; ischium with two spines; merus about 1.7 length of ischium, about five times as long as wide at base; carpus slender, shorter than merus, with small distoventral spine; propodus slightly shorter than carpus, ventrally with four small spines and one slender distoventral spine proximal to dactylus; dactylus simple, slender, less than half length of propodus, slightly curved ( Fig. 2h, i View Fig ). Fourth pereiopod similar to third ( Fig. 2j View Fig ). Fifth pereiopod very slender; ischium unarmed; merus more than twice length of ischium, about six times as long as wide at base; carpus slender, slightly longer than merus, with distal spinule; propodus about 1.3 length of carpus, ventrally with about 15 rows of setae, five-six spines and one slender distoventral spine proximal to dactylus; dactylus simple, slender, less than 1/3 length of propodus, slightly curved ( Fig. 2k, l View Fig ).
Abdominal segments I-III with posteroventral margins rounded; segment IV with posteroventral margin angular; segment V with posteroventral margin acutely projecting ( Fig. 1 View Fig ); segment VI with acute posterior projection, without articulated plate ( Fig. 1 View Fig ); preanal plate rounded posteriorly ( Fig. 2n View Fig ). Second pleopod with appendix masculina slightly shorter than appendix interna, with row of slender spines along mesial margin ( Fig. 2m View Fig ). Telson about twice as long as wide proximally; basal width about twice width of posterior margin; dorsal surface with two pairs of spines situated at some distance from lateral margin, at about mid-length and 3/4 length of telson, respectively ( Fig. 2o View Fig ); posterior margin with shallow median notch bearing two setae and two pairs of spines, lateral shorter than mesial ( Fig. 2p View Fig ); anal tubercles absent. Uropods slightly longer than telson; sympodite with acute tooth; diaeresis sinuous; lateral spine well developed ( Fig. 2o View Fig ).
Gill formula typical for genus: pleurobranchs above first to fifth pereiopods; arthrobranch above third maxilliped; podobranch absent; lobed epipods on first and second maxillipeds; mastigobranchs (strap-like epipods) on third maxilliped and first to fourth pereiopods; sets of setobranchs on first to fifth pereiopods; exopods on first to third maxillipeds.
Colour. – Whitish to pale yellowish.
Habitat. – The specimen was collected by hand under a medium-sized stone on muddy sand, at a depth of about 10 m, together with several specimens of another alpheid shrimp, Athanas parvus De Man, 1910 . The site is a transition zone between a coral reef and a sand plain, and is a muddy sand bottom with numerous dead fungiid and branching corals, coral rubble and stones, all partly covered by mud and sand.
Etymology. – Salmoneus nhatrangensis , new species, is named after the type locality, Nhatrang Bay, Vietnam.
Remarks. – The new species appears to have affinities with several species characterized by the fingers of the major cheliped armed with numerous small teeth, the merus of the major cheliped not inflated and ventrally not excavated, the eyes dorsally concealed by the orbital hoods and the carapace lacking strong mediodorsal carina. These are S. serratidigitus ( Coutière, 1896) , S. latirostris ( Coutière, 1896) , S. sibogae (De Man, 1910) , S. hilarulus (De Man 1910) , S. mauiensis ( Edmondson, 1930) , S. babai Miyake & Miya, 1966 in the Indo-Pacific, and S. teres Manning & Chace, 1990 , S. setosus Manning & Chace, 1990 and S. arubae ( Schmitt, 1936) in the Atlantic.
The new species can be separated from the problematical S. serratidigitus , as described by Coutière (1896, 1899), and redescribed by Banner & Banner (1981), by several features. It differs from S. serratidigitus in the shape of the rostrum, being much shorter and broader, with lateral margins proximally convex (vs. longer, more slender, not convex proximolaterally in S. serratidigitus ); and the orbital teeth being directed mesially towards the rostrum (vs. directed anteriorly in S. serratidigitus ). In S. nhatrangensis , new species, the stylocerite does not reach the distal margin of the second segment of the antennular peduncle, while in S. serratidigitus , the stylocerite clearly exceeds this margin. The minor cheliped of S. nhatrangensis , new species, is shorter and more robust compared to that of S. serratidigitus . The major cheliped is similar although there is a small difference in the number of teeth on the cutting edges of the fingers: 9- 10 in S. nhatrangensis , new species, and 12-13 in S. serratidigitus . The live colour of S. serratidigitus was described by Coutière (1899) as bright yellow-orange, while that of S. nhatrangensis , new species, was noted as whitish.
Salmoneus nhatrangensis , new species, differs from S. sibogae , as described and illustrated by De Man (1911, 1915) by the same morphological criteria as S. serratidigitus , except for the minor cheliped (unknown in S. sibogae sensu De Man ), the number of teeth on the fingers of the major chela (9-10 in both S. sibogae and S. nhatrangensis , new species) and the colour pattern (unknown in S. sibogae sensu De Man ). A further point of difference is the median notch on the posterior margin of the telson: broad and triangular in S. sibogae , but small, shallow and rounded in S. nhatrangensis , new species.
Salmoneus nhatrangensis , new species, appears to be most closely related to the poorly described S. latirostris from the Red Sea and the Gulf of Aden ( Coutière, 1896, 1899), differing from the latter however, by the shorter rostrum and the shape of the extra-corneal teeth. More importantly, the colour pattern of S. latirostris was described as transversely banded with red and white ( Coutière, 1899; Banner & Banner, 1981), while our specimen of S. nhatrangensis , new species, did not have red bands.
The new species can be separated from S. hilarulus and S. brevirostris ( Edmondson, 1930) by the very different shape of the frontal margin (cf. De Man, 1911, 1915; Edmondson, 1930). Salmoneus nhatrangensis , new species, can be differentiated from S. mauiensis by the shape of the rostrum; the greater number of teeth on the fingers of the major chela (6 in S. mauiensis , 9-10 in the new species); and the shape of the posteromedian notch on the telson (broad, conspicuous in S. mauiensis , small, inconspicuous in the new species). Salmoneus nhatrangensis , new species, cannot be confused with S. babai , which is characterized by the very unequal fingers on the major chela and very stout dactylus on the third to fifth pereiopods (Miyake & Miya, 1966). Furthermore, both S. mauiensis and S. babai were described as bright orange-yellow or yellow ( Edmondson, 1930; Miyake & Miya, 1966).
The new species markedly differs from the first two of the afore-mentioned Atlantic species. It differs from S. arubae by the configuration of the frontal margin; the presence of a small, posteromedian notch on the telson; and the general shape of the major cheliped ( Schmitt, 1936; Holthuis, 1990). It differs from S. setosus by the absence of thick, erect setae on the carapace and the abdomen; the configuration of the frontal margin; and the shape of the major cheliped (Manning & Chace, 1990). The last species, S. teres , surprisingly shows close affinities to S. nhatrangensis , new species, especially in the configuration of the telson, the frontal region, including the rostrum, and most features on the first to fifth pereiopods. However, the new species from Vietnam can be separated from S. teres by the presence of two strong spines on the ischium of the third pereiopod (lacking in S. teres ); the more pronounced incisions between the rostrum and the extra-corneal teeth; the major chela bearing complex grooves near the articulation with the dactylus; and a blunt process near the pollex.
The small, rounded depressions or pits on the carapace, giving it a somewhat granulated appearance, were previously observed only in S. arubae ( Holthuis, 1990) and S. aff. sibogae ( Banner & Banner, 1982) . The pits or interconnected depressions are also present in S. teres (R. Lemaitre, pers. comm.; A. Anker, pers. obs.), a new species close to S. teres from Brazil (Anker, in prep.), S. nhatrangensis , new species, and another new species described below. The presence or absence of these pits could prove to be a further important taxonomic character for species of the genus Salmoneus .
Distribution. – Presently known only from the type locality, Nhatrang Bay, Vietnam.
| ZMMU |
Zoological Museum, Moscow Lomonosov State University |
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