Salmoneus alpheophilus, Marin, 2006

Marin, Arthur Anker Ivan N., 2006, New Records And Species Of Alpheidae (Crustacea: Decapoda) From Vietnam. Part I. Genus Salmoneus Holthuis, 1955, Raffles Bulletin of Zoology 54 (2), pp. 295-319 : 310-313

publication ID	https://doi.org/ 10.5281/zenodo.13245424
persistent identifier	https://treatment.plazi.org/id/03AB572D-FFEB-FFA4-FF5B-FA90FE15DFC6
treatment provided by	Felipe
scientific name	Salmoneus alpheophilus
status	sp. nov.

Treatment

Salmoneus alpheophilus View in CoL , new species

( Figs. 12 View Fig , 13 View Fig )

Material examined. – Holotype, ovigerous female (CL 3.9, TL 10.8)( ZMMU Ma 5446), South China Sea , Vietnam, Nhatrang Bay , Tre Island, Dam Bay, 12 ° 10'20"N 109 ° 15'30"E, tidal sand-mud flat, low tide, in burrow of goby-associated Alpheus sp. , bait suction (yabby) pump, coll. I. Marin, 4 Jun.2004. GoogleMaps

Paratypes: 1 post-ovigerous female (CL 4.5, TL 13.3)( ZMMU Ma 5447) [dissected], same data as for holotype, from the same burrow; 1 non ovigerous specimen (CL 4.5, TL 13.0)( ZMMU Ma 5448) [major cheliped lacking], same data as for holotype, from a different burrow GoogleMaps .

Description. – Carapace setose ( Fig. 12a, e View Fig ), without pits, laterally with slight suture starting from lateral margin proximal to base of antenna ( Figs. 12c View Fig ), dorsally with small postrostral tubercle ( Fig. 12b, c View Fig ). Rostrum long, slender, reaching to about 3/4 of second segment of antennular peduncle ( Fig. 12b View Fig ), much longer than broad at base; ventral margin with conspicuous subapical tooth ( Fig. 12 View Fig c-e); lateral margins slightly concave ( Fig. 12b View Fig ); rostral carina feebly developed. Extra-corneal teeth relatively small, acute, directed anteriorly or anteromesially; margin between rostrum base and extra-corneal teeth broadly U-shaped ( Fig. 12b View Fig ). Pterygostomial angle rounded. Eyes with small anteromesial tubercle, largely exposed in dorsal and lateral view ( Fig. 12 View Fig a- e, j, k). Epistomial sclerite with strong acute process. Ocellar beak inconspicuous, situated well below and between eyes.

Antennular peduncle stout, second segment slightly shorter than visible portion of first segment, subequal to third segment; ventromesial carina of first segment with acute tooth as illustrated ( Fig. 12f View Fig ); stylocerite reaching between half and 2/3 length of second segment, distally acute ( Fig. 12b, c View Fig ); lateral flagellum biramous, with shorter ramus situated at third segment ( Fig. 12c View Fig ). Antenna with basicerite bearing medium-sized ventrolateral tooth ( Fig. 12c View Fig ); scaphocerite oval, broad, anterior margin of blade convex, slightly exceeding distolateral tooth ( Fig. 12b View Fig ); carpocerite short, reaching slightly beyond half length of scaphocerite ( Fig. 12c View Fig ).

Mouthparts not dissected, appearing typical for genus in external view. Third maxilliped slender ( Fig. 13g View Fig ); lateral plate rounded ( Fig. 13h View Fig ); ultimate segment distally tapering, with two small subapical spines and one apical spine ( Fig. 13i View Fig ); arthrobranch well-developed ( Fig. 13h View Fig ).

First pereiopods (chelipeds) very asymmetrical, unequal ( Figs. 13a, d View Fig ), carried flexed ventrally in life, mesially when preserved ( Fig. 12a View Fig ); major cheliped ( Fig. 13 View Fig a-c) with ischium slightly elongate, armed with strong ventral spine ( Fig. 13a View Fig ); merus slender, elongate, distally slightly widening, ventrally depressed; carpus cup-shaped ( Fig. 13a, b View Fig ), ventrally with deep grooves, distally with lobes ( Fig. 13b, c View Fig ); chela somewhat swollen, subcylindrical; palm longer than fingers, proximoventrally with deep complex groove ( Fig. 13b View Fig ), continuing as notch on mesial surface ( Fig. 13a, c View Fig ), rest of palmar surface smooth; pollex with cutting edge bearing 14 rounded-triangular, regularly spaced teeth, distal portion unarmed, tip strongly curved; dactylus with cutting edge bearing 13 teeth, most distal portion unarmed, tip curved ( Fig. 13c View Fig ). Minor cheliped slender; ischium elongate, shorter than merus, armed with spine ventrally; carpus subequal to merus, subcylindrical, distally slightly widening; chela simple, not enlarged, fingers about as long as palm, cutting edges unarmed ( Fig. 13d View Fig ).

Second pereiopod slender; ischium about 5/6 length of merus, armed with two spines ventrally ( Fig. 13e View Fig ); carpus with five segments having ratio of approximately 7/2/1/1.5/2.5; chela simple, fingers as long as palm ( Fig. 13e View Fig ). Third pereiopod slender; ischium with two spines ( Fig. 12f View Fig ); merus slender, 1.3 times length of ischium, six times as long as wide at base; carpus more slender and shorter than merus, with small ventral spine distally; propodus slightly longer than carpus, ventrally with three slender spinules and one slender distoventral spine proximal to dactylus; dactylus simple, slender, about half length of propodus, slightly curved ( Fig. 12f View Fig ). Fourth pereiopod generally similar to third ( Fig. 12a View Fig ). Fifth pereiopod slender, ischium unarmed; merus slightly longer than carpus; propodus longer than carpus, ventral margin with several slender spinules, distal 3/5 with at least 13 rows of setae ventrolaterally; dactylus similar to that of third pereiopod, slightly expanded proximally.

Abdominal segments I-III with posteroventral margins rounded; segment IV with posteroventral margin angular; segments V and VI with posteroventral angles acutely projecting ( Fig. 12a View Fig ); segment VI with acute posterior projection near telson, without articulated plate ( Fig. 12a View Fig ); preanal plate rounded posteriorly ( Fig. 12g View Fig ). Second pleopod with appendix masculina shorter than appendix interna, bearing slender spines on tip and along lateral margins ( Fig. 13j View Fig ). Telson more than twice as long as wide proximally; basal width less than 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 telson length, respectively ( Fig. 12h View Fig ); posterior margin with shallow Ushaped median cleft furnished with four long plumose setae and two pairs of spines, lateral slightly shorter than mesial ( Fig. 12i View Fig ); anal tubercles absent. Uropods slightly longer than telson ( Fig. 12a View Fig ); sympodite with acute tooth; diaeresis simple, slightly sinuous; lateral spine small. Gill formula typical for genus: see under S. nhatrangensis , new species. Ovigerous female with six remaining eggs (diameter 0.8 x 0.5 mm).

Colour. – White-semitransparent, eggs or gonads bright yellow.

Habitat. – Intertidal sand-mud flats, fringed with mangroves, in burrows of Alpheus species ( A. cf. rapacida De Man, 1909 , A. sp. aff. bellulus Miya & Miyake, 1969 and Alpheus sp. ) associated with gobies ( Cryptocentrus cf. leptocephalus Bleeker, 1876 and Cryptocentrus sp. ). Salmoneus alpheophilus , new species, probably live as facultative commensals in these burrows, similar to S. rostratus Barnard, 1962 (see below).

Etymology. – The specific name (“ Alpheus -loving”) is the reference to the habits of S. alpheophilus , new species, to dwell in burrows of Alpheus species.

Variation. – Slight variation exists in the shape and length of the rostrum (see Fig. 12c, j, k View Fig ).

Remarks. – Salmoneus alpheophilus , new species, appears to be related to S. gracilipes , S. colinorum , S. falcidactylus , new species, S. pusillus , new species (see above), S. seticheles , S. cavicolus , and possibly the problematic S. tafaongae . However, the unique combination of several morphological features enables a separation of S. alpheophilus , new species, from all these species. For instance, it may be distinguished from S. gracilipes , S. colinorum and S. falcidactylus , new species, by the presence of a robust spine on the ischium of both chelipeds and two spines on the ischium of the second pereiopod (cf. Miya, 1972, 1984; De Grave, 2004; see also above); from S. seticheles by the absence of long flexible setae on the major chela (cf. Anker, 2003b); and from S. tafaongae by the much shorter rostrum (cf. Banner & Banner, 1966a). For distinction between S. pusillus , new species, and S. alpheophilus , new species, see under the former species.

Salmoneus alpheophilus , new species, shares many features with the western Atlantic S. cavicolus , e.g. the general shape of the rostrum, the presence of a small tubercle on the anteromesial margin of the eyestalk, and a spine on the ischia of the first and second pereiopods (cf. Felder & Manning, 1986). However, S. alpheophilus , new species differs from S. cavicolus by the much stouter second segment of the antennular peduncle, almost as long as wide (vs. much longer than wide in S. cavicolus ), and the posterior margin of the telson bearing a small rounded median cleft (vs. straight in S. cavicolus ) (cf. Felder & Manning, 1986).

Distribution. – Presently known only from the type locality, Nhatrang Bay, Vietnam.