Synalpheus liui, Wang & Sha, 2015

Wang, Yan-Rong & Sha, Zhong-Li, 2015, A review of the genus Synalpheus (Crustacea: Decapoda: Caridea: Alpheidae) from China seas, Zoological Systematics 40 (4), pp. 357-435 : 394-397

Synalpheus liui sp. nov.

( Figs 26–28 )

Material examined. Holotype. (MBM 283382), non-ovigerous individual, CL 3.2 mm, TL 8.1 mm, Zhubi Jiao, Nansha Islands, Sta. 9 (10°54.997′N, 114°05.813′E), depth 3 m, 5 May 2004, coll. Yong-Liang Wang from coral reef. Paratype (MBM 283382), non-ovigerous individual, CL 4.3 mm, TL 9.6 mm, same data as holotype.

Description. Carapace smooth, glabrous; rostrum with lateral margins slightly convex, rounded tip reaching 1/2 length of visible part of first segment of antennular peduncle, bearing two short setae, slightly upturned; orbital hoods about 1.5 as wide at base as rostrum, length almost equal to rostrum, rounded tip bearing two short setae, slightly upturned; pterygostomial corner produced into blunt acute angle.

Abdominal somites smooth, glabrous, posterolateral margin of sixth pleura each with one blunt tooth, posterior corner of first pleura bluntly produced ventrally; second-fifth with lower margin produced into acute angle. Telson about 1.1 as long as wide at base; lateral margins slightly concave posteriorly; dorsal surface slightly convex, with median groove, with two pairs of large spines, inserted approximately at 2/5 and 1/2 length of telson; posterior margin not produced, slightly concave, fringed with long setae, posterolateral angle each with two pairs of spines, lateral 1/2 length of mesial, posterolateral margins forming right angles. Eyes concealed in lateral and dorsal view.

Antennular peduncle with distally acute stylocerite, latter hardly reaching distal margin of first segment of antennular peduncle; second segment distinctly longer than wide; visible part of first segment longer than second and about twice as long as third segment. Antenna with basicerite with acute distodorsal tooth, 1/2 length of distolateral tooth, subequal to stylocerite, distolateral tooth distinctly longer than stylocerite, overreaching middle of second antennular segment; carpocerite beyond end of antennular peduncle by the length of third segment; scaphocerite blade narrow, reaching end of second segment of antennular peduncle, lateral spine robust, with lateral margin slightly concave posteriorly, overreaching antennular peduncle, shorter than carpocerite.

Mouthparts not dissected. Third maxilliped far beyond antennular peduncle and carpocerite when extended; antepenultimate segment longest, about five times as long as wide; penultimate segment about 2.5 times as long as wide at base; tip of ultimate segment bearing crown of 5–6 spine-like long setae, with several brush consisting of 6–8 transverse rows of setae along ventral margin. Origin of marginal setae on pleopod two exopod close to base.

Major cheliped with merus 3.8 times as long as wide at base, superodistal margin with acute triangular tooth, inferointernal margin with acute tooth; carpus cup-shaped, with setae distodorsally; chela cylindrical, not a bit compressed or twisted, with palm about 2.6 times as long as dactylus, superodistal margin produced into prominent tubercle with little subacute ventrally directed tooth; dactylus distinctly longer than pollex.

Minor chela with merus about 4.4 times as long as wide, longer than that of major cheliped, superodistal margin with acute triangular tooth; carpus cup-shaped, proportionally longer than that of major cheliped; palm 1.5 times as long as fingers; dactylus excavate and denticulate, with flexor margin slightly convex, distal with one large tooth medially, smaller tooth adjacently, lateral margin bearing row of long setae; pollex tapering distally, with flexor surface obliquely convex, distal single tooth, lateral margin bearing row of long setae.

Second pereiopod with ischium distinctly shorter than merus; carpus five-segmented, segment ratio subequal to 4.7: 1: 1: 1: 2.1, with first segment little shorter than sum of last four segments; fingers 1.2 times as long as palm. Third pereiopod stout; merus longer than propodus, about three times as long as wide, without spines on ventral margin; carpus about 1/2 merus length, with dorsal margin extended into an obtuse tooth, ventral margin with one long distal spine; propodus with usual seven spines along ventral margin plus one distal pair of spines near dactylus; dactylus around 1/6 propodus length, biunguiculate, moderately slender, extensor tooth 1.5 times length of flexor tooth, thicker at base than flexor tooth, notch between extensor tooth and flexor tooth V-shaped. Fourth pereiopod generally similar to third; but ventral margin of carpus without distal spine. Fifth pereiopod stout, with merus about three times as long as wide, without spines on ventral margin; carpus about 7/9 merus length, ventral margin without distal spine; propodus slightly longer than merus, with one moveable spine and 7–9 transverse rows of short setae along on ventral margin plus one distal pair of spines near dactylus, dactylus similar that of three and four pereiopod.

Etymology. The specific name is in honor of Prof. J-Y Liu (Institute of Oceanology, Chinese Academy of Sciences).

Type locality. Zhubi Jiao, Nansha Islands.

Distribution. Zhubi Jiao, presently known only from the type locality in Nansha Island, South China Sea.

Remarks Synalpheus liui sp. nov. can be distinctly distinguished by following characters: posterolateral margin of sixth pleura each with 1 blunt tooth; the palm of major cheliped with superodistal margin produced into prominent tubercle with little subacute ventrally directed tooth; the longer distodorsal tooth of basicerite, which subequal to the stylocerite, and the longer tooth of uropods of protopodite, which was 1/2 length of outer uropod.

There are another 9 species in the Indo-Pacific waters with the posterior margin of the sixth pleura armed with 2, 3, 4 or 7 teeth, S. septemspinosus de Man, 1910 (7 teeth), S. mortenseni Banner & Banner, 1985 (7 teeth), S. quadrispinosus de Man, 1910 (4 teeth), S. trispinosus de Man, 1910 (3 teeth), S. triacanthus de Man, 1910 (3 teeth), S. bispinosus de Man, 1910 (2 teeth), S. cretoculatus Banner & Banner, 1979 (2 teeth), S. sciro Banner & Banner, 1975 (2 teeth) and S. pescadorensis Coutière, 1905 (2 teeth). The later four species show same number of teeth. However, the new species has the dactylus of minor chela excavate and denticulate, while tapering in S. bispinosus and S. cretoculatus .

S. liui sp. nov. is morphologically very similar to S. sciro and S. pescadorensis by following characters: orbital hoods subequal in length to rostrum, slightly upturned at tip and without orbitorostral process, dactylus and pollex of minor chela broadened and excavate to tip, dactylus of the third pereiopod, extensor tooth longer than flexor, and thicker at base than flexor tooth, and dorsal surface of telson all bearing two pairs of large moveable spines. But it can easily be distinguished from S. sciro by following: protopodite of uropods with tooth about 1/2 length of outer uropod rather than usual 1/3 length of outer uropod, distodorsal tooth of basicerite subequal to stylocerite rather than distinctly shorter than stylocerite, second pereiopod with the first segment of carpus little shorter than the sum of four following rather than little longer. S. liui sp. nov. is different from S. pescadorensis by following: distolateral tooth of basicerite reaching to middle of second antennular segment rather than end of first antennular segment; distodorsal tooth hardly reaching end of first antennular segment rather than half as long as inferior tooth, merus of major and minor chela with superodistal margin bearing acute triangular tooth rather than without any projecting, and tips of third maxilliped bearing crown of 5–6 spine-like long setae rather than only setae.

Figures

Fig. 26. Synalpheus liui sp. nov., male (cl 3.2 mm) (MBM 283382). a–b. Frontal region. a. Dorsal view. b. Lateral view. c. Left third maxilliped, lateral view. d–e. Large chela. d. Dorsal view. e. Lateral view. f–g. Small chela, lateral view. f. Total. g. Fingers. h. Merus. Scale bars: a, b, d–h=1 mm; c=0.5mm.

Fig. 27. Synalpheus liui sp. nov. male (cl 3.2mm) (MBM 283382). a. Left second pereiopod, lateral view. b. Left third pereiopod, lateral view. c. Dactylus of third pereiopod, lateral view. d. Abdomen and telson, later view. e. Telson, dorsal view. Scale bars: a–b, d =1 mm; c, e=0.5mm.

Fig. 28. Synalpheus liui sp. nov. male (cl 3.2 mm) (MBM 283382). a. Distal of minor chela dactylus, lateral view. b. Left Third maxilliped, dorsal view. c. Left four pereiopod, lateral view. d. Left five pereiopod, lateral view. e. Left two pleopod. f. Left uropod. Scale bars: a=0.2mm; b–f =0.5 mm.