Synalpheus trispinosus de Man, 1910

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 : 424-428

3.2.30 Synalpheus trispinosus de Man, 1910 ( Figs 46–47 )

Synalpheus trispinosus de Man, 1910 . Tijdschr. ned. dierk. Vereen, 11(4): 300; 1911. Siboga Exped. , 39(2): 288, pl. 12, fig. 58; Banner & Banner, 1981. Zool. Med. Leiden, 190: 82; Banner & Banner, 1981. Mémoires Orstom. Vol. 91: 221, figs. 2a-c; Banner & Banner,

1983. Travaux et Documents de l’Orstom, 158: pl. 107.

Material examined. ( MBM 042237), 6♀, 6♂, CL 5.3–8.6 mm, TL 13.1–21.5 mm, East China Sea, Sta. 4082, depth 84 m, 1 July 1959; ( MBM 042234), 3♀, 3♂, CL 5.1–9.5 mm, TL 13.5–24.1 mm, East China Sea, Sta. 4082, depth 86 m, 25 October 1959, coll. Rui-Yu Liu; ( MBM 107822), 1♂, CL 6.2 mm, TL 14.1 mm, East China Sea, Sta. V-2, depth 99 m, 5 July 1976, coll. Zhi-Chan Tang; ( MBM 081144), 1♂, CL 5.6 mm, TL 13.9 mm, East China Sea, Sta. 4083, depth 90 m, 8 December 1959, coll. Yu-Hang Cui; ( MBM 081143), 1♀, CL 8.1 mm, TL 19.8 mm, East China Sea, Sta. 4061, depth 81m, 5 December 1959; ( MBM 270162), 1♀, 2♂, CL 5.9–9.1 mm, TL 14.3–22.5 mm, East China Sea, Sta. 4081, depth 81 m, 2 February 1959, coll. Jie-Shan Xu; ( MBM 042236), 4♀, 1♂, CL 6.6–8.8 mm, TL 14.9–22.5 mm, East China Sea, Sta. 4081, depth 79 m, 3 July 1959, coll. Li-Ren Cheng; ( MBM 042232), 1♀, 1♂, CL 9.2 mm, TL 20.5 mm, CL 7.1 mm, TL 15.2 mm, East China Sea, Sta. 4081, depth 79 m, 25 October 1959, coll. Bao-Lin Zhang, Rui-Yu Liu; 3♀, ( MBM 107825), 2♂, CL 5.4–7.7 mm, TL 12.1–17.9 mm, East China Sea, Sta. V-7, depth 100 m, 10 October 1975, coll. Zhi-Chan Tang, Jie-Shan Xu; ( MBM 042238), 1♀, CL 8.4 mm, TL 20.2 mm, East China Sea, Sta. 4081, depth 79 m, 9 December 1959, coll. Yu-Hang Cui; ( MBM 107814), 5♀, 2♂, CL 5.3–7.8 mm, TL 12.5–17.4 mm, East China Sea, Sta. V-3, depth 105 m, 27 August 1959, coll. Zhi-Chan Tang; ( MBM 158587), 1♀, CL 8.1 mm, TL 18.3 mm, East China Sea, Sta. 0108, depth 94m, 9 December 1959, coll. Yu-Hang Cui.

Description. Carapace smooth, glabrous; rostrum slender, about 3.7 times as long as wide at base, with lateral margins slightly convex, rounded tip bearing two short setae, varying from hardly reaching to slightly overreaching end of first segment of antennular peduncle, tip strongly curved upturned; orbital hoods distinctly shorter than rostrum, reaching middle of first segment of antennular peduncle, acute tip strongly curved upturned; pterygostomial corner produced into blunt acute angle; cardiac notch well developed.

Abdominal somites smooth, glabrous, posterior margin of sixth pleura with each angle one acute tooth, and an third tooth at middle, slightly shorter. Telson about 1.35 times as long as wide at base; lateral margin slightly concave posteriorly; dorsal surface with two pairs of moderately small spines, inserted approximately at 2/5 and 3/5 length of telson; posterior margin strongly produced, fringed with long setae, posterolateral angle each with two pairs of shorter spines, lateral slightly longer than mesial, posterolateral margins each produced into acute large tooth, slightly longer than lateral spines.

Eyes concealed in dorsal view, slightly exposed in lateral view.

Antennular peduncle slender, with distally acute stylocerite, latter reaching about 1/5 length of second segment of antennular peduncle, longer than or as long as rostrum; second segment about twice times as long as wide; visible part of first segment longer than second and more than twice as long as third. Antenna with basicerite with acute distodorsal tooth, less 1/2 length of distolateral tooth, latter distinctly shorter than stylocerite; carpocerite slightly beyond end of antennular peduncle; scaphocerite blade moderately narrow, hardly reaching end of third segment of antennular peduncle, lateral spine developed, with lateral margin slightly concave posteriorly, slightly overreaching end of antennular peduncle, shorter than carpocerite.

Third maxilliped far beyond antennular peduncle and carpocerite when extended; antepenultimate segment longest; penultimate segment twice as long as wide at base; tip of ultimate segment bearing crown of five long spine-like setae, with several transverse rows of setae along ventral margin.

Major cheliped with short, stout ischium; merus about 3.25 times as long as wide at base, superodistal margin without triangular tooth, but infero-external and infero-external margin each bearing acute triangular tooth; carpus cup-shaped, with setae distodorsally; palm about twice as long as dactylus, distodorsal of palm with one large triangular tubercle directed obliquely upturned, bearing fine setae; dactylus distinctly longer than pollex, bearing fine setae.

Minor chela with merus about 4.5 times as long as wide, longer than that of major cheliped, superodistal margin without any projecting; carpus cup-shaped, proportionally longer that of major cheliped; palm about 1.1 times as long as fingers; dactylus and pollex tapering, distal single tooth.

Second pereiopod with ischium shorter than merus; carpus five-segmented, segment ratio subequal to 6: 1: 1: 1: 2, with first segment longer than sum of last four segment; dorsal margin of palm convex; fingers subequal to palm. Third pereiopod moderately stout; merus subequal to propodus, about 3.7 times as long as wide at base, with 5–9 spines on ventral margin; carpus about 1/3 merus length, with dorsal margin extended into an obtuse tooth, ventral margin with one distal spine; propodus with nine spines along ventral margin plus one distal pair of spines near dactylus, dorsal margin with fine setae; dactylus around 1/8 propodus length, biunguiculate, extensor tooth longer than flexor tooth, and as wide at base as flexor tooth, notch between extensor and flexor tooth U-shaped. Fourth pereiopod generally similar to third; ventral margin of merus with six spines; ventral margin of carpus with one distal spine. Fifth pereiopod similar to third and fourth pereiopods, but ventral margin of carpus without distal spine, with merus about 3.3 times as long as wide, ventral margin without spines; carpus about 3/4 merus length, ventral margin without distal spine; propodus as long as merus, with 6–9 transversal rows of setae and 3 spines along ventral margin.

Remarks. The species was original described by de Man (1910) based on a ovigerous female and a younger specimen collected from southern part of Molo-strait, in a depth 54–90 meters. The original description was actually rather simple and without figures. Synalpheus trispinosus was taken as a new species according to the posterior margin of sixth abdominal somite being trispinose. De Man (1911) redescribed this species in detail and provided some figures, based on the type materials.

S. trispinosus is morphologically most similar to S. triacanthus de Man, 1910 in the spines on the posterior margin of sixth abdominal somite. However, the merus of third pereiopods in S. triacanthus is not bearing spines, which can be separated from S. trispinosus .

The present materials (40 specimens), collected from the East China Sea, in the depth 79–105 meters, are agreed well with the holotype illustrated in de Man (1911), except the length of rostrum, which is variable from hardly reaching to slightly overreaching the end of first segment of the antennular peduncle.

Distribution. East China Sea, South China Sea; Gulf of Aden and eastern Africa to Philippines and Indonesia.

Figures

Fig. 46. Synalpheus trispinosus de Man, 1910, female (cl 9.5mm) (MBM 042234). a–b. Frontal region. a. Lateral. b. Dorsal. c. Third maxilliped, tip, ventral. d–f. Major cheliped. d. Mesial. e. Chela, mesial. f. Merus, lateral. g–h. Minor cheliped. g. Mesial. h. Chela, lateral. i. Second pleopod. Scale bars=1 mm.

Fig. 47. Synalpheus trispinosus de Man, 1910. a–i. Male (cl 9.5 mm) (MBM 042234). a. Second pereiopod, lateral. b–c. Third pereiopod. b. Lateral. c. Distal propodus and dactylus, lateral. d. Fourth pereiopod, lateral. e–f. Fifth pereiopod. e. Lateral. f. Propodus and dactylus, ventral. g. Telson and uropod, dorsal. h. Third maxilliped, ventral. i. Abdomen, lateral. j. Female (cl 9.5 mm) abdomen, lateral. Scale bars: a–b, d–j=1 mm; c =0.5 mm.