Synalpheus bispinosus 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. 355-435 : 359-361

3.2.1 Synalpheus bispinosus de Man, 1910 ( Fig. 1 )

Synalpheus bispinosus de Man, 1910 . Tijdschr. ncd. dierk. Vereen., 11(4): 302; 1911, Siboga Exped. , 39(2): 280, fig. 54.

Material examined. ( MBM 270524), 1♀, 1♂, CL 10.1 mm, TL 30.1 mm; CL 8.5 mm, TL 24.0 mm Tonkin Gulf (Beibu Gulf), Sta. 7502, depth 32 m, 21 August 1962; ( MBM 159286), 1♂, CL 2.5 mm, TL 6.3 mm, Yezhu Island N-side, depth 9 m, 21 March 1992; ( MBM 270607), 2♂, CL 4.5 mm, TL 11.5 mm, Tonkin Gulf (Beibu Gulf), Sta. 6218, depth 62 m, 18 April 1960, coll. Zhen-Gang Fan; ( MBM 270606), 1♀, 1♂, CL 6.8 mm, TL 17.5 mm; CL 6.1 mm, TL 16.5 mm, Tonkin Gulf (Beibu Gulf), Sta. 6276, depth 26 m, 7 July 1960, coll. Shou-Peng Shen; ( MBM 270475), 1♂, CL 4.5 mm, TL 11.5 mm, Tonkin Gulf (Beibu Gulf), Sta. 7902, depth 59 m, 10 October 1962; ( MBM 270601), 1♀, CL 5.1 mm, TL 12.8 mm, Tonkin Gulf (Beibu Gulf), Sta. 7503, depth 47 m, 15 January 1962, coll. Fu-Zeng Sun; ( MBM 107770), 1♂, CL 4.5 mm, TL 11.1 mm, Yalong Bay, Yezhu Island N-coast, depth 8 m, from dead coral, 27 March 1992, coll. Newmann.

Description. Carapace smooth, glabrous; rostrum twice as long as wide at base, with lateral margins slightly convex, rounded tip bearing two short setae, reaching 1/2 length of visible part of first segment of antennular peduncle; orbital hoods three times as wide at base as rostrum, subequal to rostrum, with rounded tip bearing two short setae, notches between orbital hoods and rostrum V-shaped; pterygostomial corner produced into blunt acute angle.

Abdominal somites smooth, glabrous, posterolateral margin of sixth pleura each with one acute tooth; first-three pleura with posterior corner rounded; fourth and fifth pleura with lower margin produced into acute angle. Telson about 1.2 times as long as wide at base; lateral margin slightly concave posteriorly; dorsal surface with median groove, with two pairs of large spines, inserted approximately at 1/6 and 1/2 length of telson; posterior margin strongly convex, fringed with long setae, posterolateral angle each with two pairs of spines, lateral 1/2 length of mesial, posterolateral corner right angle.

Eyes concealed in lateral and dorsal view.

Antennular peduncle with distally acute stylocerite, latter reaching 1/3 of second segment of antennular peduncle; second segment twice as long as wide; visible part of first segment longer than second and about twice as long as third. Antenna with basicerite with acute distodorsal tooth, 1/4–1/3 length of distolateral tooth, latter subequal to stylocerite; carpocerite beyond end of antennular peduncle by length of third segment; scaphocerite blade narrow, 4/5 length of third segment of antennular peduncle, lateral spine with lateral margin slightly concave posteriorly, overreaching end of third segment, shorter than carpocerite.

Third maxilliped far beyond antennular peduncle and carpocerite when extended; antepenultimate segment longest, about 5 times as long as wide; penultimate segment about 1.7 times as long as wide at base; tip of ultimate segment bearing crown of 5–6 spine-like setae, with several brush consisting of 6–8 transverse rows of setae along ventral margin.

Major cheliped with short, stout ischium; merus three times as long as wide at base, superodistal margin ending in subacute tooth; carpus cup-shaped, with long setae distodorsally; chela cylindrical, not a bit compressed or twisted, with palm about 3.3 times as long as dactylus, distodorsal tooth palm subacute, slightly upturned; dactylus distinctly longer than pollex.

Minor chela with ventral margin of ischium bearing long setae; merus about 3.4 times as long as wide, longer than that of major cheliped, superodistal margin rounded, without any projecting, ventral margin bearing row of short setae; carpus cup-shaped proportionally longer that of major cheliped; palm about 1.7 times as long as fingers, lateral face near dactylus bearing patch of stiff setae; dactylus tapering, with flexor margin concave, distal single tooth, lateral margin bearing row of long setae; pollex tapering, 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: 1: 1: 1: 2, with first segment shorter than sum of last four segment, segments 2–4 slightly wider than long; fingers 1.5 times as long as palm. Third pereiopod with merus longer than propodus, about 4.8 times as long as wide at base, without spines on ventral margin; carpus about 4/11 merus length, with dorsal margin extended into an obtuse tooth, ventral margin with one 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 subequal to flexor tooth; extensor tooth as wide as flexor at base; notch between extensor and flexor tooth U-shaped. Fourth pereiopod generally similar to third; but ventral margin of carpus without distal spine. Propodus of fifth pereiopod with six transversal rows of setae along ventral margin plus one pair of spines near dactylus.

Variation. The smaller specimens may be an immature male having those following two differences: propodus of third pereiopod with ten spines along ventral margin rather than usual seven spines; notch between extensor and flexor tooth V-shaped.

Remarks. Synalpheus bispinosus was originally described by de Man (1910). It is closely related to S. coutierei , but different by the posterior margin of the sixth abdominal. Although Banner & Banner (1975) doubted the validity of this species, they still accepted the specific name because of the stability of the above character and S. bispinosus had been not collected together with S. coutierei . Our research supports their point. The present specimens were also not collected with S. coutierei together, and the posterior margine of the sixth abdominal somite always bearing two spines on each side. Therefore, we also think S. bispinosus is a valid species.

This species maybe an social snapping shrimp, similar to the other six Synalpheus shrimp, including S. regalis , S. filidigitus , S. fossor , S. hastilicrassus , S. neptunus neptunus , S.aff. neomeris (Duffy & Macdonald, 1999; Didderen et al., 2006), because some female specimens own the characters (1–5 pleura with posterior corner rounded, and second pleura proportionally longer and wider, carried huge number of eggs, apparently more than the smaller ovigerous female), which are similar to the characters of “queen” reported before.

Distribution. South China Sea; Indonesia; Australia.

Figures

Fig. 1. Synalpheus bispinosus de Man, 1910, male (MBM 157976). a. Frontal region, lateral. b–c. Third maxilliped. b. Ventral. c. Tip, dorsal. d–e. Major cheliped. d. Lateral. e. Chela, mesial. f–g. Minor cheliped. f. Lateral. g. Chela, lateral. h. Second pereiopod, lateral. i–j. Third pereiopod. i. Lateral. j. Distal propodus and dactylus, lateral. k. Telson, dorsal. Scale bars: a–b, d–i, k= 1 mm; c, j=0.25 mm.