Synalpheus streptodactylus Coutière, 1905

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 : 417-421

3.2.27 Synalpheus streptodactylus Coutière, 1905 ( Figs 41–43 )

Synalpheus neomeris streptodactylus Coutière, 1905 . Fauna and Geog. Maid, and Laccad., 2(4): 870, fig. 1.

Alpheus neomeris de Man, 1897 . Zool. Jb. Syst., 9: 734 (partim); Coutière, 1905, Op. Cit.: 869, fig. 1.

Synalpheus streptodactylus de Man, 1911 . Siboga Exped. , 39(2): 226, pl. 7, fig. 29; Banner & Banner, 1975. Records of the Australian Museum, 29(12): pl. 362, fig. 23.

Synalpheus metaneomeris streptodactylus Coutière, 1921 . Trans. Linn. Soe. Lond. II, 17(4): 414, pl. 60, fig. 4.

Synalpheus streptodactylus streptodactylus Banner & Banner, 1966 . Pacif. Sci., 20(2): 157; 1966. Siam Soc. Mono., 3, p. 50, fig. 14; Miya, 1972. Publ. Amakusa Mar. Biol. Lab., 3(1): 69, pl. 14.

Synalpheus streptodactylus hadrungus Banner & Banner, 1966 . Pacif. Sci., 20(2): 158.

Synalpheus jedanensis Barnard, 1950 . Ann. S. Afr. Mus., 38: 738, fig. 139c—i (nec de Man); Fourmanoir, 1958. Naturaliste malgache, 10(1–2): 115, fig. 3 (nec de Man).

Material examined. CL 3.2–5.7 mm, TL 6.5–12.4 mm. ( MBM 270607), 1♂, Tonkin Gulf (Beibu Gulf), Sta. 6216, depth 67 m, 10 April 1962, coll. Fu-Zeng Sun; ( MBM 270607), 1♂, Tonkin Gulf (Beibu Gulf), Sta. 6216, depth 67 m, 10 April 1962, coll. Fu-Zeng Sun; ( MBM 270216), 1 ovigerous ♀, Tonkin Gulf (Beibu Gulf), Sta. 6216, depth 57 m, 13 March 1960, coll. Fu-Zeng Sun; ( MBM 270223), 1♂, Tonkin Gulf (Beibu Gulf), Sta. 6252, depth 56.2 m, 7 July 1960, coll. Shou-Peng Shen; ( MBM 270222), 1 non-ovigerous, Tonkin Gulf (Beibu Gulf), Sta. 6251, depth 47 m, 7 February 1960, coll. Zhen-Gang Fan; ( MBM 270221), 1 non-ovigerous, Tonkin Gulf (Beibu Gulf), Sta. 6262, depth 49.6 m, 7 July 1960, coll. Zhen-Gang Fan; ( MBM 270219), 2♂, Tonkin Gulf (Beibu Gulf), Sta. 6273, depth 46 m, 25 October 1960, coll. Shou-Peng Shen; ( MBM 270220), 1♂, Tonkin Gulf (Beibu Gulf), Sta. 6222, depth 24 m, 13 February 1960, coll. Zhen-Gang Fan, Si-Ming Lv; ( MBM 270217), 1♂, Tonkin Gulf (Beibu Gulf), Sta. 6249, depth 30.5 m, 13 July 1960, coll. Fu-Zeng Sun; ( MBM 270227), 1♂, Tonkin Gulf (Beibu Gulf), Sta. 7405, depth 65 m, 12 October 1962; ( MBM 107815), 1♂, East China Sea, Sta. III-4, depth 82 m, 27 June 1976, coll. Shou-Peng Shen; ( MBM 107813), 2 non-ovigerous, Tonkin Gulf (Beibu Gulf), Sta. 7405, depth 42 m, 12 January 1962, coll. Shou-Peng Shen; ( MBM 270197), 1 ovigerous ♀, East China Sea, Sta. III-4, depth 82 m, 27 June 1976, coll. Shou-Peng Shen; ( MBM 081123), 1 ovigerous ♀, East China Sea, Sta. 4083, depth 89 m, 24 October 1959, coll. Riu-Yu Liu; ( MBM 270415), 1 non-ovigerous, Tonkin Gulf (Beibu Gulf), Sta. 7404, depth 49.6 m, 13 October 1962; ( MBM 270226), 1♂, Tonkin Gulf (Beibu Gulf), Sta. 6262, depth 51.5 m, 8 February 1960, coll. Zhen-Gang Fan; ( MBM 270201), 1♂, Tonkin Gulf (Beibu Gulf), Sta. 6167, depth 48 m, 8 February 1960, coll. Fu-Zeng Sun; ( MBM 270218), 1♂, Tonkin Gulf (Beibu Gulf), Sta. 6243, depth 93 m, 11 December 1959, coll. Xiu-Tong Ma; ( MBM 270472), 1 ovigerous ♀, 2 non-ovigerous, Tonkin Gulf (Beibu Gulf), Sta. 6182, depth 18 m, 11 February 1960, coll. Fu-Zeng Sun; ( MBM 270453), 9 ovigerous ♀, Tonkin Gulf (Beibu Gulf), Sta. 6276, depth 29 m, 6 November 1960, coll. Bao-Lin Zhang; ( MBM 270363), 1♂, Tonkin Gulf (Beibu Gulf), Sta. 7302, depth 30 m, 10 April 1962, coll. Fu-Zeng Sun; ( MBM 270452), 1♂, Tonkin Gulf (Beibu Gulf), Sta. 6265, depth 60 m, 1 December 1959, coll. Xiu-Tong Ma; ( MBM 270637), 1 ovigerous ♀, 1♂, depth 53 m, 22 August 1962; 1♂, East China Sea, Sta. 4083, depth 88 m, 4 July 1959, coll. Li-Ren Cheng; ( MBM 081146), 2 non-ovigerous, East China Sea, Sta. 4084, depth 100 m, 1 February 1959, coll. Jie-Shan Xu; ( MBM 270424), 1 non-ovigerous, Tonkin Gulf (Beibu Gulf), Sta. 6240, depth 58 m, 9 December 1960, coll. Zhen-Gang Fan; ( MBM 270525), 1 ovigerous ♀, Tonkin Gulf (Beibu Gulf), Sta. 7503, depth 52m, 22 August 1962, coll. Fu-Zeng Sun; ( MBM 270134), 1♂, Tonkin Gulf (Beibu Gulf), Sta. 7702, depth 55 m, 12 January 1962, coll. Fu-Zeng Sun; ( MBM 107809), 1 ovigerous ♀, 1♂, Nanji island, depth 15 m, 24 October 1979, coll. Xian-Qiu Ren; ( MBM 107805), 2 ovigerous ♀, 2♂, East China Sea, Sta. V-7, depth 100 m, 10 October 1975, coll. Zhi-Chan Tang, Bao-Lin Zhang; ( MBM 107817), 1 non-ovigerous, East China Sea, Sta. V-2, depth 85 m, 4 July 1976, coll. Zhi-Chan Tang, Feng-Shan Xu; ( MBM 107818), 2 non-ovigerous, East China Sea, Sta. V-7, depth 131 m, 5 July 1976, coll. Zhi-Chan Tang, Rui-Yu Liu; ( MBM 107804), 1 non-ovigerous, East China Sea, Sta. V-6, depth 115 m, 4 July 1976, coll. Rui-Yu Liu; ( MBM 107816), 1 ovigerous ♀, 2♂, East China Sea, Sta. V-10, depth 110 m, 10 October 1975, coll. Zhi-Chan Tang, Jie-Shan Xu; ( MBM 107808), 1 ovigerous ♀, 1♂, East China Sea, Sta. V-4, depth 99 m, 5 July 1976, coll. Zhi-Chan Tang, Yao-Quan Wu; ( MBM 270594), 1 ovigerous ♀, 1♂, East China Sea, Sta. 6277, depth 31 m, 17 May 1960, coll. Zhen-Gang Fan; ( MBM 107810), 2 ovigerous ♀, 1♂, East China Sea, Sta. V-2, depth 99 m, 5 July 1976, coll. Zhi-Chan Tang; ( MBM 107814), 16 ovigerous ♀, 12♂, East China Sea, Sta. V-3, depth 105 m, 27 August 1976, coll. Zhi-Chan Tang; ( MBM 270591), 1♂, Tonkin Gulf (Beibu Gulf), Sta. 6277, depth 35 m, 9 March 1960, coll. Zhen-Gang Fan; ( MBM 107807), 2♂, East China Sea, Sta. V-5, depth 90 m, 11 October 1975, coll. Zhi-Chan Tang; ( MBM 107806), 2 ovigerous ♀, 7♂, East China Sea, Sta. V-5, depth 100 m, 10 October 1975, coll. Zhi-Chan Tang, Feng-Shan Xu; ( MBM 107820), 1 ovigerous ♀, 1♂, East China Sea, Sta. V-6, depth 112 m, 5 July 1976, coll. Zhi-Chan Tang, Feng-Shan Xu; ( MBM 107812), 1 ovigerous ♀, East China Sea, Sta. V-7, depth 126 m, 21 September 1976, coll. Zhi-Chan Tang, Feng-Shan Xu; ( MBM 107811), 2 ovigerous ♀, East China Sea, Sta. V-3, depth 105 m, 11 June 1978, coll. Bao-Lin Zhang. 1 ovigerous ♀, ( MBM 270588), Tonkin Gulf (Beibu Gulf), Sta. 6265, depth 62 m, 25 May 1960, coll. Fu-Zeng Sun; ( MBM 270609), 1♂, Tonkin Gulf (Beibu Gulf), Sta. 7901, depth 52 m, 17 August 1962, coll. Fu-Zeng Sun; ( MBM 107740), 1 ovigerous ♀, 2♂, Nanhai, Xincun, depth 1–3 m, 26 March 1992, coll. Rui-Yu Liu; 1♂, Yezhu Island, 11 April 1992; ( MBM 042231), 1♂, East China Sea, Sta. 4081, depth 79 m, 25 October 1959, coll. Bao-Lin Zhang; ( MBM 158542), 1♂, Yezhu Island, depth 97 m, from living millipede, 25 March 1992; ( MBM 159262), 1♂, Sanya, Dadonghai, E-side, depth 4–6 m, 1 December 1997; ( MBM 158375), 1♂, East China Sea, Sta. V-8, depth 79 m, 10 October 1975, coll. Zhi-Chan Tang; ( MBM 158076), 1♂, Sanya, Dadonghai, E-side, depth 6–9 m, 27 November 1997, coll. Xin-Zheng Li; ( MBM 158209), 1♂, Sanya, Dadonghai, 1 March 1997, coll. Xin-Zheng Li; ( MBM 158652), 1♂, Yalong Bay, coll. Rui-Yu Liu; ( MBM 270720), 1 ovigerous ♀, Xinying, 14 January 1956; ( MBM 158334), 1♂; ( MBM 159319), 3 ovigerous ♀, 2♂, Nanhai, Xincun, depth 1–3 m, 26 March 1992; ( MBM 159319), 1 ovigerous ♀, 2♂, Nanhai, Xincun, depth 1–3 m, 21 March 1992; ( MBM 159279), 1 ovigerous ♀, 1♂, Yezhu Island, 27 March 1992; ( MBM 159278), 1♂; ( MBM 158223), 1 ovigerous ♀, 4♂, Tiaozhou Island, 26 December 1954, coll. Rui-Yu Liu; ( MBM 107777), 1♂, Shalao, depth 12 m, 4 April 1992; ( MBM 107766), 1 ovigerous ♀, Yezhu Island, 17, November 1990. ( MBM 159299), 1♂.

Description. Carapace smooth, glabrous; rostrum about 2.7 times as long as wide at base, acute tip not reaching end of first segment of antennular peduncle; orbital hoods about 5/8 length of rostrum; pterygostomial corner produced into acute angle; cardiac notch well developed.

Telson about 1.4 times as long as wide at base; dorsal surface with two pairs of moderately large 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 spines, lateral about 1/3 length of mesial, posterolateral margins each produced into acute small tooth, but distinctly shorter than lateral spines.

Eyes concealed in lateral and dorsal view.

Antennular peduncle moderately slender, with distally acute stylocerite, latter reaching about 1/4 length of second segment of antennular peduncle; second segment about 1.5 times as long as wide at base; visible part of first segment longer than second and about twice as long as third. Basicerite with acute distodorsal tooth, distolateral tooth almost as long as stylocerite; carpocerite overreaching end of third segment of antennular peduncle; scaphocerite blade moderately broad, reaching 3/4 length of third segment of antennular peduncle, lateral spine developed, overreaching end of antennular peduncle, slight longer than carpocerite.

Third maxilliped far beyond antennular peduncle and carpocerite when extended; antepenultimate segment longest; penultimate segment about 1.3 times as long as wide at base; tip of ultimate segment bearing crown of five spine-like setae, with transverse rows of setae along ventral margin.

Major cheliped with short, stout ischium; merus about 2.7 times as long as wide at base, superodistal margin with one acute triangular tooth; carpus cup-shaped, with setae distodorsally; palm about 2.8 times as long as dactylus, distodorsal of palm with one acute projecting, slightly curved to dactylus; dactylus slightly longer than pollex, distally slightly curved.

Minor chela with merus about 3.7 times as long as wide at base, superodistal margin with one acute triangular tooth; carpus cup-shaped, proportionally longer that of major cheliped; palm about 1.5 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 5: 1: 1: 1: 1.8, with first segment slightly longer than sum of last four segment; dorsal margin of palm convex; fingers about 1.5 times as long as palm. Third pereiopod moderately slender; merus slightly shorter than propodus, about 4.5 times as long as wide at base, ventral margin with 2–5 spines; carpus about 1/2 length of merus, with dorsal margin extended into an obtuse tooth, ventral margin with one distal spine; propodus with seven spines along ventral margin plus one distal pair of spines near dactylus; dactylus about 1/4 length of propodus, slightly curved to propodus, biunguiculate, extensor tooth slight shorter than flexor tooth, notch between extensor and flexor tooth V-shaped, flexor tooth about twice as wide at base as extensor tooth. Fourth pereiopod generally similar to third; merus shorter than propodus, ventral margin of propodus with seven spines. Fifth pereiopod similar to third and fourth pereiopods, ventral margin of propodus with six transversal rows of spine-like setae and two spines.

Remarks. This species was original described by Coutière (1905). Its variations and differences with S. neomeris , the morphological similar species, were well discussed by Banner & Banner (1975). S. streptodactyloides de Man, 1909 was described as a new form based on single specimen, which was subsequently synonymized as S. streptodactylus by Banner & Banner (1985).

The present abundant specimens are generally similar to each other, and all in the smaller size than S. neomeris . Additionally, two of our specimens are aberrant at the frontal teeth: the tip of the rostrum being bispineous ( Fig. 43a ), or another lost the rostrum ( Fig. 43b ). Those differences might be affected by the environment.

Distribution. East China Sea, South China Sea; Red Sea; Eastern and South Africa to Thailand; Indonesia; Japan; Australia to Hawaii; Philippines.

Figures

Fig. 41. Synalpheus streptodactylus Coutière, 1905, female (cl 5.1mm) (MBM 270223). a–b. Frontal region. a. Dorsal. b. Lateral. c–d. Third maxilliped. c. Ventral. d. Tip, dorsal. e–f. Major cheliped (left). e. Lateral. f. Chela, lateral. g. Minor cheliped (right), lateral. h. Second pereiopod, lateral. i. Third pereiopod, lateral. j. Distal propodus and dactylus, lateral. Scale bars: a–i=1mm; j= 0.5 mm.

Fig. 42. Synalpheus streptodactylus Coutière, 1905, female (cl 5.1 mm) (MBM 270223). a–b. Fourth pereiopod. a. Lateral. b. Distal propodus and dactylus, lateral. c. Fifth pereiopod, propodus and dactylus, ventral. d. Second pleopod. e. Abdomen, lateral. f. Telson and uropod, dorsal. Scale bars: a, d–f=1 mm; b–c=0.5 mm.

Fig. 43. Synalpheus streptodactylus Coutière, 1905. a. Male (cl 3.1mm) (MBM 158375) frontal region, dorsal. b. Male (cl 4.5mm) (MBM 107814) frontal region, dorsal. Scale bars=1 mm.