Synalpheus charon (Heller, 1861)

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 : 370-373

3.2.6 Synalpheus charon (Heller, 1861) ( Figs 9–10 )

Alpheus charon Heller, 1861 . Sbr. Akad. Wiss. Wien, 44(1): 272, pl. 3. fig. 21, 22; 1865. Reise Novara Crust., 2 (3): 107; Paulson, 1874.

Invest. Red Sea Crust., 1: 104, pl. 8, fig. 4. Synalpheus charon de Man, 1911 . Siboga Fxped. , 39(2): 245, figs 37; Banner, 1953. Pacif. Sci., 7(1): 37, fig. 11; Banner & Banner,

1967. Bishop Mus. Oec. Pap., 23(12): 262; Banner & Banner, 1975. Records of the Australian Museum, 29(12): pl. 369, fig. 25. Synalpheus charon charon Banner, 1956 . Pacif. Sci., 10(3): 331. Synalpheus charon obscurus Banner, 1956 . Pacif. Sci., 10(3): 329. fig. 5. Synalpheus prolificus Spence Bate, 1888 . Challenger Rept., 24: 556, pl. 99, fig. 4. Synalpheus helleri de Man, 1911 . Siboga Exped. , 39(2): 245, fig. 37.

Material examined. CL 4.1–5.3 mm, TL 10.2–14.1 mm. (MBM 233243), 1♂, Dong Island, Xisha Islands, Sta. 3, 10 June 1975; (MBM 107741), 1 ovigerous ♀, 1♂, Yongxing Island, Xisha Islands, 11–13 June 1980, coll. Xiu-Bin Fang; (MBM 107650), 1 ovigerous ♀, 1♂, Jinqing Island, Xisha Islands, 25 April 1958, coll. Zhen-Gang Fan, Jie-Shan Xu; (MBM 107755), 1♂, Yongxing Island, Xisha Islands, 11–13 June 1980, coll. Xiu-Bin Fang; (MBM 107736), 1♂, Jinyin Island, Xisha Islands, 14 May 1980, coll. Xiu-Bin Fang; (MBM 107743), 2 ovigerous ♀, 2♂, Zhaoshu Island, Xisha Islands, 11 May 1980, coll. Xiu-Bin Fang; (MBM 107724), 1♂, 1 immature specimens, Shi Island, Xisha Islands, 10 May 1980, coll. Xiu-Bin Fang; (MBM 107223), 1 ovigerous ♀, 1♂, Sanya, Dadonghai, depth 5–9 m, 3 December 1997, coll. Xin-Zheng Li; (MBM 158865), 1♂, Nansha Islands, 22 April 1987; (MBM 158746), 1♂; (MBM 158434), 1♂, Yezhu Island N-side, 22 March 1992; (MBM 158033), 1 ovigerous ♀, 28–29 April 1958, coll. Zhen-Gang Fan, Jie-Shan Xu; (MBM 157745), 4 ovigerous ♀, 9♂; (MBM 158071), 1 ovigerous ♀, Dengqing island, 3 May 1958, coll. Zhen-Gang Fan, Jie-Shan Xu; (MBM 157986), 1♂, Dengqing island, 3 May 1958, coll. Zhen-Gang Fan, Jie-Shan Xu.

Description. Carapace smooth, glabrous; rostrum about twice as long as wide at base, triangular tip not reaching end of first segment of antennular peduncle; orbital hoods distinctly shorter than rostrum, about twice as wide at base as rostrum; pterygostomial corner produced into acute angle; cardiac notch well developed.

Telson about 1.25 times as long as wide at base; dorsal surface with two pairs of moderately small spines, inserted approximately at 1/2 and 3/4 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 not produced.

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

Antennular peduncle slender, with distally acute stylocerite, latter reaching 2/3 length of second segment of antennular peduncle; second segment about 1.25 times as long as wide at base; visible part of first segment slightly longer than second and less twice as long as third. Basicerite without distodorsal tooth, distolateral tooth distinctly shorter than stylocerite, overreaching end of first segment of antennular peduncle; carpocerite far overreaching end of third segment of antennular peduncle; scaphocerite blade moderately broad, overreaching end of third segment of antennular peduncle, lateral spine developed, overreaching end of antennular peduncle, distinctly longer than carpocerite.

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

Major cheliped with short, stout ischium; merus about 2.4 times as long as wide at base, superodistal margin with one subacute triangular tooth; carpus cup-shaped, with setae distodorsally; palm about 1.7 times as long as dactylus, distodorsal of palm with one small obtuse projecting; dactylus slightly longer than pollex.

Minor chela with merus about 3 times as long as wide at base, superodistal margin with one subacute triangular tooth; carpus cup-shaped, proportionally longer that of major cheliped; palm about 1.3 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: 1.2: 1.3: 2.3, with first segment slightly shorter than sum of last four segment; dorsal margin of palm convex; fingers slightly longer than palm. Third pereiopod moderately stout; merus near as long as propodus, about 3 times as long as wide at base; carpus about 1/2 length of merus, with dorsal margin extended into an obtuse tooth, ventral margin with one distal spine; propodus with five spines along ventral margin plus one; dactylus about 3/10 length of propodus, slightly curved to propodus, biunguiculate, extensor tooth with acute tip, near as long as flexor tooth, flexor tooth much wider at base than extensor tooth, inferior margin of flexor tooth with excavate “pocket”. Fourth pereiopod generally similar to third; merus near as long as propodus, ventral margin of propodus with five spines. Fifth pereiopod similar to third and fourth pereiopods, ventral margin of carpus without one distal spine; ventral margin of propodus with distal three spines.

Remarks. This species was originally described by Heller. It could be easily recognized by the dactylus of the posterior three pereiopods ( Banner & Banner, 1975).

The present specimens is generally agreed with the redescriptions of Miya (1972) and Banner & Banner (1975), and also variable in size and shape of the rostrum ( Banner & Banner, 1967).

Distribution. South China Sea; Suez Canal and eastern Africa to Philippines, Indonesia, Australia, and most of Pacific islands, but not including Japan, Hawaii, or Society Islands.

Figures

Fig. 9. Synalpheus charon (Heller, 1861), female (cl 4.9mm) (MBM 107743). 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–h. Minor cheliped (right). g. Lateral. h. Chela, lateral. i. Second pereiopod, lateral. j. Third pereiopod, lateral. k. Distal propodus and dactylus, lateral. l–m. Fourth pereiopod. l. Lateral. m. Distal propodus and dactylus, lateral. n. Fifth pereiopod, lateral. Scale bars: a–c, e–j, l, n=1mm; d, k, m= 0.5 mm.

Fig. 10. Synalpheus charon (Heller, 1861), female (cl 4.9 mm) (MBM 107743). a. Second pleopod. b. Telson and uropod, dorsal. Scale bars =1mm.