Synalpheus demani Borradaile, 1900

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 : 376-379

3.2.8 Synalpheus demani Borradaile, 1900 ( Figs 14–15 )

Synalpheus demani Borradaile, 1900 . Willey's Zool. Res., 4: 416; de Man, 1911. Siboga Exped. , 39(2): 257, fig. 42; Banner & Banner, 1968. Microncsica, 4(2): 274; Banner & Banner, 1975. Records of the Australian Museum, 29(12): pl. 324, fig. 13; Miya, 1972. Publ. Amakns a Mar. Biol. Lab., 3(1): 60, pl. 11.

Alpheus triunguiculatus de Man, 1888 . Archiv. Naturgeseh., 53: 504, pl. 22, fig. 1 (nec Paul’son).

Synalpheus spiniger Spence Bate, 1888 . Challenger Repl., 24: 560, pl. 100, fig. 3 (nec Stimpson).

Synalpheus broekii Nobili, 1901 . Ann. del Mus. Zool. Napoli, 1(3): 2.

Material examined. ( MBM 157933), 2♂, CL 4.1–5.9 mm, TL 10.1–13.5 mm, Luhuitou, Sanya (16.8°N, 112.3°E), 30 December 1959, Yu-Lin Liao; ( MBM 107803), 2♀, 3♂, Yalong Bay, Yezhu Island N-coast, depth 8 m, from Comanthus sp. , coll. Newmann; ( MBM 107800), 1♂, CL 8.2 mm, TL 21.1 mm, Yalong Bay, Yezhu Island, 19 November 1990; ( MBM 158952), 5♀, 2♂, CL 6.1–10.1 mm, TL 14.3–26.2 mm, Xincun, 19 April 1958; ( MBM 107801), CL 8.1–9.1 mm, TL 20.2–24.5 mm, Yezhu Island, 19 November 1990, coll. Yong-Qiang Wang; ( MBM 158952), 1♂, 5 immature specimens, CL 7.2 mm, TL 15.2 mm, Xincun, 19 April 1958.

Description. Carapace smooth, glabrous; rostrum about 3.4 times as long as wide at base, acute tip not reaching end of first segment of antennular peduncle; orbital hoods 2/3 length of rostrum; pterygostomial corner produced into acute angle; cardiac notch well developed.

Telson about 1.3 times as long as wide at base; dorsal surface with two pairs of small spines, inserted approximately at 1/2 and 2/3 length of telson; posterior margin slightly produced, fringed with long setae, posterolateral angle each with two pairs of spines, lateral about 2/3 length of mesial, posterolateral margins each produced into acute small tooth, distinctly shorter than lateral spines.

Eyes concealed in lateral and dorsal view.

Antennular peduncle moderately stout, with distally acute stylocerite, latter reaching about 1/3 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 slightly shorter than stylocerite, distolateral margin bearing setae, superior margin of basicerite bearing third short subacute tooth medially; carpocerite slightly overreaching end of third segment of antennular peduncle; scaphocerite blade moderately broad, reaching middle of third segment of antennular peduncle, lateral spine developed, reaching end of antennular peduncle, distinctly shorter than carpocerite.

Third maxilliped far beyond antennular peduncle and carpocerite when extended; antepenultimate segment longest; penultimate segment about 1.5 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 rounded, without triangular tooth; carpus cup-shaped, with setae distodorsally; palm about 1.8 times as long as dactylus, distodorsal of palm with one subacute projecting, slightly curved to dactylus; dactylus slightly longer than pollex, distally slightly curved.

Minor chela with merus about three times as long as wide at base, superodistal margin rounded, ventral and dorsal margin bearing fine short setae; 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: 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 stout; merus near as long as propodus, about 3.7 times as long as wide at base; carpus about 1/2 length of merus, with dorsal margin extended into an obtuse tooth, ventral margin without distal spine; propodus slightly curved, distal with three spines and dense patches of setae; dactylus slightly curved to propodus, triunguiculate, middle tooth about three times as long as extensor tooth, flexor tooth about 1.5 times as long as extensor tooth, notch between extensor and middle tooth V-shaped, middle tooth distinctly much wider than extensor tooth at base, notch between middle tooth and flexor tooth U-shaped, middle tooth slight wider at base than flexor tooth. Fourth pereiopod generally similar to third; merus shorter than propodus, ventral margin of propodus distally bearing patches of setae. Fifth pereiopod similar to third and fourth pereiopod.

Remarks. This species was original described by de Man (1888), under the name Alpheus triunguiculatus de Man, 1888 . Borradaile (1900) transferred it into the genus Synalpheus and given it a new specific name, S. demani . This species was original described based on two male specimens collected from Lifu, Loyalty Islands. It was redescribed or illustrated by Miya (1972), Banner & Banner (1975), Chace (1988) and Bruce (1989), which are generally similar to each other.

The present materials are similar from each other and agreed well with the description of Banner & Banner (1975) except the length of the rostrum. It is a pity that the major chela was lost in their description. The major chela in the present specimens is agreed with the description of Miya (1972), in which the second tooth on the superior margin of basicerite was not mentioned. In addition, this species was found only with four segments in the carpus of second pereiopod in Japan Sea, which was not found in our specimens. Furthermore, the length of the rostrum was taken variable in Chace (1988), which reaching to overreaching the end of the first segment of the antennular peduncle. But it is not reaching that end in our specimens.

Distribution. South China Sea; Red Sea, Japan, Philippines, Indonesia, Australia, and Marshall and Loyalty islands.

Figures

Fig. 14. Synalpheus demani Borradaile, 1900, male (cl 4.5 mm) (MBM 107803). a–b. Frontal region. a. Dorsal. b. Lateral. c–d. Third maxilliped. c. Ventral. d. Tip, ventral. e–f. Major cheliped (right). e. Mesial. f. Chela, lateral. g–h. Minor cheliped (left). g. Lateral. h. Chela, mesial. i. Second pereiopod, lateral. Scale bars: a–c, e–i=1 mm; d=0.5mm.

Fig. 15. Synalpheus demani Borradaile, 1900. a–b. Third pereiopod. a. Lateral. b. Distal propodus and dactylus, lateral. c–d. Fourth pereiopod. c. Lateral. d. Distal propodus and dactylus, lateral. e. Fifth pereiopod, propodus and dactylus, lateral. f. Abdomen, lateral. g. Telson and uropod, dorsal. Scale bars=1 mm.