Synalpheus nilandensis 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. 357-435 : 408-411

3.2.21 Synalpheus nilandensis Coutière, 1905 ( Figs 35–36 )

Synalpheus Nilandensis Coutière, 1905 . Fauna and Geog. Maid, and Laccad.: 871, plate 70, figs 4–4d; Banner & Banner, 1975. Records of the Australian Museum, 29(12): pl. 327, fig. 14.

Synalpheus Nilandensis var. oxyceros Coutière, 1905 . Fauna and Geog. Maid, and Laccad.: 871, plate 70, figs 5–5a.

Synalpheus Nilandensis var. bandaensis de Man, 1909 . Tijdschr. ned. dierk. Vereen, 11(2): 121.

Material examined. ( MBM 042230), 1♂, CL 4.9 mm, TL 11.2 mm, East China Sea, Sta. 4081, depth 74 m, 5 April 1959, coll. Guang-Yu Lin, Yu-Lin Liao; ( MBM 081125), 1♀, 2♂, CL 5.5–6.5 mm, TL 19.3–22.3 mm, East China Sea, Sta. 4081, depth 81 m, 2 February 1959, coll. Jie-Shan Xu; ( MBM 081145), 1♂, CL 7.2 mm, TL 19.1 mm, East China Sea, Sta. 4081, depth 79 m, 3 July 1959, coll. Li-Ren Cheng; ( MBM 107826), 1♀, East China Sea, Sta. 4083, 8 December 1959; ( MBM 042234), 1♀, East China Sea, Sta. 4081, depth 79 m, 3 July 1959; ( MBM 042231), 1♂, East China Sea, Sta. 4081, depth 79 m, 25 October 1959, coll. Bao-Lin Zhang; ( MBM 107821), 3♀, 4♂, East China Sea, Sta. V-3, depth 105 m, 27 August 1976, coll. Zhi-Chan Tang; ( MBM 158690), 1♀, 2♂, Nansha Islands, South China Sea, Sta. 55 (16°27′57″N, 111°44′17″E), depth 46 m, 8 June 1990; ( MBM 158622), 1♀, Nansha Islands, Sta. E13 (3°53.08.40N ， 112°16.22.80E), depth 50 m, 28 April 1986; 1♀, Nansha Islands, South China Sea, Sta. 55 (16°27′57″N, 111°44′17″E), depth 46 m, 8 June 1990.

Description. Carapace smooth, glabrous; acute tip of rostrum not reaching middle of first segment of antennular peduncle, strongly upturned; orbital much longer than rostrum, slightly upturned at tip; pterygostomial corner produced into acute angle; cardiac notch well developed.

Telson about 1.2 times as long as wide at base; dorsal surface with two pairs of spines, inserted approximately at 1/3 and 7/11 length of telson; posterior margin slightly produced, fringed with long setae, posterolateral angle each with two pairs of spines, lateral about 1/2 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 slender, with distally acute stylocerite, overreaching end of first segment of antennular peduncle; second segment about 1.3 times as long as wide at base; visible part of first segment much longer than second and about 3 times as long as third. Basicerite with acute distodorsal tooth, distolateral tooth shorter than stylocerite, distolateral margin bearing setae; carpocerite overreaching end of third segment of antennular peduncle; scaphocerite blade moderately narrow, not reaching end of third segment of antennular peduncle, lateral spine developed, overreaching end of antennular peduncle, subequal to 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 long 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 small acute triangular tooth; carpus cup-shaped, with setae distodorsally; palm about 2.4 times as long as dactylus, distodorsal of palm with one acute projecting; dactylus distinctly longer than pollex.

Minor chela with merus about 3.5 times as long as wide at base, superodistal margin rounded; carpus cup-shaped, proportionally longer that of major cheliped; palm about 1.8 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 5.4: 1: 1: 1: 2.2, with first segment slightly longer than sum of last four segment; dorsal margin of palm convex; fingers slightly longer than palm. Third pereiopod moderately stout; merus longer than propodus, about 4.5 times as long as wide at base, ventral margin with 4 moderately large spines; carpus about 1/3 length of merus, 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; dactylus curved to propodus, triunguiculate, middle tooth about 3 times as long as extensor tooth, extensor tooth about 1.5 times as long as flexor tooth, notch between extensor and middle tooth V-shaped, middle tooth distinctly much wider at base than extensor tooth, notch between middle tooth and flexor tooth U-shaped, middle tooth wider at base than flexor tooth. Fourth pereiopod generally similar to third; merus near as long as propodus, ventral margin with two spines; ventral margin of propodus bearing ten spines. Fifth pereiopod similar to third and fourth pereiopods, ventral margin of carpus without one distal spine; ventral margin of propodus with seven transversal rows of spine-like setae and two spines.

Remarks. This species was originally described by Coutière (1905 b). It was complex, mainly because of the variation of the anterior region and the dactylus of the third pereiopod ( Banner & Banner, 1975). The present specimens from East China Sea was similar to S. nilandensis forma alpha: the rostrum much shorter than the orbital hoods, the tips of both upturned; the dactylus of third pereiopod moderately stout and the middle tooth of it at right angles to the axis of the dactylus. The specimens from the South China Sea was most similar to the original description ( Coutière, 1905 b): the rostrum slightly longer than the orbital hoods, and upturned at the tip; the distolateral tooth of the basicerite shorter than the stylocerite; the dactylus of the third pereiopod about 1.5 times as long as wide at base, the extensor tooth slender and reduced, the middle tooth heavy and turning right angle to the axis of the dactylus, the flexor tooth shortest. The third form (the rostrum longer than the orbital hoods; the distolateral tooth of the basicerite longer than the stylocerite; the dactylus of the third pereiopod slender ( S. nilandensis forma bandaensis )) was reported by Banner & Banner (1975) collected from near the Hong Kong, but not found in the present specimens.

Distribution. China seas; Red Sea; Maldives and Laccadives; Andaman Sea; Indonesia; Borneo; Hong Kong; Tuamotus Archipelago.

Figures

Fig. 35. Synalpheus nilandensis Coutière, 1905, male (cl 5.9 mm) (MBM 107821). a–b. Frontal region. a. Dorsal. b. Lateral. c–d. Third maxilliped. c. Ventral. d. Tip, dorsal. e–g. Major cheliped (left). e. Mesial. f. Chela, lateral. g. Merus, lateral. h–i. Minor cheliped (right). h. Lateral. i. Chela, mesial. j. Second pereiopod, lateral. k–l. Third pereiopod. k. Lateral. l. Distal propodus and dactylus, lateral. Scale bars: a–c, e–k=1 mm; d, l=0.5 mm.

Fig. 36. Synalpheus nilandensis Coutière, 1905, male (cl 5.9 mm) (MBM 107821). a–b. Fourth pereiopod. a. Lateral. b. Distal propodus and dactylus, lateral. c. Fifth pereiopod, lateral. d. Second pleopod. e. Telson and uropod, dorsal. f. Abdomen, lateral, male (cl 6.1mm) (MBM 158690). g. Frontal region, dorsal. h–i. Third pereiopod. h. Lateral. i. Distal propodus and dactylus, lateral. Scale bars: a, c–h =1mm; b, i=0.5mm.