Synalpheus stimpsonii ( de Man, 1888 )

Prakash, S. & Marimuthu, N., 2020, Notes on some crinoid associated decapod crustaceans (Crustacea: Decapoda) of Lakshadweep Archipelago, Central Indian Ocean, Zootaxa 4766 (1), pp. 86-100 : 91

Synalpheus stimpsonii ( de Man, 1888)

( Figs 3g, h, i , 4c )

Restricted synonymy:

Alpheus stimpsoni de Man, 1888: 53 (1), 513, pi. 22, fig. 3.

Synalpheus consobrinus de Man, 1909 : (2), lll, 1911: 39(2), 204, fig. 21

Synalpheus brucei Potts, 1915: 8 , 76, pl. 1, fig. 2, textfigs 1 a–b, 2 a–c, 3.

Synalpheus stimpsoni Banner & Banner, 1966b: 3 , p. 46, fig. 12, 1968: 4(2), 274, Banner and Banner, 1975: 29 (12), 292–296, fig. 2m, 4.

Material examined. Three specimens: One ovigerous female (cl 9.6 mm, tl 28.5 mm), India, Lakshadweep, Kalpeni Island, 10 o 04.970’N 73 o 38.979’E, depth 20m, on Comaster multifidus , 20 February 2018 (ZSI/ Crustacea / C8016/2).

One ovigerous female (cl 5.7 mm, tl 19.9 mm), India, Lakshadweep, Agatti Island, 10 o 51.917’N 72 o 10.570’E, depth 30m, on Phanogenia gracilis , 05 February 2018 (ZSI/ Crustacea /C8021/2).

One female (cl 6.5 mm, tl 19.4 mm), India, Lakshadweep, Kavaratti Island, 10 o 32.256’N 72 o 37.083’E, depth 25m, on Phanogenia multibranchiata , 10 February 2018 (ZSI/ Crustacea /C8026/2).

Short Description. Rostrum slightly concave dorsally, wider at base than the orbital teeth, reaching the distal margin of first article of the antennular peduncle. Orbital teeth with acute tips but not carinate. Carapace like S. comatularum but in lateral view rostral region of carapace depressed on the gastric region. Stylocertite slightly overreaching the distal margin of the first article of antennular peduncle. Scaphocerite reaching the distal margin of the third article of the antennular segment. Large chela broad, superior margin bearing tooth on the dactylar articulation, carpus cup-shaped bearing long acute tooth on the supero distal margin. Merus bearing small acute tooth on the inferointernal margin and acute tooth on the superior margin. Small chela long with dactylus slightly curved, carpus like large chela but greatly depressed, merus bearing small tooth on the supero distal margin. Last three pereiopods with propodus longer than merus with spines on the lower margin, merus armed with acute tooth distally, dactylus biunguiculate, unguis slightly curved, superior unguis longer and thicker than the inferior.

Coloration. Carapace with longitudinal stripes against the white background. Several brown color spots (chromatophores) are visible between the stripes. Rostrum white. Major chela with longitudinal stripes against the white background like carapace. The distal portion of fixed finger and movable finger dark brown. Small chela like major chela. Other pereiopods are brown to dark brown. Abdominal segments with transverse dark stripes on the edges and numerous brown spots were visible throughout the abdomen. Pleopods brown to dark brown. Telson somewhat white. Exopods and endopods of the uropods brown to dark brown.

Distribution. Indo-Pacific: Indonesia, Singapore, China Sea, Thailand, Celebes, Philippines, Japan, Marshall and Gilbert Islands and Australia ( Banner & Banner 1966a, 1975, Wang & Sha 2015). In India, the species has been reported earlier from Andaman and Nicobar Islands ( Sastry 1977) and Gulf of Mannar. Now from Lakshadweep.

Host. Observed from different host crinoid species from different Islands of Lakshadweep. On Comaster multifidus (Kalpeni Island), Phanogenia gracilis (Agatti Island), P. multibrachiata (Kavaratti Island).

Remarks. S. stimpsonii was originally described by De Man (1888). Always vary in morphological characteristics such as length of the rostrum, orbital hoods arrangement, length of the first segment of antennular peduncle compared to other two segments, length of distodorsal and distolateral tooth, the proportion of pereiopods, the position of dorsal and posterolateral spines on telson etc. ( Banner & Banner 1975). So many species have been described as new, however, then synonymized with S. stimpsonii (see remarks section of Wang & Sha 2015). S. stimpsonii is previously recorded from Andaman Islands (1977) and the present observation has extended its distribution range to Lakshadweep.

Figures

FIGURE 3. a. Microscopic image of Synalpheus carinatus (De Man, 1888) carapace, lateral view; b. same, anterior region of carapace along with the major chela, dorsal chela; c. same, posterior abdominal segments and telson, dorsal view; d. S. comatularum (Haswell, 1882)—whole animal, lateral view; e. same, posterior region of carapace, dorsal view; f. same, dorsal view of telson; g. S. stimpsonii (De Man, 1888)—carapace, dorsal view; h. same, anterior region of carapace dorsal view; i. same, major chela, venterolateral view; j. Palaemonella pottsi (Borradaile, 1915)—whole animal, lateral view; k. same, anterior region of carapace, dorsal view; l. same, dorsal view of telson showing posterior spines, Scale bar: a,d,e,g,h,i= 2mm, b,c,f,j–l= 1 mm.

FIGURE 4. Crustacean decapods associated with crinoids collected from the Lakshadweep Islands. a. Synalpheus carinatus (De Man, 1888), lateral view; b. S. comatularum (Haswell, 1882), lateral view; c. S. stimpsonii (De Man, 1888), lateral view; d. Palaemonella pottsi (Borradaile, 1915); e. Permanotus purpureus (Gordon, 1934).