Synalpheus comatularum ( Haswell, 1882 )

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 : 90-91

Synalpheus comatularum ( Haswell, 1882)

( Figs 3d, e, f , 4b )

Restricted synonymy:

Alpheus comatularum Haswell, 1882 a: 6 (4): 762. Miers, 1884: p. 289 [redescription using Haswell’s specimen]. Synalpheus comatularum Pearson, 1905: 83–84 . Potts, 1915: 8, 76, pt 1, fig.1, text-figs lc, 2 d, Banner & Banner, 1975,:29(12), 289–291, fig. 3.

Material examined. Five specimens: Two ovigerous females (cl 6.7 mm and 4.3 mm, tl 22.6 mm and 17.6 mm), India, Lakshadweep, Agatti Island, 10 o 49.901’ N 72 o 08.875’E, depth 20m, on Phanogenia distincta , 06 February 2018 (ZSI/ Crustacea /C8019/2 and ZSI/ Crustacea /C8020/2).

Two ovigerous females (1 not measured, cl 7.8 mm, tl 24.8 mm), India, Lakshadweep, Kavaratti Island, 10 o 34.945’N 72 o 38.323’E and 10 o 32.256’N 72 o 37.083, depth 25m, on Stephanometra indica and Phanogenia multibranchiata , 08 February 2018 and 10 February 2018 (ZSI/ Crustacea /C8022/2 and ZSI/ Crustacea /C8027/2).

One ovigerous female (cl 5.4 mm, tl 17.8 mm) (C8024/2) and Two females (cl 5.5 mm and 7.8 mm, tl 15.1 mm and 24.9 mm), India, Lakshadweep, Amini Island, 11 o 07.739’N 72 o 44.119’E, depth 10 m, on Phanogenia gracilis , 17 February 2018 (ZSI/ Crustacea /C8023/2 and ZSI/ Crustacea /C8025/2).

Short Description. Rostrum reaching the middle region of the second article of antennular peduncle, bears knife-like carina that extends to the cardiac region. Carapace in lateral view gives humped like appearance. Orbital teeth directed straight and dorsally rounded. Pterygostomial region strongly projecting at an acute angle. The first article of antennular penduncle longer than the second and third articles. Stylocerite not reaching the distal region of first antennular segment. Scaphocerite almost reaching the distal region of the third article of antennular peduncle. Major chela subcylindrical, dactylus articulated with two acute teeth, merus broad and superodistal margin with acute tooth. Small chela dactylus crescentric and curved with acutely hooked tip crossing and extending beyond the fixed finger, carpus bearing strong tooth on superodistal margin and long slender tooth on the lower margin. Last three pereiopods bearing distal tooth on the merus, propodus slightly larger than merus, dactylus with acute narrow tip that are hooked and longer than the inferior tooth. Telson broad on the posterior margin, strongly arcuate, spines on the dorsal surface strong. Abdomen with last three segments slightly sharped tip.

Coloration. Carapace with longitudinal stripes against the white or brown background. Several brown color spots (chromatophores) are visible between the stripes. Rostrum white in color. 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. Antenna and antennule with brown bands. Pleopods brown to dark brown. Telson somewhat white. Exopods and endopods of the uropods brown to dark brown.

Distribution. Indo-Pacific: Widely distributed in Australia and Torres Strait ( Banner & Banner 1975), Maldives, and Ceylon ( Pearson 1905). Now from Lakshadweep, India.

Host. In the present study, S. comatularum was collected from different species of crinoids at different Islands of Lakshadweep. On Phanogenia distincta (Agatti Island), P. gracilis (Amini Island) and Stephanometra indica (Kavaratti Island).

Remarks. S. comatularum can be easily distinguished from its closely related S. carinatus and S. stimpsonii based on the sickle-shaped dactylus in the small chela, dactylus of the third pereiopod with inferior unguis rudimentary and superior unguis strongly hooked. S. comatularum collected from different species of host indicates that the shrimps are not host specific. Previously reported from the Gulf of Mannar, Ceylon ( Pearson 1905), however, no further record was observed after that. The present record extended the 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).