Lysmata ternatensis De Man, 1902

Madhavan, Manu, Purushothaman, P., Akash, S., Bharathi, S., Jose, Sheena, Dhinakaran, A., Ravi, Charan, Kumar, T. T. Ajith & Lal, K. K., 2019, New record of Thor hainanensis Xu & Li, 2014 and taxonomical remarks on Lysmata ternatensis de Man, 1902 (Decapoda: Thoridae & Lysmatidae) from the Lakshadweep Islands, India, Zootaxa 4624 (3), pp. 351-364 : 356-357

Lysmata ternatensis De Man, 1902

( Fig 2b , 4 , 5 )

Palaemon dentatus —De Haan, 1844 : pl–45, fig. 13 (type locality: Japan).

Lysmata seticaudata —De Haan, 1849:176 .

Lysmata seticaudata var. ternatensis — De Man, 1902: 846 (type locality: Ternate, Indonesia, possibly also Ambon and, less likely, Japan).

Hippolysmata acicula — Rathbun, 1906: 912 , pl 24: fig. 6 (type locality: Puolo Point, Kauai, Hawaii).

Lysmata affinis — Borradaile, 1915:209 (type locality: recorded from four localities in the Lakshadweep Islands, Chagos Archipelago, and the Seychelles).

Lysmata dentata — Holthuis, 1947:64 .

Lysmata ternatensis —Chace, 1997: 77 ;—Xu & Li, 128–130, fig. 12 (type locality: China seas);—Zhibin & Li, 2018: 214;— Wang & Zhong, 2018: 39.

Material examined. NBFGR-LYS-LT-01, 2 males (CL 8.0–9.0 mm), 3 females (CL 6.0–9.0 mm), Arabian Sea, off Agatti Islands, Lakshadweep, India, 10°50’43”N, 72°11’21”E, 0.5–2 m deep, December 2018 and January 2019.

Diagnosis: Carapace (fig. 5A) smooth, glabrous; eye short, developed cornea with longer and broader than stalk, orbital margin regularly concave. Antennal spine stronger than pterygostomian and fused with orbital angle, hepatic spine absent. Rostrum short, nearly straight, 0.32–0.35 times as long as carapace and almost reaching distal end, 2 nd antennular peduncle distantly armed with fixed teeth originated mid of the carapace dorsally with setae interspaces and anterior end of ventral margins; bearing 5–6 dorsal (including 2 teeth on carapace) and 2 ventral teeth.

Abdomen ( Fig. 5B ) smooth, glabrous; pleura of 1 st to 3 rdsomites were rounded, posteroventral margin of 4 th somite slightly angular; 5 th somite produced acute tooth in posterior ventrally, 6 th somite with acute, and sharply produced posterior-lateral angle. Telson 1.5–1.8 times as long as 6 th abdominal somite; dorsal surface bearing 2 pairs of stout dorsolateral spines; posterior margin bearing 1 pair of each of spines and stiff setae mesially.

Antennular and antennal flagellums were developed; dorsal antennular flagellum found distinct accessory branches of about 14–18 articles; first segment of antennular peduncle longer than combination of second and third segments; stylocerite well developed and acute with outer margin barely curving upward, nearly reaching the distal end of 1 stantennular peduncle. Antennal scale slender, 4.0 times as long as wide; lateral margin almost straight and ending with lateral spines which extend beyond the margin of scale (fig. 5C).

Third maxilliped ( Fig. 5A ) with exopod extended beyond the distal end of antennal scale; ultimate segment 2.1–2.7 times as long as penultimate segment armed with 5–7 spines disto-dorsally; medial and lateral surfaces furnished with dense setae. First pereiopod (fig. 5D) robust, slightly overreaching distal end of 3 rdantennular segment; Chela 1.5–1.7 times as long as carpus, tapered proximally; dactylus slender; carpus bearing long setae ventral and dorsally; merus 0.9–0.95 times as long as carpus. Second pereiopods (fig. 5E) slender and longer overreaching distal end of antennal scale; dactylus almost half of length propodus with bunch of long setae distally; carpus elongate, 2.0–2.4 times as long as merus, composed of 19–25 segments; merus subdivided into 14–15 segments. Distal side of ischium composed of 2 segments. Third pereiopod (fig. 5F) overreaching distal end of antennal scale; dactylus biunguiculate, with tufts of setae on terminal margin to distal end of carpus, armed with 3–4 small spinules; ventral margin of propodus with 6–9 spinules; merus with 5–7 disto–lateral spines and long setae.

Colouration in life: Generally body and appendages are reddish and transparent with 8–9 red oblique bands running on dorsally (fig. 2). Rostral dorsal carina slightly reddish; epigastric and epicardiac regions of carapace were reddish with small white dots. Antennal scales are transparent; telson and uropods are marginally reddish with bands vertically; Third maxilliped and pereopods are transparent with red dots dorsally; eye stalks are dorsally transparent reddish.

Distribution and Ecological notes: Lysmata ternatensis is widely distributed in the Indian and Pacific oceanic regions: Yellow Sea, East and South China Sea, Seychelles, Lakshadweep Islands, Chagos Archipelago, Japan, Indonesia at depth of 2– 50 m. The present specimens were collected from the crevices and rocks at a depth of 0.5–2.0m in intertidal region of Agatti Island ( Lakshadweep). This rock pool shrimps are known to show different behaviors like shyness, staying mostly inside rocks and shells, and changing the original colour from reddish to brownish green during collection.

Remarks: The present specimens agree well with the diagnostic keys of this species provided by Chace (1997) and Xu & Li (2015). However, the following minor discrepancies were observed: rostrum straight with strong 5–6/2 teeth and reaching distal end 2 ndantennular peduncle, dorsal antennular flagellum with distinct accessory branch of 14–18 articles, color transparent with 9 fine red longitudinal lines, second pereiopods overreaching distal end of antennal scale with carpus composed of 19–25 segments; merus subdivided into 14–15 segments, slight variation in length of pereopods. Previously, this species was identified as L. affinis in Lakshadweep waters by Borradaile (1915). Later, it was reclassified into L. ternatensis by Chace (1997). Similarly, Lysmata amboinensis , L. debelius , L. vittata , L. seticaudata , and L. moorei were closely related species to L. ternatensis morphologically. L amboinensis , L. debelius , and L. vittata were differed with L. ternatensis by presence of dorsal antennular flagellum with accessory branch lacking or vestigial, consisting of no more than 2 articles, antennular peduncle with stylocerite reaching or not reaching of basal segments, colouration of the species: L. amboinensis has a pair of longitudinal continuous white line from the rostrum to telson dorsally; L. debelius has uniform deep red on carapace including rostrum, chelipeds, pereopods and pleopods, presence of brilliant white on propodus and dactylus regions, large circular white spots on carapace and epistome ( Prakash et al., 2016); Body of L. vittata semi-transparent with longitudinal, oblique, transverse reddish-brown stripes; with an almost complete transverse stripe on the anterior and posterior ends. L. seticaudata differed by the presence of disto-lateral tooth in antennal scale overreaching the blade (Chace, 1997). L. moorei was differed with L. ternatensis by having antennal scale lesser than 3 time as long as wide, chela of 1 stpereopod more than 1.5 times as long as carpus length. L. intermedia , L. nilita and L. galapagensis differed with presence of concave lateral marine of antennal scale. Further, mitochondrial COI sequences were generated for the collected specimens and submitted to Genbank (Accession No: MK766460 , MK766461 ). K2 genetic divergence of the species was calculated in comparison with 21 species of the genus, Lysmata which is available from BOLD system and NCBI ( Table 1 ). The ML analysis revealed that the present specimens form a robust monophyletic clade with L. ternatensis ( KP759426 ) with 0.3% divergence and against 21.4% divergence with L. moorei (fig. 6). Similarly, divergence values with L. amboinensis and L. debelius were 22-25.1%, 20.0-25.1% respectively indicating higher interspecific genetic divergence of the species with the genera Lysmata which is in close agreement with morphological differences.

Figures

FIGURE 2. Picture representations of Thor hainanensis Xu& Li, 2014 (A) and Lysmata ternatensis De Man, 1902 (B) in live.

FIGURE 4. Lysmata ternatensis De Man, 1902 from Agatti Island, Lakshadweep, India

FIGURE 5. Morphological characters of Lysmata ternatensis De Man, 1902 from Agatti Island, Lakshadweep, India:A—Carapace: 1—Third maxilliped, 2—Upper nntenular flagellum; B—Abdomenal segments; C—dorsal view of rostrum and antennal scale (1); D—first pereopod; E—second pereopod: F—third pereopod; G—Chela of 2nd pereopod; H—Dectylus of third pereopod.