Plesionika semilaevis, Spence Bate, 1888

Kuberan, G., Chakraborty, Rekha Devi & Maheswarudu, G., 2020, Misidentification and notes on Plesionika semilaevis, Spence Bate, 1888 (Crustacean: Decapoda: Caridea) from the southern coast of India, Zootaxa 4861 (2), pp. 297-300 : 298

Plesionika semilaevis, Spence Bate, 1888 ( Fig. 1 )

Plesionika semilaevis: Spence Bate, 1888: 644 , pl. 68 fig.3; Chace, 1985: 113, figs 51–54; Hanamura & Takeda 1987: 116, fig. 3c, d; Ohtomi & Hayashi 1995: 1035, fig. 1; Chan & Crosnier 1997: 213; Li & Komai 2003: 268; Kuberan et al. 2017: 21, fig. 1.

Plesionika martia var. semilaevis: De Man 1920:116 , pl. 10: fig. 24

Plesionika martia: Suseelan 1985: 110 , pl. 9: fig. 4–13

Material examined: India, Arabian Sea (AS): Kalamuku , Sakthikulangara, 2 male (CL: 16–20 mm), 2 female ovigerous (CL: 20 mm); Bay of Bengal ( BOB): Tuticorin, 1 male (CL: 17 mm), 1 female ovigerous (CL: 20 mm), 1 female non ovigerous (CL: 18 mm); 200–350 m, 2014–2017 .

Characters of specimen from southern India Carapace smooth, rostrum long and slender, extending beyond the antennal scale, dorsally armed with 7–8 teeth, including 3 on carapace posterior to level of orbital margin, none with barbed tip, ventrally minutely serrate and armed with 35–44 teeth; eyes kidney shaped, maximum diameter 0.3 mm; stylocerite long bluntly acute, slightly overreaching dorsal arc of distal margin of 1 st annular segment; antennal scale less than 5 times as long as wide, distolateral tooth reaching at most to level of distal margin of blade; 3 rd maxilliped with epipod; abdomen is smooth, without a posteromesial tooth or median dorsal carina on any somite, none of abdominal pleura with distinct marginal tooth, 6 th somite about twice as long as maximum height; telson about as long as 6 th somite, with 4 pairs of dorsolateral spinules, including lateral pair of posterior spines. First four pereopods with epipods, 2 nd pair sub-equal, with 20 carpal articles, 3 rd pair extending beyond the antennal scale by lengths of dactylus, propodus,and carpus, none of the pereopods are extremely slender or thread-like. Maximum carapace length about 25 mm (modified Chace, 1985).

Coloration: Most parts of the body were consistently reddish to rose red without longitudinal or transverse bands. The ventral part of the carapace and distal segments of the III maxilliped were deep red. Pereiopod I to V with anterior and posterior segments of the carpus, merus, and propodus are whitish except reddish dactyls. The pleopods and uropods are pale red. Eggs light green.

Distribution: Philippines, Indonesia, South and East China Seas, Japan and Australia. Now distributed from the south-west and south-east coast of Indian EEZ. Depth range: 200–350 m

Remarks: Plesionika martia ( Milne-Edwards 1883) , pl. 21 (type locality: Mediterranean); East Atlantic, 399–1198 m; French Polynesia, ( Chan & Crosnier 1997) was earlier reported from India ( Alcock 1901; Suseelan 1985) was considered to be an important catch in deep sea fishery in India ( Chakraborthy 2013). The specimens were observed in three deep-sea fish landing center from the southern coast of India ( AS: Kalamuku and Sakthikulangara & BOB: Tuticorin) is actually represented P. semilaevis without exception. The morphological record of P. semilaevis from the southwest coast of India was confirmed by ( Kuberan et al. 2017) with a morphological description. The present specimen concur well with the identification key proposed by ( Chace 1985; Li & Komai 2003; Spence Bate 1888). Apart from the rostral teeth difference in both the dorsal and ventral in the range (7–8 and 35–44) and antennal scale which is less than 5 times as long as wide. The anterior part of the postrostral carina elevated and distinctly far away from the carapace, orbital margin not vertical distinctly curved backward and stylocerite long which are an important morphological character in P. semilaevis which differentiates P. martia . On close examination, the present study confirmed that the species occurring in Indian waters is P. semilaevis and not P. martia .

The sequence lengths are 600 bp and 700 bp for 16S rDNA and cytochrome c oxidase I (COI) genes respectively. Among the 16S rDNA ( KX364190 & KX364191 ) sequences revealed a genetic distance of 0–0.02 % while COI ( KX364192 & KX364193 ) sequence did not vary genetically (0%). In addition, only one sequence (16S rDNA) of P. semilaevis was available in NCBI database was retrieved (Accession no: KP725640 ) which revealed less genetic distance of 16.3% in comparison with COI (5.6 -17.8%: KP759500 , JX681789 , and JX681784 ). However, P. martia 16S rDNA ( KP725638 and JN412688 ) exhibited 16.8–18.6% which was found to be lesser than COI (26.1%: JN412728 ). From Indian water, a sequence (COI: KU708836 ) of P. martia was retrieved from NCBI and compared with the genetic distance of the species P. semilaevis , the distance ranged high of about 27.7% and also compared with P. martia ( JN412728 ) which showed high variation to about 25%.

Figures

FIGURE 1. A. Plesionika semilaevis Spence Bate, 1888, male specimen (CL: 25 mm); B. lateral view of rostrum; C. SS—Stylocerite spine, lateral view of carapace; D. lateral view of fourth abdomen; E. lateral view of telson with dorsal spines