Lethrinus olivaceus Valenciennes, 1830

Mohanty, S R, Patnaik, L & Mohapatra, Anil, 2023, First record of Lethrinus olivaceus Valenciennes, 1830 (Perciformes: Lethrinidae) from the northern east coast of India, Indian Journal of Geo Marine Sciences 52 (3), pp. 155-157 : 155-156

Lethrinus olivaceus Valenciennes, 1830 : Long-face emperor

Materials examined

EBRC/ZSI/F10715, 1 specimen, 415 mm SL. Collection site: Gopalpur coast, Odisha, India .

Diagnostic characters

The species is identified by the presence of the following distinguishing characteristics: Moderately elongated body with depth 3.5 times that of standard length. Head length 0.8 times the depth of the body. Body slender and covered by cycloid scales; anus about the middle of the body; snout pointed with clearly visible lips, its length without lips 0.7 times in cheek height; lateral teeth in jaws conical; cheek devoid of scales; interorbital space convex to flat, operculum scaly towards the posterior end, lateral line slightly curved below the dorsal fin and runs straight towards caudal peduncle with 48 scales; 5½ scale rows between lateral line and base of middle dorsal-fin spines & 17 transverse series of scale rows present in between origin of the anal fin and lateral line. Seven scales on supratemporal patch. These characteristics separates the species from its congener, as described in the discussion. Dorsal fin originates before the level of pectoral fin origin; third dorsal fin spine is the longest among the dorsal spines; pectoral fin originates below the level of opercular margin, and the base of its inner surface lacks scales. The details of morphometric measurements and the meristic formula are provided in Table 1 .

Colour

Body light grey with scattered irregular dark blotches in a fresh specimen, and colour becomes whitish towards the ventral side. Wavy dark streaks on the snout were observed at the landing centre but become faded over. Upper jaw slightly reddish. Dorsal, anal fin membrane is pinkish. The membrane between the rays of the pelvic fin with dense melanophores.

Distribution

The species is distributed in New Caledonia, Thailand, Maldives, Guam, the Philippines, French Polynesia, Australia, Indonesia, and India 7. In India, it is found Wadge Bank 6, 8 off the southern tip of India (Kerela and Tamil Nadu).

Tables

Table 1 — Morphometric measurements and meristic counts of Lethrinus olivaceus Valenciennes, 1830 from the Odisha coast

Characters	Current Study
Total length, mm	495
Standard length, mm	390
Fork length, mm	105
Meristic counts
Dorsal-fin rays	X,9
Anal-fin rays	III,8
Pectoral-fin rays	13
Pelvic-fin rays	I,5
Supratemporal patch scales	6
Lateral-line scales	49
Scales above lateral line	5
Scales below lateral line	16
Measurements as % of standard length
Snout length	20.5
Snout length excluding lips	17.4
Head length	36.4
Head width	15.8
Body depth	30.3
Predorsal-fin length	40.8
Dorsal-fin base length	45.4
Prepectoral-fin length	36.9
Pectoral-fin length	20.3
Prepelvic-fin length	20.1
Pelvic fin length	21.0
Preanal length	64.6
Anal-fin base length	16.9
Caudal-fin length	25.9
Caudal-fin median ray length	7.9
1 st dorsal-fin spine length 2 nd dorsal-fin spine length 3 rd dorsal-fin spine length	6.7 10.5 10.8
4 th dorsal spine length	10.5
Pelvic spine length	13.1
1 st anal-fin spine length	3.8
2 nd anal-fin spine length	6.4
3 rd anal-fin spine length	7.9
Caudal-peduncle depth	11.5
Measurements as % of head length
Snout length	56.3
Snout length excluding lips	47.9
Upper-jaw length	34.5
Lower jaw length	33.1
Eye diameter	18.3
Interorbital width	22.5