| Diagnosis: |
Dorsal spines (total): 0; Dorsal soft rays (total): 11; Anal spines: 0; Anal soft rays: 20-22; Vertebrae: 33-35. Diagnosis: Distinguished from its congeners except L. insularis, L. lankensis, L. ruhuna, and L. varuna by its colour pattern, including a dark stripe along the middle of the posterior third of the side or slightly shorter, anteriorly replaced by 6–11 short vertical bars (vs. presence of a dark stripe along the side but no bars in L. fasciata, L. parafasciata, and L. trevori; plain sides or presence of a very narrow posterior stripe in L. khujairokensis, L. latens, and L. laubuca; indistinct vertical bars anteriorly on the side, followed by a dark stripe ending in a triangular spot on the caudal-fin base in L. siamensis; a few dark bars present anteriorly on the side but lateral band absent in L. caeruleostigmata); distinguished from L. fasciata, L. latens and L. trevori also by more dorsal-fin rays (ii.8½ vs. ii.7½) and from L. siamensis by the absence of a dark spot on the caudal-fin base; distinguished from L. insularis by fewer scales in the lateral line (29–32 vs. 34–36), shorter pelvic fin (not reaching to vent, vs. reaching to bases of anal-fin rays 3–8); from L. lankensis by fewer scales in the lateral line (29–32 vs. 34–37); from L. ruhuna and L. varuna by the presence of an entire, narrow lateral band on the posterior third of the body, vs. a series of blotches along the side which may form a broad band extending anteriorly to about the middle of the side (Ref. 118870).
Description: Elongate, strongly compressed laterally; predorsal contour slightly ascending, levelling out close to dorsal fin-base, minor indentation at commencement of squamation; dorsal-fin origin marking 2/3 of standard length, immediately posterior to vertical from anal-fin origin; dorsal-fin base contour slanting, continuous with dorsal contour of caudal peduncle; caudal peduncle only slightly tapering caudad; snout shorter than orbital diameter, triangular in lateral aspect, rounded in dorsal aspect; mouth terminal, lower jaw at about 50° angle, tip anterior to upper jaw, not quite reaching level of upper margin of orbit; eyes large, lateral, in middle of head length, well visible in ventral aspect of head, in dorsal aspect only slightly; anterior nostril tubular, opening anterolaterad; supraorbital ending anteriorly in sharp point; long shallow frontal and rostral neuromast grooves present; barbels absent; tubercles absent; lower jaw with wide band of minute papillae, tentatively identified as neuromasts; ventral outline more arched than dorsal; slanting about straight to under pectoral-fin base, posteriorly about straight horizontal to anal-fin insertion; anal-fin base contour straight ascending; chest flat close to isthmus; from pectoral-fin base caudad to pelvic-fin base strongly compressed, posteriorly strongly compressed and with sharp keel formed by margins of opposed left and right side abdominal scales; all scales cycloid, thin, transparent; lateral line anteriorly descending for about 5 scales, posteriorly paralleling ventral outline, ending on lower half of caudal peduncle, continued by 1–2 scales basally on caudal fin; single row of scales along base of anal fin; elongate axillary pelvic-fin scale present; lateral line scales 29 (1), 30 (2), 31 (7), 32 (3) in Cox’s Bazar specimens; 29 (1), 30 (5), 31 (7) in Rakhine specimens; predorsal scales 16 (1), 17 (6), 18 (4) in Cox’s Bazar specimens; 16 (2), 17 (7), 18 (1) in Rakhine specimens; circumpeduncular scales 12 (27); scales between dorsal fin origin and lateral line ½6 (28); between lateral line and anal-fin origin 3 (28), of which distal scale part of abdominal keel; dorsal-fin origin at about posterior 3:rd of body, slightly posterior to origin of anal fin; with straight distal margin, rays gradually shorter from 2:nd unbranched ray to last ray; dorsal-fin rays ii.8½ (29); anal fin with longer base than dorsal fin; short rounded anterior lobe, posterior rays gradually shorter; anal-fin rays iii.16½ (3), iii.17½ (3), iii.18½ (8) in Cox’ Bazar specimens; iii.18½ (3), iii.19½ (10, iii.20½ (2) in Rakhine specimens; pectoral-fin long, falcate, unbranched ray longest or unbranched and 1st branched ray equally long, not reaching to vent; two large scales covering bases of branched fin rays and adjacent chest; caudal fin forked to about middle of fin; pectoral-fin rays i.10 (1), i.11 (10), i.11 (3) in Cox’s Bazar specimens; i.10 (4), i.11 (9), i.12 (2) in Rakhine specimens; pelvic fin inserted slightly anterior to middle of side; short, unbranched ray longest with short prolongation, not reaching to vent; pelvic-fin rays i.5 (1), i.6 (13) in Cox’s Bazar specimens; i.6 (15) in Rakhine specimens; Vertebrae: predorsal 16 (2), 17 (5), precaudal+caudal 15+18 (1), 15+19 (5), 16+19 (1), within caudal peduncle 5 (4), 6 (3) in Cox’s Bazar specimens; predorsal 16 (1), 17 (5), precaudal+ caudal 15+18 (1), 15+19 (4), 16+19 (1), within caudal peduncle 5 (4), 6 (2) in Rakhine specimens (Ref. 118870).
Coloration: In in formalin-fixed specimens: Ground colour pale yellowish white with diffuse grey or black markings except for round black cleithral spot size of pupil; dorsum sparsely pigmented; brown stripe on dorsal midline from occiput to end of caudal peduncle; thin black or brown stripe along middle of caudal peduncle or slightly longer, anteriorly replaced by 6–11 grey or brown short vertical bars, not reaching ventrally onto abdomen, less distinct in some larger specimens; a few black dots along middle of abdomen; fins hyaline (Ref. 118870). In ethanol-fixed specimens: with silvery opercle and sides; vertical bars indistinct, dorsum grey, abdominal sides pale yellow; cleithral spot and lateral band black (Ref. 118870). In life: specimens observed only in the type locality , with silvery reflections dorsally, abdomen white, sides blue, along middle a wide iridescent green cleithral spot flanked by golden (Ref. 118870). |
