Lethrinus variegatus Valenciennes

Wilson, G. G., 1998, A description of the early juvenile colour patterns of eleven Lethrinus species (Pisces: Lethrinidae) from the Great Barrier Reef, Australia, Records of the Australian Museum 50 (1), pp. 55-83 : 79

Lethrinus variegatus Valenciennes

PI. 3D, Fig. 10

Material examined. (29 specimens: 14-114 mm). AUSTRALIA Great Barrier Reef region , AMS 1.32476 - 004 (2: 16 mm), AMS 1.34911 - 011 (1: 30 mm), AMS 1.34911 - 012 (1: 25 mm), AMS 1.34933 - 001 (2: 14 mm), AMS 1.34934 - 001 (2: 28-47 mm), AMS I.34935-001 (3: 34-35 mm), AMS 1.34936 - 001 (1: 32 mm), AMS 1.36201 - 001 (1: 15 mm), AMS 1.37803 - 001 (1: 16 mm), USNM 336691 (3: 26-35 mm), not retained (9: 24-69 mm) ; FIJI Suva , AMS 1.22232 - 016 (1: 114 mm) ; INDONESIA EasternArchipelago , NMV 46329 (1: 73 mm) ; PAPUA NEW GUINEA Trobriand Islands , AMS I.17102-015 (1: 38 mm) .

Diagnosis. Body slender, body depth 3.1-3.5 in SL; 4.5 dorsal scale rows, 13-14 ventral scale rows; maxillary serrations absent at greater than 23 mm; cheek scales retained until 47-50 mm; dorsal spine 4 the longest.

Diagnostic colour notes. Dorsum finely-mottled grey-tan, seldom with dark banding, dorsal margin of lateral-line off-white; dark mid-lateral stripe semi-permanent, yellowish brown, width approximately 4.0 in body depth, shoulder blotch inconspicuous or absent; ventral half of body abruptly silvery off-white; dark suborbital blotch at greater than 30 mm; fins hyaline.

Pre-settlement colour notes. At 14-16.5 mm ( Fig. 10 ): head and body translucent off-white, melanophores overlying yellow-orange xanthophore pigmentation; distinct dark stripe extending from lips to orbit margin, continuing as dark mid-lateral stripe between posterior margin of orbit and caudal peduncle, may appear as series of irregular blotches; lateral-line cryptic, 3-5 irregular blotches along dorsum, interspaces silver, occasionally 3- 6 less-distinct blotches extending below dark mid-lateral stripe from pectoral fin to mid-way along caudal peduncle, further 2-3 irregular blotches adjacent to anal fin; fins hyaline.

Colour notes. A distinctive species with minimal ontogenetic variation following settlement, few differences noted between field and captive or freshly-killed colouration. At 25-50 mm: dorsum and nape finely-mottled grey-tan, 4-6 narrow dark bands above lateral-line and 2- 3 similar bands along caudal peduncle, often switched off in field, lateral-line bordered dorsally by silvery off-white interspace in field; yellow-brown mid-lateral stripe extending from lips through orbit to base of upper caudal rays, semi-permanent (cf. intermittent stripe in other species), width 4.0 in body depth, may appear as series of dark blotches in captivity ( PI. 3D), blotch below dorsal spines 3-4 forming diffuse cuboidal shoulder blotch; ventral half of body and head abruptly silvery white, without dark markings in field, often 2-3 diffuse brown stripes or bands between pectoral and anal fins in captivity ( PI. 3D) or after death, 3-4 dark blotches on cheek and operculum from 25 mm; fins mostly hyaline, anterior half of spinous fins with diffuse dark patches over off-white to pale yellow, caudal fin pale yellow with 2-3 indistinct dark bands at greater than 40 mm.

Colour in alcohol. At 25-50 mm, dorsum and nape uniform pale tan; lips and snout with dense melanophores, dark dorsal bands retained though dulled, often connecting with broad blotches on flank, dark mid-lateral stripe identical hue to dorsum, shoulder blotch usually visible; body abruptly off-white ventrally, faintly mottled; fins hyaline, sparse melanophores retained along spines.

Ecology. Moderately common in shallow seagrass beds on lagoonal or fringing coral reefs ( Cymodocea , Halodule , Thalassia ; 0.2-4 m), absent from non-seagrass areas at Green Island at less than 100 mm; solitary when recentlysettled (20-40 mm), larger juveniles occasionally join small multi-species schools with congeners, particularly L. atkinsoni , L. genivittatus , L. harak , and L. obsoletus ; observed resting on the substrate among seagrass shoots at night, not fleeing when approached.

Field identification. Distinguished from other Lethrinus species by its elongate body and snout profile, and prominentyellow-brownmid-lateralstripe. Whenobserved from behind, may be confused with species such as L. obsoletus or L. genivittatus on the basis of their similar dark mid-lateral stripes. When freshly collected, particularly at night, may appear a uniform pale olivaceus cream; the dark mid-lateral stripe and shoulder blotch becoming visible after 10-30 seconds.

Previous descriptions. Colour plates of juveniles were included in Kuiter & Debelius (1994) and Kuiter (1996) (size not given in each case), and Lee (1993) (specimen 147 mm, misidentified as L. semicinctus ).

Figures

Fig. 10. Lethrinus variegatus 13.9 mm SL, late pre-settlement stage. Composite drawing based on AMS 1.34933-