Lethrinus erythracanthus 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 : 67-69

Lethrinus erythracanthus Valenciennes

PI. ID

Material examined. (3 specimens: 25-26 mm). AUSTRALIA Great Barrier Reef region , AMS I.34914-001 (1: 25 mm), AMS 1.34914 - 002 (1: 26 mm), USNM 336680 (1: 25 mm) .

Diagnosis. At 25-26 mm, body moderately deep, depth 2.8-2.9 in SL; 4.5 dorsal scale rows, 16 ventral scale rows; maxillary serrations 4-5; cheek scales present; dorsal spine 3 or 4 the longest.

Diagnostic colour notes. At 25-26 mm, dorsum and flanks yellow-orange, belly off-white yellow; 4 narrow silver primary stripes (4-6 at 50-100 mm, PI. ID), broad interspaces yellow-orange; no dark markings on body or cheeks; fins hyaline (but see "Identification note" below).

Colour notes. A species characterised by marked colour changes throughout life history, although little ontogenetic variation apparent during early postsettlement phase; no rapid colour pattern changes. At 25-26 mm, freshly collected: dorsum deep yelloworange, fading to pale orange belly, no dark banding or mid-lateral stripe patterns, silver peritoneal lining faintly visible; 4 narrow silver stripes below lateral-line, originating behind operculum and pectoral fin base, orbital stripe extending to base of caudal rays, other stripes terminating near base of caudal peduncle, interspaces broaderthan stripes and of similar colouration to rest of body; cheek and operculum off-white to silver, no dark markings, snout and lips grey to pale yelloworange, nape slightly reddish; fins hyaline, spinous fins with moderately-dense melanophores, yellow tinge distally, inner pelvic membranes without dense melanophores (but see "Identification note" below).

At 50-80 mm, in field ( PI. ID): body yellow-orange, dorsal scales pale-centred, lateral-line denoted by row of silver dots, head yellowish grey; pectoral fins hyaliQe, caudal, dorsal and anal fins dusky yellow, fading posteriorly, pelvic fins off-white; 5-8 narrow silver stripes along flanks, medial stripe of greatest intensity, extending from lower margin of orbit to base of caudal rays, remaining stripes running from operculum to base of caudal peduncle.

Colour in alcohol. At 25-26 mm, head and body uniform off-white yellow, peritoneum off-white; silver primary stripes inconspicuous, initially darker than surrounding body, faded after ca. 2 years; fins hyaline, melanophores retained.

Ecology. Settlement and nursery sites unknown, rare at Green Island, three recently-settled specimens were collected from a sheltered seagrass bed (0.5-2.0 m; Cymodocea and Thalassia ) adjacent to the shoreline; field behaviours unknown.

Field identification. Early-juvenile L. erythracanthus

individuals are rarely encountered in the field; no underwater observations were made during the present study. At the size examined, L. erythracanthus field colouration could be confused with both L. genivittatus and L. atkinsoni juveniles of a similar size. All three species may be yellow-orange over at least the snout and dorsum. The lack of dark intermittent patterns in L. erythracanthus may distinguish it from other species.

Identification note. The density of pigmentation on the innermost pelvic membranes varies among L. erythracanthus individuals ( Carpenter & AlIen, 1989). In the specimens examined, this ranged from a faint covering of fine melanophores to absence. Although the small sample and narrow size range did not allow ontogenetic effects to be distinguished from variation at the individual orpopulation level, this character may be useful for separating L. erythracanthus from other lethrinid juveniles.

Previous descriptions. The L. erythracanthus juvenile stage has been figured by Carpenter & AlIen (1989; length not given) and Lieske & Myers (1994; length not given), and colour plates included in Myers (1989; 150 mm), Randall et al. (1990; length not given), Kuiter (1992; 80 mm, reproduced here in PI. ID) and Masuda & Kobayashi (1994, 50 mm total length).