Choerodon fasciatus ( Günther, 1867 )

Martin F., Martin F., 2017, A review of the tuskfishes, genus Choerodon (Labridae, Perciformes), with descriptions of three new species, Memoirs of Museum Victoria 76, pp. 1-111 : 56-58

Choerodon fasciatus ( Günther, 1867)

Harlequin Tuskfish

Xiphochilus fasciatus Günther, 1867: 101 , pl. X, Cape York (Queensland), Australia.

Lepidaplois mirabilis Snyder, 1908: 96 , Japan and Riu Kiu Islands.

Choerodon balerensis Herre, 1950: 149 , Baler, Quezon (Tayabas) Province, Luzon ( Philippines).

Diagnosis. Dorsal fin rays XII, 8; anal fin rays III, 10; pectoral fin rays ii, 13, dorsalmost ray of moderate length 21.3–52.6% pectoral fin length, ventralmost rays shorter than those above, posterior edge of fin obliquely straight, dorsoposterior corner bluntly pointed, posteroventral corner angular to broadly rounded; body moderately deep, 39.2–44.7% SL, caudal peduncle depth 15.1–17.1% SL, head depth 27.8–31.9% SL; head bluntly pointed, dorsal profile of snout moderately steep, snout length 10.5–14.9% SL; predorsal scales approximately 10–14, reaching forward on dorsal midline to above centre of eye; cheek with small partially embedded scales in about 8 or 9 diagonal rows, posteriormost with about 10 scales to upper extent of free preopercular edge, reaching forward almost to corner of upper lip crease above mouth, with very broad naked margin posteriorly and ventrally on preopercle; 1 or 2 rows of about 8 small scales (only about 2 scales in second row when present) on subopercle adjacent preopercular edge extending forward nearly to anterior end of ventral preopercular margin; each lateral line scale with unbranched laterosensory canal tube; scales above lateral line about 3½; cephalic sensory canal pores confined to lines or short branches associated with major canals on top of head, scattered pores more numerous anteroventral to eye; second pair of canines in lower jaw mostly straight directed dorsolaterally; dorsal and anal fins with relatively deep scaley basal sheath comprising approximately about 2–4 enlarged scales; posterior lobe of dorsal and anal fins reaching just short of hypural crease; caudal fin truncate, corners pointed; pelvic fin not reaching anus, length 21.1– 25.6% SL. (See Table 2 for additional meristic and morphometric ranges.) Head and body with prominent vertical bands, dark grey and white in juveniles, red to black and white in adults.

Reaches moderately small maximum size, largest specimen examined 188 mm SL but reported in the literature to reach 300 mm TL.

Pigmentation in alcohol. Juveniles with narrow well-defined dark-edged dusky bands and contrastingly immaculate interspaces extending from tip of snout to base of tail, with prominent ocellated dark spots at front and rear of dorsal fin, midway along anal fin, and at base of pelvic fin, and much smaller dark spots dorsally and ventrally on caudal fin base. Adults pale with prominent broad dark-edged vertical dusky bands on head and body becoming poorly defined ventrally on sides and merging into broad dark area below segmented rays of dorsal fin, continuing narrowly onto base of dorsal fin and broadly onto base of anal fin; posterior end of caudal peduncle and caudal fin abruptly pale; pair of dark lines crossing snout in front of eye with broad dark edged dusky band across top of head between eyes; anterior 2 broad dusky bands on head contiguous with those of opposite side ventrally; dorsal, anal and pelvic fins with narrow dark margins; dark blotch between first 3 spines of dorsal fin; caudal fin with fine dusky edge posteriorly; pectoral fin pale.

Fresh colours. Juveniles with similar patterns as adults but banding brown with dark brown to black edges and with prominent eye-sized ocellated black spots anteriorly and posteriorly on dorsal fin, midway along anal fin and on basal half of pelvic fin. (fig. 27A; Masuda et al., 1984: pl. 194, fig. E, as Lienardella fasciatua ; Kuiter, 2010: 61, figs C–E)

Adults yellow to white with green dorsum and prominent violet edged bright red transverse bands on head and side, 3 crossing head and 6 across side; anterior head band covering snout and jaws, interrupted in front of eye by pair of horizontal blue lines, second through eye, third encircling head at middle of operculum (fig. 27B & C); first band on side broad, passing through dorsal fin origin, subsequent bands narrower and evenly spaced, last across scaly base of caudal fin, posterior bands often obscured in life by dark blue to black pigmentation; teeth blue. Dorsal and anal fins red with blue basal and distal margins, dorsal fin with black spot between first 2 spines; caudal fin white often with broad pink distal margin, sometime yellow near centre. Pectoral fin yellow, red basally; pelvic fin red with blue anterior and posterior margins. ( Masuda et al., 1984: pl. 194, fig. F, as Lienardella fasciata ; Shen, 1993: pl. 144, fig. 2; Okamura & Amaoka, 1997: 465, right bottom; Chen et al., 2010: 384, fig. B; Kuiter, 2010: 61, figs A, B & F; Allen & Erdmann, 2012: 646, top; Motomura & Matsuura, 2014: 383, 3 figs)

Etymology. The name fasciatus is Latin for “enveloped with bands”, in reference to the brilliant red body banding characterising adults of this species.

Distribution. Anti-equatorial from Okinawa in southern Japan to the northern Philippines in the Northern Hemisphere, and Papua New Guinea, the Queensland coast of Australia, Lord Howe Island and New Caledonia south of the equator (fig. 28). Usually shelters in caves or beneath ledges in bays and inner reefs to outer reef lagoons at depths of 4– 15 m.

Comments. Günther (1867: 101, pl. X) based his description of Xiphochilus fasciatus on two dried specimens (BPBM 1867.6.24.3, lectotype, 161 mm SL, and BPBM 1867.6.24.4, paralectotype, 143 mm SL) from Cape York, Australia. Snyder (1908: 96) was unlikely to have been familiar with Günther’s species because he erred in the generic placement of his Lepidaplois mirabilis and the two descriptions are remarkably similar, at least with respect to colouration. The two would be distinct only if the Northern and Southern Hemisphere populations are found to be separate species. Genetic comparisons remain to be done. Similarly, Herre (1950: 149) must have been unfamiliar with the previous two descriptions because he, like the other authors, commented on “its brilliant colors and striking color pattern”.

The prominent colouration described by the authors of the species and its synonyms is highly attractive to fish fanciers making it a popular aquarium species in the tropical marine aquarium trade. The distinctive pattern easily separates the species from congeners, although the more obscure banding in juveniles of a number of species and adults of C. graphicus are no doubt ancestral precursors. Donaldson (1995: 313) described the courtship and spawning of this species on the Great Barrier Reef, Queensland.

Material examined. 49 specimens, 31–188 mm SL; see appendix