Choerodon graphicus ( De Vis, 1885 )

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 : 27-29

Choerodon graphicus ( De Vis, 1885)

Graphic Tuskfish

Choerops graphicus De Vis, 1885: 878 , Queensland Coast (Cardwell).

Choerodon transversalis Whitley, 1956: 258 , fig. 7, Heron Island , Great Barrier Reef, Queensland.

Diagnosis. Dorsal fin rays XIII, rarely XII, 7; anal fin rays III, 10; pectoral fin rays ii, 14, dorsalmost ray dorsalmost ray of moderate length 35.4–47.9% pectoral fin length, ventralmost rays shorter than those above, posterior edge of fin obliquely straight, dorsoposterior corner bluntly pointed, posteroventral corner angular; body deep, 35.3–44.2% SL, head depth 27.4–35.1% SL, caudal peduncle depth 14.5–17.2% SL; head bluntly pointed, dorsal profile of snout moderately steep, snout length 12.2– 16.3% SL; predorsal scales approximately 5–7, reaching forward on dorsal midline to above posterior edge of preopercle; cheek with small partially embedded scales in about 7–9 diagonal rows, posteriormost with about 15 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 4–7 small scales (only 1 or 2 scales in second row when present) on subopercle adjacent preopercular edge extending forward to about middle of ventral preopercular margin; each lateral line scale with multiple branching laterosensory canal tube; scales above lateral line about 2½ or 3; numerous cephalic sensory canal pores on top of head behind eye and on cheek anteroventral to eye, fewer between eyes and on snout; second pair of canines in lower jaw directed anterodorsally, very little laterally; dorsal and anal fins with very low basal sheath comprising 1–3 progressively smaller accessory scales at deepest; posterior lobe of dorsal and anal fins reaching beyond hypural crease; caudal fin truncate to slightly rounded, upper and lower corners rounded; pelvic fin reaching to anal fin origin in large individuals, length 21.2–25.5% SL. (See Table 3 for additional meristic and morphometric ranges.) Juveniles and adults olive yellow with broad irregular, angled darker bands on side and broad darker lines radiating from eye; dark spot or blotch on lateral line below middle dorsal fin spines.

Reaches moderately large maximum size, largest specimen examined 368 mm SL, but reported to about 500 mm.

Pigmentation in alcohol. Juveniles pale with 6 broad dusky bands, anterior 2 across nape, subsequent 3 below dorsal fin and last across posterior half of caudal peduncle and base of caudal fin; bands below dorsal fin and on caudal peduncle subdividing to form more numerous narrower dusky bands with broader pale interspaces, areas near middle of several darkened as dark midlateral spots; narrow dusky bands on head radiating from eye, narrow band or pair of bands directed dorsally across top of head, pair of bands directed anterodorsally across snout, band directed anteroventrally across mouth midlaterally traversing underside of lower jaw, band directed ventrally across underside of head behind mouth, and 2 bands directed posteriorly from eye, one towards upper end of pectoral fin base and other towards origin of lateral line; about 4 dusky bands on side extending onto dorsal fin and 3 extending onto anal fin; caudal fin base with small darker spot on dorsal and ventral corners and pair of smaller spots separated by pale space midlaterally; dorsal, anal and caudal fins otherwise pale to transparent; pectoral fin transparent; pelvic fin broadly dusky to dark along leading edges, pale to transparent along posterior edges. Initial phase adults retaining juvenile bands, although those on body more uniformly broad and often fainter and those on head narrower; band directed posteroventrally from eye towards pectoral fin base usually darker; usually with large rather dark spot on lateral line below central dorsal fin spines and second on dorsal profile of side at base of last segmented dorsal fin ray. Terminal phase adults with faint bands on body if at all visible and band directed posteroventrally from eye rather dark.

Fresh colours. Juveniles and initial phase individuals white with 5 or 6 prominent irregular broad brown to black vertical bands from nape to base of caudal fin, band below central dorsal fin spines split vertically, anterior section superimposed with black spot on and below lateral line (fig. 9A & B); bands continuing on head as bars radiating from eye, 3 crossing forehead, 2 directed ventrally and 2 posteriorly, additional vertical bar crossing operculum; dorsal, anal and caudal fins crossed by blue lines or rows of fine blue spots. ( Kuiter, 2010: 50, bottom of page figs B and C)

Terminal phase individuals olive yellow with slate grey to brownish grey anastomosing transverse bands with green flecks, most body scales behind pectoral fin with vertical blue streak (fig. 9C); head dull orange to yellow on cheeks and operculum, chin bright green, bars radiating posteriorly from eye black; fins mostly dark slate grey, dorsal fin with blue margin, reddish orange submarginal line, and scattered blue and orange markings; anal fin blue with numerous fine orange markings; pectoral fin brown, although more grey basally, with green and brown base ( Kuiter, 2010: 50, bottom of page fig. A).

Etymology. The name graphicus is from the Greek “graphikos”, “of writing”, perhaps in reference to the complex markings on the side of the head and body resembling letters.

Distribution. A species with limited range restricted to the Queensland coast from Nymph Island off the Cape York Peninsula and south, at least to Southport near the New South Wales border, and New Caledonia (fig. 10). Found on inshore reefs, lagoons and estuaries with open substrate and rubble at depths of 2– 36 m.

Comments. De Vis’s (1885) brief description of Choerops graphicus agrees with the species described above, while a specimen registered as the type (QMB I. 944, 360 mm TL) with the same collection information and approximate length given in the original account (14 inches) confirms the identity. Only C. fasciatus with XII, 8 dorsal fin rays has a prominent darkly banded colour pattern at this size within the genus. Whitley’s (1956) Choerodon transversalis is based on a terminal phase specimen (AMS IB. 3527, 296 mm SL) collected at Heron Island, Queensland.

The distinctive colouration of this species is unlike that of other species except at a small juvenile size. Individuals of less than about 40 mm SL approach those of C. anchorago and C. azurio of similar size in overall pattern. Choerodon graphicus is separable from the former by pectoral fin count and vertebral formula and from the latter by distance, the two occurring on opposite sides of the tropics.

Material examined. 25 specimens, 13.4–368 mm SL; see appendix.