Choerodon cephalotes ( Castelnau, 1875 )

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 : 20-23

Choerodon cephalotes ( Castelnau, 1875)

Purple Tuskfish

Choerops cephalotes Castelnau, 1875: 39 , Cape York (Queensland).

Choerops perpulcher De Vis, 1885: 877 , Moreton Bay (Queensland).

Choerodon macleayi Ramsay & Ogliby, 1887 a: 241, Port Jackson (New South Wales).

Choerops Hodgkinsonii Saville-Kent, 1893: 296 , 370, pl. 15, fig. 2, Port Denison (Queensland).

Diagnosis. Dorsal fin rays XIII, 7, rarely XVI, 6; anal fin rays III, 10; pectoral fin rays ii, 17, rarely 16, dorsalmost ray of moderate length 36.4–53.1% pectoral fin length, ventralmost rays shorter than those above, posterior edge of fin obliquely straight, dorsoposterior corner bluntly pointed, posteroventral corner angular; body moderately deep, 37.0–42.2% SL, head depth 27.9–36.8% SL, caudal peduncle depth 12.1–17.8% SL; head blunt, dorsal profile of snout steep, snout length 12.8– 18.3% SL; predorsal scales approximately 5 or 6, reaching forward on dorsal midline to above posterior edge of preopercle; cheek with small mostly embedded scales in about 1–5 diagonal rows, posteriormost with about 4 or 5 scales to upper extent of free preopercular edge, variably reaching forward from below eye posteriorly to nearly corner of upper lip crease above mouth, with very broad naked margin posteriorly and ventrally on preopercle; tiny patch of about 1–3 scales in one or two rows on dorsal end of subopercle adjacent preopercular edge; each lateral line scale with multiple branching laterosensory canal tube; scales above lateral line about 3½; cephalic sensory canal pores extremely numerous especially anteriorly and posteriorly in front of predorsal scales; second pair of canines in lower jaw directed anterodorsally and curved slightly to strongly laterally; dorsal and anal fins with low basal sheath comprising 1–3 progressively smaller accessory scales at deepest; posterior lobe of dorsal and anal fins reaching well past hypural crease in large individuals; caudal fin rounded to broadly pointed centrally; pelvic fin reaching to base of second anal fin ray in large individuals, length 22.0–33.2% SL. (See Table 3 for additional meristic and morphometric ranges.) Adults olivaceous above, creamy white below with horizontal dark patch on upper half of side from below middle dorsal fin spines to dorsal side of caudal peduncle; snout and forehead crossed by 6–8 transverse orange lines.

Reaches moderately large maximum size, largest specimen examined 253 mm SL.

Pigmentation in alcohol. Juveniles pale dusky above with about 7 obscure darker bands dorsally, first broad above eye, second narrower on nape, third below anterior part of dorsal fin, 4th broad with darker anterior and posterior margins below middle dorsal fin spines, 5th broad below first few dorsal fin rays, 6th noticeably darker on top of caudal peduncle and 7th narrow traversing caudal fin base; side ventrally pale; sometimes with midlateral row of about 4 large dusky rectangular blotches on posterior half of body and faint remnants of banding dorsally adjacent to dorsal fin; dark dusky spot dorsally on pectoral fin base and axilla; head with several dusky bands across snout and in front of eye, 6 or 7 slender transverse bands developing above and in front of eye with growth; narrow dusky bands radiating from front of eye towards rear of upper jaw, ventrally from eye behind corner of mouth, and posteriorly from eye towards pectoral fin base; dorsal fin pale with scattered small dusky patches; anal fin pale with small dusky patches basally and fine dusky vermiculations distally; caudal fin pale with narrow dusky bands darkest distally (central part of fin appearing dark when fin not spread); pectoral and pelvic fins pale. Adults dusky above and pale below with posteriorly tapering dark dusky blotch below lateral line from below middle dorsal fin spines variably to below soft dorsal fin rays and in some onto dorsal half of caudal peduncle; dorsal surface of head dark dusky crossed by up to nine narrow pale lines from about centre of eye gradually slanting anteriorly, last to snout tip; short dusky bar directed dorsoposteriorly from eye and second anteroventrally from eye; curved dusky mark posteroventral to eye; cheeks dusky with fine pale spots, opercle darker with spots ventrally; teeth blue; small dark spot on top of pectoral fin base; dorsal fin pale basally, distal half dusky; anal fin pale with narrow pale stripes distally and posteriorly; caudal fin dusky with numerous narrow pale cross bands; pectoral and pelvic fins pale to slightly dusky.

Fresh colours. Juveniles grey above, white ventrally with obscure broad orange brown stripe above lateral midline on head and body superimposed with broad black to dark brown stripe posteriorly from below middle dorsal fin spines (fig. 5A); head with blue lines as in adults. Dorsal fin of larger juveniles with horizontal rows of blue spots or narrow stripes ( Kuiter, 2010: 53, figs A, C & E).

Initial phase adults greenish grey to purple above, white to yellow below; variable horizontally elongate dark brown to black patch on side dorsoposterior to pectoral fin to upper side of caudal peduncle (fig. 5B & C); black line in axial of pectoral fin; body scales edged with blue; snout and forehead blue to violet crossed by 6–8 transverse orange lines; underside of lower jaw white crossed by 3 transverse blue bands; orbit rimmed with blue with broader blue mark directed dorsoposteriorly from eye and short blue horizontal mark posteroventral to eye; numerous fine orange to yellow spots on cheeks and operculum; teeth blue. Alternating blue and orange bands across caudal fin and distally on dorsal and anal fins; pelvic fin green with lengthwise blue lines ( Marshall, 1964: colour plate 43, fig. 293; Sainsbury & Kailola, 1984: 257, bottom; Kuiter, 2010: 53, figs B, D, F and G).

Terminal phase adults similar to initial phase but with more vivid colours; blue lines on scales joined to form closely packed fine blue lines crossing sides; horizontal black stripe on side, sometimes extending to caudal fin base; dorsal midline of head and snout intensely blue crossed by numerous orange lines.

Etymology. The name cephalotes appears to be a Latinisation of the Greek kephalotos meaning “headed”, perhaps in reference to the large colourful head of this species.

Distribution. Occurs around the northern coast of Australia from Shark Bay, Western Australia to at least Southport, Queensland, with only the holotype of C. macleayi reported to have been collected south of that in Sydney Harbour (fig. 6). Found in areas with rather open rubble or weed bottom at depths of 0.3–80 m, with juveniles sometimes inhabiting algal covered reefs in estuaries ( Kuiter, 2010: 53).

Comments. Castelnau’s (1875) description of Choerops cephalotes generally matches both C. anchorago and the species treated here, but the omission of any mention of a prominent white wedge-shaped spot behind the pectoral fin and rectangular blotch on the caudal peduncle characteristic of the former favours its identity as the latter. The type was not found by Bauchot (1963: 22) or Eschmeyer (2015) and is presumed lost. Based on museum collection records, C. anchorago appears to be rather uncommon in the Cape York region, whereas this species is abundant at this locality. The colour description of De Vis’s (1885) Choerops perpulcher is diagnostic for the species treated here and the name is clearly a junior synonym. Two specimens in the Queensland Museum collection are regarded as syntypes of that species (QMB I 945 and QMB I 9920). Although De Vis provided only a maximum size of 14 inches (350 mm) for the species, he does refer to both wet and dry material. QMB I 945 is currently in alcohol but was originally prepared as a dry specimen. It currently has a TL of about 335 mm with a badly frayed tail and may be the basis for the maximum length given by De Vis. As pointed out by Ramsay and Douglas-Ogilby (1857), their C. macleayi is a rare example of a species of this genus reaching as far south as the type locality Port Jackson (Sydney Harbour). Of the three species known to occur at this locality, C. cephalotes , C. schoenleinii and C. venustus , the authors’ description roughly matches the first two. The extremely high number of branched pectoral fin rays 17 and conversely very few scales on the subopercle identifies it as a junior synonym of C. cephalotes . Choerodon schoenleinii is the only other member of the genus that regularly has as many as 16 branched pectoral fin rays and similarly greatly reduced subopercular squamation.

Choerodon cephalotes and the very similar C. cyanodus have nearly identical distributions and are the most frequently encountered members of the genus in the shallow waters of Australia’s northern coast. The series of narrow orange and blue bands crossing the forehead in adults is distinctive for this species.

Material examined. 198 specimens, 29.1–253 mm SL; see appendix.