Choerodon (Choerodon)

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 : 10-15

Choerodon (Choerodon)

Tables 2 & 3

Choerodon Bleeker, 1847: 10 , type species – Labrus macrodontus Lacepède (= C. anchorago ) by monotypy (published as nomen nudum in Bleeker, 1845: 513).

Choerops Rüppell, 1852: 20 , type species – Choerops meleagris Rüppell (= C. anchorago ) by monotypy.

Cossyphodes Bleeker, 1858b: 408 , type species – Labrus macrodontus Lacepède (= C. anchorago ) by monotypy.

Hypsigenys Günther, 1861: 383 , type species – Labrus macrodontus Lacepède (= C. anchorago ) by monotypy.

Torresia Castelnau, 1875: 36 , type species – Torresia austialis Castelnau (= C. schoenleinii ) by monotypy.

Choerodon (Macrochoerodon) Fowler & Bean, 1928: 200 , type species – Crenilabrus oligacanthus Bleeker, 1851 by monotypy.

Diagnosis. Dorsal fin rays XIII, 7; anal fin rays III, 9 or 10; pectoral fin rays ii, 13–16, rarely 17, dorsalmost ray of moderate length 24.9–53.9% 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, 31.4–47.3% SL, head depth 23.7–41.0% SL, caudal peduncle depth 11.8–17.8% SL; head blunt, dorsal profile of snout moderately steep, snout length 9.0–18.6% SL; predorsal scales approximately 4–9, reaching forward on dorsal midline, not quite to above posterior edge of preopercle, to about midpoint between posterior extent of orbit and posterior edge of preopercle, or somewhere between; cheek with small partially embedded scales in about 1–10 diagonal rows, posteriormost with about 4–15 scales to upper extent of free preopercular edge, reaching forward to or almost to corner of upper lip crease above mouth, with broad naked margin posteriorly and ventrally on preopercle; 1–3 rows (only about 2 scales in second and third rows when present) of small to moderately large scales on subopercle adjacent preopercular edge extending forward to about anterior end of ventral preopercular margin, confined to upper end of preopercular surface, or reaching somewhere between, with about 1–8 scales in outermost row; each lateral line scale with triple to multiple branching laterosensory canal tube; scales above lateral line about 2½–4½; cephalic sensory canal pores relatively few confined to lines or short branches associated with major canals or numerous; dorsal and anal fins with very low basal sheath comprising 1–5 progressively smaller accessory scales at deepest; posterior lobe of dorsal and anal fins not reaching or reaching just beyond hypural crease; second pair of canines in lower jaw directed anterodorsally and little to strongly laterally, greatly curved in some; caudal fin truncate to distinctly rounded or with concave posterior profile. (See Table 1 for additional meristic and morphometric ranges.) Usually separate juvenile, initial phase and terminal phase colour patterns.

Reaches moderately large maximum size, one or more species reported to attain a metre SL.

Comments. As the second largest subgenus of Choerodon , this complex comprises nine species, most of which reach a larger size than those of other subgenera. Two are widely distributed in the western Pacific, one also occurring in the north-eastern Indian Ocean. The evolutionary hypothesis presented by Puckridge et al. (2015) implies clades within the major (subgeneric) clades, the largest within this subgenus comprising at least four species, C. cephalotes , C. cauteroma , C. rubescens and C. schoenleinii (fig. 1, clade 3). Morphological support for this clade includes a reduction in subopercular squamation and the highest number of branched pectoral fin rays, regularly 15–17. A species of Choerodon not included in the genetic analysis, C. graphicus , is of similar body form to others in the subgenus, shares the reduced subopercular squamation and is likely to be a member of this clade. A second clade within the subgenus comprises C. anchorago , C. cyanodus and Choerodon oligocanthus .

The four earliest group names proposed for the subgenus were all based on the type species, C. anchorago , albeit in reference to two of its junior synonyms. Early confusion undoubtedly arose from limited communication during the 14 years between the publication of the first and last of the four names, although a justification for Bleeker’s second name Cossyphodes was not provided (Gill, 1908; Gomon, 1997). Castelnau (1875) was certainly familiar with the genus Choerodon because he treated three species assigned to the genus (as Chaerops ) in the publication in which he presented his new Torresia , but probably failed to make the generic link because of the juvenile form of his type specimen. Torresia australis appears to be a junior synonym of C. schoenleinii . Macrochoerodon was proposed as a subgenus by Fowler and Bean (1928) to distinguish C. oligacanthus from other species of Choerodon by its elongate pelvic fins, which extend past the anal fin origin in adults. In all other regards, the species is consistent with those of the subgenus.