Choerodon (Xiphocheilus) Bleeker, 1856

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 : 61-62

Choerodon (Xiphocheilus) Bleeker, 1856

Table 2

Xiphocheilus Bleeker, 1856: 223 – Xiphocheilos typus Bleeker,

1856, by monotypy.

Diagnosis. Dorsal fin rays XII, 8; anal fin rays III, 10, rarely 9 or 11; pectoral fin rays ii, 14, rarely 12, 13 or 16, dorsalmost ray of moderate length 24.6–33.8% pectoral fin length, ventralmost rays shorter than those above, posterior edge of fin obliquely straight, dorsoposterior corner bluntly pointed, posteroventral corner angular; body shallow, 24.6–33.7% SL, head depth 21.8–25.5% SL, caudal peduncle depth 12.8– 14.2% SL; head blunt, dorsal profile of snout steep, snout snout length 8.3–9.8% SL; predorsal scales approximately 7–10, reaching forward on dorsal midline to or slightly in advance of above centre of eye; cheek covered by large imbricate scales in about 3 nearly vertical rows, posteriormost with about 6 scales to upper extent of free preopercular edge, reaching forward in advance of corner of upper lip crease above mouth, below posterior half of eye, with narrow naked margin posteriorly and ventrally on preopercle; about 5 large scales covering subopercle forward to about anterior end of ventral preopercular margin; each lateral line scale with multiple branching laterosensory canal tube; scales above lateral line about 2 or 2½; cephalic sensory canal pores numerous but confined to lines or short branches associated with major canals; second pair of canines in lower jaw directed anterodorsally and slightly laterally; dorsal and anal fins without basal sheath, 1–3 progressively smaller accessory scales adjacent to fin base; posterior lobe of dorsal and anal fins barely reaching hypural crease at most; caudal fin truncate to slightly rounded, upper corner slightly produced in largest individuals; pelvic fin reaching well short of anus in small individuals, to anus in largest, length 18.5–26.1% SL. (See Table 2 for additional meristic and morphometric ranges.) Olive above, somewhat orange to pink below, with black bar between lateral line and base of middle dorsal fin spine; numerous posteroventrally angled oblique yellow-edged blue lines on side; additional, anteroverntrally angled lines on head.

Reaches small maximum size, largest specimen examined 110 mm SL.

Comments. The name Xiphocheilus has appeared under several spellings, including within Bleeker’s (1856: 223) initial description of the genus and the accompanying description of the type species Xiphoceilos typus Bleeker (1856: 224) . The latter is regarded as a typographical error. Subsequent referral of species to the nominal genus by Günther introduced the spelling Xiphochilus ( Günther, 1861, 1862, 1867, 1880; Playfair & Günther, 1866). In more recent years, regarded as a valid genus, the generic boundary of the taxon was much less clear in the years following its proposal, as Günther alone referred species in four of the six subgenera of Choerodon recognised here to it. Gomon (1997: 861) acknowledged that Xiphocheilus has characters consistent with species of Choerodon but hypothesised it diverged prior to species within that genus primarily based on patterns of head squamation. Puckeridge et al. (2015: fig. 1) found it to be sister to a clade within Choerodon corresponding to the subgenus Choerodon (Pealopesia) . Based on genetic evidence inferring interrelationships, reduction or expansion of head squamation is likely not to have been unidirectional within the complex or reduction has occurred independently on more than one occasion. The sister relationship of C. typus with the complex of species constituting C. ( Peaolopesia ) hypothesised is supported by the shared small maximum size attained but larger first pectoral fin ray present in C. typus that approaches the condition in other subgenera. Choerodon (Xiphocheilus) is therefore recognised as a monotypic subgenus (fig. 1, clade 1b).