Choerodon margaritiferus Fowler & Bean, 1928

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 : 81-83

Choerodon margaritiferus Fowler & Bean, 1928

Pearlyscale Tuskfish

Choerodon margaritiferus Fowler & Bean, 1928: 197 , Jolo Market, Jolo ( Philippines).

Choerodon sp. A White et al., 2013: 266, fig. 89.19 (Lombok, Indonesia).

Diagnosis. Dorsal fin rays XII, 8; anal fin rays III, 10; pectoral fin rays ii, 13, dorsalmost ray short 7.3–12.9% pectoral fin length, ventralmost ray distinctly longer than those immediately above, posterior edge of fin falcate, dorsoposterior corner bluntly pointed, posteroventral corner sharply pointed ted; body shallow, 24.7–30.8% SL, head depth 19.4–25.2% SL, caudal peduncle depth 9.4–10.5% SL; head bluntly pointed, dorsal profile of snout shallow curve, snout length 9.4–12.1% SL; predorsal scales approximately 6 or 7, reaching forward on dorsal midline almost to midpoint between posterior extent of eye and posterior edge of preopercle; cheek with small partially embedded scales in about 3 or 4 diagonal rows, posteriormost with about 5 or 6 scales to upper extent of free preopercular edge, reaching forward to below middle of eye with very broad naked margin posteriorly and ventrally on preopercle; 1–3 rows of about 6–8 small scales (only about 2 scales in second row when present) on subopercle adjacent preopercular edge extending forward to about midpoint of ventral preopercular margin; each lateral line scale with unbranched or single branched laterosensory canal tube; scales above lateral line about 2½ or 3; cephalic sensory canal pores variable, mostly confined to lines or short branches associated with major canals to numerous scattered on top of head and anteroventral to eye and apparently not confined to lines or short branches associated with major canals; second pair of canines in lower jaw directed dorsolaterally and curved posterolaterally; dorsal and anal fins without basal sheath, additional small scale at top of some oblique rows; posterior lobe of dorsal and anal fins not quite reaching hypural crease; caudal fin truncate, often with posterior margin slightly convex medially; pelvic fin not quite reaching anus, length 19.0–21.3% SL. (See Table 5 for additional meristic and morphometric ranges.) Initial phase pink overall with white underside and broad orange stripe just above lateral midline; caudal fin with bright reed posterior margin. Terminal phase green above, white below, with interrupted blue stripe midlaterally, horizontal row of blue scales on lateral line anteriorly, row of blue scales adjacent base of dorsal fin posteriorly and horizontal blue stripe below eye from tip of snout to preopercular edge; blue-edged, reddish brown blotch crossing lateral line below 9th to 11th dorsal fin spines.

Reaches moderately small maximum size, largest specimen examined 115 mm SL.

Pigmentation in alcohol. Juveniles uniformly pale. Initial phase adults pale with narrow dusky to dark posterior margin on caudal fin. Terminal phase dusky above, paler below, with narrow pale stripe from tip of snout to lower edge of eye, continuing as broken row of pale spots to pale irregular narrow blotch in pectoral fin axilla continuing as pale spots to above middle of anal fin base; second narrow pale band in form of spots from behind eye across opercle to side posterior to just above pectoral fin tip; pale band from middle of opercular margin across pectoral fin base; narrow pale stripe below dorsal fin base anteriorly to dorsal caudal peduncle nearly to caudal fin base; additional narrow pale stripe midlaterally underlying lateral line along length of caudal peduncle, becoming dusky to dark with fading of overlying pale pigment. Dorsal and anal fins pale.

Fresh colours. Juveniles unknown.

Initial phase adults pink overall, darker on dorsal half of side and head, breast and belly white (fig. 43A); slightly darker lengthwise stripe above lateral midline to dorsal half of caudal peduncle. Dosal fin pale pink, darker near tips of spines; anal and pelvic fins white; caudal fin yellow with pink basal third and dark red posterior margin. Pectoral fin hyaline. ( White et al., 2013: 267, fig. 89.19).

Terminal phase adults greenish grey dorsally, white ventrally with pink hue midlaterally (fig. 43B); terminal phase with large red blotch centred just above lateral line below 9th to 11th dorsal fin spines with oblique grey bar on anterior edge; greyish white stripe originating on posterior edge of operculum just above pectoral fin base breaking into scalesized spots centrally on side, again becoming prominent stripe on lateral midline below posterior end of dorsal fin, terminating in point anteriorly on caudal fin; second horizontal series of greyish white spots along dorsal profile of side below segmented portion of dorsal fin and on caudal peduncle; additional greyish white spots scattered centrally on side; downward opening crescentic greyish white band on pectoral fin base; head with horizontal greyish white stripe extending from snout tip, below eye to preopercular edge; vertical greyish white mark on dorsoposterior edge of eye; scattered pink blotches, especially on operculum; eye red with yellow dorsal margin on iris and greyish white margin to eye dorsally. Dorsal fin with broad yellow basal stripe slightly narrower pink stripe distally and narrow yellow distal margin; colours less defined posteriorly; anal fin white with broad yellow midlateral stripe and fine yellow distal margin; caudal fin hyaline with pink hue. Pectoral fin hyaline with greyish white rays dorsally; pelvic fin hyaline with pink leading edge bordered by similarly narrow yellow longitudinal stripe ( Kuiter, 2010: 63, top; Allen & Erdmann, 2012: 246, bottom; Miyamoto et al., 2015: 84, fig. 1A and B).

Etymology. The name margaretiferus is Latin for “pearl bearer”, in reference to the series of pearlescent spots on the side of the body.

Distribution. Known conclusively only from Okinawa in southernmost Japan, Taiwan, Philippines, and Indonesia off eastern Sulawesi and Lombok (fig. 38) at depths to at least 30 m.

Comments. Choerodon margaritiferus was described by Fowler and Bean (1928) from a single specimen (USNM 13558, 115 mm SL) purchased at a market in Jolo, Philippines. The apparent absence of other specimens in collections until recently and the overall similarity of members of this complex to one another has caused confusion over the identity of the species to which the name was affixed.

The name C. margaritiferus was appropriately applied by Puckridge et al. (2015: 5, fig. 1, as Choerodon margaritiferus ) in their investigation of the interrelationships of species of the genus employing genetic markers. The study recovered C. margaritiferus as sister to C. gomoni , a species so similar that Randall and Allen (2002: 110) designated a specimen of the former from the Bangai Islands off eastern Sulawesi, Indonesia as a paratype of the latter. The two appear to be among the smallest species of Choerodon . They are extremely similar and difficult to separate at initial phase and juvenile sizes.

The specimen from which the tissue was taken for Puckridge et al. ’s (2015) sequences of C. margaritiferus was treated and figured by White et al. (2014: 266, fig. 89.19) as Choerodon sp. A “Redtip Tuskfish”. Like C. gomoni , freshly caught individuals have an overall bright rosy hue that obscures underlying colouration and rapidly fades after death. The specimen featuring in the above two studies is a female that differs markedly in colouration from the male shown by Miyamoto et al. (2015: 84, fig. 1A & B). The last study also recovered the taxonomic relationships found by Puckridge et al. (2015). The species in all three studies tentatively identified as C. cf. margaritiferus is C. albofasciatus , a new name for Choerodonoides japonicus Kamohara , proposed above.

Material examined. 11 specimens, 82.8–115 mm SL; see appendix.