Choerodon zamboangae ( Seale & Bean, 1907 )

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 : 52-55

Choerodon zamboangae ( Seale & Bean, 1907)

Zamboangan Tuskfish

Choerops zamboangae Seale and Bean, 1907: 236 , fig. 6, Zamboanga ( Philippines).

Choerodon melanostigma Fowler and Bean, 1928: 199 , Jolo Market, Jolo ( Philippines).

Choerodon pescadorensis Yu, 1968: 10 , fig. 4, Pescadores (Taiwan).

Diagnosis. Dorsal fin rays XII, 8; anal fin rays III, 10; pectoral fin rays ii, 14, dorsalmost ray of moderate length 23.9–38.6% pectoral fin length, ventralmost rays shorter than those above, posterior edge of fin obliquely straight, dorsoposterior corner bluntly pointed, posteroventral corner angular; body deep, 36.1– 40.7% SL, head depth 29.0–34.5% SL, caudal peduncle depth 13.3–15.8% SL; head blunt, dorsal profile of snout steep, snout length 12.3–16.2% SL; predorsal scales approximately 7 or 8, variably reaching forward on dorsal midline almost to or distinctly in advance of midpoint between posterior extent of orbit and posterior edge of preopercle; cheek with small partially embedded scales in about 6–9 diagonal rows, posteriormost with about 10 or 11 scales to upper extent of free preopercular edge, reaching forward just in advance of corner of upper lip crease above mouth, with very broad naked margin posteriorly and ventrally on preopercle; 1 or 2 rows of about 6–11 small scales (only 1–4 scales in second row when present) on subopercle adjacent preopercular edge extending forward to about anterior end of ventral preopercular margin; each lateral line scale with multiple branching laterosensory canal tube; scales above lateral line about 2½ or 3; dorsal and anal fins with very low basal sheath comprising 2 or 3 progressively smaller accessory scales at deepest; posterior lobe of dorsal and anal fins reaching to or beyond hypural crease; cephalic sensory canal pores numerous dorsoposterior to eye but relatively few associated with major canals elsewhere; second pair of canines in lower jaw directed mostly dorsally and strongly curved 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 just past hypural crease; caudal fin truncate to slightly rounded, upper and lower corners square, only barely produced at most in large individuals; pelvic fin reaching to or just short of anus, length 21.1–24.9% SL. (See Table 4 for additional meristic and morphometric ranges.) Brown to green above, white below, separated by anteriorly tapering dark brown wedge-shaped band from behind pectoral fin base to below rear third of dorsal fin, with nearly horizontal yellow to orange stripe immediately below; head with blue lines above and below eye and on lower jaw.

Reaches moderate maximum size, largest specimen examined 249 mm SL.

Pigmentation in alcohol. Juveniles and subadults pale with large elongate dark blotch angled anteroventrally from bases of first few segmented dorsal fin rays, followed posteriorly by distinctly pale smaller blotch adjacent to dorsal edge of side. Initial phase adults pale with faint dusky to dark anteroventrally tapering wedge-shaped blotch below bases of soft dorsal fin rays directed towards inner side of pectoral fin base; head pale with short, broad dark line directed anteriorly from middle of anterior border of eye, second horizontal line beneath eye from anterior third of eye nearly to preopercular edge; similar dark mark on top of eye; broad dusky horizontal stripe on lower jaw from symphysis to anterior end of preoperculer edge; opercular margin with faint narrow dusky margin posteroventrally; pectoral fin base with dusky band at base of dorsalmost rays; dorsal fin pale with narrow dark distal edge becoming slightly broader posteriorly; anal fin pale with dusky basal and margin stripes, as well as third narrow dusky stripe separated from marginal stripe by narrow pale stripe; caudal fin pale to slightly dusky with darker periphery; pectoral and pelvic fins pale. Terminal phase adults similar to initial phase with pronounced dusky area anterodorsally and pale area posteroventrally, abrupt demarcation between areas angled from inner base of pectoral fin to bases of last couple of dorsal fin spines, dusky area quite dark above lateral line; freshly preserved specimens with immaculate anteroventrally tapering wedge-shaped area below middle of dorsal fin base adjacent to dusky area; dorsal fin with similar pigmentation as that on adjacent side.

Fresh colours. Juveniles and subadults with dark brown to black slanted wedge-shaped patch instead of orange stripe or patch obscuring stripe mesoposteriorly from midside below central dorsal fin spines to bases of segmented dorsal fin rays followed posteriorly by prominent yellow spot at termination of dorsal fin base (fig. 25A); blue markings on head as in adults (Allen & Erdmann, 649, centre left).

Initial phase adults red to reddish brown dorsally, white ventrally with dark reddish brown to black anteriorly tapered wedge-shaped oblique band angled from midside below central dorsal fin spines to bases of segmented dorsal fin rays followed posteriorly by prominent yellow spot at termination of dorsal fin base, dark wedge overlying angled orange stripe from axilla of pectoral fin to caudal fin base just above lateral midline (fig. 25B); cheeks yellow, opercle orange; underside of head and chest pale blue, extending dorsally to free margin of opercle and preopercle; 3 short blue lines and spot adjacent to eye. Dorsal fin pale blue to purple anteriorly, reddish purple posteriorly with dark blue to purple basal and distal margins and yellow subdistal stripe; anal fin blue to purple with yellow basal stripe, spots and and ocelli; caudal fin red with blue to purple distal margin and yellow submarginal streaks. Pectoral fin red, base golden; pelvic fin pale blue with blue marginal and yellow submarginal lines on leading edge. ( Chen et al., 2010: 382, fig. E; Kuiter, 2010: 54, top figs B & C; Allen & Erdmann, 2012: 649, top right)

Terminal phase adults dark red above, paler below with horizontal orange stripe from upper end of pectoral fin base to middle of caudal peduncle (fig. 25C); some with broad oblique yellow stripe angled from upper side of pectoral fin base towards bases of last few dorsal fin spines; dorsal side of head and nape slate green; lips yellow with blue submarginal line; head colouration otherwise as in initial phase individuals ( Masuda et al., 1984: pl. 194, fig. C, as C. robustus ; Sainsbury & Kailola, 1984: 259, bottom; Shen, 1993: pl. 144, fig. 5, as C. robustus ; Shibukawa, Peristiwady & Suharti, in Kimura & Matsuura, 2003: 147, as C. robustus ; Kuiter, 2010: 54, top figs A, D & E; Allen & Erdmann, 2012: 649, centre right; White et al., 2013: 267, fig. 89.18 male).

Etymology. The name zamboangae acknowledges the type locality of this species, Zamboanga in the Philippines.

Distribution. Reliable occurrences range from Wabuka in southern Honshu, Japan ( Ikeda & Nakabo, 2015: 454, pl. 177-4) and Taiwan, through the Philippines to Lombok and Raja Ampat, Indonesia, Timor Leste and north-western Australia south of Rowley Shoals (fig. 25). Reported from seaward reef slopes and rubble bottom at depths of 20–140 m ( Allen & Erdmann, 2012: 649).

Comments. Choerops zamboangae was described by Seale and Bean (1907) from two preserved adult specimens (USNM 57846: 236, 226 mm SL, holotype, USNM 61154, 203 mm SL, paratype) collected in Zamboanga, Mindinao, Philippines, with the remnants of an orange lateral stripe present in fresh material. The types of Fowler and Bean’s (1928: 199) Choerodon melanostigma are smaller (USNM 89967, 171 mm SL, holotype; USNM 5578, 95.6 mm SL and USNM, 5579, 164 mm SL, paratypes) than the C. zamboangae types and have a dark wedge-shaped blotch from the midside to the base of the rear third of the dorsal fin with contrasting pale areas preceding and following the dark area. Morphologically, the two appear identical. Kuiter (2010: 54) and Allen and Erdmann (2012: 649) figured some individuals with the horizontal orange stripe on the side described by Seale and Bean (1907: 236–237) and others with the dark marking described by Fowler and Bean (1928: 199–200) as C. zamboangae , as well as a few with both, stating that the dark marking is present in juveniles and females but not in larger, presumably male, individuals. Their interpretation appears to be justified.

Choerodon pescadoresis Yu, 1968 was synonymised (as Choerodon pescadorensis ) with C. robustus by Parenti & Randall (2000: 10) on the authority of S. C. Shen (personal communication). As with C. quadrifasciatus , Yu’s type of C. pescadoresis was not found at the National Museum of Marine Biology and Aquarium, Pintung, Taiwan and is thought to be lost. The original description more closely matches C. zamboangae and is considered to be a synonym of that species.

Choerodon zamboangae closely resembles C. robustus in general colouration and in particular the markings on the head and tail. Specimens of the former examined in Japanese and Taiwanese collections were frequently misidentified as the latter. Morphologically, the profile of the head and snout is more rounded in initial phase adults of C. zamboangae and the body is slightly shallower. The blue stripe on the lower jaw of the former broadly wraps around the underside at the front, while the stripe in C. robustus tapers to a narrow line across the symphysis. The scales on the sides of C. zamboangae lack the blue spot or vertical blue line characteristic of C. robustus . In preservation, the demarcation between the dusky and pale areas on the side is between the inner side of the pectoral fin and the base of the last couple of dorsal fin spines in C. zamboangae , except in smaller individuals that retain remnants of the dark anteroventrally tapering wedge-shaped blotch below the bases of the soft dorsal fin rays (fig. 24B). In C. robustus the two areas are separated between the inner side of the pectoral fin and the rear end of the dorsal fin base (fig. 24A). The two species appear to be mostly allopatric with C. robustus , which is by far the more broadly distributed. Documented overlap areas are confined to southern Japan and Taiwan. Puckridge et al. (2015: figs 1 & 2d) and the reanalysis provided above both recovered the two as sister species.

Material examined. 36 specimens examined, 95.6–249 mm SL; see appendix.