Apogonichthyoides opercularis ( Macleay, 1878 )

Fraser, Thomas H. & Allen, Gerald R., 2010, Cardinalfish of the genus Apogonichthyoides Smith, 1949 (Apogonidae) with a description of a new species from the West-Pacific region, Zootaxa 2348, pp. 40-56 : 53-54

Apogonichthyoides opercularis ( Macleay, 1878)

Figure 2G & H; Table 1–2

Type material: Apogon opercularis Syntypes AMS I.16309-001 formerly MAMU F406 (20, 44.5–89.8), Australia, Port Darwin. Now: AMS I.16309-001 Lectotype (1, 76.6), x-ray. AMS I.16309-003 formerly AMS I.16309-001 Paralectotypes (17, 44.5–89.8), x-ray 1 spec 70.0. Syntypes; non Apogon opercularis ; AMS I. 16309-002 formerly AMS I.16309-001 (2, 71.1–75.1).

Other material: Australia, Northern Territory: AMS I. 24678-059 (31, 32.4–71.9), NT, Darwin, East Point, 31 Aug 1984, 1 m. NTM S.11488-004 (22, 18.6–73.4), Vesteys Beach Reef, Darwin, 5 Nov 1982, 0– 0.25 m. NTM S.14472-009 (11, 14.3–68.8), North Side "Turtle Reef", Field Island, 12.068°S 132.318667°E, 5 Jun 1997, 0– 1 m. NTM S.14966-008 (6, 39.6–76.3), North Side, Field Island, 12.0586667°S 132.388667°E, 10 Sep 1999. NTM S.16159-046 (8, 10.3–27.0), Moira Reef, Port Patterson, 12.514167°S 130.5105°E, 8 Nov 2002. USNM 173869, (1, 46); Yirrkala, Gulf of Carpentaria, 14 Jul 1948, cleared and stained. Western Australia: WAM 30849.002 (15, 12–70), Careening Bay, 25 Sep 1994. WAM 31085.012 (12,16–73), Long Island, Vansittart Bay, 24 Nov 1995. WAM 31204.042 (1, 47), Kingfisher Island, 27 Sep 1996.

Diagnosis: Blackish-tipped first-dorsal fin; no brownish bars on body, faint darker basicaudal mark in adults; darkish mid-postocular mark just posterior of preopercular edge; pectoral-fin rays 16 without small darkish spot above axil; soft dorsal-fin with 10 rays; soft anal fin with 9 rays.

Description: Range of proportions (as percentage of standard length) in Table 1 with lectotype first and paralectotypes in parentheses.

Dorsal fin VII(I)-I,10, rarely VII(I)-I,11; anal fin II,9; pectoral-fin rays 16–17; pelvic fin I,5; longest procurrent caudal rays segmented, 1+8-7+1 principal caudal rays; pored lateral-line scales 24; transverse scale rows above lateral line 2, one large, one small; transverse scale rows below lateral line 6; median predorsal scales 3; circumpeduncular scale rows 12 as 5+2+5; total gill rakers and rudiments 14–17, well developed 7– 8, upper arch 2+1, lower arch 6-7+5-7; second arch with small tooth patches or low rudiments.

Villiform teeth in band on premaxilla and dentary; 3–4 rows on vomer; 2–4 rows on the palatine; none on ectopterygoid, endopterygoid or basihyal.

Vertebrae 10+14. Interhamal gap 1+3 ( Table 2 ). Five free hypurals; one pair of slender uroneurals with anterior small expansion; three epurals, anterior with expansion; a free parhypural; one autogenous haemal spine. Three supraneurals, two supernumerary spines on first dorsal pterygiophore. No procumbent spines (spurs). Basisphenoid present. Supramaxilla absent. Posttemporal serrate on posterior margin. Preopercle ridge smooth, edges serrate on vertical margin, ventral edge smooth becoming serrate posteriorly. Infraorbitals smooth. Infraorbital shelf present on third bone. Eighth dorsal spine a hidden nubbin, distal radial free. A pair of rounded scleral bones.

Scales ctenoid on cheek, subopercle, opercle, nape, isthmus, base of pectoral fin, ctenoid behind pectoral fin and on body; predorsal scales cycloid, largest sometimes partly ctenoid; two large scales on base of pelvic fin, anterior cycloid to ctenoid, posterior cycloid, no axillary scale. Pored lateral-line scales complete, fourth scale with 2–3 pores above and 2–3 below main canal; last pored lateral-line scale elongate with small accessory lateral pores along edges.

Head with many small pores. Anterior end of supra-orbital canal as a broad slit pore at edge of snout with a cleft-like distal edge open, no large pore over eye; lachrymal with large, elongated anterior pore near both nares; two large ventral slit pores along edge of lachrymal; anterior portion of dentary with dentary (anterior) and mental (ventral) pores; a large, slit-like articular pore just forward of anterior end of preopercle; supratemporal canal with well developed posterior canals onto nape.

Anterior nare tubular, posterior nare flat.

Caudal fin emarginate; second dorsal and anal fin with rounded distal edges.

Life colors: Unknown. Postmortem colors: generally brown without definite dark bars, but occasionally with hint of broad bars below each dorsal fin; head with bronzy reflections; narrow diagonal, dark brown band sloping ventrally and posteriorly from lower edge of mid eye to edge of preopercular angle; fins generally dusky brownish, except pectorals translucent.

Preserved color pattern: See figure 2G & H. Narrow darkish cheek mark from lower margin of eye to corner of preopercle often not visible; tiny to small darkish mid-eye level spot at edge of preopercle; no snout stripes; lips and gular area uniform; body brownish, generally uniform without faint darkish bars, sometimes a faint basicaudal spot; first dorsal, second dorsal, anal and caudal fins dusky, second-dorsal fin with a dark, narrow stripe; base of pelvic fin darkish; pectoral fins pale; peritoneum, intestine and stomach pale.

Distribution: This species is known only from Australia west of Cape York in Queensland to North West Cape in Western Australia. There are no known collections from the opposite coastal waters off the island of New Guinea.

Remarks: Macleay’s type series included 20 specimens. Two specimens had fin counts of VII-I,9 for the dorsal fin and II,8 for the anal fin, 14 pectoral rays, 19–20 total gill rakers and rudiments, 10–11 welldeveloped gill rakers very different from the other 18 specimens. A 76.6 mm specimen in AMS I.16309-001 is designated as the lectotype and the remaining 17 specimens as paralectotypes. The other two syntypic specimens were removed to AMS I.16309-002.

Apogonichthyoides opercularis is superficially similar to A. timorensis and the two species have been frequently confused. However, the present study confirms they are readily separable by soft dorsal and anal fin-ray counts.