Onigocia macrocephala ( Weber, 1913 )

Imamura, Hisashi, 2012, Validity and redescription of the flathead fish, Onigocia macrocephala (Weber, 1913) (Teleostei: Platycephalidae), Zootaxa 3450, pp. 23-32 : 25-31

Onigocia macrocephala ( Weber, 1913)

(Proposed English name: Southern Notched Flathead) ( Figures 2–4 )

Platycephalus macrocephalus Weber, 1913: 508 , fig. 107 (original description, type locality: Bali Sea, north of Waigeo and southern Timor Sea) (in part); de Beaufort & Briggs, 1962: 146, fig. 36 (description, Bali Sea, north of Waigeo and southern Timor Sea) (in part).

Onigocia macrolepis (nec Bleeker, 1908): Gloerfelt-Tarp & Kailola, 1984: 123, an unnumbered fig. on p. 122 (short description, northwestern Australia); Sainsbury et al., 1984: 110, an unnumbered fig. on p. 111 (description, southern Indonesia and northwestern Australia); Paxton & Hanley, 1989: 467 (Northwestern Shelf, Western Australia); Knapp 1999, 2404, an unnumbered fig. (description, at least southern South China Sea, Indonesia, Northwestern Shelf, Western Australia) (in part); Hoese et al. 2006: 938 (list, Western Australia); Imamura et al., 2006: 295, fig. 3 (description, Nha Trang, Vietnam).

Lectotype (designated here): ZMA 112436 (70.6 mm SL), Bali Sea (7°2.6’S, 115°23.6’E), 100 m depth, Siboga stn. 15.

Paralectotypes (2 specimens): ZMA 112438 (52.9 mm SL), north of Waigeo (0°3.8’S, 130°24.3’E), 141 m depth, Siboga stn. 153; ZMA 112439 (68.1 mm SL), southern coast of Timor Sea, 36 m depth, Siboga stn. 296.

Non-types (32 specimens, 46.1–92.0 mm SL): AMS I.24855-003 (2 specimens, 59.2–65.0 mm SL), northnorthwest of Dampier, northwestern Australia (19°28’S, 116°29’E), 110 m depth, 26 Oct. 1983; CAS 29359 (7 of 8 specimens, 85.5–89.2 mm SL), off Taya Island, Guangdon Province, China (19°38’N, 111°30’E), ca. 92 m depth, 21 June 1958; CAS 33704 (79.3 mm SL), Batangas Bay, Luzon Island, Philippines (ca. 13.7°N, 121.0°E), 5 July 1968; CAS 88352 (5 specimens, 53.4–92.0 mm SL), 7 miles off Nha Trang, Vietnam (12°09’N, 109°25’E), 4 May 1960; CSIRO B2124 (3 specimens, 50.8–72.0 mm SL, voucher of Sainsbury et al., 1984), northwest of Dampier Archipelago, northwestern Australia (19°36’S, 116°12’E), 124 m depth, 1 June 1980; CSIRO CA4035 (78.1 mm SL), off Port Headland, northwestern Australia (19°32’S, 117°13’E), 86.0 m depth, 12 Oct. 1983; HUMZ 190600 (92.0 mm SL, voucher of Imamura et al., 2004), fish landing port, Nha Trang, Vietnam, 7 Oct. 2004; NTM S.13324-001 (75.5 mm SL), Timor Sea, Australia (12°57’S, 128°16’E), 97 m depth, 7 Dec. 1990; NTM S.14364- 0 0 1 (4 specimens, 57.4–71.5 mm SL), southeast of Vulcan Shoal, Timor Sea, Australia, 80 m depth, 13 June 1996; NTM S. 14365-001 (6 specimens, 46.1–75.0 mm SL), northwest of West Holothuria Reef, Timor Sea, Australia, 100 m depth, 13 June 1996.

Diagnosis. A species of Onigocia is separable from its congeners in having the combination of the following characters: 9–10 caudal fin rays, 1 + 4–6 = 5–7 (mode 6) gill rakers, a larger head (38.8–42.3% SL), a single ocular flap present and usually extending slightly beyond the posterior margin of the orbit, a few or several small and short papillae on the posteromedial portion of the eye in larger specimens, the upper iris lappet short and branched, the lachrymal with two distinct antrorse spines anteriorly and a notch on the suborbital ridge below the eye, and no interopercular flap.

Description. Counts and proportional measurements are given in Table 1 . Data of the following description are presented first for all specimens, then for the lectotype in parentheses.

Body depressed, mostly covered with ctenoid scales, some cycloid scales on undersurface. Head flattened; postorbital region, opercle and nape scaled. Snout slender, slightly longer than orbital diameter. Upper surface of eye with single ocular flap ( Fig. 4 A). Ocular flap having slightly thick outer margin and separated into two to six branches posteriorly; outer branch usually extending slightly beyond posterior margin of orbit, sometimes reaching posterior margin of orbit or not reaching it (reaching posterior margin of orbit in lectotype). A few or several small and short papillae present on posteromedial portion of eye in 78.8 mm SL or larger specimens ( Fig. 4 A), present or absent in 53.4 to 78.1 mm SL specimens, and absent in 50.8 mm SL or smaller specimen (present in lectotype). Upper iris lappet short and branched; lower iris lappet bilobed ( Fig. 4 B). Interorbital space narrow and concave. Top and side of head bearing spines and serrated ridges ( Fig. 4 A). Nasal with one to six small spines (one on left and two on right). One or three ethmoid spines present (one on both sides). Lachrymal with two distinct antrorse spines anteriorly and with zero to eight (one on both sides) small spines posteriorly. Anterior portion of lachrymal with inner, middle, outer and posterior ridges; middle and outer ridges ending in lachrymal spine anteriorly. Inner ridge with zero to six small spines (two), middle with zero to four (one on left, zero on right) and outer with zero to three (one). Usually one, rarely two sharp preocular spines present (one on left, two on right), without small spines or tubercles basally. Distinct preorbital spines absent. Suborbital ridge finely serrated, comprised of 13–26 small spines, tending to increase with growth (16 on left, 17 on right); distinct notch present on suborbital ridge below eye, separating spines on second and third infraorbitals. Supraorbital ridge finely serrated except for anterior portion, continuous with frontal spines posteriorly. Postorbital region with one to several small spines (one). Pterotic with two or three distinct spines (two on both sides); sometimes few small spines present near base of distinct pterotic spines (two on right). One distinct parietal spine present. Supratemporal, posttemporal and supracleithrum usually with one spine, respectively; sometimes some additional small spines on supratemporal and posttemporal (supratemporal on right side with two small spines, that on left side and posttemporal on both sides with one small spine). Preopercle usually with three spines, rarely four (three); uppermost longest, not reaching posterior margin of opercle, usually bearing single supplemental spine, rarely possessing two supplemental spines or supplemental spine absent (present on both sides); lowermost smallest. Ridges of upper and lower opercular spines usually smooth; upper ridge rarely with one spine; lower one sometimes with rough serration formed by one to three spines (both ridges smooth in lectotype). Interopercular flap absent. Maxilla beyond anterior margin of pupil, attaining middle of eye or not attaining it (not attaining it). All teeth villiform, or most teeth villiform and those on anteromedial portion of upper jaw, palatine, and/or posterior portion of vomerine tooth patch small conical (all teeth villiform); teeth in bands on jaws and palatine, and in two separate patches on vomer; tooth band on upper jaw with or without small notch medially (with it). Lip margins without papillae. Sensory tubes from suborbitals and preopercle well developed, completely covering cheek region. Pored scales in lateral line with two exterior openings posteriorly. First dorsal fin originating slightly anterior to opercular margin. First and second dorsal fin narrowly separated. Pectoral fin rounded posteriorly (damaged). Posterior tip of pelvic fin attaining base of first to third (second) anal fin ray. Caudal fin mostly straight posteriorly (damaged).

Color in alcohol. In lectotype ( Fig. 2 ), color mostly faded at present. Posterior portion of first dorsal fin brownish. Middle of pectoral fin with small brown spots. Membrane of pelvic fin with melanophores.

Lectotype Paralectotypes Non-types (upper, unbr.+middle, br.+lower, unbr.) (21 in 10, 22 in 16, 23 in 5) Pelvic fin rays I, 5 I, 5 I, 5 I, 5 Branched caudal fin rays – – 10 9–10 (9 in 9, 10 in 14) (5 in 6, 6 in 23, 7 in 2)

...... continued on next page Length of first ray of second dorsal fin – – 13.8 11.7–15.1 Length of first anal fin ray 8.2 – – 5.8–8.2 Proportional measurements (% HL):

Snout length 26.4 26.8 27.3 24.4–27.4 Orbital diameter 29.2 30.4 30.8 28.8–31.9 Upper jaw 40.8 42.4 43.0 39.0–42.5 Lower jaw 54.2 – 56.3 50.4–55.9 Interorbital width 6.7 6.7 6.3 5.1–8.0

In non-types ( Fig. 3 ), ground color of body and head light brown above, paler below. Body with two or three indistinct saddle-like brownish bands; one broad band below first dorsal fin, and one broad or two narrow bands below posterior portion of second, respectively. Indistinct brown spot below eye. First dorsal fin with one broad dark brown band distally, with small paler or transparent areas along spines. Second dorsal fin with several small brownish spots. Pectoral fin light brown, with small brown to black spots tending to form narrow bands. Pelvic fin variable: uniformly dark brown or black, except for pale outer margin; ground color pale brown, with two large black spots, with three small black spots or narrow black bands, with several small black spots tending to form narrow bands, or with one black spot basally and one dark area including about three or five small black spots on middle portion; or ground color dark brown, with several small darker spots. Anal fin pale. Caudal fin with many small brownish spots, tending to form narrow bands.

Distribution. Known at present from the South China Sea (including Guangdon Province, China, Nha Trang, Vietnam and Luzon Island, Philippines), north of Waigeo, Bali Sea, Timor Sea and northwestern Australia, at depths of 36–141 m ( Fig. 1 ).

Remarks. Weber (1913) originally described Platycephalus macrocephalus based on seven specimens. Of them, four specimens (38.3–40.7 mm SL) from Sapeh Strait are identical with Onigocia grandisquama by having characters such as I + VIII-11 dorsal and 11 anal fin rays, 32–34 lateral line scales, a single short ocular flap, lachrymal with two antrorse spines, and suborbital ridge finely serrated and without a distinct notch on suborbital ridge below the eye (see also Imamura & McGrouther, 2008 for its taxonomic characters). In contrast, other three specimens (52.9–70.6 mm SL), from Bari Sea, north of Waigeo and southern Timor Sea, are conspecific and belong to a distinct species separable from other members of the genus Onigocia (see Comparison). To solve taxonomic confusion, the lectotype of P. macrocephala should be designated. Weber (1913) illustrated a single specimen collected from station 15 (Bali Sea), which is catalogued as ZMA 112436. Therefore, the specimen is designated here as the lectotype of P. macrocephalus following ICZN (1999: Rec. 74B).

After the original description, only de Beaufort and Briggs (1962) treated O. macrocephala as a valid species and no other authors have given any taxonomic comments on this species, except for Knapp et al. (2000) who stated its taxonomic status to be unclear. It was revealed in this study that O. macrocephala is valid and has been mistakenly identified as Onigocia macrolepis (e.g., Gloerfelt-Tarp & Kailola, 1984; Sainsbury et al., 1984; Knapp 1999; Imamura et al., 2006). In addition, it was found here that O. macrocephala tends to have more southern distribution than O. macrolepis ; i.e., O. macrocephala occurs at least in the South China Sea (including Guangdon Province, China, Nha Trang, Vietnam and Batangas Bay, Luzon Island, Philippines), north of Waigeo, Bali Sea, Timor Sea and northwestern Australia, while O. macrolepis is recognized from southern Japan, Taiwan, Hong Kong and Camiguin Island (situated between Leyte and Mindanao islands, the Philippines) ( Fig. 1 ). Therefore, the two species are known sympatrically in the Philippines.

Comparison. Data used for the following comparison is from Matsubara & Ochiai (1955), Knapp (1986, 1999), Imamura & McGrouther (2008), Imamura & Knapp (2009), Imamura (2011) and this study.

The genus Onigocia includes the following eight valid species at present: Onigocia bimaculata Knapp, Imamura & Sakashita, 2000 , Onigocia grandisquama (Regan, 1908) , Onigocia lacrimalis Imamura & Knapp, 2010 , Onigocia macrolepis ( Bleeker, 1854) , Onigocia oligolepis (Regan, 1908) , Onigocia pedimacula (Regan, 1908) , Onigocia sibogae Imamura, 2011 and Onigocia spinosa (Temminck & Schlegel, 1843) . Onigocia macrocephala is similar to O. grandisquama , O. macrolepis and O. spinosa in having 9–10 caudal fin rays, one gill raker on the upper arch, a single ocular flap, short and branched upper iris lappet, lachrymal with two distinct antrorse spines anteriorly, and no interopercular flap (vs. the combination of characters absent in others). Of the three congeners, O. macrocephala most resembles O. macrolepis in having a notch on the suborbital ridge below the eye. This character is found only in the two species among Onigocia . Onigocia macrocephala differs from O. macrolepis in having a larger head (38.8–42.3% SL in O. macrocephala vs. 35.6–38.4% SL in O. macrolepis ) ( Fig. 5 ). Onigocia macrocephala is also separable from O. macrolepis in having a single ocular flap usually extending slightly beyond the posterior margin of the orbit (not reaching its posterior margin in O. macrolepis ) and a few or several small and short papillae on the posteromedial portion of the eye in larger specimens (vs. papillae absent in O. macrolepis ). The papillae are not seen in all other members of the genus Onigocia . In addition, numbers of pectoral fin rays and gill rakers are helpful to separate O. macrocephala from O. macrolepis [21–23 (mode 22) and 5–7 (6) in total in O. macrocephala vs. 19–22 (21) and 4–6 (5) in O. macrolepis ], although overlaps are recognized between the two species ( Table 2). Selected characters in O. macrolepis for the comparison with O. macrocephala are listed in Table 3 .

Pectoral fin rays Gill rakers (in total) 19 20 21 22 23 4 5 6 7 O. macrocephala (n = 34) – – 13* 16 5 – 7 * 24 3 O . macrolepis (n = 19) 1 6 11 1 – 1 14 4 – Asterisks indicate data including lectotype.

O. macrolepis (n=19, 47.6–110.6 mm SL)

Interorbital 5.5–9.1 Interopercular flap Absent width

*Based on nine specimens

Comparative materials. Other paralectotypes of Onigocia macrocephala : ZMA 112435 [4 specimens, 38.3–40.7 mm SL, identified as Onigocia grandisquama (Regan) ], Sapeh Strait, Indonesia. O. macrolepis (7 specimens): CAS 89383 (2 specimens, 71.6–75.4 mm SL), Hong Kong; HUMZ 79919 (59.3 mm SL), Taiwan; NSMT-P 57398 (57.5 mm SL), NSMT-P 59307 (1 of 3 specimens, 65.7 mm SL), Japan; USNM 99773 (47.6 mm SL), Camiguin Island, Philippines; USNM 344483 (79.7 mm SL), Taiwan.

The other 69 and 54 specimens of Onigocia , including type specimens of each species, except for O. macrolepis lacking existent types, and deposited at AMS, BMNH, BPBM, CMNH, HUMZ, MNHN, NICA, NSMT, QM, RMNH, USNM and ZMA, are listed in Imamura & Knapp (2009) and Imamura (2011).

Figures

FIGURE 1. Map showing sampling localities of two species of Onigocia. Solid circle, O. macrocephala; open circle, O. macrolepis; L, lectotype; P, paralectotype.

FIGURE 2. Dorsal (upper) and lateral (lower) views of Onigocia macrocephala, lectotype, ZMA 112436, 70.6 mm SL, Bali Sea.

FIGURE 3. Dorsal (upper) and lateral (lower) views of Onigocia macrocephala, non-type, HUMZ 190600, 92.0 mm SL, Nha Trang, Vietnam.

FIGURE 4. Dorsal view of head (A) and iris lappet (right eye) (B) in Onigocia macrocephala, non-type, HUMZ 190600, 92.0 mm SL, Nha Trang, Vietnam.

FIGURE 5. Relationship of head length (% SL) and standard length (mm) in two species of Onigocia. Solid circle, Onigocia macrocephala; open circle, O. macrolepis; L, lectotype; P, paralectotype.

Tables

TABLE 1. Comparison of counts and proportional measurements of Onigocia macrocephala.

	ZMA 112436	ZMA 112438	ZMA 112439	31 specimens
SL (mm)	70.6	52.9	68.1	46.1–92.0
Counts:
First dorsal fin rays	I+VII	I+VII	I+VII	I+VII–VIII
Second dorsal fin rays	11	11	11	(VII in 3 specimens, VIII in 28) 10–12 (10 in 2, 11 in 23, 12 in 6)
Anal fin rays	11	11	11	11–12 (11 in 4, 12 in 27)
Pectoral fin rays	?+?+8=21	2+11+8=21	2+11+8=21	2+10–13+7–10=21–23

TABLE 3. Selected characters of Onigocia macrolepis.

Counts	Proportions	Others
First dorsal fin rays I+VII–VIII (usually VIII)	% SL	Notch on suborbital Present ridge
Second dorsal fin 11–12 rays	HL 35.6–38.0	Ocular flap Single, not reaching posterior
Anal fin rays 12–13 (usually 12)	% HL	margin of orbit
Pectoral fin rays 19–22	Snout length 25.1–27.9	Papillae on Absent posteromedial
Branched caudal fin 9–11 rays	Orbital diameter 25.4–29.9	portion of eye
Pores scales in lateral 36–42 (2–5) line (with spine)	Upper jaw 38.0–41.8 length*	Upper iris lappet Short and branched
Gill rakers 1+ 3–5 = 4–6 (usually 5)	Lower jaw 50.4–55.0 length*	Lachrymal spines Two (antrorse)