Zenopsis stabilispinosa, Nakabo & Bray & Yamada, 2006

Nakabo, Tetsuji, Bray, Dianne J. & Yamada, Umeyoshi, 2006, A new species of Zenopsis (Zeiformes: Zeidae) from the South China Sea, East China Sea and off Western Australia, Memoirs of Museum Victoria 63 (1), pp. 91-96 : 91-94

Zenopsis stabilispinosa sp. nov.

Figures 1–3A , 4 , Tables 1–2

Zenopsis sp. nov. Bray, 1983: 106, fig. 16; Zenopsis sp. (off Western Australia): Williams et al., 1996: 150 (off Western Australia), Tyler et al., 2003: 2 (South China Sea and off Western Australia).

Material examined. Holotype. FAKU 64803 (307.2 mm SL), South China Sea , 19°45.0'N, 114°04.0'E, 457–767 m, JAMARC ( Japan Marine Fishery Resource Research Center), 20 Jun, 1991.

Paratypes. FAKU 64804 (410.1 mm SL), South China Sea, 19°47.0'N, 114°05.0'E, 465–505 m , JAMARC, 21 Jun 1991; AMS I.22826-004 (206.1 mm SL), North-west Shelf , Western Australia 210 km NW of Port Hedland, 18°44'S, 117°02'E, 396–406 m , J. R. Paxton , CSIRO RV Soela, 13 Apr, 1982; AMS I.31146-001 (2, 100.2– 103.3 mm SL), off North-west Cape , Western Australia, 21°37.9'S, 113°59.3'E, 209–215 m , J. R. Paxton , CSIRO RV Southern Surveyor , 24 Jan, 1991; AMS I.31147-002 (3, 80.4–104.5 mm SL), off North-west Cape, Western Australia, 21°44.5'S, 113°52.5'E, 290–320 m , J. R. Paxton , CSIRO RV Southern Surveyor , 24 Jan, 1991 ; ASIZ P.0057609, off Donggang, Pintung , Taiwan, 22 28 12 N, 120 25 48 E , K. T. Shao, 8 Oct , 1985 ; ASIZ P.0060011, fish market, Dahsi, Ylian , Taiwan, 24 57 00 N, 121 52 48 E , B. H. Gao, 10 Aug , 1997 .

Diagnosis. Zenopsis stabilispinosa differs from its congeners in the following combination of characters: dorsal fin with 7 spines; anal fin with first 2 spines movable and 3rd spine immovable, fused with its pterygiophore; pelvic fin short, 1.69–1.79 in HL, in adult specimens greater than 300 mm SL; bony bucklers along bases of spinous and soft-rayed portions of dorsal fin 3– 4+5–6; bucklers along ventral body margin anterior to pelvic fin and between pelvic- and anal-fin origins, and along anal-fin base 5–6+6–7+5–6 and vertebrae 32 (13 abdominal + 19 caudal).

Description. (values for paratypes in parentheses if different from holotype). Dorsal fin VII, 26; anal fin III, 23; pectoral fin rays 12 (12–13); gill rakers 3+9 (3–4+8–10); dorsal bucklers 4+6 (3–4+5–6); ventral bucklers 6+6+5 (5–6+6–7+5–6); vertebrae 13+19. Body deep, strongly compressed, scales absent except along lateral line. Head strongly compressed, dorsal profile slightly concave. Nostrils located just before eye; anterior nostril rounded, posterior nostril oblong. Mouth large, strongly oblique; upper jaw extremely protrusible. Teeth in upper jaw in 2 separate bands; anterior band with 3 irregular rows of small caniform teeth, inner teeth larger than outer ones; posterior band very narrow, long with minute caniform teeth. Lower jaw with 2 irregular rows of small caniform teeth; 2 teeth on inner row of anteriormost part larger than other teeth. Vomer with 1 small caniform tooth on right side, 2 small caniform teeth on left side (with 0–3 caniform teeth on right side, 0–7 on left side; mode 2 on both sides). Palatine toothless. Tongue thick, long and pointed. Gill-rakers on 1st gill-arch short. Pseudobranchiae welldeveloped. Lateral line arched below spinous portion of dorsal fin, following midline axis of body from below anterior one-third of soft dorsal fin, to caudal-fin base. Caudal peduncle moderately long, narrow. Dorsal-fin origin vertically to almost vertically above posterior tip of operculum; anterior dorsal-fin spines long with filamentous membranes; soft dorsal fin convex, rays increasing in length to 18th ray. Anal fin origin near vertical through notch between spinous and soft-rayed portions of dorsal fin; 1st and 2nd anal-fin spines small, movable, 3rd spine immovable (fused with pterygiophore); 2nd and 3rd anal-fin spines and 1st anal-fin ray connected by membrane; soft anal fin convex, rays increasing in length to about 16th ray. Pectoral fin rounded, reaching to vertical below bases of 4th and 5th dorsalfin spines. Pelvic fin relatively short, 1.69 in HL (1.79 in paratype 324.4 mm SL, but somewhat longer, 0.98–1.26 in HL, in juvenile paratypes 80.4–206.1 mm SL), origin anterior to vertical through pectoral-fin base, fin not reaching anus when depressed (extending to anus in paratypes less than 105 mm SL). Caudal fin slightly emarginate.

4 (3–4) bony bucklers along base of spinous dorsal fin and 6 (5–6) bony bucklers along soft dorsal-fin base; each buckler with a dorsal spine. 6 (5–6) bony bucklers anterior to pelvicfin base. 6 (6–7) bony bucklers with posterior spine between origins of pelvic and anal fins. Bucklers absent from base of anal-fin spines. 6 (5–6) bony bucklers, each with a vertical spine, along base of soft anal fin.

Colour when fresh. Body silver (with many dark spots in juvenile paratypes less than 105 mm SL). Dorsal margin of head and body dark-brown from snout to caudal peduncle. Spinous dorsal fin with a transverse broad dark-brown band on membrane; soft dorsal fin dusky distally, white basally. Anal fin dusky distally, white basally. Pectoral fin pale basally, dusky distally, with a small dark-brown spot dorsally on fin base. Pelvic fin with 4 irregular black bands (6–7 dark bands in juvenile paratypes less than 105 mm SL). Caudal fin with dark semicircular mark on base and broad dark band on posterior margin.

Etymology. The specific name, stabilispinosa , refers to the fused anal-fin spine.

We recommend that the standard name for this species be the Fixed-spine Mirror Dory.

* along spinous and soft dorsal-fin bases

**anterior to pelvic fin + between pelvic fin and anal fin + along anal-fin base

Relationships. Zenopsis stabilispinosa differs from Z. nebulosa , Z. conchifer and Z. oblonga in having the first two anal-fin spines movable and a third fused to the pterygiophore (versus three movable anal-fin spines in the other three species; in some specimens of Z. conchifer the third anal-fin spine is more or less fixed, but is not fused with the pterygiophore, fig. 3C). As the movable third anal-fin spine is based on the second anal pterygiophore in the latter three species (fig. 3B), it is likely that the spine-like posterior process projecting from the third anal pterygiophore of Z. stabilispinosa represents the third anal-fin spine fused to its pterygiophore (fig. 3A). Fused anal-fin spines have previously been reported in two other zeiform families: family Parazenidae – Cyttopsis rosea Lowe, 1843 , and family Cyttidae – Cyttus novaezelandiae Arthur, 1885 and C. traversi Hutton, 1872 ( Bray, 1983, Heemstra, 1980, Tyler et al., 2003).

Zenopsis stabilispinosa also differs from its congeners in having seven dorsal-fin spines (versus eight to ten dorsal-fin spines), 19 caudal vertebrae (versus 22–23 caudal vertebrae) and a smaller pelvic fin, 1.69–1.79 in HL in specimens greater than 300 mm SL of Z. stabilispinosa (versus almost the same as or more than HL in other species).

Zenopsis stabilispinosa is similar to Z. nebulosa in having five to six ventral bony bucklers anterior to the pelvic fin (versus two to three bucklers in Z. conchifer and Z. oblonga ). Zenopsis stabilispinosa and Z. conchifer resemble Z. conchifer in lacking ventral bony bucklers along the anal-fin spines (versus having one to two ventral bony bucklers in Z. nebulosa and Z. oblonga ).

Remarks. Opinion differs regarding whether the first pelvic-fin element in Zenopsis is a spine or a ray. Here, we follow Tyler et al., 2003 in regarding the first pelvic-fin element as a ray because it is completely divided throughout its entire length, despite being neither segmented nor branched.

Figures

Figure 1. Zenopsis stabilispinosa sp. nov. Holotype, FAKU 64803 (307.2 mm SL).

Figure 2. Diagrammatic figure (A), and teeth on jaws and vomer (B) of the holotype of Zenopsis stabilispinosa sp. nov., FAKU 64803.

Figure 3. Diagrammatic figures of anal-fin pterygiophores and spines of 3 species of Zenopsis: A, Z. stabilispinosa, holotype, FAKU 64803 (307.2 mm SL); B, Z. nebulosa, FAKU 64805 (379 mm SL); C, Z. conchifer, RUSI 14070 (135.5 mm SL). Scales indicate 10 mm.

Figure4.Diagrammaticfigureofajuvenileof Zenopsis stabilispinosa, AMS I.31147-002 (80.4 mm SL), paratype.