Metzia parva, Luo, Wen, Sullivan, John P., Zhao, Hai-Tao & Peng, Zuo-Gang, 2015

Luo, Wen, Sullivan, John P., Zhao, Hai-Tao & Peng, Zuo-Gang, 2015, Metzia parva, a new cyprinid species (Teleostei: Cypriniformes) from south China, Zootaxa 3962 (1), pp. 226-234 : 228-231

Metzia parva , new species ( Fig. 1 ; Table 1 )

Holotype. SWU 20140620012, 57.6 mm SL, the Cheng-jiang River, a tributary flowing into Hongshui-He River of the Pearl River basin at Anyang Town, Du’an County, Guangxi Province, south China (23°93' N, 108°10' E), collected by J.H. Lan, November 2012.

Paratypes. (11) SWU 20140620005–20140620011, 48.3–54.2 mm SL, same data as holotype; CUMV 98211- 98214, 51.1–57.7 mm SL, same data as holotype.

Diagnosis. The following characters distinguish Metzia parva from congeners: smaller body size with standard length between 48.3–57.7 mm (vs. 58.3–151.4 mm); lateral line complete, but interrupted in some specimens along ventral margin above anal-fin; 12–14 branched anal-fin rays (vs. 10–11 or 15–20); 10 branched pectoral-fin rays (vs. 11–16); 6 branched pelvic-fin rays (vs. 7–9); longer caudal peduncle (17.8–21.7% vs. 14.8–17.4% SL); shorter preanal length (60.9–66.0% vs. 69.0–73.0% SL); interorbital width distinctly larger (28.4–33.0% vs. 20.2–24.7% HL).

Description. Morphological characteristics of the genus Metzia were presented by Chen et al. (1998) and Gan et al. (2009) and are not repeated herein. Morphometric data of the twelve type specimens are shown in Table 1 . Dorsal-fin rays soft with 3 unbranched, 7* (12) branched rays ( Fig. 2 A), final ray split to base, fin slightly shorter than head length, origin located behind pelvic-fin insertion, nearer to caudal-fin base than to tip of snout, and nearer to vertical through anal-fin origin than to pelvic-fin origin; distal margin straight. Anal-fin with 3 unbranched, 12* (2) or 14 (10) branched rays ( Fig. 2 B), outer margin concave, nearer to pectoral-fin insertion than to caudal-fin base, origin opposite terminus of dorsal-fin base, distal margin slightly concave, anal-fin base 1.5–2.1 times greater than dorsal-fin base. Pectoral-fin arc-shaped, with 1 unbranched and 10* (12) branched rays, shorter than HL, tip not extending beyond pelvic-fin origin. Pelvic-fin with 1 unbranched and 6* (12) branched rays, its origin nearer to snout tip than to caudal-fin base, length approximately equal to pectoral fin and nearly reaching anus when depressed. Caudal-fin deeply bifurcated with 10 + 9* (2), or 9 + 8 (10) branched rays, tip of each lobe sharply rounded. Lateral line complete and difficult to observe, sharply deflected ventrally anterior to pelvic-fin origin, then running parallel with ventral profile and ending midlaterally below caudal-fin origin (however, 8 specimens of type series show interruptions on ventral margin above anal-fin). Lateral-line scales 40* (8), 43 (3), or 44 (1) with 2 or 3 scales basally at midlateral point of caudal-fin; scale rows above and below lateral line 10* (9) or 9 (3) and 4* (12), respectively. Circumpeduncular scales 14* (7) or 15 (5). Gill rakers on outer surface of first gill arch 14– 16.

A small fish with standard length up to 57.7 mm. Body fusiform, compressed and moderately deep. Dorsal profile of head slightly concave, predorsal profile strongly convex/arched. Abdominal keel between pelvic-fin insertion and anus. Caudal-peduncle depth 46.1%–50.7% SL. Head short, compressed, length shorter than body depth. Snout rounded, short, size similar to eye diameter. Mouth sub-superior, oblique, lower jaw projecting beyond upper, corner of upper jaw extending beyond nostril, but not to anterior margin of eye. Eye large, positioned laterodorsally in anterior half of head, diameter slightly less than interorbital width, distance from posterior margin of eye to tip of snout greater than to posterior of operculum. Interorbital width broad, approximately 1.1 times eye diameter. Scales cycloid, scales on formalin-fixed specimens inconspicuous and difficult to count.

Five infraorbital bones with fifth fairly small, almost invisible ( Fig. 3 A). Pharyngeal teeth in three rows: 5, 3, 2 - 2, 3, 5 ( Fig. 3 B). Air bladder bipartite, posterior chamber 1.5 times longer than anterior chamber with rounded posterior end ( Fig. 4 A). Vertebrae 4 + 32.

Coloration in formalin. The preserved holotype specimen is shown in Fig. 1 . Body pale-yellowish, darker above. All fins semi-translucent with fine black spots on fin spine. Black longitudinal stripe extends along side of body from posterior of operculum to caudal-fin base.

Distribution. Known from the Cheng-jiang River, a tributary flowing into Hongshui-He River of the Pearl River basin at Anyang Town, Du’an County, Guangxi Province, south China (23°92′N, 108°10′E, 161 meters altitude above sea-level, Fig. 5 ).

Reproduction. Females contained a large number of eggs. Reproductive system of males not examined closely, and no data are available on reproductive behavior.

Etymology. Metzia parva was named for its small body size with the Latin word parva (gender feminine) meaning small or little.

Comparative material. Metzia longinasus : SWU 20140325001–10, 10 type specimens, 74.10–128.50 mm SL, Hongshui-He River of the Pearl River, Guangxi Province, south China.

Figures

FIGURE 1. Metzia parva preserved in formalin (holotype, 57.6 mm SL, SWU 20140620012, Hongshui-He River of the Pearl River basin, Guangxi Province, south China). (A) Lateral, (B) dorsal, and (C) ventral views.

FIGURE 2. (A) Dosal fin with pterygiophores and (B) anal fin with pterygiophores of Metzia parva.

FIGURE 3. (A) Lateral view of infraorbital bones and (B) mesial view of pharyngeal tooth of Metzia parva. Abbreviation: IO, infraorbital.

FIGURE 4. Gas bladder in ventral view of (A) Metzia parva, and (B) M. longinasus (SWU 20140325001, 74.1 mm SL).

FIGURE 5. Distributions of Metzia parva (red star) and other Chinese species of Metzia: M. longianus (filled circle), M. formosae (open triangle), M. lineata (filled square), and M. mesembrinum (open square). 1 Taiwan Island, 2 Hainan Island, 3 Jin-Jiang River, 4 Jiulong-Jiang River, 5 Dong-Jiang River, 6 Xi-Jiang River, 7 Liu-Jiang River, 8 Rong-Jiang River, 9 Qing- Jiang River, 10 Nanliu-Jiang River.