Rhodeus albomarginatus, Li, Fan & Arai, Ryoichi, 2014

Li, Fan & Arai, Ryoichi, 2014, Rhodeus albomarginatus, a new bitterling (Te le os te i: Cyprinidae: Acheilognathinae) from China, Zootaxa 3790 (1), pp. 165-176 : 167-174

Rhodeus albomarginatus , new species

( Figs. 1–8 ; Table 1 )

Holotype. SOU 1306001, male, 53.4 mm SL; Lvjiang River, Yangtze River system, Xuling Town, Qimen County, Anhui Province, China; 10 May 2013.

Paratypes. SOU 1306002, male, 53.6mm SL; SOU 1306003–1306005, 3 females, 43.3–47.2 mm SL; same data as holotype. SOU 1110001–1110008, 8 males, 44.5–58.4 mm SL; SOU 1110011–1110013, 3 females, 39.8–45.0 mm SL; NSMT-P 114853, male, 43.2 mm SL; NSMT-P 114854, female, 42.6 mm SL; ZUMT 61948, male, 45.8 mm SL; ZUMT 61949, female, 38.8 mm SL; same locality as holotype; 5 Oct. 2011.

Diagnosis. Rhodeus albomarginatus is unique amongst species of Rhodeus in having a white margin on the anal fin in adult males (vs. black margin). It is also distinguished from other congeneric species by the following combination of characters: branched dorsal fin rays 10; branched anal fin rays 10–11; pelvic fin rays i 6; vertebrae 33–34 (mode 33); in adult males, iris black, belly reddish-orange, central part of caudal fin red.

Description. Morphometric and meristic data of holotype and paratypes are shown in Table 1 . Body compressed. Mouth sub-inferior. Barbels absent. Pearl organs on snout and area between nostril and eye in adult males, absent in females.

Dorsal fin with 3 simple and 10 branched rays. Anal fin with 3 simple and 10–11 branched rays. Pectoral fin with 1 simple and 10–11 branched rays. Pelvic fin with 1 simple and 6 branched rays. Principal caudal rays 19, including branched rays 17 (9 + 8); dorsal procurrent rays 7–9, ventral procurrent rays 6–7. First simple ray in dorsal and anal fins very small, hidden under skin. Longest simple ray of dorsal fin strong and stiff, distally segmented; width of basal portion much wider than that of first branched ray; longest simple dorsal-fin ray segmented from area corresponding to that between second and third branching points of first branched ray ( Fig. 2 ).

Longitudinal scale series 34–36 (32–34 on body and 1–2 on caudal fin). Lateral line incomplete. Pored scales 4–7. Transverse scale rows 11. Predorsal scale rows 13–15. Scale rows around caudal peduncle 14.

Abdominal vertebrae 16; caudal vertebrae 17–18; total vertebrae 33–34. Inserted position of first pterygiophore in dorsal fin 9–10. Inserted position of first pterygiophore in anal fin 16 ( Fig. 3 ). Pharyngeal teeth in one row, 0.0.5- 5.0.0, occlusal grooves relatively reduced ( Fig. 4 ). Gill rakers on external side of first gill arch 11–12.

FIGURE 9. Sampling locality of Rhodeus albomarginatus . (★) Unfertilized ripe eggs ellipsoid, ratio of major axis to minor axis, 1.9–2.1 ( Fig. 5 A). Larvae with wing-like yolk sac projections ( Fig. 5 B).

Coloration in life. Ground colour of adult males grayish, lighter towards belly. A blue vertical blotch on 4th–5th scales in lateral series and a longitudinal stripe running from below dorsal fin to the end of caudal peduncle on each side of body. Dorsal, anal, and pelvic fins with white margin, broader in anal and pelvic fins than in dorsal fin. Two whitish spots present on each of dorsal and anal fin rays. Iris black. Belly reddish-orange. Posterior caudal peduncle and central caudal fin bright red ( Figs. 6 A, 7). Adult males usually keep the coloration all the year around, but are brighter during breeding season.

Females lack a blue vertical blotch on flank and white margins of fins. The longitudinal stripe on flank extremely slender and indistinct ( Fig. 6 B).

In postlarvae and juveniles, a large black blotch on anterior part of dorsal fin. A broad white stripe present on outer side of the black blotch, and a slender white stripe present on the anterior margin of dorsal fin in postlarvae ( Fig. 5 C), but absent in juveniles ( Fig. 8 ).

Colour in preservative. Ground colour of body yellowish. Longitudinal stripe on flank distinct in males, but less distinct in females. Margin of scales grayish, darker on dorsal portion of body than on ventral portion of body. Dorsal and anal fins grayish with two pale stripes, margins of males pale; females without pale fin margins.

Distribution and ecology. Known only from Lvjiang River, a tributary flowing into Poyang Lake of the Yangtze River basin, in Qimen County, Anhui Province, China (Fig. 9). The type locality was a hill stream. The bottom consisted of mud mixed with stones. The water level was low, the depth mostly less than 100 cm ( Fig. 10 ). Rhodeus albomarginatus was collected from the upper portion of the stream, while R. sinensis , R. fangi , and R. ocellatus were found in the lower portions. Spawning season is summer, from June to August. Rhodeus albomarginatus spawns several times during the spawning period and usually releases 10– 20 eggs at one time. Host mussel of Rhodeus albomarginatus is Ptychorhynchus murinum ( Fig. 11 ).

Etymology. The specific name, albomarginatus , is derived from the Latin albo (white) and marginatus (margin), an adjective, a reference to the diagnostic white margin on the anal fin in adult male.

holotype paratypes

Figures

FIGURE 1. Rhodeus albomarginatus, China: Anhui Province: Qimen County: Lvjiang River. A, SOU 1306001, holotype, 53.4 mm SL, male; B, SOU 1306003, paratype, 44.3 mm SL, female.

FIGURE 2. Rhodeus albomarginatus, SOU 1306004, paratype, female. Simple and first branched rays of dorsal (A) and anal (B) fins.

FIGURE 3. Rhodeus albomarginatus, SOU 1110004, paratype, 58.4 mm SL, male. Radiograph.

FIGURE 4. Rhodeus albomarginatus, pharyngeal teeth.

FIGURE 5. Eggs and larvae of Rhodeus albomarginatus, under water temperature of 27 ° C. A, unfertilized ripe eggs; B, larvae of 1 day after hatching; C, larva of 15 days after hatching.

FIGURE 6. Rhodeus albomarginatus in breeding season, male (A) and female (B).

FIGURE 7. Rhodeus albomarginatus, anal fin of an adult male.

FIGURE 8. Rhodeus albomarginatus, juvenile, 21.5 mm SL.

FIGURE 10. Habitat of Rhodeus albomarginatus, China: Anhui Province: Qimen County.

FIGURE 11. Host mussel of Rhodeus albomarginatus. Ptychorhynchus murinum, 35 mm shell length.