Sinorhodeus microlepis, Li & Liao & Arai & Zhao, 2017

Li, Fan, Liao, Te-Yu, Arai, Ryoichi & Zhao, Liangjie, 2017, Sinorhodeus microlepis, a new genus and species of bitterling from China (Teleostei: Cyprinidae: Acheilognathinae), Zootaxa 4353 (1), pp. 69-88 : 73-81

Sinorhodeus microlepis sp. nov. Li, Liao & Arai

( Figs. 2–9 ; Table 4)

Holotype. SOU 1604001, male, 48.7 mm SL; a tributary of Yangtze River , Banan District, Chongqing City, China; 16 April 2016.

Paratypes. SOU 1604002–1604009, 8 males, 34.2–58.1mm SL; SOU 1604011–1604022, 12 females, 35.7– 46.6 mm SL; NSMT-P 130011, male, 42.7 mm SL; NSMT-P 130012 , female, 36.3 mm SL; same data as holotype. Non-type specimen. SOU 1604024, female, 36.5 mm SL, cleared and stained , same data as holotype.. Diagnosis. See generic diagnosis.

Description. Morphometric and meristic data of holotype and paratypes presented in Table 4. Body compressed. Mouth large and subterminal, corner of mouth extending to vertical of anterior margin of orbit. Barbels absent. Pearl organs developed on snout, area between nostril and eye, and top of head in mature males; absent in females. A short ovipositor present in mature females, maximum length approximately 7–10 mm.

Dorsal fin with 3 simple and 8 branched rays (rarely 6 or 9). Anal fin with 3 simple and 8 branched rays (rarely 7 or 9). 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 second branching point of first branched ray ( Fig. 3A ). Longest simple ray of anal fin soft and distally segmented; width of basal portion equivalent to that of first branched ray; longest simple anal-fin ray segmented from area corresponding to first branching point of first branched ray ( Fig. 3B ). Pectoral fin with 1 simple and 12–13 branched rays. Pelvic fin with 1 simple and 6–7 branched rays. Principal caudal rays 19, including branched rays 17 (9 + 8); dorsal procurrent rays 6–7, ventral procurrent rays 5–6.

Longitudinal scales 41–46 (40–45 on body, 0–1 on caudal fin). Lateral line incomplete. Pored scales 3–5. Transverse scales 16–18. Predorsal scales 17–20. Circumpeduncular scales 18–20.

Abdominal vertebrae modally 16 (15–17); caudal vertebrae modally 19 (18–20); total vertebrae modally 35 (34–37). Position of first dorsal-fin ray pterygiophore (D-PTG-1) = 10 (between 10th and 11th vertebrae, denoted as 10; rage from 9 to 11). Position of first anal-fin ray pterygiophore (A-PTG-1) = 16 (range from 15 to 17) ( Fig. 4 ). Pharyngeal teeth in one row, formula 0,0,4–4,0,0; occlusal grooves developed (six adult specimens dissected, Fig. 5). Gill rakers on external side of first gill arch 7–9.

Four infraorbital bones (io) present. Cephalic sensory canals of adult specimens highly reduced: infraorbital canal interruptedly incomplete, usually separated into 3 (corresponding to io1, io2, and io3) or 4 (corresponding to io1, io2, io3, and io4) parts in males, but 1 (corresponding to io1) or 2 (corresponding to io1 and io3) parts in females; temporal canal present; supratemporal canal absent; supraorbital canal not connecting to infraorbital sensory canal; infraorbital canal not connecting to preopercular canal ( Fig. 6 ). Asymmetry common in cephalic sensory canal system of adult specimens.

Ripe eggs short pear-shaped, length of major axis approximately 2 mm, ratio of major axis to minor axis 1.3– 1.4 ( Fig. 7A ). Larvae with less developed wing-like yolk sac projections ( Figs. 7B, 7C ).

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) &1 & ­A&1 0 &3 1A&. & / 3.A ­ 0 & A /) 1 0 1 2A. 3 0A1 0 / 3 / A­ 1 /.A0 2)) 3/ 2 3. A 12 2 3 / A1 &))) && 3 && 2A&1 3 &2 A&1 2)) & 1 A & 0 A Coloration in life. Adult males are strikingly colorful during breeding season: body color mostly red, with bluish sheen dorsally. A light red vertical band covering 3rd–4th scales in lateral series. Dorsal fin blackish without stripes. Anal fin blackish with a red longitudinal band in center. Inner part of anal fin usually fully filled with red in large males. Pectoral fin, pelvic fin, and basal part of caudal fin reddish. Iris red ( Fig. 8A ). In females, all fins hyaline. Iris blackish in small individuals, but reddish-orange in large individuals. Egg tube (ovipositor) whitish ( Fig. 8B ).

In juveniles, dorsal fin without a black blotch ( Fig. 9 ).

Color in preservative. Ground color brown, darker on dorsal portion of body than on ventral portion of body. Vertical light band present on anterior flank in males; absent in females. Narrow longitudinal stripe on each side of body running from below dorsal fin and ending about 3 scales in front of caudal-fin base. Dorsal fin of males blackish; anal fin whitish with blackish margin. Dorsal and anal fins of females hyaline without white spots on fin rays. ( Fig. 2 ).

Distribution and ecology. Known only from a tributary of Yangtze River, in Banan District, Chongqing City, China ( Fig. 10 ). The type locality was a slow-flowing stream at an altitude of 625 meters. The substrate consisted of mud mixed with gravel. Other syntopic species were Rhodeus ocellatus , Hemiculter leucisculus and Pseudorasbora parva .

Surveys were also conducted in the streams of peripheral regions in same basin, and only one bitterling, Rhodeus ocellatus , was collected. The limited distribution suggests that S. microlepis may be rare and stenotopic. Conservation for S. microlepis may be necessary.

Sinorhodeus microlepis exhibits a unique host preference. It spawns in the gills of freshwater clam, Corbicula fluminea ( Figs. 11A, 11B ), from March to October, and usually releases 10– 15 eggs at one time. The breeding peak time is spring (April to May).

Etymology. The specific name, microlepis , is derived from the Greek micro, meaning small, and lepis, meaning scale, a noun in apposition, in reference to the diagnostic small scales of this species.

Figures

FIGURE 2. Sinorhodeus microlepis, China: Chongqing City: Banan District. A, SOU 1604001, holotype, 48.7 mm SL, male; B, SOU 1604011, paratype, 44.3 mm SL, female.

FIGURE 3. Sinorhodeus microlepis, SOU 1604001, holotype, male. Simple and first branched rays of dorsal (A) and anal (B) fins.

FIGURE4. Sinorhodeus microlepis, SOU 1604001, holotype, 48.7 mm SL, male.Radiograph.

FIGURE 6. Portion of cephalic sensory canal system of Sinorhodeus microlepis. A, SOU 1604024, 36.5 mm SL, female; B, SOU 1604001, holotype, 48.7 mm SL, male. Abbreviations: io1–4, infraorbital bones 1–4; p, parietal bone; pt, pterotic bone; IOC, infraorbital sensory canal; SOC, supraorbital sensory canal; TC, temporal sensory canal.

FIGURE 7. Eggs and larvae of Sinorhodeus microlepis, at a water temperature around 23?. A, unfertilized ripe eggs; B, larvae immediatelyafter hatching; C, larvae 3 days after hatching.

FIGURE 8. Sinorhodeus microlepis in breeding season, male (A) and female (B).

FIGURE 9. Sinorhodeus microlepis, juvenile, 11.5 mm SL.

FIGURE10. Sampling locality of Sinorhodeus microlepis ().

FIGURE11.Host clam of Sinorhodeus microlepis, Corbicula fluminea. A, shell of C.fluminea, 18 mm shell length.B, eggs of S. microlepis in gills of C.fluminea (four yellow blotches in the middle; B by Mr.Yi Yu, 15 April 2017).