Labeo fisheri, Jordan & Starks, 1917

Sudasinghe, Hiranya, Ranasinghe, R. H. Tharindu, Goonatilake, Sampath Alwis & Meegaskumbura, Madhava, 2018, A review of the genus Labeo (Teleostei: Cyprinidae) in Sri Lanka, Zootaxa 4486 (3), pp. 201-235 : 214-218

Labeo fisheri Jordan & Starks, 1917

( Figures 6–8 )

Labeo fisheri Jordan & Starks, 1917: 436; Deraniyagala, 1952: 42; Munro, 1955: 47; Mendis & Fernando, 1962: 117; Senanayake, 1980: 152; Pethiyagoda, 1991: 84; Talwar & Jhingran, 1991: 209; Jayaram & Dhas, 2000: 35.

Labeo (Morulius) gadeya: Deraniyagala, 1929:75

Labeo lankae (not Deraniyagala, 1952): Anonymous, 2011; De Silva et al. 2015: 171

Material examined. SU 23234, Labeo fisheri , Paratype, 230 mm SL, Sri Lanka, Mahaweli River basin: Kandy ; 2017.04.01.NH (92.2 mm SL), 2017.04.02.NH (104 mm SL), Sri Lanka, Mahaweli River basin, Kabarawa: Kabarawa oya ; UPZM uncatalogued, 12, 98.7–362 mm SL, Sri Lanka, Mahaweli River basin: Kandy.

Diagnosis. Labeo fisheri is distinguished from all its Sri Lankan and peninsular-Indian congeners by the combination of the following characters: a well developed rostral fold; only a single pair of (maxillary) barbels; dorsal fin with 10–12 branched rays; lateral line with 37–39 scales; scales in transverse series 7+1+4½–6; circumpeduncular scales 17–20; eye diameter 13.4–25.4 % HL.

Description. General appearance in Figure 6 ; morphometric data provided in Table 3. Medium sized Labeo , maximum size 362 mm SL. Caudal peduncle short, its depth 76.7–108 % its length. Eyes medium-sized (13.4–18.1 % HL in specimens> 200 mm SL, 20.3–25.4 % HL in specimens <200 mm SL), located dorsolaterally, but visible in ventral view.

Rostral fold well developed, overlapping upper lip. Tubercles acanthoid with 3–5 apical spines, tuberculation prominent on rhinal, rostral, and infraorbital fields, minute tuberculation on preorbital, infraorbital, ethmoid, and interorbital fields ( Figure 7 ). In an uncatalogued, 335 mm SL UPZM specimen, minute tuberculation present on preopercle as well ( Fig. 7A ). Upper labial fold with minute papillae in 5–6 rows; lower labial fold with prominent lobed papillae in 4–5 rows ( Fig. 7C,F ). Maxillary barbels embedded in lip fold, tips externally visible. Rostral barbels absent.

Dorsal fin with two simple and 10 (1), 11 (8), 12 (5) branched rays; first simple ray stiff, about half length of second simple ray. Pectoral fin with one simple and 12 (1), 13 (1), 14 (1), 15 (4), 16 (5), 17 (1) or 18 (1) branched rays. Pelvic fin with one simple and eight (14) branched rays. Origin of pelvic fin beneath 3rd branched ray of dorsal fin. Anal fin with two simple and five (14) branched rays; first simple ray stiff, less than half length of second simple ray. In larger specimens, bases of dorsal and anal fins covered by fleshy lappets. Caudal fin forked with 9+8 branched rays in upper and lower lobe respectively. Upper caudal-fin lobe longer than lower.

Lateral line complete with 37 (6), 38 (5), 39 (3) + 1–3 scales. Scales in transverse series 7+1+5 (2), ½7+1+4½ (1), ½7+1+5 (6), ½7+1+5½ (4), 8+1+6 (1). Predorsal scales 14 (1), 16 (1), 17 (1), 18 (2), 19 (3), 20 (3), 22 (2), 24 (1). Prepelvic scales 27 (1), 30 (1), 31 (3), 32 (2), 33 (2), 34 (2), 35 (2), 38 (1). Circumpeduncular scales 17 (1), 19 (7), 20 (6).

Coloration. In 10% formalin ( Figure 8 ): head and body dull greyish brown dorsally, becoming lighter laterally and off-white ventrally. All fins with greyish melanophores along rays. Interradial membrane on fins darker than rays. Tubercles white. A black blotch at caudal peduncle, 5–7 scales long, 4–5 scales high.

In life ( Figure 6 ): juveniles and young adults (<~ 200 mm SL) dorsally yellowish brown, becoming lighter laterally, ventrally white. A black blotch at caudal peduncle, 5–7 scales long, 4–5 scales high. All fin rays reddish orange. Black pigmentation on interradial membrane of fins. Sclera reddish orange. Tubercles whitish. Adults (>~ 200 mm SL) with olive green body coloration dorso-laterally, venter white. All fins darker than in smaller specimens, with a tinge of reddish-orange remaining on fin rays, mostly the dorsal fin. Black blotch at caudal peduncle disappears in some individuals. Sclera reddish orange.

TABLE 3. Morphometric data for Labeo lankae (n=9; FF6 24, NMSL uncatalogued, DZ 3749, DZ 3750, DZ 3755, UPZM/F/0100), L. fisheri (n=14; NMSL uncatalogued, UPZM uncatalogued), L. porcellus (n=3; NMW48827, NBFGRKU.2016.10.10.01–02) and L. heladiva (n=18; UPZM uncatalogued, DZ 3821, DZ 3148, DZ 3166, DZ 3168, 2018.08.01.NH).

Comparative morphometrics. Labeo fisheri is distinguishable from L. lankae by having 7–8 (vs. ½8) scales between the origin of the dorsal fin and the lateral line; 5–6 (vs. 6–7½: Fig. 4C ) scales between the lateral line and the origin of the anal fin; 17–20 (vs. 21–24: Fig. 4D ) circumpeduncular scales and a shorter dorsal fin (18.5–23.4 vs. 23.3–28.2 % SL). Labeo fisheri is distinguished from L. heladiva by having 37–39 (vs. 44–51: Fig. 4A ) lateral line scales; a count of 7–8+1+4½–6 (vs. ½8–½9+1+6–7½: Fig. 4B ) scales in transverse series; 17–20 (vs. 19–22: Fig. 4D ) circumpeduncular scales; and 4–5 (vs. 2–3) rows of prominent lobed papillae on the lower labial fold.

Labeo fisheri can be distinguished from the introduced L. rohita by having 5–6 scales (vs. 6–6½) between the lateral line and the origin of the anal fin; 17–20 (vs. 20–22) circumpeduncular scales; and a well-developed (vs. poorly developed: Figure 9 ) rostral fold.

Labeo fisheri differs from its South Indian congeners L. dussumieri , L. potail , L. porcellus , L. fimbriatus , L. kontius , L. nigrescens , L. calbasu , and L. gonius by possessing only a single pair of barbels (vs. two pairs except in L. potail , which altogether lacks barbels). This species can be distinguished from L. dussumieri , L. boggut , L. fimbriatus , and L. gonius by having scales in transverse series of 7–8+1+4½–6 (vs. ½8–10+1+ 6–8 in L. dussumieri ; ½10–12+1+8½– 9 in L. boggut ; ½9–10+1+6½–7½ in L. fimbriatus ; and 12–14+1+10½– 13 in L. gonius ). Labeo fisheri further differs from L. dussumieri , L. boggut , L. fimbriatus , L. calbasu , L. dyocheilus , L. gonius , and L. pangusia by having 37–39 lateral-line scales (vs. 50–60 in L. dussumieri ; 55–65 in L. boggut ; 42–47 in L. fimbriatus ; 40–44 in L. calbasu ; 40–43 in L. dyocheilus ; 65–80 in L. gonius ; and 40–42 in L. pangusia ) and from L. boga and L. kawrus by having 10–12 branched dorsal fin rays (vs. 8–9).

Figures

FIGURE 4. Boxplots representing the distribution of A, lateral-line scales; B, total scales in transverse series; C, scales between lateral line and anal-fin origin; and D, circumpeduncular scales in Labeo lankae (N=9), L. porcellus (N=3), L. fisheri (N=14), L. heladiva (N=42), and L. dussumieri (N=7), based on material examined.

FIGURE 6. Coloration of Labeo fisheri; A, in natural habitat (~115 mm SL, not collected); B, in aquarium (~115 mm SL, not collected), Sri Lanka, Sulugune, Heen ganga, tributary of Mahaweli River; and C, ~300 mm SL, not collected, Moragolla, Kandy, photo courtesy of Ranil Nanayakkara.

FIGURE 7. Detail of head of Labeo fisheri in A,D, lateral; B,E, dorsal; and C,F, ventral view. (A, UPZM uncatalogued, 335 mm SL; B–C, UPZM uncatalogued, 258 mm SL; D–F, UPZM uncatalogued, 114 mm SL).

FIGURE 8. Coloration of Labeo fisheri in preservation (UPZM uncatalogued, 258 mm SL, Sri Lanka, Kandy).

FIGURE 9. Labeo rohita, in preservation (WHT 30826, 124 mm SL).