Key to species of Pectenocypris

1 Black mid-lateral stripe absent or indistinct; lower
jaw not or only indistinctly projecting beyond upper
jaw .......................................................................... 2
Black mid-lateral stripe distinct; lower jaw distinctly

projecting beyond upper jaw .................................................. 3

2 Black mid-lateral stripe absent; black spot at base of
caudal fn elongated; 165 –240 gill-rakers; Jambi, Sumatra ..................... Pectenocypris micromysticetus
Black mid-lateral stripe absent or indistinct; black
spot at base of caudal fn rounded to triangular; 95 –
135 gill-rakers; Kalimantan Tengah, Borneo
............................................................................... Pectenocypris korthausae

3 Black spot at base of caudal fn absent; dark grey
scales with pale fawn margin; no symphyseal knob on
lower jaw; Kapuas, Borneo ... Pectenocypris balaena —
Black spot at base of caudal fn present; pale fawn
scales with dark grey to blackish margin; lower jaw
with symphyseal knob .......................................................... 4

4 Black mid-lateral stripe straight, not narrowing on
caudal peduncle; mid-axial streak present; caudal
peduncle short, high; lower jaw with large, whitish
symphyseal knob; 29 scales in lateral series; 
160 gillrakers, Riau, Sumatra ................................................. Pectenocypris nigra

Black mid-lateral stripe arched, narrowing on caudal
peduncle; mid axial streak absent; caudal peduncle
long, narrow; symphyseal knob on lower jaw small,
greyish; 32 scales in lateral series; 202 gill-rakers,
Riau, Sumatra ................................................................. Pectenocypris rubra