Key to the Species of Hymenocephalus in Taiwan

1a. V 7–9..................................................................... 2

1b. V 11 or 12................................................................. 3

2a. Barbel long, about 50% HL; orbit diameter 27–31% HL.................... H. longiceps

2b. Barbel about 11–18% HL; orbit diameter 34–45% HL........ H. striatissimus striatissimus

3a. Barbel absent; orbit diameter 28–35% HL; color grayish brown in preservative, somewhat silvery in life...................................................... H. lethonemus

3b. Barbel rudimentary, about 4% HL; orbit diameter 23% HL; color mostly blackish........................................................................ H. papyraceus