Key to Blasconura modified from Bedos & Deharveng (2000)

1 Cephalic tubercles An and Fr fused....................................................................... 2

- Cephalic tubercles An and Fr separated................................................................... 8

2 Cephalic chaeta O absent............................................................................... 3

- Cephalic chaeta O present.............................................................................. 6

3 Unguis without inner tooth, 2 tubercles Di on head close to each other................... B. triangulum sp. nov. (Japan)

- Unguis with inner tooth, 2 tubercles Di on head distinctly separate.............................................. 4

4 Ant. I with 7 chaetae, chaetae formula of tubercle Di on Th. I–Abd. V as 1, 2, 2/2, 2, 2, 2, 2.......................................................................................... B. batai Bedos & Deharveng, 2000 (Vietnam)

- Ant. I with 9 chaetae, tubercle Di of Abd. V with 3 chaetae.................................................... 5

5 Macrochaeta palmate, chaetae formula of tubercle Di on Th. I–Abd. V as 1, 3, 3/2, 2, 2, 2, 3................................................................................... B. hirtella (Börner, 1906) (South and Southeast Asia)

- Macrochaeta smooth, chaetae formula of tubercle Di on Th. I–Abd. V as 2, 4, 4/3, 3, 3, 3, 3..................................................................................................... B. toda Cassagnau, 1988 (Inde)

6 Ant. I with 8 chaetae, chaetae formula of tubercle Di on Th. I–Abd. V as 1, 3, 3/2, 2, 2, 2, 2–3........................................................................................... B. ceylonica Cassagnau, 1988 (Sri Lanka)

- Ant. I with 7 chaetae, chaetae formula of tubercle Di on Th. I–Abd. V as 1, 3, 4/4, 4, 4, 3, 3.......................... 7

7 Macrochaeta strongly serrated, chaeta Ocm about 6–7 times longer than anterior eye diameter................................................................................................. B. sholica Cassagnau, 1988 (Inde)

- Macrochaeta weekly serrated, chaeta Ocm about 3–4 times longer than anterior eye diameter................................................................................................. B. prabhooi Cassagnau, 1988 (Inde)

8 Chaeta O on head absent............................................................................... 9

- Chaeta O on head present............................................................................. 10

9 Tubercles An and Cl fused, tubercle De of Th. III with 5 (4+s) chaetae, chaetae formula of tubercle Di on Th. I–Abd. V as 1, 3, 3/2, 2, 2, 2, 3.................................................................... B. cordis sp. nov. (Japan)

- Tubercles An and Cl separated, tubercle De of Th. III with 4 (3+s) chaetae, Chaetae formula of tubercle Di on Th. I–Abd. V as 1, 2, 2/2, 2, 2, 2, 3..................................................... B. anamalensis Cassagnau, 1988 (Inde)

10 Chaeta O on tubercle An, chaetae formula of tubercle Di on Th. I–Abd. V as 2, 3, 3/3, 3, 3, 3, 3.............................................................................................. B. palniensis Cassagnau, 1988 (Inde)

- Chaeta O on tubercle Fr, chaetae formula of tubercle Di on Th. I–Abd. V as 3, 3, 3/2, 2, 2, 2, 2................................................................................................ B. separata (Denis, 1934) (Vietnam)