Based on the above descriptions and discussion, the three known species of Porobelba may be identified using the following key:

1 First pair of prodorsal setae (c1) very long, typically lyriform shape. Other notogastral setae minute, thin. Prodorsum with one pair of tubercles behind insertions of interlamellar setae. Body length 390-405 µm.. ....................................................................................................................................... P. weigmanni n. sp.

- Setae c1 longer than other notogastral setae, but straight, parallel, oriented forwards. Remaining notogastral setae shorter and thinner, but well visible. Without tubercles on prodorsum ....................................... 2

2(1) Spinae adnatae present, body length 345-420 µm ............................................ P. spinosa (Sellnick, 1920)

- Spinae adnatae absent, body length 380-400 µm .......................................... P. grandjeanica Subias, 1977