1	Compound chaetae of all parapodia with short blades, all similar or with slight dorsal to ventral gradation	Parexogone hebes (Webster & Benedict, 1884) (1, 8)
–	Some compound chaetae (1–3) with long blades, at least on anterior parapodia	2
2	Dorsal simple chaetae with few (1–3) very long, thin spines (aristae), extending beyond the tips	Parexogone longicirris (Webster & Benedict, 1887) (2)
–	Dorsal simple chaetae without aristae	3
3	All blades of compound chaetae elongated, slender, unidentate, with long, thin spines on margin. Aciculae with thin tips	Parexogone campoyi San Martín, Ceberio & Aguirrezabalaga, 1996 (1)
–	Most compound chaetae with short blades, without long spines on margin. Aciculae rounded distally	4
4	Lateral antennae minute; median antenna shorter than prostomium and palps combined	Parexogone caribensis San Martín, 1991 (1)
–	Lateral antennae similar in length to prostomium; median antenna longer than prostomium and palps combined	Parexogone convoluta (Campoy, 1982) (1)