1	Females brooding dorsally	2
–	Females brooding ventrally, developing juveniles, or viviparous	4
2	Two pairs of tentacular cirri. Body smooth	Salvatoria
–	Single pair of tentacular cirri. Body with papillae	3
3	Some dorsal cirri with a retractile cirrostyle. Antennae short. Pharynx relatively long and wide; pharyngeal tooth usually located far from anterior margin. Compound chaetae always with short, unidentate blades	Prosphaerosyllis
–	Antennae and dorsal cirri more or less elongate, without distal cirrostyle. Pharynx relatively slender; pharyngeal tooth usually located near anterior margin. Compound chaetae with elongate blades, bidentate, unidentate, or both	Erinaceusyllis
4	Body smooth	5
–	Body covered with papillae	Sphaerosyllis
5	Two pairs of tentacular cirri	Brania
–	Single pair of tentacular cirri	6
6	Palps basally fused to half or 2/3 of their length. Dorsal cirri bowling-pin shaped. Distinct parapodial glands	Parapionosyllis
–	Palps fused along their entire length or with terminal notch. Dorsal cirri small, papilliform. Parapodial glands indistinct or minute, apparently absent	7
7	Compound chaetae all bidentate falcigers, with both teeth similar; some species may have elongate, spiniger-like blades on some chaetae but their structure is similar to that of the shorter falcigers	Parexogone
–	Blades of compound chaetae of 2 different types; some elongated, spiniger-like, others short falcigers; some with blades missing or fused to shafts	Exogone