1	Antennae, tentacular and dorsal cirri minute, papilliform	Prosphaerosyllis giandoi (Somaschini & San Martín, 1994) (6)
–	Antennae, tentacular and dorsal cirri typical of the genus, with a papilliform cirrostyle and a bulbous cirrophore	2
2	Blades of compound chaetae all short; dorsal ones with long spines, ventral ones smooth or very slightly spinulose	Prosphaerosyllis campoyi (San Martín, Acero, Contonente & Gómez, 1982) (1)
–	Blades of compound chaetae without long spines	3
3	Dorsal papillae of two lengths, arranged in four longitudinal rows	Prosphaerosyllis tetralix (Eliason, 1920) (1)
–	Dorsal papillae all similar, not arranged in longitudinal rows	4
4	Palps densely papillated. Dorsal papillae small, rounded. Without long papillae on dorsal cirri	Prosphaerosyllis laubieri Olivier, Grant, San Martín, Archambault & McKindsey, 2011 (7)
–	Palps with few papillae. Dorsal papillae digitiform	5
5	One long, distinct papilla on dorsal cirrus	Prosphaerosyllis chauseyensis Olivier, Grant, San Martín, Archambault & McKindsey, 2011 (7)
–	Without papillae on dorsal cirri	Prosphaerosyllis xarifae (Hartmann-Schröder, 1960) (1)