6. Prelabral chaetae two; Th. III with 5 + 5 to 6 + 6 central mac.; collophore with
2 + 2 posterior chaetae; Costa Rica and USA . . . S. bidentata (Handschin, 1927)
6
. Prelabral chaetae four; Th. III with 5 + 5 to 9 + 9 central mac.; collophore with
3 + 3 to 6 + 6 posterior chaetae; Costa Rica . . . S. thibaudi Soto-Adames, 2010