Medium-sized to large, yellow to dark brown. Eye spots paired, single, or absent (Telmatogeton torrenticola).
Dorsal sclerites of head distinct and separated, or fused.
Very short, < 20% mandible length; 4 segmented; basal segment no more than 2x as high as wide; remaining segments small; segment 3 never annulate. Blade bifid, subequal to flagellum. Lauterborn organs small. Style weak.
All S seta well-developed, simple, bases separate. Chaetae a tuft of simple or serrate setae. Labral lamellae absent. although anterior margin of labrum is variably divided into 3 weak lobes. Labral margin wide and strong. Pecten epipharyngis of 3 subequal scales, each with unequal teeth. Chaetulae laterales narrow, simple and serrate; chaetulae basales small or absent. Premandible broad and heavily sclerotised with up to 3 apical teeth and strongly developed brush.
With single apical tooth and 3-6 inner teeth. Pecten mandibularis absent. Seta subdentalis usually long. Seta interna with 6-7 fine simple branches. Seta interna and seta subdentalis lie on dorsal surface of mandible, lateral setae on ventral surface.
With 11-15 teeth; median tooth with median nipple (lost on worn specimens). Ventromental plate very small; beard absent. Setae submenti retracted on postmentum.
Nearly square. Palp small and bearing sensillae and setae. Numerous tetrahedral lamellae on palpiger, some serrate. Galea without lamellae or pecten galearis. Lacinia with numerous fine setae. Appendix absent.
Parapods well developed, the anterior pair fused basally; both pairs with simple dark claws (rarely serrate on anterior parapods). Procercus absent; 2-3 anal setae present. Anal tubules absent in all examined species. Body setae variably developed, never longer than half the segment length.