Small larvae, pale brownish yellow, with brown mandibular teeth, mentum and occipital margin.
Antenna 5 segmented, perhaps with minute 6th as darkened apex; with segment 3 much shorter than 4th. Blade short. Lauterborn organs indistinct/small, style apparently absent.
Labrum with SI plumose; remaining S setae simple, normal. Weak labral lamellae present between SI bases. Chaetae undescribed. Pecten epipharyngis with 3 small spines. Chaetulae laterales undescribed. Premandible with 3 teeth, beard undescribed, probably absent.
Mandible with apical tooth shorter than combined width of 3 inner teeth; Seta subdentalis small, extending only to innermost tooth. Seta interna with 4-5 plumose branches.
Mentum with single median teeth recessed relative to double first lateral teeth (associated with ventromentum) and further 4 pairs of lateral teeth, which evenly decrease in size. Ventromental plates strong, extending well beyond outermost mental tooth; beard absent.
Body with anterior parapods separated bearing simple, or small-toothed claws. Posterior parapods separate, with claws. Procercus small, squat, the 6 short anal setae. Anal tubules about as long as posterior parapods.
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The immature stages of the type-species Unniella multivirgata is known from south-east USA, where the immature stages were found in streams and a road-side ditch (Caldwell, 1986).