Small larvae, up to 3.3 mm long. Head capsule pale; body yellowish to yellowish-brown.
Antenna with 5 segments; segments 3, 4 and 5 subequal in length, combined length slightly longer than segment 2. Ring organ in basal 1/4 of segment 1. Blade as long as 2nd segment. Lauterborn organs as long as segment 3. Style undescribed.
SI bifid, branched right at base, SII, SIII and SIV a and b normal. Labral lamellae absent. Chaetae numerous, simple; spinulae simple. Pecten epipharyngis consisting of 3 scales. Chaetulae laterales simple to serrate; chaetulae basales present. Ungula U-shaped. Premandible with 2 apical teeth and large inner bulge; brush very weak or absent.
Apical tooth shorter than combined width of 3-4 inner teeth; innermost tooth appearing as swollen mola. Seta subdentalis apically hooked. Seta interna thin, with 5 branches, all serrate. Mola smooth.
Mentum with 1 shallowly bifid median and 5 pairs of evenly decreasing lateral teeth. Ventromental plate broad extending beyond lateralmost mental teeth, beard of numerous fine setae. Sclerotization of mentum not uniform with irregular longitudinal bands or dark sclerotization alternating with lighter bands thus appearing striated.
Body with separate anterior and posterior parapods, each bearing an apical crown of claws. Procercus well developed, but less than 1.5 times long as wide; 6-7 anal setae present; basal and subapical seta short. Anal tubules shorter than posterior parapods. Body setae simple, very short.
Larval Naonella are abundant in New Zealand streams, and although present all year, are most abundant in spring and summer when maximal adult emergence takes place. Larval behaviour and diet is unknown.