Small to medium-sized larvae, up to 6 mm long. Head yellowish-brown, proximal 1/3 dark brown; body pale to brown, with reddish-brown flecks. Head capsule slender; cephalic index 0.50-0.55. Dorsally DP absent, S5 quite retracted, posteromesial to S8 and S7; S8 mesial to S7. Ventrally S9-S10-SSm forming transverse straight to curved line; VP eye-shaped, posterior to alignment. All setae simple.
Somewhat less than 1/2x as long as head, 3x as long as mandible. Antennal ratio about 2.5-3.0. Basal segment about 10x as long as basal width, with ring organ at 0.6; segment 2 about 11x as long as wide; segment 3 5x as long as wide, 1/4 longer than last segment. Style extending to middle of last segment. Peg sensilla large, blunt apically, about 2/3 length of segment 3. Blade and accessory blade about as long as segments 2-4; basal ring almost 3x as high as wide.
Strongly narrowed and moderately curved in apical 1/2. Apical tooth about 2.5x as long as basal width, 1/3 length of mandible. Inner tooth blunt, large, but not overlying seta subdentalis; small accessory tooth at same level; mola strongly expanded into very large, blunt, 2-lobed, tooth, seta subdentalis long, inserted between lobes. Ventrolateral setae approximately aligned on proximal 1/2 on outer mandible; seta 1 with small pit, 2 and 3 simple; distance between ring organ and seta 3 somewhat longer than between setae 2 and 3.
Basal segment of palp 2-segmented, about 4.5x as long as wide, with large ring organ between segments.
Without fringe of swim-setae. Anal tubules 1/2 or 3/4 as long as posterior parapods. Procercus dark or bicoloured, posteriorly brown, 3x as long as wide, with 7 dark apical setae. Claws of posterior parapod 16; larger claws with small spines on inner and/or outer margin. Small claws simple and pale yellowish-brown, or with 2 bifid small claws (P. smithae Sublette), or with 1 dark claw (Indo-Australian and Brazilian examples).
Paramerina differs from Zavrelimyia only in the segmented basal palp. The other described genus with 2- or multi-segmented basal palp is Ablabesmyia, in which SSm, S9, and S10 are unaligned, DP is present, and the radula is narrow with granulation in parallel, longitudinal rows, not broadened basally or adjoining a sclerotized apodeme. An undescribed taxon from Thailand with Paramerina-like divided palp differs in strongly outwardly-curved inner ligula teeth, a single bifid claw on posterior parapod, but shares the large mandibular molar tooth, broad pseudoradula, and similar arrangement of cephalic setae and pits, including transversely-aligned SSm, S9, S10 and absence of DP. Undescribed species from Brazil and California have one dark posterior parapod claw (Stur and Fittkau, 1997; Cranston and McCluen pers. obs.). It seems very likely that Paramerina is not distinct from Zavrelimyia, but lies within the genus - further, the divided palp may not be of a single origin.
Larvae of Paramerina are eurythermic, living in a variety of standing waters of all sizes but also are present in small lotic habitats including in pools in rivers.
Five species are described from the Nearctic with 2 named species recorded from central America: P. fasciata from Guatemala (Sublette and Sasa, 1994) (new record: Costa Rica; J.H. Epler) and P. smithae from Mexico. Five species are known from the Palaearctic. In Japan these include the endemic P. okimaculata, and the widespread Palaearctic P. divisa (under many synonyms) (Kobayashi and Endo, 2008). The larva and pupa of an unnamed species is described from Brazil (Stur and Fittkau, 1997). Several named and unnamed species have been reported from Australia and s.e. Asia (Cranston & Dimitriadis, 2004; Cranston 2007) from both unimpacted and disturbed standing and flowing waters.