Medium-sized larvae, 8 mm long. Head pale yellow, posterior margin slightly darkened; gular margin pale; body pale yellow. Head capsule elongate-oval, cephalic index 0.6. Dorsally, DP present, S5 mesial to S7, near DP; S7, S8 near each other with S8 slightly mesial, both anterolateral to DP. Ventrally, S9, S10, VP form tight group, in equilateral triangle shape; S9 lateral to S10, VP posteriorly, intermediate between S9, S10; SSm posteromesial to this group. Form of cephalic setae unknown, missing.
Almost 1/2 as long as head. Antennal ratio 4.4. Basal segment about 12x as long as basal width, 2x as long as mandible, with ring organ at 0.7 from base, outer margin produced into apical point; segment 2 about 15x as long as wide; apical segment almost as long as segment 3. Style capitate, extending to middle of apical segment. Peg sensilla about 1/2 as long as segment 3. Blade somewhat shorter than flagellum; basal ring 3x as high as wide. Accessory blade apparently shorter than blade.
Gradually curved, strongly narrowed in distal 1/2, almost 3x as long as broad. Apical tooth 2x as long as basal width, 1/4 length of mandible; distal 1/3 blackish brown. Inner tooth small, but distinguishable, bluntly- rounded, deeply recessed; mola indistinct, not protruding beyond inner margin of mandible; seta subdentalis arising from dorsal groove. Ventrolateral setae located adjacent to outer margin of basal 1/2 of mandible; seta 1 probably peg-shaped, 2 probably simple, seta 3 divided; gap between setae 2 and 3, 2x as great as that between setae 1 and 2; ring organ situated proximal to seta 3.
Basal segment of palp 4.6x as long as wide, with ring organ at 0.8 from base; b sensillum 3-segmented, basal segment 2x as long as wide, and 0.4 as long as middle segment.
Abdominal segments without lateral fringe, but possessing long scattered setae, as long as 1/3 width of segment. Anal tubules missing. Procercus about 3x as long as wide, with 7 apical setae. Subbasal seta simple. Posterior parapod with 16 simple claws; margins without spinules; four smaller claws somewhat darkened without clear lamellae.
Lobomyia belongs to the tribe Pentaneurini, and lies within the Thienemannimyia-group of genera. It further separates into the subgroup consisting of Conchapelopia, Coffmania, Helopelopia and some Rheopelopia, in having a maxillary b-sensillum in 3 sections. Lobomyia can be differentiated from all preceding genera by the proximity of cephalic seta S9 and S10, which in the other genera are typically very close together, separated by about the width of the VP; whereas, in Lobomyia the setae are further apart, about 3x the width of the VP. Also, Lobomyia has uniform size granulation on the pseudoradula, which become larger basally in the other genera.
Lobomyia represented by a single species L. immaculata, has been collected only from a spring and small streams in Japan.