The genus Nigronia includes two North American species, N. fasciata and N. serricornis. They are found in lotic-erosional and -depositional habitats, usually in streams with coarse sediments and detritus, often clinging/climbing under or on rocks, especially under bark or in crevices of woody debris. Like other hellgrammites, they are engulfing predators. These species are found throughout eastern and central United States and Canada.
Southeast: up to 5.8
Upper Midwest: up to 0
Midwest: up to 2.7
Engulfer / Predator
Widespread (east of the Rocky Mtns.)
+ Expanded Character List
Order: Larval wings/wing pads absent. Eye spots present, but compound eyes absent. Segmented legs present on thorax. Abdominal segment 9 with either one slender tail or pair of anal prolegs, each with two hooks. Seven or eight pairs of filaments or gills laterally on abdomen, with never more than one pair per segment.
Family: Abdominal segments 1–8 with paired, 2-segemented, lateral filaments. Abdominal segment 10 has pair of 1-segemented filaments. End of abdomen with pair of anal prolegs, each bearing 2 claws. Mature larvae 30–65 mm long.
Genus: Head without conspicuous color pattern. Abdominal ventral gill tufts absent. Last pair of dorsal abdominal spiracles positioned at distal ends of short respiratory tubes and are about same size as other spiracles; respiratory tubes much shorter than anal prolegs.