T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network

Mayfly nymph (Genus: Coloburiscu) Coloburiscus humeralis

Kingdom: Animalia
Phylum: Arthropoda
Subphylum Hexapoda
Subclass Pterygota
Class: Insecta
Order: Ephemeroptera
Superfamily: Heptagenioidea
Family: Coloburiscidae
Genus: Coloburiscus
Species: C. humeralis
Binominal name: Coloburiscus humeralis
Common name: Spinygilled mayfly

Coloburiscus humeralis is a medium-sized, slightly flat nymph. The mouthparts, which sits at the base of the head are large and adapted to filter food particles from the water. The nymphs have cactus-like gills covering the top of the abdomen. The front and mid legs are very hairy and they trap drifting food particles consisting of plant fragments and small invertebrates.
They use their legs and trakégjellene (part of breathing system) to hold on between rocks, they can also swim well, with nodding head movements. Since they use trakégjellene to cling onto rocks they can not wave them to increase oxygen uptake and are therefore dependent on highly oxygenated water, hence they live in cold, fast-flowing streams and rapids, preferably with stony or gravely bottom. They like bush covered streams.
A female adult mayfly can lay up to 12,000 eggs. Development from egg to adult insect can take from six months to three years.

Coloburiscus humeralis are the prey of:
Ameletopsis perscitus (nymphs of Yellow dun mayflies)
Hydrobiosella stenocerca (nymphs of the Fingernet caddisflies)
Stenoperla prasinia (nymph of the large green stonefly)
Anguilla dieffenbachia (longfin eel)
Cambaridae (freshwater crayfish)
Hydrobiosidae (nymphs of caddisflies)
Polyplectropus puerilis (nymphs of tube maker caddisflies)
Salmo trutta (Brown trout)
Galaxias depressiceps (Flathead galaxias)
Paranephrops zealandicus (South Island crayfish)
Hydrobiosis parumbripennis (nymphs of uncased caddisflies)
Galaxias (small freshwater fish)
Archichauliodes diversus (nymph of toe-biter dobsonfly)
Galaxias brevipennis (Climbing galaxias) 

The underside view of a Coloburiscus humeralis nymph.
