Single gill mayfly (Deleatidium)

Taxonomic group

Leptophlebiidae: Deleatidium

Diagnostic features

Deleatidium mayfly nymphs have a flattened body form, single leaf-like gills and a wide labrum (top “lip”).

[Deleatidium]. Single, leaf-like gills. Image: Stephen Moore Image — Deleatidium. Single, leaf-like gills. Image: Stephen Moore

[Deleatidium]. Wide labrum. Image: Stephen Moore Image — Deleatidium. Wide labrum. Image: Stephen Moore

Typical habitats

Deleatidium larvae are the most abundant invertebrates in many fast-flowing, stony-bottom streams with cool and well aerated water, especially in the South Island.

Feeding

Leptophlebiid mayflies feed by scraping diatom algae and other organic matter from stone surfaces.

Indicator value

Hard bottom: 8
Soft bottom: 5.6

The tolerance values (ranging from 0 to 10) give an indication of which are the sensitive taxa (values of 8 or more) and which are the tolerant taxa (values of 3 or less). For more information see: Indicator species

High abundances of Deleatidium suggest good habitat and water quality conditions, especially if other mayfly or stonefly groups are abundant. Deleatidium has tolerance values of 8 (hard bottom sites) and 5.6 (soft bottom sites).