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Swimming mayfly (Siphlaenigma)

Taxonomic group

Siphlaenigmatidae: Siphlaenigma

Diagnostic features

Siphlaenigma mayfly nymphs have a torpedo-like body form, and look like small delicate Nesameletus, but unlike Nesameletus they have antennae that are much longer than the head.

Typical habitats

Siphlaenigma larvae are infrequently recorded, but they have been found amongst submerged vegetation in slow flowing, bush covered streams.


We suspect the larvae feed on algae or decomposing plant matter on the streambed.

Indicator value

  • Hard bottom: 9
  • Soft bottom: unassigned

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

Siphlaenigma are most likely to be found in streams with good habitat and water quality. They have the high tolerance value of 9 for hard bottom sites (there is no tolerance value for soft bottom sites).