9 species: To difficult to tell species apart in field
2 dark bands on the foot, one at either end. Dark line along front edge of each body segment
2 dark bands on the foot, one at either end. Pale line and dots on a dark background of each body segment
Single dark band on foot.
Underside of body generally unmarked
Dark markings along the underside of body.
Tuft of filaments alongside the last gill
Alternate dark/light pattern on tails.
Absence of small protuberances on pronotum
Plain unbanded tails.
Conspicuous protuberances on either side of pronotum
Gills are produced into a sharp point
No reliable characters to separate Rhithrogena spp.
R. germanica generally larger than R semicolorata
Mature larvae found in March or early April likely to be
Mature larvae found in late spring are likely to be
B9: Spines on the amongst the hairs on edge of the gills
B9: No spines. Series of 2-4 light dots on each body segment
B9: No spines. No light dots on each body segment
B10: No small bump on outer edge of bottom segment of the antenna
B10: Small bump on outer edge of bottom segment of the antenna
S2: Flattened outer edges of body marked with dark streak
S2: No obvious dark marks on outer edges of body
Two tusk like projections from head
Thick feathery gills held over back
L2: First gill much smaller than other gills
Teeth on claw cover about half the length of the claw
L3: Teeth on claw cover about half the length of the claw
L3: Teeth on claw cover about 3/4 length of the claw
L4: broad area of gill rounded, ends abruptlyteeth on claw cover about 2/3 length of claw
L4: broad area of gill tapers into long filament gillteeth of claw cover almost whole length of claw
Use body markings to
separate species
Tails and legs with alternating black and white marks
Tails and legs of uniform colour