Blue Riverdamsel (Pseudagrion microcephalum)

The Blue Riverdamsel (Pseudagrion microcephalum) is a damselfly species of the family Coenagrionidae, which contains 30 species in Australia.

The identification key to the family Coenagrionidae consists of 54 couplets, 13 of which are pertinent to Pseudagrion microcephalum. Click on the numbers on the right to display the corresponding couplets. Or click on the ALLin1 button to see all the relevant couplets together in a single, scrollable window.

#	Family	Species	Couplet No.
	Coenagrionidae	Blue Riverdamsel (Pseudagrion microcephalum)	Coenagrionidae: Key couplet 1 of 54 ○ Damselflies without this combination of characters b ↑ Coenagrionidae: Key couplet 14 of 54 ● Anal vein leaving wing margin well basal to the level of Ac in both wings, so there is a basal segment of anal vein about the same length as Ac a ↑ Coenagrionidae: Key couplet 15 of 54 ○ Hindwing longer than 22 mm a ↑ Coenagrionidae: Key couplet 16 of 54 ○ Abdominal segments 2-4 bronze-black above ⇒ genus: Pseudagrion b ↑ Coenagrionidae: Key couplet 18 of 54 ○ Synthorax blue and black a ↑ Coenagrionidae: Key couplet 19 of 54 ● Superior anal appendages with deep, V-shaped notch at tip, the lower branch longer than the upper ⇒ species: Blue Riverdamsel (Pseudagrion microcephalum) a ↑ Coenagrionidae: Key couplet 23 of 54 ● Dark pigmentation on abdominal segments 3-5 less extensive, tapered to rounded in front, narrowing to back, abruptly expanded distally, so that lateral pale areas are clearly visible from above, and lateral margin is sinuate b ↑ Coenagrionidae: Key couplet 26 of 54 ● Finger-like processes much longer than height of anterior lobe at point of attachment b ↑ Coenagrionidae: Key couplet 27 of 54 ● Transverse ridge curving progressively into inner ridge ⇒ species: Blue Riverdamsel (Pseudagrion microcephalum) b ↑ Coenagrionidae: Key couplet 40 of 54 ○ No such markings on thorax or abdomen b ↑ Coenagrionidae: Key couplet 41 of 54 ○ Synthorax with extensive brown or yellow areas, sometimes pruinescent ⇒ genus: Pseudagrion a ↑ Coenagrionidae: Key couplet 43 of 54 ● Ac of hindwing beyond alignment of basal antenodal crossvein ⇒ genus: Pseudagrion b ↑ Coenagrionidae: Key couplet 49 of 54 ● Ac of hindwing beyond alignment with basal antenodal crossvein ⇒ genus: Pseudagrion b ↑
1			Coenagrionidae: Key couplet 1 of 54 ● Arculus in hindwing situated beyond distal antenodal crossvein by at least the length of subcostal part of antenodal ○ Very small damselflies, hindwing shorter than 14 mm ⇒ genus: Agriocnemis a ↑ b ↓ ○ Damselflies without this combination of characters
2			Coenagrionidae: Key couplet 14 of 54 ● Anal vein leaving wing margin well basal to the level of Ac in both wings, so there is a basal segment of anal vein about the same length as Ac a ↑ b ↓ ● Anal vein leaving wing margin nearer to or beyond level of Ac ● Basal segment of hindwing anal vein, if present, not more than half length of Ac
3			Coenagrionidae: Key couplet 15 of 54 ○ Hindwing longer than 22 mm a ↑ b ↓ ○ Hindwing shorter than 22 mm
4		Male only	Coenagrionidae: Key couplet 16 of 54 ○ Abdominal segments 2-4 black and blue or blue-grey above ⇒ species: Large Riverdamsel (Caliagrion billinghursti) (part) a ↑ b ↓ ○ Abdominal segments 2-4 bronze-black above ⇒ genus: Pseudagrion
5		Male only	Coenagrionidae: Key couplet 18 of 54 ○ Synthorax blue and black a ↑ b ↓ ○ Synthorax with extensive brown to yellow areas, sometimes pruinescent
6		Male only	Coenagrionidae: Key couplet 19 of 54 ● Superior anal appendages with deep, V-shaped notch at tip, the lower branch longer than the upper ⇒ species: Blue Riverdamsel (Pseudagrion microcephalum) a ↑ b ↓ ● Superior appendages with shallow, wide emargination at tips, the upper branch longer than the lower ⇒ species: Northern Riverdamsel (Pseudagrion cingillum)
7		Female only	Coenagrionidae: Key couplet 23 of 54 ● Abdominal segments 3-5 brownish black above except for narrow, pale band at extreme base ● Lateral margin of dark upper surface almost straight a ↑ b ↓ ● Dark pigmentation on abdominal segments 3-5 less extensive, tapered to rounded in front, narrowing to back, abruptly expanded distally, so that lateral pale areas are clearly visible from above, and lateral margin is sinuate
8		Female only	Coenagrionidae: Key couplet 26 of 54 ● Length of forwardly-directed, finger-like process on each side of posterior lobe of pronotum less than height of anterior lobe at point of attachment ⇒ species: Northern Riverdamsel (Pseudagrion cingillum) a ↑ b ↓ ● Finger-like processes much longer than height of anterior lobe at point of attachment
9		Female only	Coenagrionidae: Key couplet 27 of 54 ● Transverse ridge above mesothoracic spiracle meeting ridge flanking its inner margin at a sharp angle, equal to or less than a right angle ⇒ species: Gold-Fronted Riverdamsel (Pseudagrion aureofrons) a ↑ b ↓ ● Transverse ridge curving progressively into inner ridge ⇒ species: Blue Riverdamsel (Pseudagrion microcephalum)
10		Male only	Coenagrionidae: Key couplet 40 of 54 ○ Extensive dull orange to red markings on head, thorax and anterior abdomen ⇒ species: Red & Blue Damsel (Xanthagrion erythroneurum) a ↑ b ↓ ○ No such markings on thorax or abdomen
11		Male only	Coenagrionidae: Key couplet 41 of 54 ○ Synthorax with extensive brown or yellow areas, sometimes pruinescent ⇒ genus: Pseudagrion a ↑ b ↓ ○ Synthorax blue and black
12		Male only	Coenagrionidae: Key couplet 43 of 54 ● Ac of hindwing aligned, or almost aligned, with basal antenodal crossvein ⇒ species: Large Riverdamsel (Caliagrion billinghursti) (part) a ↑ b ↓ ● Ac of hindwing beyond alignment of basal antenodal crossvein ⇒ genus: Pseudagrion
13		Female only	Coenagrionidae: Key couplet 49 of 54 ● Ac of hindwing aligned with basal antenodal crossvein ⇒ species: Large Riverdamsel (Caliagrion billinghursti) (part) a ↑ b ↓ ● Ac of hindwing beyond alignment with basal antenodal crossvein ⇒ genus: Pseudagrion