Cephalaeschna Selys, 1883

Dawn, Prosenjit, 2021, A new species of Cephalaeschna Selys, 1883 (Odonata: Anisoptera: Aeshnidae) from Neora Valley National Park, West Bengal, India, with notes on C. acanthifrons Joshi & Kunte, 2017 and C. viridifrons (Fraser, 1922), Zootaxa 4949 (2), pp. 371-380 : 376

Key to the Indian Species of Cephalaeschna Selys, 1883 (Modified from Fraser 1936, Asahina 1983 and Joshi & Kunte 2017)

1. Larger species (abdomen length> 50 mm including anal appendages) with dense wing venation, more number of veins (antenodal nervures in forewing>25); constriction present in the middle of cerci in lateral view......................... 2

- Smaller species (abdomen length including anal appendages <50 mm) with comparatively open wing venation, less number of veins (antenodal nervures <25); no constriction visible in the cerci in lateral view.................................. 3

2. Wings without prolonged subcostal vein beyond the node............................................... triadica

- Prolonged subcostal vein present beyond the node.................................................... acutifrons

3. Tip of the cerci not upcurved, rather flat in lateral view....................................................... 4

- Tip of the cerci upcurved and visibly emarginate upwards..................................................... 6

4. Dorsal midline of abdomen undeveloped, often obscured and abdominal marking restricted to jugal and postjugal vertical spots on S2–S8; tip of the cerci ending obtusely; crest of the frons roundly inflated but without any projection........... masoni

- Thin greenish yellow dorsal midline present on S2–S7, only interrupted at the jugal line and completely lost from S9 & S10; tip of the cerci not completely rounded but with a slight angulation at the outer margin in dorsal view; crest of the frons with projection........................................................................................... 5

5. Crest of frons with well-developed hornlike projection; median ridge of the cerci form prominent outward angulation................................................................................................ acanthifrons

- Projection on crest of frons less developed, only like a small tubercle; the angulation at the tip of the cerci less developed, sometimes almost rounded in appearance.......................................................... viridifrons

6. Frons much inflated, crest of frons overall rounded without prominent tubercular process, distal end of the cerci not distinctly broadened................................................................................... orbifrons

- Frons moderately inflated; crest of frons with a blunt tubercular projection; cerci gradually broadens towards tip......... 7

7. Midlobe of labium pale, lateral lobes black; thoracic anterolateral green stripe complete; tip of the cerci upcurved but not distinctly bent inward............................................................................ klapperichi

- Labium completely black; thoracic anterolateral meso-thoracic stripe broken into two separate green spots connected with a fine line; tip of the cerci upcurved and prominently bent inward to form a blunt tubercular process in dorsal view..... patrai