This species was described by Asahina from
, the name of the species
specifies the locality of holotype. Thailand
They are green brow and elongate damselflies with very slim typical abdomen. The head is dark green with shining emerald green compose eyes. The labrum is bright white make it quite remarkable in dark of the forest. The round prothorax is same colour to the labrum in both dorsal and lateral sides. Their synthorax is shining green in dorsal side but it change to red brownish with white or cream yellow marking on lateral sides. Their wings are hyaline with dark pterostigma, length of the wing is shorter haft of the abdomen. Their legs are dust white brow. The abdomen is round, long and slim with the segments are shining black at apical and white cream at base except two last segments. They are short and thick; the basal one is dull black white the apical one is cream white. The anal appendages of male are black.
This species has the same size to Protosticta santoi but they are difference in color of the body and structure of anal appendages.
The species was found in cleaning running water in pristine forests and distribute from North to South of Vietnam. The larvae of this species usually hide under dead leafs of the water.
They fly in the dark of the forests but never fly far away their breeding sides. Some time they were found at vegetation under waterfalls of rocky mountain in very high humidity condition. They fly slowly above dark vegetation layer just over the ground surface of the forests.
Male of P. khaosoidaoensis, photographed by Cuong Do
Male of P. khaosoidaoensis with bend upward abdomen, photographed by Cuong Do
Teneral female of P. khaosoidaoensis, photographed by Cuong Do