Indolestes tenuissimus is a species of damselfly in the family Lestidae, commonly known as the slender reedling. It is found only in north-eastern Australia. Its natural habitats are freshwater swamps, ponds and pools. The adult is a medium-sized damselfly (wingspan 50mm, length 45mm) with the thorax being mainly pale blue with darker patches. The abdomen is mid to dark grey on dorsal surfaces, lighter below, with segment ten forming a distinct pale band. In Australia, the distribution is in suitable habitat in the north-eastern part of the continent from the tip of Cape York Peninsula to central Queensland. The taxon has not been assessed in the IUCN Red List, but it does appear in the Catalogue of Life.