Guwahati: A damselfly with a striking black body and flashes of blue along its abdomen has turned out to be a species new to science, helping researchers resolve a taxonomic puzzle that persisted for years across Northeast India and Bangladesh.

Named Dysphaea assamensis, the species was formally described by Rima Amsih of Dibrugarh University, Arajush Payra of Dr Vishwanath Karad MIT World Peace University, K. A. Subramanian of the Zoological Survey of India and Samrat Sengupta of Debraj Roy College (Autonomous), Assam.

Their findings, published in the journal Zootaxa  establish that the insect, long confused with another species, is distinct.

The discovery also highlights how much remains to be documented in the biodiversity-rich landscapes of Northeast India, where even familiar-looking insects can conceal previously unrecognised species.

The damselfly had earlier been mistaken for Dysphaea walli, a species described in 1927 from what is now Myanmar. Reports of similar-looking insects from India and Bangladesh had largely relied on photographs and field sightings, without physical specimens that could be examined in detail.

The confusion began to clear in 2020, when researchers questioned the identification. A 2024 study subsequently documented the differences between the insects but stopped short of formally naming the new species because no physical specimen was available.

That changed during field surveys in Karbi Anglong in May and June 2026, when the researchers collected five male specimens. These provided the material needed to formally describe and name the species.

Blue markings provide a vital clue

The newly described damselfly can be distinguished from Dysphaea walli by its wing patterns, body colouration and other anatomical features.

The male has opaque black patches at the bases of its wings, with the patch on the hindwing extending farther than that on the forewing. Its abdomen carries conspicuous blue markings against a predominantly black background.

In contrast, D. walli has a different pattern of wing pigmentation and a largely black abdomen with yellowish lateral markings.

The male specimens measured around 52.5 to 54.3 mm in total body length, according to the study.

The female was described from a photograph rather than a collected specimen, with researchers noting differences in its markings and body shape.

The scientific name assamensis refers to Assam, where the specimens used for the formal description were collected.

A forest stream is its home

The researchers observed the species along a partially shaded, lowland forest stream originating in the foothills of Karbi Anglong. The stream flows through the Nambor and Garampani wildlife sanctuaries before joining the Dhansiri river.

About 13 metres wide and roughly 60 centimetres deep at the surveyed site, the stream had herbs and shrubs along one bank, while dense forest bordered the other.

The damselflies were seen perched on woody logs in the water, generally alone or in groups of two males.

Based on collected specimens and earlier photographic records, D. assamensis has been recorded from Assam, Meghalaya, West Bengal and Tripura, as well as northeastern Bangladesh.

Researchers believe the species inhabits forested streams and riverbanks bordered by mature, mixed-moist deciduous forest.

Photographs helped solve the mystery

One significant aspect of the discovery is the role played by photographs taken before scientists obtained physical specimens.

Naturalists and amateur photographers had documented the damselfly at different locations over the years. These observations helped researchers recognise that the insect was not the same as D. walli.

The authors say such records can complement conventional taxonomic research, particularly in biodiversity-rich tropical regions where collecting specimens may be difficult or restricted.

However, the study also underscores the importance of physical specimens, known as voucher specimens, in formally establishing a new species and distinguishing it from closely related insects.

The newly collected material allowed the team to compare anatomical characteristics, including the structure of the male reproductive organs, alongside wing and body markings.

The holotype, the specimen designated as the principal reference for the species, has been deposited with the Zoological Survey of India in Shillong.

Conservation concerns remain

The discovery brings the number of recognised species in the genus Dysphaea worldwide to 10. India is now known to have three representatives of the genus, including D. assamensis.

But the researchers warn that the discovery comes against a backdrop of habitat loss in parts of Karbi Anglong.

The species’ apparent association with shaded forest streams makes the condition of its habitat particularly important. The paper points to forest loss linked to urbanisation and agricultural expansion and intensification in the type locality.

The authors call for a better understanding of the species’ distribution and population status, alongside protection of the forest streams it inhabits.