Prodasineura haematosoma (Platycnemididae) is one of the 16 species (1) of this genus present in Borneo (2 not yet described in 2013), including 13 in Sarawak (2). Some are inconspicuous species, found in forests; some are very rarely encountered, very rare, in hard-to-access areas. Others are much more common. Prodasineura haematosoma is one of these rarities, and before our survey, there were only two photos on iNaturalist.
These species that live in the shade have the particularity of being very sensitive to the flash's pre-flash, taking off before the main flash can fire; hence, sometimes quite successful, yet involuntary, photos in flight.
I think they are difficult to confuse with another species, with the face, head, and thorax completely black except for a light lateral stripe, and the abdomen orange or red, except for the last three segments, which are black and adorned with light anal appendages.
Lieftinck (3) tells us that its abdomen measures 29 to 31 mm, so it must reach 36 mm in total. We encountered it near a forest river, on a stream branching off from it, perched on a branch above the water, well in the shade. The subject in photo 3, more brightly lit, was likely wandering and was resting on a bridge over this river, in a more open habitat.
A little later, we were fortunate enough to encounter a female; at the time, we did not know that it was the female of this species, even though we had not met any other Prodasineura nearby. But as Lieftinck wrote, she is very different from the male: "Differs considerably from the male." I had therefore filed these photos separately, and it was only upon reading Lieftinck's description that I made the connection. These are the first photos of a female Prodasineura haematosoma on the Web.
And it is true that it is surprising to see this orange antehumeral stripe, absent in the male (in the mature male, at least...), a stripe that narrows as it extends upward. The head, in front of the ocelli, carries an orange line that is thicker laterally; the pronotum shows three lateral spots, the first two of which are joined; finally, extending from the thin antehumeral stripes, two small orange spots are located just before the wing bases. So many distinct elements described by Lieftinck (3).
Prodasineura haematosoma female, Sarawak, Bung Ngiraja, 26/03/2025
And above all, the shape of the posterior margin of the pronotum corresponds entirely to what Lieftinck mentions: "Posterior lobe upright, posterior margin forming on each side a blunt, horn-like projection, flattened in the transverse plane, directed upward and then forward."
Prodasineura haematosoma female, Sarawak, Matang Wildlife Center, 19/03/2025
On March 26, we encountered this female very close to the male, a little later, she too perched above a stream.
A week earlier, at another site, we had encountered an identical female (below); but in the absence of males, we had not been able to identify her.
L'espèce est endémique de Bornéo et ne se rencontre qu'à l'ouest du Kalimantan et à l'extrême ouest du Sarawak.
IUCN Red List.
Etymology of Prodasineura haematosoma
Prodasineura (Cowley, 1934) (2) ; I was unable to find the document in which Cowley separates this genus from Disparoneura (Selys, 1860). Disparoneura means "distinct venation" to emphasise its distinctiveness, and Cowley, keeping this idea in mind, created this anagram of Disparoneura, as this genus presents a very similar venation.
Haematosoma, from the Greek "haem" meaning "blood" and "soma" for "body", certainly referring to the colour of the male's abdomen.
Prodasineura haematosoma male, Sarawak, Bung Ngiraja, 26/03/2025
1- Dow & Ngiam, 2013 - Prodasineura yulan (Odonata: Zygoptera: Platycnemididae), a new species from Sarawak - Zootaxa 3670 (1): 087–090
2- Dow, 2021 – AN ANNOTATED CHECKLIST OF THE ODONATA (INSECTA) KNOWN FROM SARAWAK WITH RECORDS TO DISTRICT LEVEL – Sarawak Museum Journal · January 2021
3- Lieftinck, 1937 – Descriptions and records of South–east Asiatic Odonata. Treubia 16: 55–119. P. 84.