Sarasaeschna as a genus was established by Karube & Yeh in 2001 to differentiate a group of species from Oligoaeschna on structural characteristics. These are generally species frequenting damp areas, often without a lot of or even any open water, in forested surroundings. They are spring species and due to their habitat preferences often overlooked. For instance, only in recent years has it become clear that this is a much more diverse group, with only in Taiwan now already 5 different species identified. In Vietnam only one species was known, S. niisatoi, a little known and rare species only reported from Pia Oac Mountain from a small swampy area now destroyed (subsequently it was also reported from Hainan). Karube (pers. comm.) reported finding larvae of Sarasaeschna also in Sa Pa, but the species was unknown. This basically was the state of affairs for Vietnam until this spring.
On May 15 I was surveying the Tu Le area in Yen Bai Province when I noticed a hovering Aeshnid above a small depression in partly logged primary forest. After capture it became clear that this was a Sarasaeschna species, but not S. niisatoi. When I contacted Wen-Chi Yeh about it, it turned out this was a species currently being described and to be published in July, known only from a specimen collected in China. I observed at least two different males. For now I will publish this here as species novum, its true identity will be revealed upon publication of the paper.
|Sarasaeschna species novum, Tu Le|
|Facial pattern of the male species novum from Tu Le|
|The Sarasaeschna yoshitomii from Sa Pa, as seen on discovery day|
|One week later, the male Sarasaeschna yoshitomii from Sa Pa in hand|
|Distinctive facial pattern with a lot of yellow|
|Posed male of Sarasaeschna niisatoi|
|Male of Sarasaeschna niisatoi in hand|
|And its facial pattern|
And finally, on May 30 I was visiting Xuan Son National Park looking for Idionyx selysi, when I noticed a rather large Aeshnid flying inside the forest. I was able to capture it. It turned out to be an old female of an unknown species. The wing venation reminded me of Planaeschna, and although it was strange to find an old specimen so early in the season, that is what I assumed it was. Until at home I had a closer look and noticed the flattened frons. Communication again with Wen-Chi confirmed this was yet another Sarasaeschna. It shares quite a few characteristics with S. chiangchinlii of Taiwan, but has different thorax pattern and it even larger, 66 mm. It appears to be a closely related, but undescribed species. Its identity will have to wait for confirmation until the male is located. A nice challenge for next year.
|Female Sarasaeschna species novum from Xuan Son|
|And its distinctive facial pattern|