Lee Kong Chian Natural History Museum

Heliaeschna crassa Kr├╝ger, 1899

Kingdom:Animalia
Phylum/Division:Arthropoda
Class:Insecta
Order:Odonata
Family:Aeshnidae
Genus:Heliaeschna
Species:H. crassa
Common Names:Nighthawker
Status:Very Rare

Description

In males, the hindwing is 49 to 52 mm in length and the total body length ranges from 72 to 77 mm. The eyes and thorax of the male are bottle green. The top of the frons is black, without a T-mark. The median space at the base of the wings has four to five crossveins, lacking in other aeshnid genera. Markings on the base of the abdomen are green. The third segment of the abdomen is well constricted. The ground colour of the abdomen is dark reddish brown with green transverse flecks on segments three to 8. The female has a brown-coloured body and olive green to brownish eyes. It has smoky-brown wings. There is no constriction at the third segment. The hindwing base of the female is well rounded.

Heliaeschna crassa and Heliaeschna idae (Brauer, 1865) are almost identical, but H. idae is on average slightly larger than H. crassa. The male appendages differ slightly and provide the only reliable way of separating the species. In H. crassa, seen from the side view, the inferior anal appendage is only slightly recurved whereas that of H. idae is distinctly recurved. Females cannot be reliably separated, so the identity of the known female specimens from Singapore remains uncertain.

Read more about the Odonata order.
Read more about the Aeshnidae family.

Distribution

Confined to Sundaland, where the species may be common and widespread.

Localities

Recorded in MacRitchie Reservoir, former Bukit Timah University Campus and Kent Ridge Campus.

Locality Map

Records

A male Heliaeschna crassa specimen (identity confirmed by Wen-Chi Yeh) was photographed in a stream at MacRitchie Reservoir in June 2009. Earlier two females had been photographed at the same site in December 2008 and in January 2009. Two female specimens, which are either Heliaeschna crassa or the closely related Heliaeschna idae (Brauer, 1865) have been collected in Singapore: at the former Bukit Timah University campus in 1964 and at Kent Ridge in 1986.

References

Tang, H. B., L. K. Wang & M. Hämäläinen, 2010. A Photographic Guide to the Dragonflies of Singapore. Raffles Museum of Biodiversity Research, National University of Singapore, Singapore. 222 pp.

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