Genus : Gynacantha

 

Gynacantha is a genus of mainly large species found throughout the world's tropics. Seven species are found in Borneo, one endemic.

The males are generally recognized by the very swollen, almost spherical base to the abdomen with large rounded ear-like auricles on segment 2 followed by an extremely constricted third segment and long, thin, simple superior appendages. The base of the abdomen is often very colorful with bright green flecks on the dorsum and bright blue auricles, but some species are more somberly colored. The easiest way to separate both males and females from the sometimes similar Heliaeschna is by the lack of any cross veins in the median space at the base of the wing ..

Female Gynacantha are difficult to identify to species. They are typically a little larger in wingspan than the males and have extremely long anal appendages. These however are seldom intact and apparently always break off during mating. The third abdominal segment is distinctly constricted, though less so than in the males.

Gynacantha species are found from lowland swamp forest to about 1000 m in the case of basiguttata, bayadera and dohrni.

Typically they are seen hawking at dawn or just before and after dusk and in these situations it is quite common to see virgin females with intact appendages which in flight appear very like males.

 


Gynacantha species become active in the evening and often come to artificial light.

This is the third Gynacantha basiguttata in 2007 visited our sitting room in early evening. Gemok Hill is 2 kilometers away, that hill could be the habitat from where they came from.

More about Gemok Hill of Sabah...

Males of basiguttata and dohrni guard these pools, or if the pool is large, several males may share it, each defending a well defined territory. They perch conspicuously on emergent twigs with the abdomen hanging vertically in the manner typical of all aeshnids. Females arriving are normally mated before they are allowed to oviposit, inserting their eggs into dead leaves and twigs.

The larvae are typically aeshnid in general form, but are easily separated from other genera by the presence of long fine bristles on the labial palps. They are found in leafy forest pools but may be difficult to discover among deep layers of litter.

 

During the day they are found resting in deep undergrowth or in overhangs at the head of small gullies, but from noon onwards they may be reproductively active around shallow leaf-bottomed pools in deep forest shade.

Photo Left : This is a matured female with long anal appendages which is un intact half broken.


Gynacantha basiguttata. is the most common species of Sabah. It is larger than G. dohrni and the male superior appendage is expanded into a distinct spatulate shape with a concentrated tuft of hairs at its tip. The inferior appendage is almost half as long as the superiors.

Photo Left : A female Gynacantha basiguttata


  Gynacantha dohrni is  another common species and is a moderately large insect, brightly colored in life.

The pale, narrowly triangular, inferior anal appendage is less than one third the length of the long thin superiors, which are very slightly distally expanded with a small hook at the tip.

 


Gynacantha demeter is very similar to Gynacantha dohrni  in size and structure.  Gynacantha demeter is endemic.


Gynacantha subinterrupta is widespread through Sabah but uncommon to see one.


Gynacantha maclachlani  is slightly larger  from north and west Borneo. All differ from one another in slight details of the male appendages and the coloration of the thorax and are quite difficult to separate.
 


Gynacantha limbalis ( hw, 61 mm) is the largest Bornean species. But this species has not been seen in Sabah yet. The superior appendages are quite straight and narrow as in dohrni but the inferior is between one third and half the length of the superiors. Also there is a distinctive brown streak along the leading edge of both wings. It might be mistaken for a Tetracanthagyna species but for the basally swollen abdomen constricted at the third segment. In Borneo it has been recorded only from Sarawak.


Gynacantha bayadera  is fairly common and ubiquitous species, and easily the smallest member of the genus ( hw, 37-41 mm). It is immediately recognized by the basal segments of the abdomen which are only slightly swollen, the auricles which are triangular instead of semicircular, the less pronounced constriction of the third segment and the fairly short, absolutely straight superior appendages. The hind wing is relatively broad, being as wide as in the considerably larger Gynacantha dohrni.

Biota
   Domain Eukaryota - eukaryotes
     Kingdom Animalia Linnaeus, 1758 - animals
       Subkingdom Bilateria (Hatschek, 1888) Cavalier-Smith, 1983 - bilaterians
         Branch Protostomia Grobben, 1908 - protostomes
           Infrakingdom Ecdysozoa Aguinaldo et al., 1997 ex Cavalier-Smith, 1998 - ecdysozoans
             Superphylum Panarthropoda
               Phylum Arthropoda Latreille, 1829 - arthropods
                 Subphylum Hexapoda
                   Class Insecta Linnaeus, 1758 - insects
                     Subclass Dicondylia
                       Infraclass Pterygota
                         Division Odonata
                           Order Odonata  Fabricius, 1793 - dragonflies and damselflies
                             Suborder Anisoptera Selys, 1854
                               Superfamily Aeshnoidea
                                 Family Aeshnidae 
                                   Genus Acanthaeshna
                                   Genus Anax Leach, 1815
                                   Genus Basiaeschna Selys, 1883
                                   Genus Boyeria McLachlan, 1896
                                   Genus Brachytron Selys, 1850
                                   Genus Cephalaeschna
                                   Genus Coryphaeschna Williamson, 1903
                                   Genus Epiaeschna Hagen, 1877
                                   Subfamily Gomphaeschninae
                                   Genus Gynacantha Rambur, 1842
                                   Genus Hemianax Selys, 1839
                                   Genus Nasiaeschna Selys, 1900
                                   Genus Oligoaeschna
                                   Genus Oplonaeschna Selys, 1883
                                   Genus Planaeschna
                                   Genus Remartinia Navas, 1911
                                   Genus Triacanthagyna Selys, 1883
                                   Subfamily Aeshninae 

 

INDEX OF DRAGONFLY

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