Last Updated on : Tuesday, 01 March, 2016 12:08:11 AM
Five species of this genus are recorded from Borneo.
|Among the most impressive and colorful
family of Gomphid species are the Macrogomphus
which fly along slow silty streams in lowland forest. Compared with other large
Anisoptera they are relatively slow in flight.
The males are encountered much more frequently than the females.
Males of Macrogomphus can easily be recognized, as they are the only medium-large gomphids in which the superior anal appendages are strongly forked. Both sexes are also distinguished by the presence of a tiny antenodal cross vein basal to the first main bracing antenodal, a feature they share with the smaller Leptogomphus.
As far as is known the larvae all have a short thick snorkel at the tip of the abdomen. This is a characteristic of deep burrowing species which live in fine silt. The snorkel protrudes just above the surface of the mud, allowing the animal to inhale clean water while it grubs deeply for worms and other burrowing prey. The forelegs are modified for digging.
Macrogomphus parallelogramma is found chiefly on the low coastal plains from Brunei to the west and south of the island. It may be common where it occurs, typically on slower flowing streams in lowland dipterocarp forest with a sandy rather than muddy substratum. Males patrol largish reaches of the streams along several hundred meters. They are only moderately rapid in flight and are fairly easily observed and captured when they emerge from shadow. Females oviposit over shallow gravel beds or even in deep swift flowing runnels. Macrogomphus parallelogramma is quite variable in size, although larger specimens are commoner.
Two smaller, rarely collected Macrogomphus species are
Macrogomphus phalantus and
M, phalantus (S hw, 35 mm) looks like a small Macrogomphus parallelogramma, differing from it only in small details of the markings and the form of the male anal appendages. It is found in swampy forest in low country in west Borneo.
The slightly larger Macrogomphus decemlineatus (S hw, 37 mm) is readily distinguished by the presence of five yellow bands (including the antehumerals) on either side of the synthorax giving it its Latin name which means 'ten-lined'. It is a rare species, found in sluggish forested streams in low country. The female is unknown.
Macrogomphus abnormis, known only from females taken in the 19th century and generally recorded in faunal lists as a Bornean endemic, is most probably a form of Macrogomphus quadratus.