Genus Euphaea 幽蟌科

Euphaea fall into two groups :

First Group Second Group
Euphaea subnodalis hw, 27-28 mm
Euphaea subcostalis hw, 23-24 mm
Euphaea tricolor hw, 24-26 mm
Euphaea basalis  hw, 27-28 mm
Euphaea impar

Euphaea ameeka

Males have brilliant blue-green metallic patches on the hind wing.

Lack metallic colors on the hind wing

Females all have hyaline wings and drab brown bodies marked with yellowish outlines on the thorax.

 

The males of Euphaea tricolor, Euphaea subcostalis and Euphaea subnodalis especially are very similar and can be separated only by reference to a number of minute characters.

For example Euphaea tricolor is distinguished by the white upper sides of the pseudoauricles-small triangular projections from the side of the second abdominal segment.

Euphaea tricolor and Euphaea subcostalis occur universally on rocky, swift flowing forest streams up to about 600 m, although seldom so high for E. tricolor.

The males perch on logs and any other emergent vegetation towards midstream where the current is swiftest.

Females lay their eggs in the sound wood of fallen logs, guarded at a short distance by males.

By contrast Euphaea subcostalis prefers small tributaries well within primary forest. The males perch low on leaves of riparian vegetation, often at high densities of one every two meters, and territorial disputes and rapid chases are frequent. It is likely that some form of courtship occurs, but as the action is very rapid and often takes the insects out of sight it is difficult to observe clearly. When a female is ready to accept a mating she typically lands on a leaf following a chase. The male lands beside her and in some cases faces her for a few moments before attempting copulation. After a brief mating the female lays in pieces of wood in the stream bed, mostly unguarded by the male. Females are extremely inconspicuous and, unlike chlorocyphids, never take long in laying their eggs; they are seldom observed unless deliberately sought.

It should be noted that Euphaea subcostalis is quite a variable species throughout its range and, in the past, variants have been treated as two distinct species.


Euphaea subnodalis (hw, 27-28 mm)


 

Euphaea subcostalis (hw, 23-24 mm)

 

Euphaea tricolor (hw, 24-26 mm) and it lacks the white pseudoauricles of the latter species. The dark hind wing patch is narrowly cleared along the costa for a short distance from its inner margin. It is common on forest streams at about 400-1000 m on Mount Kinabalu and the Crocker Range and in different localities it overlaps with each of the other three species.

 

Euphaea basalis  (hw, 27-28 mm) is easily recognized. The metallic-blue coloration on the hind wing reaches almost to the wing base and it is of a deeper blue than in other species. It is found only on Mount Kinabalu at 1000-1700 m. Its habits are similar to those of  subcostalis.

 

The females all have hyaline wings and drab brown bodies marked with yellowish outlines on the thorax.


Euphaea impar male is recognizable by its heavy build with bright blue sides to the thorax, and broad dark patch at the tip of the hind wing. It is common in clear rocky forest streams and small, partially-shaded forest streams.


Euphaea ameeka - the blue on the thorax is even more extensive, reaching well onto the upper side of the synthorax. The wings are narrower than in impar and are without any dark marking. It has been found only in Brunei, where it is remarkably widespread and abundant in the same localities where impar occurs. The females of these two species are marked on the thorax with the same pattern as the males, but the blue color is replaced by dull olive green. Territorial and mating behavior of both species are much the same as in other forest-dwelling members of the genus.


INDEX : Damselfly     March 10, 2016 09:16:48 PM