Type species: passalis Fabricius (Sri Lanka
Synonyms: Syntomis Ochsenheimer (type species phegea Linnaeus,
Europe); Coenochromia Hübner (type species passalis Fabricius); Hydrusa
Walker (type species bicolor Walker, Australia); Asinusca Wallengren
(type species atricornis Wallengren, S. Africa); Buthysia Wallengren
(type species sangaris Wallengren = huebneri Boisduval, Java); Callitomis
Butler (type species syntomoides Butler, Kashmir). The genus Leopoldina
Hering (type species leopoldi Hering) is probably based on a synonym
of Amata sperbius Stoll.
This genus, for which the Palaearctic taxa were reviewed by Obraztsov
(1966), is best defined on genitalic characters, as it exhibits great variety in
wing pattern and abdominal banding.
The genitalia are asymmetric in both sexes. In the male the tegumen has
prominent lateral lobes. The valves have strong, curved, asymmetric processes
from the base of the costa and are themselves asymmetric. The aedeagus vesica
contains a row (or rows if it has more than one lobe) of small cornuti, some of
which can become very long. In the type species of Hydrusa and Buthysia
there is no asymmetry, and lobes to the tegumen are lacking. Both species
have the valve apex produced into a setose process. Despite extreme facies
differences (H. bicolor lacks patches or windows on the wings) the
species would appear to be related, and the genera are best retained in synonymy
with Amata as they possess the aedeagus vesica ornamentation that
characterises that genus.
In the female genitalia the ostium is set asymmetrically between the
eighth and seventh tergites.
The larva of the type species has been described by Sevastopulo (1941)
and Bell (MS). The mature larva is cylindrical, constricted at segment margins,
each segment bearing typical arctiid verrucae with tufts of long hairs. The head
is reddish orange but the body is deep blackish purple. The hairs on the
verrucae are a mixture of feebly pectinate black ones and strongly pectinate
grey ones, giving the larva a generally grey appearance.
Rammert (1987) described defensive glands in European Amata, associated
with the large dorsal verrucae on each segment. These rupture when the larva is
attacked, releasing a noxious fluid stored in a subcutaneous cavity.
The host-plants of A. passalis are Ipomoea (Convolvulaceae;
Bell (MS)), Cajanus (Leguminosae; CIE records), Dahlia, Cosmos (Compositae;
Sevastopulo (1941)) and Santalum (Santalaceae; Browne (1968)), but Bell
noted marked cannibalism amongst the larvae.
The pupa is in a slight cocoon of brown silk, interwoven with a few of
the larval hairs, though most of these are not shed.
The egg is white, spherical, slightly flattened at the base, unsculptured, and laid in large batches.
Bell (MS) noted that A. passalis males sembled upwind to freshly
emerged females. He also reared A. cyssea Stoll and A. elongata Hampson,
the larvae of both of which were moss or lichen browsers, found on tree-trunks
or walls. However, Browne (1968) referred to A. cyssea as a polyphagous
There are numerous species in Borneo, here grouped loosely on the basis
of facies into: a white-spotted group, the posterior distal spot of the forewing
single (wallacei Moore to pleurosticta Hampson); a yellow spotted
group, usually with the most distal of the posterior pair of forewing spots set
at an angle and wedge-shaped, and the posterior patch of the distal pair divided
by a vein, the hindwing broadly basally yellow and often modified in shape in
the male (egenaria Walker to kinensis Hampson); a slender montane
group, often with elongate markings (pseudextensa Rothschild to mjobergi
Talbot); a robust, extensively transparent group with broad, angled valve
apices in the male genitalia (cantori Moore, pryeri Hampson, symphona
Swinhoe), associated with a number of other more transparent species.
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