Genitalic studies of Amerila eugenia ( Fabricius ) ( Lepidoptera : Arctiidae ) from Karnataka , India

In this manuscript, external male and female genitalic characters of Amerila eugenia (Fabricius) have been studied and illustrated for the first time. Besides this, a dichotomous key for the separation of all four Indian species of this genus has been provided.

Genus Amerila was proposed by Walker in 1855 for its type species astreus Drury from Bengal, India.It is a diverse old world tropical genus with distinctive facies such as shape of fore wing margin; small hind wings, with (in males) modified scales along the rather produced tornus; general colouration is white, pale pinkish-brown or dark brown with areas of pink on the abdomen and the legs; antennae with more (80) segments (Holloway 1988).Hampson (1894) synonymised the genus Amerila Walker under Pelochyta Hübner and later on Hampson (1901) treated Amerila under Rhodogastria Hübner.Strand (1919) catalogued five species under Rhodogastria Hübner, i.e., astreus (Drury), eugenia (Fabricius), omissa Rothschild, rhodopa (Walker) and phaedra (Weymer) from India.However, Hampson (1920) restricted R. phaedra (Weymer) to East Africa, thus, leaving four Indian species under the genus Rhodogastria.Watson et al. (1980) accepted Amerila Walker as a valid generic name and mentioned that the correct type species of Rhodogastria Hübner & Amerila Walker are Phalaena amasis Cramer, and Sphinx astreus Drury, respectively.Whereas, Arora & Chaudhary (1982) again referred to Strand (1919) and reassigned astreus Drury to the genus Rhodogastria along with the confirmation of five Indian species under it.On the other hand, Koda (1987) described the male and female genitalic attributes of astreus (Drury) and studied it under the genus Amerila.The same nomenclature was followed by Holloway (1988).Häuser & Boppré (1997) restricted the species A. phaedra Weymer to East and South Africa.Singh & Singh (1999) added another species i.e.Amerila arthusbertrandi (Guérin-Méneville) to the Indian fauna, once again, raising the number of species under Amerila to five.But this species seems to be a wrong identification of Amerila omissa (Rothschild).Recently Dubatolov (2010)reassigned the previously known four species to the Indian Amerila.
In the present work, the external male and female genitalia of A. eugenia (Fabricius) has been studied and illustrated for the first time.In addition to this, the other three Indian species of the genus Amerila were also interpreted in respect to their external morphological characters, which revealed that A. astreus (Drury) and A. omissa (Rothschild) are easily separable, but A. eugenia (Fabricius) and A. rhodopa Walker are morphologically similar, which can only be separated by the slightly different colour of their abdomen.From the literature (Rothschild 1914;Hampson 1920) it is also clear that the area of distribution of both these species is almost similar.Therefore, the examination of external male and female genitalia of A. rhodopa Walker is of utmost importance for further review of both these species.A dichotomous key to all the four Indian species of the genus Amerila Walker has also been formulated and included.

Materials and Methods
The members of the genus Amerila Walker were exclusively collected with the help of light traps (equipped with mercury bulb) at night.The collected moths were euthanized in glass jars, fumigated with ethyl acetate vapours.The dead specimens were preserved in ento boxes, fumigated with napethalene balls.Identification was done with the help of literature and confirmed by comparison with the photographs of types received from the Natural History Museum (NHM), London.For the preparation of permanent slides of fore and hind wings, the method proposed by Common (1970) and advocated by Zimmerman (1978) was followed.For the study of external male and female genitalia, the methodology given by Robinson (1976) was followed.The diagrams of genitalia were drawn with the help of a graph eye piece fitted in a stereo zoom binocular on graph paper and was photographed with the help of a Leica stereo-microscope equipped digital camera.The terminology given by Klots (1970) has been followed in the present study for nomenclature purposes.
Diagnosis: Labial palpi upturned; antennae simple in both sexes with more segments (80); forewing with vein R 3 & R 4 anastomoses to form short areole, R 2 & R 5 from areole, M 2 & M 3 from lower angle of cell; hindwing small with vein Rs & M 1 originating from upper angle of cell, Cu 1 before lower angle of cell; hind tibia with two pair of spurs; male genitalia with uncus short, vinculum u-shaped, saccus present, valve rounded, harpe hook/plough-like, outer wall of valve bears a retractile scent lobe, juxta divided into a dorsal plate and a ventral pocket, aedeagus short and broad with tubular vesica bearing two cornuti, ductus ejaculatorius entering sub apically; female genitalia with corpus bursae membranous, signa present, basal half of ductus bursae sclerotized and second half membranous.
Adult description: Male 52mm; female 52mm.Vertex and frons whitish, spotted with black.Antennae simple in both sexes, scape light crimson, flagella brown.Labial palpi upturned, irrorated with crimson scale, extremity of each segment with a black band, underside white.Collar and tegula white with black spots.Thorax with white and black spots.Abdomen crimson, proximal half of first segment white, lateral and sub lateral series of black spots, underside white.Forewing with ground colour whitish opaque, two   Male genitalia: Uncus short and broad, gradually narrowing towards tip, setosed with short setae, sclerotized, tip pointed; acrotergite absent; tegumen longer than uncus, broad v-shaped; vinculum as long as tegumen, u-shaped, uniformly sclerotized; saccus weakly developed.Valve rounded with costa narrow and linear, weakly sclerotized; sacculus well differentiated; harpe well sclerotized, plough like; cucullus and valvula not differentiated; tip of valvae rounded, laden with small setae; outer wall of valvae with well developed retractile scent glands.Transtilla weakly sclerotized; aedeagus short and broad at base, slightly narrowing towards tip; vesica membranous, with two well sclerotized spines; ductus ejaculatorius entering subapically.