STUDIES ON THE MORPHOLOGY OF MALE GENITALIA OF SOME SPECIES OF SCARABABIDAB (COLEOPTERA).

Scarabaeidae is one of the largest families of Coleoptera and contains about 25,000 described species under 2000 genera from all over the world. In Indi~ about 1,590 species under 203 genera a:re known (Annonymus, 1991; Arrow, 1937; Balthaser, 1963, 1964; Scbenkling, 1921; Young, 1989). The species of this family can easily be recognised by the presence of characterstic form of antennae. However, the genitalia of male (aedeagus) plays an important role in identification of closely related species of scarabaeid beetles. Hence, scanning electron microscope (SEM) was used to study the morphological differences of male genitalia of 10 species of scarabaeid beetles collected from Andaman and Nicobar Islands (Figs. 1-13).


INTRODUCTION
Scarabaeidae is one of the largest families of Coleoptera and contains about 25,000 described species under 2000 genera from all over the world. In Indi~ about 1,590 species under 203 genera a:re known (Annonymus, 1991;Arrow, 1937;Balthaser, 1963Balthaser, , 1964Scbenkling, 1921;Young, 1989). The species of this family can easily be recognised by the presence of characterstic form of antennae. However, the genitalia of male (aedeagus) plays an important role in identification of closely related species of scarabaeid beetles. Hence, scanning electron microscope (SEM) was used to study the morphological differences of male genitalia of 10 species of scarabaeid beetles collected from Andaman and Nicobar Islands (Figs. 1-13).

MATERIAL AND METHODS
Fresh samples containing males of 10 different species of Scarabaeidae were seperated and cleaned under laboratory using an ultrasonic cleaner. The male genitalia (aedeagus) of each species were dissected out usiQg a fine Q,eedle and dehydrated in different concentrations (SO, 60, 70 and 100%) of acetone. The air dried samples were coated with carbon and gold in a vaccum coater JEOL JEE-4X. The coated samples were sqanned under JEOL JSM-840A electron microscope.

RESULTS AND DISCUSSION
The size of the external male genitalia (aedeagu,s) of sc~abaeid beetles normally varies from 1 mm to 10 mm in length and in most cases their length does not exceed S mm, which makes some times very difficult to study the details of aedeagus with the Jight microscope. The male genetalia has been one of the characters employed in scarabaeid taxonomy especially for identification of species and subspecies. Further it also helps in grouping the taxa at all leavels. Hence, the present study has been made on the morphology of male genitalia of fresh samples using scanning electron micrographs. The result obtained is shown in Figs. 1-13, which will help in the identification of species subspecies of scarabaeidae.
Observations on the scanning electron micrographs of aedeagus of 10 species of scarabaeid beetles are as follows: Size of aedeagus 1·65 mm; phallobase longer than parameres ; parameres broad at base and narrewing apically, overlapping each other upto middle and apex with a characteristic longicudinal carina with dentations and small grooves laterally; carina e with asymetrical spines studded medially ~on lateral constrictions.
PhaeochroDs intermedius iDtermedius Pic ( Fig. S) Size of aedeagus .4·75 mm; phallobase four times longer than parameres; parameres assymetrical; characteristic longer paramere far extended towards base and narrowing apically; short paramere slightly widening in apical half, an angular protrusion laterally and bluntly rounded at apex.
From the present study it is apparent that the application of SEM to the systematic studies of Scarabaeidae will be a valuable tool to the investigator particularly if micrographs of genitalia could be gathered into a reference atlas.

SUMMARY
Genitalia of male scarbaeid beetles play an important role in the identification of species and subspecies and also in grouping the taxa at all levels. M<?rphology of 10 species of scarabaeid beetles occuring in Andaman and Nicobar Istands have been studied using scanning electron microscope. Descriptions have been made using the micrographs and it has been suggested that the application of scanning electron microscopy to systematic studies of the species of scarbaeidae will be a valuable tool to the investigator, particularly if micrographs of diagnostic features c(juld be gathered into a reference atlas.