Distinguishing between the two sympatric species Bactrocera carambolae andB-papayae (Diptera : Tephritidae) based on aedeagal length

Aedeagal length was measured to distinguish among fruit fly males in Singap ore, where 2 closely related species, Bactrocera carambolae (Drew & Hancock ) and B. papayae (Drew & Hancock), are sympatric. Although aedeagal length did not segregate into 2 distinct distributions, when it was plotted agains t body size, males could be divided into 2 groups, those with shorter aedea gus (S-group) and those with longer aedeagus (L-group). The aedeagal length of the S-group ranged from 2.39 to 2.68 mm, and that of the L-group from 2 .66 to 3.34 mm. Thus, the 2 groups overlapped between 2.66 and 2.68 mm. To clarify the relationship between aedeagal length and other morphological tr aits, the transverse black band on tergite 4 was categorized into 4 types, A, A', B', and B. Also, costal band depth at the apex of the wing was categ orized into 4 types, 4, 3, 2, and 1. Although the S-group was composed of b and types A/A', the L-group included all 4 band types, indicating that male s in Singapore can be categorized into 3 groups, types A/A' of S-group (Sa) , types A/A' of L-group (La), and types B/B' of L-group (Lb). It was notice d that all of the Sa type had wing types 4/3, whereas the La type was chara cterized by wing types 2/1, except for 1 male of band type A' which had win g type 3. Therefore, it is judged that the Sa type is B. carambolae and bot h the La and Lb types should belong to B. papayae.