. Bulletin of the British Museum (Natural History) Entom Supp. DIPTERA FROM NEPAL 121 2. Sex-combs are present but the hooked scaly bristles absent (ananassae and melanogaster subgroups, obscura group). Stage 3. Sex-combs are better developed, inducing homeotic expression of the hooked scaly bristles (suzukii and takahashii subgroups, D. (T.) gracilis). Stage 4. Sex-combs are further well developed, the hooked scaly bristles being compensatorily weakened in expression (ficusphila subgroup). Stage 5. Further compensation is pronounced, resulting in disappear- ance or non-development of the hook
. Bulletin of the British Museum (Natural History) Entom Supp. DIPTERA FROM NEPAL 121 2. Sex-combs are present but the hooked scaly bristles absent (ananassae and melanogaster subgroups, obscura group). Stage 3. Sex-combs are better developed, inducing homeotic expression of the hooked scaly bristles (suzukii and takahashii subgroups, D. (T.) gracilis). Stage 4. Sex-combs are further well developed, the hooked scaly bristles being compensatorily weakened in expression (ficusphila subgroup). Stage 5. Further compensation is pronounced, resulting in disappear- ance or non-development of the hooked scaly bristles (montium and nipponica subgroups). Fig. 328. Compensation HSB Stage anan suzu f- mont Mam^meU taka ™PP, T^m Obsc MelaT Fig. 328. Homeotic and compensatory relationships between the hooked scaly bristles (HSB) of male mid leg and the sex-combs (SC) of male fore leg. Mela., melanogaster group ; Obsc, obscura group ; Momm., mommai group ; Will., willistoni group ; anan., ananassae subgroup ; ficus., ficusphila subgroup ; mela., melanogaster subgroup ; mont., montium subgroup ; nipp., nipponica subgroup ; suzu., suzukii subgroup ; taka., takahashii subgroup. For further explanations see text. C. Homology in the components of phallic organs and the systematic ANALYSIS OF PHALLIC FORMULAE As is frequently stressed, the phallic organs of insects are systematically and diagnostically essential key characters. Their extensive diversification, however, makes it often difficult to establish homology of their components even between closely related taxa. Those of Drosophilidae are not exceptional, , the present author (1956) considered the ventral recurved process of aedeagus (u) of the genus. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original British Museum (Natural History). London : BM(NH)
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