On the male of Rosenbergia megalocephala, v. d. Poll

In the foregoing volume of the »Notes”, I have described (p. 32) a ♀ specimen of a Batocerid belonging to the genus Rosenbergia Rits., on which I bestowed the specific name megalocephala on account of the enormous development of the head. Having been fortunate enough to procure lately a ♂ specimen, I think it will be of interest to point out the sexual differences, which do not only consist of the usual characteristic of the antennae. Firstly the head and mandibles are not extraordinarily developed but are well proportioned to the size of the insect; the antennae are of course more robust and longer, measuring 75 mm., thus overreaching the body with 30 mm. The thoracic spines are slightly directed upwards, the humeral tooth is somewhat larger, and the flattened granules are less numerous on the apical portion of the elytra. Very misleading is the orange pile on the cheeks along the eyes, as well as the presence of an orange stripe on each elytron, beginning just below the shoulder and nearly touching the apex. Now it is a well known fact that the spots of the Batocerids are reddish or orange when the insect is alive, but almost all the specimens we receive have lost this coloration and show white spots. The ♀ I described formerly has also entirely lost this peculiarity, and the orange stripe is only indicated by a streak of more closely set white hairs. As both the typical species ( mandibularis and vetusta) have been described from ♂ specimens, it remains an interesting question whether the large head of the ♀ will prove to be a sexual difference for the whole genus, or not.