On Aegus capitatus, Westw

Among the Lucanidae brought together in Deli (East-Sumatra) by Dr. B. Hagen and presented by him to the Leyden Museum, I found a male specimen of minor development, belonging to the genus Aegus, which was at first sight unknown to me. A careful examination, however, convinced me of its close relationship with Aegus capitatus Westw., a species represented in Dr. Hagen’s collection by a few males and females, but I could not decide whether it was the extreme varietas minor of this species or that of a new one. I wrote therefore to Mr. Neervoort van de Poll asking him to look at the matter, and most courteously he sent me from his extensive collections all connecting links between my specimen and the varietas major of Aegus capitatus. Taking into consideration that among the described forms of the male of this species the smallest form (that what I regard as the true var. minor) is not to be found, I thought it not without interest to publish a detailed description of it. With the higher developed forms it has some important characteristics in common, viz.: the shape of the inner edge of the mandibles with the conical basal tooth on a level below that of the surface; the shape of the fore margin of the head between the mandibles (broadly and angularly emarginate, the emargination terminating in a produced point at each end); the shape of the hinder angles of the thorax (subangular, not emarginate); the conformation of the lateral margin of the second and following abdominal segments (thickened and glossy, widened out on the last segment where this margin is notched at the apex).