Notes on Ruteline Coleoptera. 379 



XLI. — Notes on Ruteline Coleoptera and Descriptions of 

 a few new Species in the British Museum. By Gilbert 

 J. Arrow, F.Z.S., F.E.S. 



(Published by permission of the Trustees of the British Museum.) 



[Plate VIII.] 



The wonderful silvery insect Plusiotis melior, Roths. & Jord., 

 proves on close examination to be the normal phase of the 

 previously-named P. optima, Bates, the unique type of which 

 is a beautiful fiery crimson. The non-acute apex of the 

 pygidium, in which the describers of P. melior believed a 

 structural difference to be found, is a characteristic of the 

 female of the species. Exactly similar red phases occur in 

 other beetles in which the same silvery and golden colouring 

 prevails normally — for example, the Australian Anoplo- 

 gnathus parvulus and aureus. The metallic lustre is also 

 liable to disappear in patches, as though by abrasion, leaving 

 a red-brown surface, and the type of Anoplognathus concinnus, 

 Blackb., is an abnormal specimen of A. aureus, Wat., in 

 which the golden colour is entirely absent from the greater 

 part of the surface, lingering only upon the back of the 

 head, the hinder part of the elytra, and the middle of the 

 sternum. 



Whether these abnormalities are due to accident of some 

 kind or merely to immaturity it is not possible to say. A 

 metallic-red colour seems to be very exceptional as a normal 

 condition in beetles, although individual specimens so 

 coloured commonly occur amongst species typically of some 

 shade of metallic green — for example, in the common Rose- 

 chafer (Cetonia aurata) a red variety is occasionally found. 

 In non-metallic green beetles a corresponding red variety 

 also occurs exceptionally. In one or two instances in which 

 a metallic-red colour is normal (e. g., Poropleura bacca) it 

 was found by the late C. O. Waterhouse that prolonged 

 exposure to light in the British Museum galleries had 

 changed the colour to a bright metallic green, so that it 

 seems possible that the occasionally-found red specimens 

 may be individuals which have not attained their mature 

 colouring. On the other hand, I have described one re- 

 markable insect (Anomala imperialis) of which the female is 

 metallic green and the male a deep crimson. 



The following is another species, hitherto undescribed, of 

 a beautiful golden colour: — 



2S* 



