On (lie Melolonthid Genua Ancistrosoma. 425 



LI. — Synopsis of the Melolonthid drum Ancistrosoma, with 

 Descriptions of new Species and an allied new Genus. By 

 G. J. Arrow. 



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



The species of Ancistrosoma were reviewed by Salle in 188(5 

 (Ann. Soc. Ent. France, p. 465), and corrections of his 

 classification were published by himself in the following year 

 (Bull. Soc. Ent. France, 1887, p. 127) and by Brcnske in 

 L890 (Wien. ent. Zeit. ix. p. 13S). Salle regarded A. vitli- 

 gerum, Fi\, as identical with A. flavovittatum, Bl., while 

 Brenske declared it to be a distinct species : but neither lias 

 distinguished it from A. kl"yi, Curtis, from which Erichson 

 si parated it only by the occurrence of a pair of setose spots 

 on the pronotum. As this is a variable feature in A. klngi, 

 1 see no reason to doubt that Erichson's two forms are con- 

 specific and both belong to A. klugi. The study of the 

 genitalia shows this insect, which ranges from Ecuador to 

 Bolivia, to be a very variable one ; but in the British Mu- 

 seum collection I have found specimens from the Pry 

 Collection, not separated from it and occurring like it in 

 Peru, which certainly belong to another vet undescribed 

 species. . Other specimens in the collection are also un- 

 described, and as two of them are of economic importance, 

 1 have thought it opportune to prepare a synoptical revision 

 of the genus. The most remarkable feature of the genus is 

 the ventral spine at tire base of the abdomen of the males : 

 and it is a curious fact that in many females a definite 

 corresponding patch is found denuded of setae near the end 

 of the suture, whilst in fresh specimens it is absent. 



Salle gives as a specific character of A. melolonthoides (of 

 which the type has been kindly lent me by M. Oberthiir) 

 the bifurcation of the claws of the middle and hind feel ; 

 but it seems probable that this applies to the male alone, 

 and that, as occurs in all the other species, all the claws are 

 bifid in the female. 



The species can be distinguished as follows: — 



Elytra with setose sulci ; front and middle claws 

 of ■' simple. 



Elytra! setsa darh coloured rttfipes, Latr. 



Elytral Betse 'lark and light coloured intermedium, sp. n. 



>:nl elytra! stripe produced forward. 

 Pronotum without median line; femora 



and tibiae black 6 Salle". 



Ann. .I- Mag. X. Hist. Ser. 8. Vol. xii. 31 



