1920] Hoioe — Odonata of Chatham, Massachjsetts 59 



THE BRACONID GENUS TRACHYPETUS GUfiRIN. 



By Charles T. Brues, 

 Bussey Institution, Harvard University. 



In 1839 Guerin^ published an account of a very strange Austra- 

 lian Braconid for which he erected the genus Trachypetus. He 

 placed Trachypetus in proximity to Helcon, Sigalphus and 

 Chelonus and recent authors {e. g. Ashmead and Szepligeti) have 

 tabulated it as a member of the Cheloninse, next to Sphseropyx. 

 Apparently this insect remained unknown in nature to hymenop- 

 terists since Guerin's time, until 1911 when Schulz^ examined two 

 specimens in the Saussure collection, obtained in New South 

 Wales. Schulz {loc. cit.) makes Trachypetus the type of a new 

 subfamily Trachypetinse which he places provisionally in the 

 " Cryptogastrini." Among these, he would distinguish the Trachy- 

 petinae by the petiolate abdomen in which the first segment is 

 articulated to and not fused with the post-abdomen as is the case 

 in the other Cryptogastrini except Sphaeropyx.' 



Last summer, I received from Dr. R. J. Tillyard, two specimens 

 of a magnificent Braconid collected at Woy Woy, Queensland, 

 which Dr. Tillyard was unable to place satisfactorily in any 

 family. These prove to be Guerin's Trachypetus clavatus which is 

 very carefully described at considerable length in the first publica- 

 tion cited above, and in still greater detail by Schulz. 



Trachypetus is undoubtedly a Braconid, but it is much more 

 difficult to locate it in any of the recognized subfamilies. Super- 

 ficially it is somewhat similar to Sphseropyx in the form of the 

 abdomen which, however, lacks the deeply concave venter charac- 

 teristic of the Cheloninae. The wings, aside from the radial cell, 

 and the neuration of the hind pair, are somewhat like those of 

 Sphseropyx as are also the form of the propodeum, multiarticulate 

 antennae and the legs; here, however, the similarities cease. There 



» Voyage de la Coquille, Zool., vol. 2, pt. 2, p. 201 ; atlas, pi. 8, fig. 7. 



' Zool. Ann., vol. 4, p. 85. 



• Sphaeropyx includes one well known and widespread European species, S. irrorator Fabr. 

 and several North American species described by Provancher and Cresson. Whether all these 

 may be considered as congeneric, I do not know, but Cresson's species, S. bicolor is quite similar 

 to S. irrorator and could scarcely be separated although much smaller and of somewhat different 

 habitus. I do not know Tetrasphajropyx Ashmead which is based on Rhogat pilo»u$ Cresson, 

 but Mr. Rohwer has kindly examined Ashmead's type and writes me that it is a Rhogadine. 



