PTILODACTTLA. 627 



Group PTILODACTYLINI. 



PTILODACTYLA. 



Ptilodactyla, Latreille, Begne Anim. ed. 2, iv. p. 461 (1829) ; Lacordaire, Gen. Col. iv. p. 279; 

 Horn, Trans. Am. Ent. Soc. viii. p. 90. 



This neglected genus includes a very large number of species, and it is one of the 

 most characteristic forms of Coleoptera in Tropical America, extending northwards to 

 the Southern United States and southwards to Argentina. Of the forty-four described 

 species, four only are from the Old World, the remainder being all American, these 

 latter including two from the Southern States, four from Colombia, seven from Guiana, 

 sixteen from Peru *, four from Brazil, one from Argentina, and six from Cuba. Not 

 a single species, therefore, has up to the present time been described from within our 

 limits, whence no fewer than fifty-nine are now recorded ; and, judging from the 

 numerous specimens left unnamed for want of sufficient material, and the limited area 

 within which many of the others have been found, it is probable that more than one 

 hundred species exist in Central America. To Ptilodactyla belong many very closely 

 allied species, several of which can only be distinguished with certainty by the form of 

 the fifth ventral segment in the males, or, in some cases, by that of the tarsal claws in 

 this sex. The various species may be grouped by the form of the claws (when both 

 sexes are available for examination), or by that of the scutellum — characters ignored by 

 most of the writers on these insects. 



The antennae have joints 4-10f each furnished with an articulated ramus in the males, 

 and are simply serrate in the females ; in three species (P. antennalis, P. humerosa, and 

 P. tenuis) the third joint is considerably shorter than the fourth. The apical joint of the 

 maxillary palpi varies a little in length according to the species, but it is never greatly 

 elongated, as in the males of the two insects here placed under Lachnodactyla. The eyes 

 are large, often larger and more prominent in the males than in the females. The thorax 

 is transverse, in most of the species semicircular or subcorneal in shape, and usually 

 compressed at the sides before the middle, the anterior (as well as the lateral) margin 

 being sometimes very prominent ; the base is trisinuate or bisinuate, and usually more 

 or less denticulate, often with a projecting tooth in the centre fitting into a notch in 

 the front of the scutellum. The scutellum usually has a deep notch in front, and 

 sometimes a well-defined, narrow, median sulcus as well, or is even broadly and deeply 

 sulcate down the middle ; in a few species there is no trace of emargination in front ; 

 it varies in size and also in shape, but the general shape is cordiform. The elytra in 

 most of the species are very acutely margined at the sides ; in P. caudata they differ 

 in form in the two sexes. The thorax (and sometimes the other parts of the body 



* Co-types of seven of these have been examined : — P. vilis, P. prcecellens, P. lamellifera, P. 7ieteroj>hya, 

 P. angusta, P. secedens, and P. minuta, Kirsch ; also P. cruciata, Kirscb, from Colombia. 

 t Not 3-10, as stated by Lacordaire. 



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