510 PROCEEDINGS OF THE NATIONAL MUSEUM vol. in 



p. 232). Since Prolobodes and Discostoma were proposed to replace 

 the preoccupied Lobostoma, they must both take Cydnus giganteus 

 as type, by objective synonymy. 



Distribution.^ — -Available specimen records indicate this genus 

 occurs in tropical America from Nicaragua in the north to southern 

 Brazil and Paraguay in the south. 



Discussion.- — ^There can be little doubt about the species of this 

 genus being closely allied to those of Cyrtomenus, but the foliaceous, 

 semicircular lobe on labial II sets them apart morphologically and 

 probably also represents a biological difference. Just what might 

 be the significance of such a structure is conjectural. Within it may 

 be seen the coiled, elongate stylets. This would suggest a peculiarity 

 in feeding habits. China (1931) reported that such coiling of the 

 stylets appeared in three other families of the Hemiptera, the Aradidae, 

 Termitapliididae and some Plataspidae. He further pointed out that 

 although these groups are not otherwise closely related they all feed 

 on fungi. Could it be that the members of Prolobodes are also fungus- 

 feeders? Or do they employ these long slender structures in probing 

 for roots and thus avoid the necessity of burrowing to each root 

 from which they feed? Only observations on living animals will 

 conclusively determine the exact use of such a structure. 



Key to the known species of Prolobodes 



1. Anterior pronotal lobe with not more than five or six coarse punctures later- 



ally, usually with none gigas (Signoret) (p. 512) 



Anterior pronotal lobe with 15 or more coarse, deep punctures laterally . . 2 



2. Pronotum with a weak, transverse impression near midlength, this with 



numerous crowded, coarse, deep, impressed punctures which often show 

 longitudinal rugae between them (fig. 11) . . . giganteus (Burmeister) (p. 510) 

 Pronotum without a transverse impression near midlength, punctures in 

 that area coarse, deep, but neither crowded nor impressed nor with rugae 

 between them reductum (Amyot and Serville) (p. 513) 



Prolobodes giganteus (Burmeister) 



Plate figures 11, 17, 18, 36, 110, 122, 141, 237 



Cydnus giganteus Burmeister, 1835, p. 375. 



Lobostoma giganteus Amyot and Serville, 1843, p. 88. 



Prolobodes giganteus Amyot and Serville, 1843, p. 676, pi. 2, fig. 6.- — -Lethierry 



and Severin, 1893, p. 62. 

 Lobostoma gigantea Walker, 1867, p. 147.— St§,l, 1876, p. 18.— Distant, 1880, p. 1. 

 Lobostoma giganieum Dallas, 1851, p. 111. — Signoret, 1881b, p. 194, pi. 6, fig. 14. 



Diagnosis. — The heavy pronotal punctation, especially on the 

 sides of the anterior lobe, plus the presence of a weakly impressed 

 transverse impression on the pronotum limit this species within the 

 genus. 



