92 



margin of BR. Posterior margin weakly concave; surrounds the BMA arch apex. Postero- 

 distal margin truncate. Anterior margin depressed below the posterior margin of ScA bulge; 

 extremely narrow; convex; angled antero-proximad. Embayment normal size. Distal arch 

 discontinuous with radial stem; moderately broad; convex; broadly curved proximad; 

 oriented postero-proximad. br strongly sclerotized; occupies about one-third of the 

 proximal arch; discontinuous with BR. br projection deltoid; slender; concave; distinct 

 from BScA. 



Second Basal Plate (Fig. 148) 



MA-BMA Junction absent. - MP-BMP Junction: MP broadly continuous with BMP; arises 

 from below the BMP-BCuA brace. - Crimp Patterns absent. - BMP-CuA Brace absent. 

 - BMP-BCuA Brace present but modified; discontinuous with BMP; entire and greatly 

 strengthened; extends posteriad; moderately enlarged; equally broad along the entire 

 length; convex; distinct from BMP. Terminus fused to the disto-medial section of BCuA. 

 Point of fusion continuous. 



Medial Basivenalia reduced proximally. BMA broadly scaphoid; completely fused to BMP. 

 Proximal surface convex. Medial and distal surfaces planate. Anterior margin weakly 

 concave. Proximal arch moderately long; planate and straight; oriented proximad; strongly 

 curved ventrad. Apex terminates below BR proximal arch apex. Distal arch indistinct; 

 fused to the proximal section of BMP. BMP junction with BMA discontinuous and very 

 broad; fused to brace; markedly convex; separated from both IBP and BCu by membrane. 

 Proximal section broadly deltoid; planate; slopes ventro-distad. Distal section indistin- 

 guishable from BMP-BCuA brace; long; broad; rectangular; strongly convex. 



Cubital Basivenalia narrowly fused; slender and long. Postero-proximal margin of BCuA 

 fused with the antero-proximal margin of BCuP Suture line present. BCuA very narrow 

 and long; convex; oriented distad; lies posteriad of BMP; strongly sclerotized. Anterior 

 margin with a broad shallow concavity. Distal margin continuous with CuA. BCuP weakly 

 ovoid; convex; oriented postero-distad; moderately sclerotized. Distal embayment slender 

 and moderately deep. - Cubitus Anterior fused to BCuA Junction marked by a distinct 

 suture. 



Basalare (Fig. 149) 



Head - HP lobe large; continuous with neck. Apex broadly truncate. Dorsal surface weakly 

 elevated from neck; not polished. BScP lobe claviform; weakly projects posteriad from 

 neck. Dorsal surface ovoid; weakly convex; polished; depressed from neck; slopes 

 ventrad. Ventral surface polished. - Posterior Subcostal Basivenale deltoid; polished. 



Discussion 



Although Acoma does not display any autapomorphic character states of the wing 

 articulation and wing base, it does share two apomoiphic character states of the wing 

 articulation and wing base with Melolonthinae, Hopliinae, Oncerinae and Chasmato- 

 pterinae. It is likely that these taxa together form Melolonthinae (Browne 1993). 



