43 



indicates that Bolboceratidae are the sister group of Pleocomidae (Browne & Scholtz 

 1995). 



Pleocomidae 



Introduction 



The Pleocomidae are a monotypic family. The genus Pleocoma Le Conte consists of 33 

 described species and three subspecies (Hovore 1977). Pleocoma has a very restricted 

 distribution, occurring in the western USA., especially Oregon, California and Utah. 

 Crowson (1981), Virkki (1967) and Ritcher (1966) treated Pleocomidae as a family and 

 it is regarded as such in this study. Males are winged and females flightless. 



Hind Wing Articulation Description 



First Axillary (Fig.59) 



Head - Dorsal surface large; convex; enlarged posteriorly; convex. Antero-dorsal margin 

 normal width; weakly deplanate; oriented weakly postero-distad. Antero -proximal margin 

 very strongly enlarged ventrally. Postero-proximal margin weakly enlarged proximally. 

 FSc2 convex. Base normal width. Apex rounded; oriented postero-distad. Anterior surface 

 broad; very long; not waisted medially. FScl very weak; very small and narrow; fused to 

 the ventral projection. Dorsal surface convex. Ventral surface planate. Ventral projection 

 weakly tapered from the base to apex; short but of average width; deeply concave; oriented 

 disto-ventrad and curved posteriad. Apex narrower than the base but truncate. Concavity 

 located in the preapical area; surrounded by three unequally strong ridges. Dorso-medial 

 surface concave. Ventral surface convex. Distal embayment oriented dorsad. FSc2 weakly 

 deltoid to digitate; moderately broad; oriented distad and weakly dorsad. Dorsal surface 

 very convex; not enlarged. Ventral surface weakly concave. Apex acute. Head and neck 

 dorsal surface weakly curved proximad. 



Neck normal width and length; weakly oriented antero-distad; broadly articulated with 

 2Ax. Proximal margin weakly convex; curved ventrad. Distal margin concave. Distal 

 embayment shallow and broad. 



Tail - Dorsal view: Proximal arch strongly but narrowly expanded postero-distally; falcate; 

 strongly curved postero-distad. Antero -proximal margin concave. Dorsal surface weakly 

 concave. Postero-proximal margin convex; strikingly recurved. Articulation with PRR 

 posteriorly extremely strong; very weak anteriorly; markedly enlarged posteriorly and 

 distally. Posterior margin straight. Distal arch normal size. Apex very weakly curved 

 ventrad and posteriad; aciculate. -Ventral view: Proximal arch with a narrow but prominent 

 ridge. Posterior margin with a narrow but prominent ridge. Distal arch with an extremely 

 slender but long ridge. 



Second Axillary (Fig. 60) 



Radial Fulcalare moderately broad; articulation with 2Ax ridge moderately broad. 



