NORTH AMERICAN GEOTRUPINAE — HOWDEN 289 



the middle and lateral foveae. The apical tooth of the anterior tibia of the 

 male is broadly emarginate at tip, and prolonged inwards into a slender acute 

 process. The middle tarsi of male are slightly larger than those of female, but 

 not thickened as in G. splendidus and its allies. The upper surface is opaque and 

 very densely granulated; the second joint of the antennal club is normal 

 that is, not received in the first. 



This description will suffice to separate the species of Mycotrwpes 

 from other North American Geotrupinae. However, one important 

 detail not mentioned above is the absence of the metathoracic wings. 

 Dr. T. H. Hubbell has noted that all of the species of Mycotrupes have 

 a groove by the posterior pronotal angles into which the elytral 

 marginal humeral carinae fit, forming accessory articulation points. 

 Dr. Hubbell has further pointed out in correspondence to me that 

 this unusual modification is also present in Geotrupes ulkei Blanchard 

 but has not been noted in other species. 



The above information, along with extremely detailed generic and 

 specific descriptions and an excellent key, is presented by Olson 

 and Hubbell (1954, pt. 1). Part 2 of the same work consists 

 of a very interesting discussion by Hubbell on the relationships 

 and distribution of Mycotrupes, and part 3 consists of biological 

 observations and a description of the larva of Mycotrupes gaigei by 

 Howden. 



A number of the characteristics of Mycotrupes such as the granulate 

 dorsal surface, posterior edge of pronotum sinuate and unmargined, 

 and the peculiar thoracic modification of the males are not to be 

 noted in the supposedly related forms such as Chelotrupes Jekel and 

 Thorectes Mulsant. This fact, coupled with the obvious dissimilarity 

 between Mycotrupes and other North American Geotrupes, has led me 

 to treat Mycotrupes as a distinct genus, following the conclusions 

 expressed by Olson and Hubbell {in Olson, Hubbell, and Howden, 

 1954, pt. 1). 



The speciation occurring in Mycotrupes appears to present almost 

 the same problem as that already described for Peltotrupes. The 

 various species are apterous, active from late fall to early spring, and 

 are seemingly limited in their activity to inland deep sand ridges. 

 The spotty distribution of these sand ridges, coupled with the poor 

 dispersal powers of the beetles, has led to the development of a 

 number of closely allied but rather distinct forms. Interestingly, 

 one of the species appears to have a range almost identical to that of 

 Peltotrupes profundus. 



Since a revision of the genus Mycotrupes has just been completed 

 by Olson and Hubbell {in Olson, Hubbell, and Howden, 1954), no 

 detailed account of the adult morphology of the various species is 

 given here. The few characteristics mentioned are those which, 



