1969] 
Roth — Genitalia of Blattaria 
249 
Chromosome numbers. — -The diploid chromosome numbers of fe- 
males of 5 species of Blaberus are: giganteus, 74; craniifer, 74; 
atropos, 74; parabolicus , 40; discoidalis , 38. The males have one less 
sex chromosome (Cohen and Roth, unpublished data). Evidently 
members of the Atropos Group have variable chromosome numbers. 
Addendum : Since this paper went to press I have examined the 
lectotype and paralectotype of Blabera quadrifera Walker, which is 
a synonym of B. trapezoideus Burm. The pronotum of one of these 
specimens is illustrated by Princis (1958, p. 74). The tegmina of 
these 2 specimens are hairy, as they are in B. craniifer , and their 
genitalia (Figs. 218, 220) are indistinguishable from those of 
craniifer (cf. Figs. 47-57, 62-74). As for the laterally truncate 
pronotum of trapezoideus (Figs. 217, 219), the pronotal shape is so 
variable in light colored craniifer (Figs. 221-224) that this character 
cannot be used to distinguish the 2 species. I believe that trapezoideus 
(type locality Mexico) is the light colored form of craniifer. Both 
species were described by Burmeister (Handb. Ent. 2 (2), Berlin, 
1838, p. 516). Because B. craniifer has been used widely as an 
experimental animal I select it as the valid name for this species. 
Summary 
Based on the structure of the prepuce and aedeagus, species of 
Blaberus are placed in the following three groups: 1) Giganteus 
Group ( giganteus , craniifer ), 2) Brasilianus Group {minor, brasili- 
anus, colosseus, fusif or mis , scutatus) , and 3) Atropos Group ( atropos , 
parabolicus, discoidalis, anisitsi, and boliviensis) . 
I consider Blaberus trapezoideus to be a synonym of B. craniifer, 
and B. colosseus, formerly a synonym of B. giganteus, to be a valid 
species. 
The genitalia are sufficiently distinctive to place individuals in their 
respective groups. However, intraspecific variation of the genitalia 
is so great that it is difficult and sometimes impossible to distinguish 
between certain species of a Group. 
Three of the 5 species in the A tropos Group have variable chromo- 
some numbers of 74, 40, and 38. 
Acknowledgements 
I thank the following for the loan of Museum material : Dr. E. 
M. Emsley, Academy of Natural Sciences, Philadelphia, Dr. A. B. 
Gurney, U. S. National Museum^ Dr. Howard Evans, Museum of 
Comparative Zoology, Harvard University, Dr. Karl Princis, Zoolog- 
ical Institution, Lund University, Sweden, Dr. Jerome G. Rozen, Jr., 
