DIAPERINI NORTH OF MEXICO — TRIPLEHORN 383 



Remarks. — This species is so similar to N. bicornis in general facies 

 that, following Champion (1SS6), the Central American specimens 

 were regarded as conspecific with those from the United States. An 

 apparent reversal of the cline described under A^". bicornis inspired 

 further investigation, ultimately leading to the conclusion that two 

 distinct species were involved. 



Champion could find no differences between the two, other than 

 the larger size of Central American specimens (4-5 mm.) compared to 

 that of those from the United States (3.5-4.0 mm.). He also men- 

 tioned that the horns of the former are stouter, a character which 

 cannot be confirmed in the present study. 



Differences in size and coloration, while relative in nature and sub- 

 ject to considerable overlapping, are quite stril^mg when large series 

 of each species are available. N. aeneipennis ranges from 4 to just 

 over 5 mm. in length and is usually more or less bronzed in color while 

 A'', bicornis ranges from 2.7 to 4.8 mm. in length and is always a bril- 

 liant blue or green except m teneral individuals. 



Males are easily distinguishable. The genitalia are diagnostic and 

 should always be examined in cases of doubt. In N. aeneipennis (pi. 6, 

 fig. 62), the apical sclerite is longer than broad; in N. bicornis (pi. 6, fig. 

 61), it is broader than long. In N. aeneipennis the epistomal tubercles 

 are short and obtuse (pi. 6, fig. 64), while those in A^. bicornis are long 

 and acute (pi. 6, fig. 63.). 



In both sexes in N. aeneipennis, the abdominal stemites are finely 

 and sparsely punctured and clothed v/ith rather conspicuous setae, 

 while m N. bicornis these sternites are coarsely and densely punctured 

 and the setae are much less prominent. 



Insofar as locality records are available, A^. bicornis and N. aenei- 

 pennis are completely allopatric. Specimens of the latter have been 

 taken as far north as 20 miles north of El Limon, Tamaulipas, Mexico, 

 but only one specimen (labelled "Mex." in MCZ) of N. bicornis has 

 been seen south of the Rio Grande. 



Types. — Holotype male and allotype female (BMNH): Rio Hon- 

 do, British Honduras, Blancaneau. Paratypes: British Honduras, 2 

 males, 3 females, Rio Hondo, Blancaneau (BMNH) ; 1 male, same data 

 (MCZ); 1 female, Belize, Blancaneau (BMNH); 2 males, 5 females, 

 M[ana]tee Dist[rict], August 1905 (Bowditch collection, MCZ); 1 

 male, 1 female, same data (CAT); 2 males, M[anajtee Dist[rict] 

 (Bowditch collection, MCZ). 



Other specimens examined. — From the following localities, 50: 

 Mexico: 1 male, 1 female, 18 miles south of Tamazunchale, San Luis Potosi, 

 Nov. 22, 1946, E. S. Ross (CAS). 1 female, 20 miles north of El Limon, Tamauli- 

 pas, Nov. 10, 1946, E. C. Van Dyke (CAS). 1 female, Tamazunchale, at 500 

 feet, June 18, 1937, M. A. Embury (Van Dyke collection, CAS). 1 female, 



