1962] 
Bush — Genus Anastrepha 
91 
these may prove to be metakinetic as has been shown in the IV 
chromosomes of Drosophila melanogaster Meigen (Kaufmann, 1934). 
The locality and the host fruit from which the karyotype was 
described is also included in anticipation that future studies may 
uncover chromosomal polymorphism or sibling species within this 
genus. Whenever observable sex chromosomes were present, the 
heterogametic sex was always the male, as is normal for Diptera. 
This characteristic was checked by studying spermatogonial meta- 
phase plates of adult males. 
Anastrepha ludens (Loew) 
Figure 1 
The diploid number is 12. The MCA number is also 12 in both 
sexes as all chromosomes are acrokinetic. No secondary constrictions 
were noted. The male has a small dot Y chromosome about 1/4 to 
1/3 the length of the rod-shaped X chromosome. Forty-seven meta- 
phase plates were photographed from 16 larvae. A total of over 300 
larval brain squashes from various localities were studied but not 
photographed. 
Source of cytological material. Cuernavaca, Morelos, Mexico. 
Host plant. Mango ( Mangifera indica L.). 
Collections of this species were made throughout the year from 
many host plants other than mango. These included sapote domingo 
( Mammea americana L.) ; avocado ( Persea americana Mill.) ; yellow 
chapote ( Sargentia greggii S. Wats.) ; white sapote ( Casimiroa edulis 
Llave and Lex.) ; sweet orange (Citrus sinensis (L.) Osbeck) ; sour 
orange ( Citrus aurantium L.) ; and grapefruit (Citrus grandis (L.) 
Osbeck) . 
Collections were also made in the states of Colima, Veracruz, 
Chiapas, Tamaulipas, Jalisco, Mexico, and Michoacan. No variation 
in the karyotype from these localities was noted. 
Anastrepha zuelaniae Stone 
Figure 2 
The diploid number is 12 in both sexes. The MCA number is 12 
with all chromosomes acrokinetic. No secondary constrictions were 
noted. The male has a rod-shaped Y chromosome about 2/3 the length 
of the X chromosome. Thirty-nine metaphase plates were photo- 
graphed from nine larvae. Sixty-three larval brain squashes were 
studied but not photographed. 
