1962] 
Bush — Genus Anastrepha 
95 
Anastrepha aphelocentema Stone 
Figure 5 
The diploid number in both sexes is 12. The MCA number is 
22 as there are five pairs of metakinetic autosomes. The dot Y chro- 
mosome is about 1/4 the length of the rod-shaped X chromosome 
which has a proximal secondary constriction. Twenty-five metaphase 
plates were photographed from five larvae. Approximately 35 larval 
brain squashes were studied but not photographed. 
Source of cytological material. Tamazunchale, San Luis Potosi, 
Mexico. 
Host plant. Socavite ( Lucuma standleyana Pittier). 
This species was studied only from the area surrounding Tam- 
azunchale during the months May through July, 1 957* 
Anastrepha serpentina (Wiedemann) 
Figures 6 and 7 
The diploid number in the male is 1 1 and in the female 12. The 
male (Fig. 6) has an MCA number of 20 as there are four meta- 
kinetic pairs of autosomes, one of which in some metaphase comple- 
ments has a secondary constriction on its longest arm (not visible in 
photomicrograph of the male metaphase plate). There are also three 
heteromorphic acrokinetic sex chromosomes designated XiX 2 Y. Both 
the X 1? which is the shortest, and the X 2 have small proximal sec- 
ondary constrictions which are not always visible. The long Y 
chromosome is easily distinguished as it has a short arm separated 
from the rest of the chromosome by what has been interpreted as the 
kinetochore, though future studies may show this to be a secondary 
constriction. The female karyotype (Fig. 7) has an MCA number 
of 20 with four pairs of metakinetic autosomes and two acrokinetic 
pairs of sex chromosomes. Since the X x is much shorter than the X 2 
(Xi ca. 2/3 X 2 ) , these two chromosomes are easily differentiated. 
Thirty-nine metaphase plates were photographed from 13 larvae. 
Approximately 75 larval brain squashes were studied but not photo- 
graphed. 
Source of cytological material. Monte Blanco, Veracruz, Mexico. 
Host plant. Mamey ( Calocarpum mammosum (L.) Pierre). 
Collections were also made from the states of San Luis Potosi and 
Morelos in 1957. It should be noted here that one collection of this 
species was made from Tapachula, Chiapas in 1956 from mamey. 
Samples taken from this population did not demonstrate the com- 
