AOV with repeated measures

Dear R user,

I have a question on using R to analyze data with repeated measurements. I 
have 2 species with several strains (12) per species, each of which has 
been measured twice with for a given trait. No particular covariance, just 
two measures. Now I want to analyze the data with an ANOVA (aov) 
considering these repeated measures to get the MSq and SSq for the species 
and strain level. I would like to know how to write the ANOVA model in R. I 
have done the following:

aov(trait ~ species + strain/replicate)

Is it accurate?

Thanks a lot,

Christian