To find orthologs within a defined taxonomic range, you could use hierarchical orthologous groups (HOGs) on this level. Several orthology databases provide such groups, e.g. EggNOG, OrthoDB or OMA.
For species covered by OMA (our own inference method) you can get precomputed HOGs from the web, i.e. http://omabrowser.org/oma/hogs/ARGR_STRR6/Streptococcus/
For your own set of species of interest, you could use the OMA standalone package to compute HOGs (http://omabrowser.org/standalone)
Few links that could help you to find the best solution:
You can also take a look at this program that I found really good: