Article 28. Initial letters. A family-group or genus-group name or the name of a taxon above the family group is always to begin with an upper-case initial letter, and a species-group name always with a lower-case initial letter, regardless of how they were originally published.
Recommendation 28A. Initial words. A species-group name should not be put as the first word in a sentence, to avoid its beginning with an upper-case initial letter.