MLA style was developed to be used by writers in the humanities, so we defer to our colleagues at The Chicago Manual of Style regarding how to style genus and species names. The manual notes: “Whether in lists or in running text, the Latin names of species of plants and animals are italicized. Each binomial contains a genus name (or generic name), which is capitalized, and a species name (also called specific name or specific epithet), which is lowercased (even if it is a proper adjective)” (“Genus”). See the manual for guidance on abbreviating genus names (“Abbreviation”). 

Works Cited

“Abbreviation of Genus Name.” The Chicago Manual of Style, 17th ed., sec. 8.121, U of Chicago P, 2017, www.chicagomanualofstyle.org/book/
ed17/part2/ch08/psec121.html.

“Genus and Specific Epithet.” The Chicago Manual of Style, 17th ed., sec. 8.120, U of Chicago P, 2017, www.chicagomanualofstyle.org/book/
ed17/part2/ch08/psec120.html