Headlines and Titles of Works

Q. I work on science textbooks and science trade books (I wonder why I’ve never needed to ask this question before) and have this question: Does one capitalize “sp.” (or “spp.”) in titles? For example: “Dinarda Spp.: The Sneaky Thief.” Unabbreviated, the word “species” would be capitalized. However, were it the actual species name, it would be lowercased. It does look odd capitalized, since it is never so in text, but I’m leaning toward capitalization as being correct. Possibly the answer to this question lies within (within CMOS, that is), but if so I’ve not been able to find it. What say you?

Q. Hello: When using headline-style capitalization (CMOS 8.159), does a participial preposition (CMOS 5.175) appear in lowercase or uppercase? Thanks very much.

Q. Should national anthems—for example, La Marseillaise—be set in quotes?

Q. For a book title within a book title in a language other than English, should quotation marks be inserted around the title within the title, just as we would for English-language titles (per CMOS 8.173)?

Q. I’m editing a biography (in English) of a French historical figure that contains many French-language titles of works, including plays, books, poems, and artwork. I’m applying Chicago’s rule of sentence-case capitalization to these titles (for example, La dame aux camélias). But what about a title like Les Misérables? Should that actually be written Les misérables? That doesn’t seem right.

Q. Not actually a question but a comment on one of your recent answers, regarding type style for book titles on social media platforms. You left out a common and I think preferable option: to use leading and trailing underscores (e.g., _A Tale of Two Cities_). Some software (such as Slack and WhatsApp) already converts text with that form to italics, and readers will so understand it even on platforms (such as Facebook) that do not yet do so.

Q. On social media platforms, where italics are not an option, what do we do with book titles or other titles that would normally be italicized?

Q. Hello! I work as a proofreader in retail, and we often use “on sale” in headlines. I’m not sure if “on” is acting as a preposition or an adverb, therefore I’m not sure if it should be capitalized in a headline like this: “Now on Sale.” Thank you!

Q. CMOS 11.9 states, “When the title of a work in another language is mentioned in text, an English gloss may follow in parentheses,” and “if the translation has not been published, the English should be capitalized sentence-style . . . and should appear neither in italics nor within quotation marks.” In texts that discuss in detail such a work (say, a literary analysis of a Chinese-language novel for a predominantly English-speaking readership) and where the English gloss is justifiably preferred to the original, should that gloss stay in roman, capitalized sentence-style throughout, or may it carry the features of a published translation (italics or quote marks) for ease of presentation?

Q. Do you capitalize the preposition for in headline-capitalization style in this case: “XYZ: what is it good for?” Lowercase or uppercase? Thanks a lot!