Was -i used as genitive ending for first declension masculines?

Question

In Greek masculines of the first declension borrow the singular genitive ending -ου from second declension. Latin uses the ending -ae for all of first declension: puellae, nautae, Anchisae, Aeneae. There are also occasional genitives similar to the Greek first declension feminine ones (familias, musices, Melpomenes), but these are beside my point.

Was -i ever used as a genitive ending for masculines of the first declension? If this happens, it is presumably due to Greek influence, and I suspect it is more likely to happen in words or names of Greek origin. Despite seeing many Greek loan words, I have never seen this genitive in any text or grammar. Searches for nauti and Anchisi give nothing, and Aenei gives unrelated hits for the adjective aēneus.

Answer 1

I don't see any reference to such an ending in either Allen and Greenough or Gildersleeve and Lodge, so I strongly suspect the answer is no.

That said, in another, historical sense the -ī ending was used as a first-declension gen. sg. ending, and not just for masculines. The ending -ae is historically formed from -a-ī: the -a- of the first-declension stem plus the same -ī as in the second declension. The earlier spelling of this ending was -AI, which is found in inscriptions and occasionally in poetry where a disyllabic ending was needed for the meter. (This is unlike the case of Greek, where the first- and second-declension gen. sg. endings have different origins.)

Answer 2

Sort of, but technically "no".

It seems that -i was sometimes used as a genitive singular ending for masculine names from Greek that end in -ēs in the nominative. But although many of these come from Greek first-declension nouns, they typically seem to be classified as third-declension rather than first-declension nouns in the context of Latin.

In fact, genitive singular forms in -i existed even for some masculine names ending in -ēs that weren't from Greek first-declension nouns, such as Diomedes (from Greek Διομήδης, Διομήδους) and Hercules (from Greek Ἡρακλῆς, Ἡρακλέους, but not directly: the direct source of Latin Hercules is supposed to have been an Etruscan form "Hercle"). Varro mentions the variability between -i and -is in the genitive singular of these two names in De Lingua Latina, Book 10, §49.

Even though this irregular use of Latin genitive -i looks suggestively similar to the Greek use of -ου as a masculine first-declension genitive ending, I can find no evidence that -i was ever viewed as a first-declension ending in Latin.

Grammars that mention genitive singular forms in -i for names in -es

Allen and Greenough §52a says that "Many names in -ēs belonging to the 3rd declension have also a genitive in -ī", giving the example "Thūcȳdidēs, Thūcȳdidī". This grammar classifies Thūcȳdidī as a second-declension form, and Thūcȳdidēs as a third-declension form.

Grammar of the Latin Language, by C.G. Zumpt (1836), says the following:

• "the greater part of Greek nouns in ης, ου, if not patronymics, are declined after the third declension in Latin, as Alcibiades, Miltiades, Xerxes" (Sect. VII.3, pp. 11-12).

• "Cicero very commonly, and other authors of the best age occasionally, form from Greek nouns proper in es a genitive in i, instead of is; e.g. gr. Achilli, Ulixi (see p. 15), Isocrati, Archimedi, especially from those in cles, Agathcli, Diocli, Neocli, Procli, Pericli, Themistocli. So in the barbarian names Mithridati, Xerxi, and others." (Sect XIII, Remark 1, p. 25-26).

In a comment, Draconis mentioned finding a single example of genitive singular Thūcȳdidī in Quintilian: "imitator Thucydidi et ut multo infirmior".

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Side note: I have asked a separate question about the use of third-declension forms like gen. sg. Thūcȳdidis for names like this: How are "Arsaces" and "Gotarzes" declined, and why?