Is the i in the genitive plural of tenuis a pure i vowel or the semivowel j? My feeling is for pure vowel, but I could not find a discussion anywhere.
Is this quite the right question? The u is often consonantalized, at any rate in verse (e.g. Lucr.3.232 |tenuis enim …, ib.243 … tenuius exstat|), and then of course the i is a pure vowel, as I imagine it always is.
What about pinguium in Hor. Carm. 4 . 12 . 5?
dīcunt in tenerō grāmine pinguium
According to Wikipedia, the poem should be 2nd Asclepiad and the metre of the line
– – – ᴗ ᴗ – / – ᴗ ᴗ – ᴗ x.
Not quite sure what you’re asking here. Pinguium (gen.pl.) couldn’t scan any other way. pingui- as e.g. sangui- or angui- (long-short), unproblematic, whereas tenui- is properly three shorts, though in verse (where three successive shorts is awkward at best) the u could readily be consonantalized, making it metrically amenable.