In notes on Words, Phrases and Passages from the Lord of the Rings (WPP) from the late 1950s or early 1960s, Tolkien had Q. {sāne >>} th-, sāne- “pine” derived from {✶stāna >>} ✶thānĭ-, but this note was deleted (PE17/81). It was replaced by a marginal note in which S. thôn “pine” was derived from ✶thŏno.
Neo-Quenya: In light of the final primitive form ✶thŏno, I would update the Quenya word to ᴺQ. sono [þ] “pine” for purposes of Neo-Quenya. Petri Tikka instead proposed ᴺQ. sónë [þ] in PPQ (PPQ) from the early 2000s inspired only by S. thôn “pine”, before the above primitive forms were published in 2007.
Conceptual Development: The Early Qenya “pine” word was ᴱQ. aiqaire “fir or pine” in the Qenya Lexicon of the 1910s, an elaboration of ᴱQ. aiqa “steep” (QL/29). It became ᴱQ. aikasse “pine-tree” in the Gnomish Lexicon of the 1910s, a cognate to G. aigos and derivative of primitive ᴱ✶aikasse (GL/17). This in turn became ᴱQ. aikor “pine-tree” in the Early Noldorin Dictionary of the 1920s, derived from ᴱ✶aikos-sa and still a cognate to G. aigos (PE13/158).
sánë (þ) noun "pine" (PE17:81), stem sáni- (? the primitive form is given as ¤thānĭ, which would normally give Quenya sánë/sáni-, but the Quenya noun is also cited as sáne- as if e persists before an ending).