This one has been bugging me for awhile. The one real outlier as far as guard position correlation in the Fior di Battaglia are the spear guards. Of the six spear poste, only the two Posta Finestra (right & left side) resemble their sword equivalents.
Tutta Porta di Ferro is held with the left foot forward, spear held on the right side of the body. I suppose this has a passing familiarity to the sword guard, but really the spear Mezza Porta di Ferro looks closer to the sword Porta di Ferro.
As for the left side guards, the Vera Croce looks like the sword in armour and poleaxe Vera Croce.
So we come back to the Dente di Cinghiaro, which is held rear-weighted, right foot forward, spear held to the left side of the body. This looks completely different to any other Dente di Cinghiaro shown in the MS.
Every other Dente di Cinghiaro is shown right foot forward with the point of the weapon held forward at an angle, to facilitate the "standard" play from Dente di Cinghiaro - a rising deflection to the right with a step offline of the front foot. Now the play described for the spear Dente di Cinghiaro sounds very similar -
"[I] pass out of line by first stepping offline with the foot that is forward." -Leoni 2009
Now, the fancy thing about the spear section is that the play from all six poste is the same - step offline with the front foot as you parry opponent's spear, then pass forward and thrust. From the right side this results in a rather low crossing of the spears. From the left the crossing is high - this follows Fiore's advice about parrying thrusts; from the right parry & thrust (exchange), from the left parry & strike.
The only conclusion I can draw is that Fiore calls this position Dente di Cinghiaro, even though it does not follow the form for that guard, simply because it is the left-side equivalent of the Tutta Porta di Ferro position. It might just be as simple as that.
That will teach me to ant f#$k the problem :-D