Assini contributed four goals, and Ryan added a hat trick for Niskayuna, which advances to next week's Class A regional semifinal against the Section IX champion at UAlbany.
Mossop tallied five times, Iapoce chipped in with three goals and Kelly Camardo added a pair of goals for Guilderland, which saw its 80-game Section II winning streak end.
"We never talked about the win streak," said Chatnik. "We wanted to win the championship just like Niskayuna or anyone else. We just didn't come out on the winning end this time."
In other Sectional championship action Wednesday, Burnt Hills-Ballston Lake held on for a 12-10 victory over Queensbury in the Class B final.
Becky Guess and Nicole Beardsley each scored three goals and added two assists to help BH-BL (9-10) win its first Sectional title since becoming a varsity program six years ago. Amy LeBel and Catherine Clark each added two goals, and goaltender Kelsey McDonald made 12 saves.
BH-BL returns to UAlbany next Wednesday to play the Section IX Class B champion in the regional round.""