Firefly

Largely rendered extinct during the Succession Wars, in the wake of the Fourth Succession War the Firefly light 'Mech is primarily employed by the Wolf's Dragoons, with a small volume also in-used with ComStar.

Mechwarrior Online
The Firefly is a speculated 'Mech due to its appearance in ISN news articles.

ISN News Feed History
[http://mwomercs.com/news/2012/06/298-isn-news-flash Wed. June 27, 3049: Upgraded field modifications appearing in the last two years for the Firefly fuel speculation Dragoons tied to ComStar. ]

Speculation
The ISN News Flash from 27 June, 3049 most likely refers to the FFL-4B refit developed by the Dragoons which carries an AMS system, also making reference to ComStar's FFL-4C variant which carries an impressive number of LosTech technologies including Medium Pulse Lasers, Artemis IV, Double Heat Sinks, XL Engine, and an Endo Steel Structure. Both variants debuted in 3047 and 3048 respectively.