Arnval and Strarf were built based on stolen Bacterian schematics; it is presumed that Tita Nium is the one who took the schematics when she left the Bacterians. Strarf's Alpinia seems to have some of her armor parts attached to it, like with Arnval's Anthurium. 

Additional vehicle: Strarf's Riding Viper Alpinia - Her Riding Viper is Alpinia from Solar Assault, with elements of MMS Type Demon / 02 and T-301 Vic Viper customization. Strarf pilots Alpinia from Solar Assault with her Riding Viper.