tokens: the elongated EUV channel-like structure (Zhang et al. 2012 ; Chen et al. 2014 ; Cheng et al. 2014 ) in the high-temperature passbands (e.g., 94 and 131 Å) of the Atmospheric Imaging Assembly (AIA; Lemen et al. 2012 ). More recently, the detailed structure and evolution of flux ropes in the low solar atmosphere were presented by Wang et al. ( 2015 ) and Kumar et al. ( 2015 ). The flux ropes in the low solar atmosphere show some similarities in the morphology of the filaments but have not been confirmed. The relationship between the filaments and the sigmoids and the elongated EUV channel-like structure are still unknown. However, they show some common characteristics in the formation process. For instance, in the framework of magnetic field reconnection, an increasing number of observations suggested that magnetic flux ropes are created either via flux cancellation in the photosphere (Green Kliem 2009 ; Tripathi et al. 2009b ; Green et al. 2011 ; Savcheva et al. 2012 ; Wang et al. 2015 ) or the tether-cutting reconnection in the corona (Moore et al. 2001 ; Kim et al. 2008 ; Liu et al. 2010 ; Chen et al. 2014 ; Cheng et al. 2015 ). Therefore, the study of the evolution and formation of the filament may shed new light on the evolution and formation of the flux rope. At the chromospheric level, observations always show that the dark, loop-like threadlike structures are the most prominent features observed in H α images. Those threadlike structures that mark the emergence of the new magnetic flux are called an arch filament system (Bruzek 1969 ), and those that span and transverse to older PILs of active region are called field transition arches (FTAs; Prata 1971 ). In addition, other kinds of loop-like threadlike structures are nearly parallel to the PILs. However, both of them connect with opposite polarities and trace out the magnetic line of force. In this study, employing the excellent observations from the AIA and the Helioseismic and Magnetic Imager (HMI; Schou et al. 2012 ) on board the Solar Dynamics Observatory ( SDO ; Pesnell et al. 2012 ), we present the rapid formation of a filament via magnetic reconnection between two sets of threadlike structures on 2013 May 29. In the photosphere, at a region where some ends of the two sets of threadlike structures are close to each other, magnetic flux convergence and cancellation occur. This provided us with a good opportunity to detail the evolution and formation of the filament. Detailed observations and methods are presented in Section 2 . The results are shown in Section 3 . The conclusion and the discussion are given in Section 4 . 2. OBSERVATIONS AND METHODS The event was well-observed by the SDO /AIA and HMI, as well as the Global Oscillation Network Group (GONG) at the National Solar Observatory (NSO). AIA takes full-disk images in 10 ultraviolet (UV) and EUV wavelengths covering a wide temperature range, with a pixel size of 06 at a high cadence of up to 12 s. We mainly used the Level
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