  Solar filaments are the largest magnetic structure that can be physically
traced to the chromosphere. The structure and evolution of solar filaments are
important for our understanding of solar atmosphere physics. In this work, we
investigate a giant dark channel crossing the solar equator, which consists of
two filament channels with different chiralities. From 2016 April 22 to April
27, this giant dark channel occupied the solar disk. Within this giant channel,
a filament channel with dextral chirality was detected in the northern
hemisphere, and another filament channel with sinistral chirality was observed
in the southern hemisphere. At the junction of the two filament channels, a
cusp structure was observed associated with active region (AR) 12532 near the
solar equator. The extrapolated three-dimensional magnetic fields reveal that
this cusp structure was composed of two sets of field lines belonging to two
different filament channels and was rooted on the AR positive-polarity fields.
In addition, dark material flows from filaments in the two channels to the cusp
structure were detected as well as the flux emergence and cancellation around
the cusp footpoints. On 2016 May 21, after a solar rotation, the cusp structure
had disappeared, and the giant dark channel broke in the middle where another
AR, 12546, had emerged completely. We propose that the magnetic flux emergence
and cancellation around the cusp region resulted in the disappearance of the
cusp structure and the break of the giant dark channel.
