Good photos. It is possible to distinguish between Henicopidae and Lithobiidae from some photos. Lithobiidae have spines/spurs on their legs as well as setae, while Henicopidae only have setae. In your photos I believe I can see spines on the legs making it a Lithobiidae, but the back ground makes it a little difficult. I'm not sure about Exocera, it is a genus without a family and it seems to have been known from the Caribbean, so I think we can discount it at this stage.
Its the genital segment, the underside of that segment is were you would find the genitals. I’m not sure why its orange, or if that’s characteristic of this species