Monotypic.
Plumage consistent, although during breeding season appears "brighter" but primarily due to new feathers.
M/F differ, although marginal. Female tends to have less black on face/throat/breast and a duskier (rather than yellower) bill.
Like most rails, I generally resigned myself to not expecting to see them. Then, one day, I saw three of them including one a few feet away while I was watching some ducks as it foraged in the thicket. Birding is quite the trip!